add support for map/slice conversions, tests

genmethod.go

@@ -0,0 +1,300 @@
+// Copyright 2017 Felix Lange <fjl@twurst.com>.
+// Use of this source code is governed by the MIT license,
+// which can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+	"go/ast"
+	"go/printer"
+	"go/token"
+	"go/types"
+	"io"
+	"strconv"
+	"strings"
+
+	. "github.com/garslo/gogen"
+)
+
+var NIL = Name("nil")
+
+type marshalMethod struct {
+	mtyp  *marshalerType
+	scope *funcScope
+}
+
+func newMarshalMethod(mtyp *marshalerType) *marshalMethod {
+	return &marshalMethod{mtyp, newFuncScope(mtyp.scope)}
+}
+
+func writeFunction(w io.Writer, fs *token.FileSet, fn Function) {
+	printer.Fprint(w, fs, fn.Declaration())
+	fmt.Fprintln(w)
+}
+
+// genUnmarshalJSON generates the UnmarshalJSON method.
+func genUnmarshalJSON(mtyp *marshalerType) Function {
+	var (
+		m        = newMarshalMethod(mtyp)
+		recv     = m.receiver()
+		input    = Name(m.scope.newIdent("input"))
+		intertyp = m.intermediateType(m.scope.newIdent(m.mtyp.orig.Obj().Name() + "JSON"))
+		dec      = Name(m.scope.newIdent("dec"))
+		conv     = Name(m.scope.newIdent("x"))
+		json     = Name(m.scope.parent.packageName("encoding/json"))
+	)
+	fn := Function{
+		Receiver:    recv,
+		Name:        "UnmarshalJSON",
+		ReturnTypes: Types{{TypeName: "error"}},
+		Parameters:  Types{{Name: input.Name, TypeName: "[]byte"}},
+		Body: []Statement{
+			declStmt{intertyp},
+			Declare{Name: dec.Name, TypeName: intertyp.Name},
+			errCheck(CallFunction{
+				Func:   Dotted{Receiver: json, Name: "Unmarshal"},
+				Params: []Expression{input, AddressOf{Value: dec}},
+			}),
+			Declare{Name: conv.Name, TypeName: m.mtyp.name},
+		},
+	}
+	fn.Body = append(fn.Body, m.unmarshalConversions(dec, conv, "json")...)
+	fn.Body = append(fn.Body, Assign{Lhs: Star{Value: Name(recv.Name)}, Rhs: conv})
+	fn.Body = append(fn.Body, Return{Values: []Expression{Name("nil")}})
+	return fn
+}
+
+// genMarshalJSON generates the MarshalJSON method.
+func genMarshalJSON(mtyp *marshalerType) Function {
+	var (
+		m        = newMarshalMethod(mtyp)
+		recv     = m.receiver()
+		intertyp = m.intermediateType(m.scope.newIdent(m.mtyp.orig.Obj().Name() + "JSON"))
+		enc      = Name(m.scope.newIdent("enc"))
+		json     = Name(m.scope.parent.packageName("encoding/json"))
+	)
+	fn := Function{
+		Receiver:    recv,
+		Name:        "MarshalJSON",
+		ReturnTypes: Types{{TypeName: "[]byte"}, {TypeName: "error"}},
+		Body: []Statement{
+			declStmt{intertyp},
+			Declare{Name: enc.Name, TypeName: intertyp.Name},
+		},
+	}
+	fn.Body = append(fn.Body, m.marshalConversions(Name(recv.Name), enc, "json")...)
+	fn.Body = append(fn.Body, Return{Values: []Expression{
+		CallFunction{
+			Func:   Dotted{Receiver: json, Name: "Marshal"},
+			Params: []Expression{AddressOf{Value: enc}},
+		},
+	}})
+	return fn
+}
+
+// genUnmarshalYAML generates the UnmarshalYAML method.
+func genUnmarshalYAML(mtyp *marshalerType) Function {
+	var (
+		m         = newMarshalMethod(mtyp)
+		recv      = m.receiver()
+		unmarshal = Name(m.scope.newIdent("unmarshal"))
+		intertyp  = m.intermediateType(m.scope.newIdent(m.mtyp.orig.Obj().Name() + "YAML"))
+		dec       = Name(m.scope.newIdent("dec"))
+		conv      = Name(m.scope.newIdent("x"))
+	)
+	fn := Function{
+		Receiver:    recv,
+		Name:        "UnmarshalYAML",
+		ReturnTypes: Types{{TypeName: "error"}},
+		Parameters:  Types{{Name: unmarshal.Name, TypeName: "func (interface{}) error"}},
+		Body: []Statement{
+			declStmt{intertyp},
+			Declare{Name: dec.Name, TypeName: intertyp.Name},
+			errCheck(CallFunction{Func: unmarshal, Params: []Expression{AddressOf{Value: dec}}}),
+			Declare{Name: conv.Name, TypeName: m.mtyp.name},
+		},
+	}
+	fn.Body = append(fn.Body, m.unmarshalConversions(dec, conv, "yaml")...)
+	fn.Body = append(fn.Body, Assign{Lhs: Star{Value: Name(recv.Name)}, Rhs: conv})
+	fn.Body = append(fn.Body, Return{Values: []Expression{Name("nil")}})
+	return fn
+}
+
+// genMarshalYAML generates the MarshalYAML method.
+func genMarshalYAML(mtyp *marshalerType) Function {
+	var (
+		m        = newMarshalMethod(mtyp)
+		recv     = m.receiver()
+		intertyp = m.intermediateType(m.scope.newIdent(m.mtyp.orig.Obj().Name() + "YAML"))
+		enc      = Name(m.scope.newIdent("enc"))
+	)
+	fn := Function{
+		Receiver:    recv,
+		Name:        "MarshalYAML",
+		ReturnTypes: Types{{TypeName: "interface{}"}, {TypeName: "error"}},
+		Body: []Statement{
+			declStmt{intertyp},
+			Declare{Name: enc.Name, TypeName: intertyp.Name},
+		},
+	}
+	fn.Body = append(fn.Body, m.marshalConversions(Name(recv.Name), enc, "yaml")...)
+	fn.Body = append(fn.Body, Return{Values: []Expression{AddressOf{Value: enc}}})
+	return fn
+}
+
+func (m *marshalMethod) receiver() Receiver {
+	letter := strings.ToLower(m.mtyp.name[:1])
+	return Receiver{Name: m.scope.newIdent(letter), Type: Star{Value: Name(m.mtyp.name)}}
+}
+
+func (m *marshalMethod) intermediateType(name string) Struct {
+	s := Struct{Name: name}
+	for _, f := range m.mtyp.Fields {
+		s.Fields = append(s.Fields, Field{
+			Name:     f.name,
+			TypeName: types.TypeString(f.typ, m.mtyp.scope.qualify),
+			Tag:      f.tag,
+		})
+	}
+	return s
+}
+
+func (m *marshalMethod) unmarshalConversions(from, to Var, format string) (s []Statement) {
+	for _, f := range m.mtyp.Fields {
+		accessFrom := Dotted{Receiver: from, Name: f.name}
+		accessTo := Dotted{Receiver: to, Name: f.name}
+		if f.isOptional(format) {
+			s = append(s, If{
+				Condition: NotEqual{Lhs: accessFrom, Rhs: NIL},
+				Body:      m.convert(accessFrom, accessTo, f.typ, f.origTyp),
+			})
+		} else {
+			err := fmt.Sprintf("missing required field %s for %s", f.encodedName(format), m.mtyp.name)
+			errors := m.scope.parent.packageName("errors")
+			s = append(s, If{
+				Condition: Equals{Lhs: accessFrom, Rhs: NIL},
+				Body: []Statement{
+					Return{
+						Values: []Expression{
+							CallFunction{
+								Func:   Dotted{Receiver: Name(errors), Name: "New"},
+								Params: []Expression{stringLit{err}},
+							},
+						},
+					},
+				},
+			})
+			s = append(s, m.convert(accessFrom, accessTo, f.typ, f.origTyp)...)
+		}
+	}
+	return s
+}
+
+func (m *marshalMethod) marshalConversions(from, to Var, format string) (s []Statement) {
+	for _, f := range m.mtyp.Fields {
+		accessFrom := Dotted{Receiver: from, Name: f.name}
+		accessTo := Dotted{Receiver: to, Name: f.name}
+		s = append(s, m.convert(accessFrom, accessTo, f.origTyp, f.typ)...)
+	}
+	return s
+}
+
+func (m *marshalMethod) convert(from, to Expression, fromtyp, totyp types.Type) (s []Statement) {
+	// Remove pointer introduced by ensurePointer during field building.
+	if isPointer(fromtyp) && !isPointer(totyp) {
+		tmp := Name(m.scope.newIdent("v"))
+		s = append(s, DeclareAndAssign{Lhs: tmp, Rhs: Star{Value: from}})
+		from = tmp
+		fromtyp = fromtyp.(*types.Pointer).Elem()
+	} else if !isPointer(fromtyp) && isPointer(totyp) {
+		tmp := Name(m.scope.newIdent("v"))
+		s = append(s, DeclareAndAssign{Lhs: tmp, Rhs: AddressOf{Value: from}})
+		from = tmp
+		fromtyp = types.NewPointer(fromtyp)
+	}
+
+	// Generate the conversion.
+	qf := m.mtyp.scope.qualify
+	switch {
+	case types.ConvertibleTo(fromtyp, totyp):
+		s = append(s, Assign{Lhs: to, Rhs: simpleConv(from, fromtyp, totyp, qf)})
+	case isSlice(fromtyp):
+		fromElem := fromtyp.(*types.Slice).Elem()
+		toElem := totyp.(*types.Slice).Elem()
+		key := Name(m.scope.newIdent("i"))
+		s = append(s, Assign{Lhs: to, Rhs: makeExpr(totyp, from, qf)})
+		s = append(s, Range{
+			Key: key, RangeValue: from,
+			Body: []Statement{Assign{
+				Lhs: Index{Value: to, Index: key},
+				Rhs: simpleConv(Index{Value: from, Index: key}, fromElem, toElem, qf),
+			}},
+		})
+	case isMap(fromtyp):
+		fromKey, fromElem := fromtyp.(*types.Map).Key(), fromtyp.(*types.Map).Elem()
+		toKey, toElem := totyp.(*types.Map).Key(), totyp.(*types.Map).Elem()
+		key := Name(m.scope.newIdent("key"))
+		s = append(s, Assign{Lhs: to, Rhs: makeExpr(totyp, from, qf)})
+		s = append(s, Range{
+			Key: key, RangeValue: from,
+			Body: []Statement{Assign{
+				Lhs: Index{Value: to, Index: simpleConv(key, fromKey, toKey, qf)},
+				Rhs: simpleConv(Index{Value: from, Index: key}, fromElem, toElem, qf),
+			}},
+		})
+	default:
+		invalidConv(fromtyp, totyp, qf)
+	}
+	return s
+}
+
+func simpleConv(from Expression, fromtyp, totyp types.Type, qf types.Qualifier) Expression {
+	if types.AssignableTo(fromtyp, totyp) {
+		return from
+	}
+	if !types.ConvertibleTo(fromtyp, totyp) {
+		invalidConv(fromtyp, totyp, qf)
+	}
+	toname := types.TypeString(totyp, qf)
+	if isPointer(totyp) {
+		toname = "(" + toname + ")" // hack alert!
+	}
+	return CallFunction{Func: Name(toname), Params: []Expression{from}}
+}
+
+func invalidConv(from, to types.Type, qf types.Qualifier) {
+	panic(fmt.Errorf("BUG: invalid conversion %s -> %s", types.TypeString(from, qf), types.TypeString(to, qf)))
+}
+
+func makeExpr(typ types.Type, lenfrom Expression, qf types.Qualifier) Expression {
+	return CallFunction{Func: Name("make"), Params: []Expression{
+		Name(types.TypeString(typ, qf)),
+		CallFunction{Func: Name("len"), Params: []Expression{lenfrom}},
+	}}
+}
+
+func errCheck(expr Expression) If {
+	err := Name("err")
+	return If{
+		Init:      DeclareAndAssign{Lhs: err, Rhs: expr},
+		Condition: Equals{Lhs: err, Rhs: NIL},
+		Body:      []Statement{Return{Values: []Expression{err}}},
+	}
+}
+
+type stringLit struct {
+	V string
+}
+
+func (l stringLit) Expression() ast.Expr {
+	return &ast.BasicLit{Kind: token.STRING, Value: strconv.Quote(l.V)}
+}
+
+type declStmt struct {
+	d Declaration
+}
+
+func (ds declStmt) Statement() ast.Stmt {
+	return &ast.DeclStmt{Decl: ds.d.Declaration()}
+}

internal/clasherrors/clasherrors.go

@@ -0,0 +1,7 @@
+// Copyright 2017 Felix Lange <fjl@twurst.com>.
+// Use of this source code is governed by the MIT license,
+// which can be found in the LICENSE file.
+
+package errors
+
+type Foo struct{}

internal/clashjson/foo.go

@@ -0,0 +1,7 @@
+// Copyright 2017 Felix Lange <fjl@twurst.com>.
+// Use of this source code is governed by the MIT license,
+// which can be found in the LICENSE file.
+
+package json
+
+type Foo struct{}

internal/tests/mapconv/input.go

@@ -0,0 +1,19 @@
+// Copyright 2017 Felix Lange <fjl@twurst.com>.
+// Use of this source code is governed by the MIT license,
+// which can be found in the LICENSE file.
+
+//go:generate gencodec -type X -field-override Xo -out output.go
+
+package mapconv
+
+type replacedString string
+
+type replacedInt int
+
+type X struct {
+	M map[string]int
+}
+
+type Xo struct {
+	M map[replacedString]replacedInt
+}

internal/tests/mapconv/output.go

@@ -0,0 +1,72 @@
+// generated by gencodec, do not edit.
+
+package mapconv
+
+import (
+	"encoding/json"
+	"errors"
+)
+
+func (x *X) MarshalJSON() ([]byte, error) {
+	type XJSON struct {
+		M map[replacedString]replacedInt
+	}
+	var enc XJSON
+	enc.M = make(map[replacedString]replacedInt, len(x.M))
+	for key, _ := range x.M {
+		enc.M[replacedString(key)] = replacedInt(x.M[key])
+	}
+	return json.Marshal(&enc)
+}
+
+func (x *X) UnmarshalJSON(input []byte) error {
+	type XJSON struct {
+		M map[replacedString]replacedInt
+	}
+	var dec XJSON
+	if err := json.Unmarshal(input, &dec); err == nil {
+		return err
+	}
+	var x0 X
+	if dec.M == nil {
+		return errors.New("missing required field m for X")
+	}
+	x0.M = make(map[string]int, len(dec.M))
+	for key, _ := range dec.M {
+		x0.M[string(key)] = int(dec.M[key])
+	}
+	*x = x0
+	return nil
+}
+
+func (x *X) MarshalYAML() (interface{}, error) {
+	type XYAML struct {
+		M map[replacedString]replacedInt
+	}
+	var enc XYAML
+	enc.M = make(map[replacedString]replacedInt, len(x.M))
+	for key, _ := range x.M {
+		enc.M[replacedString(key)] = replacedInt(x.M[key])
+	}
+	return &enc
+}
+
+func (x *X) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type XYAML struct {
+		M map[replacedString]replacedInt
+	}
+	var dec XYAML
+	if err := unmarshal(&dec); err == nil {
+		return err
+	}
+	var x0 X
+	if dec.M == nil {
+		return errors.New("missing required field m for X")
+	}
+	x0.M = make(map[string]int, len(dec.M))
+	for key, _ := range dec.M {
+		x0.M[string(key)] = int(dec.M[key])
+	}
+	*x = x0
+	return nil
+}

internal/tests/nameclash/input.go

@@ -0,0 +1,34 @@
+// Copyright 2017 Felix Lange <fjl@twurst.com>.
+// Use of this source code is governed by the MIT license,
+// which can be found in the LICENSE file.
+
+//go:generate gencodec -type Y -field-override Yo -out output.go
+
+package nameclash
+
+import (
+	errors "github.com/fjl/gencodec/internal/clasherrors"
+	json "github.com/fjl/gencodec/internal/clashjson"
+)
+
+// This one clashes with the generated intermediate type name.
+type YJSON struct{}
+
+// This type clashes with a name in the override struct.
+type enc int
+
+// These types clash with variables, but are ignored because they're
+// not referenced by the struct.
+type input struct{}
+type dec struct{}
+
+type Y struct {
+	Foo    json.Foo   `optional:"true"`
+	Bar    errors.Foo `optional:"true"`
+	Gazonk YJSON      `optional:"true"`
+	Over   int        `optional:"true"`
+}
+
+type Yo struct {
+	Over enc
+}

internal/tests/nameclash/output.go

@@ -0,0 +1,112 @@
+// generated by gencodec, do not edit.
+
+package nameclash
+
+import (
+	"encoding/json"
+
+	errors0 "github.com/fjl/gencodec/internal/clasherrors"
+	json0 "github.com/fjl/gencodec/internal/clashjson"
+)
+
+func (y *Y) MarshalJSON() ([]byte, error) {
+	type YJSON0 struct {
+		Foo    *json0.Foo   `optional:"true"`
+		Bar    *errors0.Foo `optional:"true"`
+		Gazonk *YJSON       `optional:"true"`
+		Over   *enc         `optional:"true"`
+	}
+	var enc0 YJSON0
+	v := &y.Foo
+	enc0.Foo = v
+	v0 := &y.Bar
+	enc0.Bar = v0
+	v1 := &y.Gazonk
+	enc0.Gazonk = v1
+	v2 := &y.Over
+	enc0.Over = (*enc)(v2)
+	return json.Marshal(&enc0)
+}
+
+func (y *Y) UnmarshalJSON(input []byte) error {
+	type YJSON0 struct {
+		Foo    *json0.Foo   `optional:"true"`
+		Bar    *errors0.Foo `optional:"true"`
+		Gazonk *YJSON       `optional:"true"`
+		Over   *enc         `optional:"true"`
+	}
+	var dec YJSON0
+	if err := json.Unmarshal(input, &dec); err == nil {
+		return err
+	}
+	var x Y
+	if dec.Foo != nil {
+		v := *dec.Foo
+		x.Foo = v
+	}
+	if dec.Bar != nil {
+		v0 := *dec.Bar
+		x.Bar = v0
+	}
+	if dec.Gazonk != nil {
+		v1 := *dec.Gazonk
+		x.Gazonk = v1
+	}
+	if dec.Over != nil {
+		v2 := *dec.Over
+		x.Over = int(v2)
+	}
+	*y = x
+	return nil
+}
+
+func (y *Y) MarshalYAML() (interface{}, error) {
+	type YYAML struct {
+		Foo    *json0.Foo   `optional:"true"`
+		Bar    *errors0.Foo `optional:"true"`
+		Gazonk *YJSON       `optional:"true"`
+		Over   *enc         `optional:"true"`
+	}
+	var enc0 YYAML
+	v := &y.Foo
+	enc0.Foo = v
+	v0 := &y.Bar
+	enc0.Bar = v0
+	v1 := &y.Gazonk
+	enc0.Gazonk = v1
+	v2 := &y.Over
+	enc0.Over = (*enc)(v2)
+	return &enc0
+}
+
+func (y *Y) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type YYAML struct {
+		Foo    *json0.Foo   `optional:"true"`
+		Bar    *errors0.Foo `optional:"true"`
+		Gazonk *YJSON       `optional:"true"`
+		Over   *enc         `optional:"true"`
+	}
+	var dec YYAML
+	if err := unmarshal(&dec); err == nil {
+		return err
+	}
+	var x Y
+	if dec.Foo != nil {
+		v := *dec.Foo
+		x.Foo = v
+	}
+	if dec.Bar != nil {
+		v0 := *dec.Bar
+		x.Bar = v0
+	}
+	if dec.Gazonk != nil {
+		v1 := *dec.Gazonk
+		x.Gazonk = v1
+	}
+	if dec.Over != nil {
+		v2 := *dec.Over
+		x.Over = int(v2)
+	}
+	*y = x
+	return nil
+}

internal/tests/sliceconv/input.go

@@ -0,0 +1,17 @@
+// Copyright 2017 Felix Lange <fjl@twurst.com>.
+// Use of this source code is governed by the MIT license,
+// which can be found in the LICENSE file.
+
+//go:generate gencodec -type X -field-override Xo -out output.go
+
+package sliceconv
+
+type replacedInt int
+
+type X struct {
+	S []int
+}
+
+type Xo struct {
+	S []replacedInt
+}

internal/tests/sliceconv/output.go

@@ -0,0 +1,72 @@
+// generated by gencodec, do not edit.
+
+package sliceconv
+
+import (
+	"encoding/json"
+	"errors"
+)
+
+func (x *X) MarshalJSON() ([]byte, error) {
+	type XJSON struct {
+		S []replacedInt
+	}
+	var enc XJSON
+	enc.S = make([]replacedInt, len(x.S))
+	for i, _ := range x.S {
+		enc.S[i] = replacedInt(x.S[i])
+	}
+	return json.Marshal(&enc)
+}
+
+func (x *X) UnmarshalJSON(input []byte) error {
+	type XJSON struct {
+		S []replacedInt
+	}
+	var dec XJSON
+	if err := json.Unmarshal(input, &dec); err == nil {
+		return err
+	}
+	var x0 X
+	if dec.S == nil {
+		return errors.New("missing required field s for X")
+	}
+	x0.S = make([]int, len(dec.S))
+	for i, _ := range dec.S {
+		x0.S[i] = int(dec.S[i])
+	}
+	*x = x0
+	return nil
+}
+
+func (x *X) MarshalYAML() (interface{}, error) {
+	type XYAML struct {
+		S []replacedInt
+	}
+	var enc XYAML
+	enc.S = make([]replacedInt, len(x.S))
+	for i, _ := range x.S {
+		enc.S[i] = replacedInt(x.S[i])
+	}
+	return &enc
+}
+
+func (x *X) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type XYAML struct {
+		S []replacedInt
+	}
+	var dec XYAML
+	if err := unmarshal(&dec); err == nil {
+		return err
+	}
+	var x0 X
+	if dec.S == nil {
+		return errors.New("missing required field s for X")
+	}
+	x0.S = make([]int, len(dec.S))
+	for i, _ := range dec.S {
+		x0.S[i] = int(dec.S[i])
+	}
+	*x = x0
+	return nil
+}

main.go

@@ -48,12 +48,59 @@ will be used to parse the value of SpecialField.
 		SpecialField specialString // overrides type of SpecialField when marshaling/unmarshaling
 	}
 
+Relaxed Field Conversions
+
+Field types in the override struct must be trivially convertible to the original field
+type. gencodec's definition of 'convertible' is less restrictive than the usual rules
+defined in the Go language specification.
+
+The following conversions are supported:
+
+If the fields are directly assignable, no conversion is generated.
+
+If the fields are convertible according to Go language rules, a simple conversion is
+emitted. Example input code:
+
+	type specialString string
+
+	func (s *specialString) UnmarshalJSON(input []byte) error { ... }
+
+	type Foo struct{ S string }
+
+	type fooMarshaling struct{ S specialString }
+
+The generated code will contain:
+
+	func (f *Foo) UnmarshalJSON(input []byte) error {
+		var dec struct{ S *specialString }
+		...
+		f.S = string(dec.specialString)
+		...
+	}
+
+If the fields are of map or slice type and the element (and key) types are convertible, a
+simple loop is emitted. Example input code:
+
+	type Foo2 struct{ M map[string]string }
+
+	type foo2Marshaling struct{ S map[string]specialString }
+
+The generated code is similar to this snippet:
+
+	func (f *Foo2) UnmarshalJSON(input []byte) error {
+		var dec struct{ M map[string]specialString }
+		...
+		for key, _ := range dec.M {
+			f.M[key] = string(dec.M[key])
+		}
+		...
+	}
+
 */
 package main
 
 import (
 	"bytes"
-	"errors"
 	"flag"
 	"fmt"
 	"go/ast"
@@ -64,9 +111,7 @@ import (
 	"io/ioutil"
 	"os"
 	"reflect"
-	"strconv"
 	"strings"
-	"text/template"
 
 	"golang.org/x/tools/imports"
 )
@@ -80,9 +125,11 @@ func main() {
 	)
 	flag.Parse()
 
-	fs := token.NewFileSet()
+	cfg := Config{Dir: *pkgdir, Type: *typename, FieldOverride: *overrides}
-	pkg := loadPackage(fs, *pkgdir)
+	code, err := cfg.process()
-	code := makeMarshalingCode(fs, pkg, *typename, *overrides)
+	if err != nil {
+		fatal(err)
+	}
 	if *output == "-" {
 		os.Stdout.Write(code)
 	} else if err := ioutil.WriteFile(*output, code, 0644); err != nil {
@@ -90,14 +137,67 @@ func main() {
 	}
 }
 
-func loadPackage(fs *token.FileSet, dir string) *types.Package {
+func fatal(args ...interface{}) {
+	fmt.Fprintln(os.Stderr, args...)
+	os.Exit(1)
+}
+
+type Config struct {
+	Dir           string // input package directory
+	Type          string // type to generate methods for
+	FieldOverride string // name of struct type for field overrides
+	Importer      types.Importer
+	FileSet       *token.FileSet
+}
+
+func (cfg *Config) process() (code []byte, err error) {
+	if cfg.FileSet == nil {
+		cfg.FileSet = token.NewFileSet()
+	}
+	if cfg.Importer == nil {
+		cfg.Importer = importer.Default()
+	}
+	pkg, err := loadPackage(cfg)
+	if err != nil {
+		return nil, err
+	}
+	typ, err := lookupStructType(pkg.Scope(), cfg.Type)
+	if err != nil {
+		return nil, fmt.Errorf("can't find %s: %v", cfg.Type, err)
+	}
+
+	// Construct the marshaling type.
+	mtyp := newMarshalerType(cfg.FileSet, cfg.Importer, typ)
+	if cfg.FieldOverride != "" {
+		otyp, err := lookupStructType(pkg.Scope(), cfg.FieldOverride)
+		if err != nil {
+			return nil, fmt.Errorf("can't find field replacement type %s: %v", cfg.FieldOverride, err)
+		}
+		err = mtyp.loadOverrides(cfg.FieldOverride, otyp.Underlying().(*types.Struct))
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// Generate and format the output.
+	// Use goimports to format the source because it separates imports.
+	code = genPackage(mtyp)
+	opt := &imports.Options{Comments: true, TabIndent: true, TabWidth: 8}
+	code, err = imports.Process("", code, opt)
+	if err != nil {
+		return code, fmt.Errorf("can't gofmt generated code:", err, "\n"+string(code))
+	}
+	return code, nil
+}
+
+func loadPackage(cfg *Config) (*types.Package, error) {
 	// Load the package.
-	pkgs, err := parser.ParseDir(fs, dir, nil, parser.AllErrors)
+	pkgs, err := parser.ParseDir(cfg.FileSet, cfg.Dir, nil, parser.AllErrors)
 	if err != nil {
-		fatal(err)
+		return nil, err
 	}
 	if len(pkgs) == 0 || len(pkgs) > 1 {
-		fatal(err)
+		return nil, fmt.Errorf("input directory must contain exactly one package")
 	}
 	var files []*ast.File
 	var name string
@@ -109,89 +209,72 @@ func loadPackage(fs *token.FileSet, dir string) *types.Package {
 		break
 	}
 	// Type-check the package.
-	cfg := types.Config{
+	tcfg := types.Config{IgnoreFuncBodies: true, FakeImportC: true, Importer: cfg.Importer}
-		IgnoreFuncBodies: true,
+	tpkg, err := tcfg.Check(name, cfg.FileSet, files, nil)
-		FakeImportC:      true,
-		Importer:         importer.Default(),
-	}
-	tpkg, err := cfg.Check(name, fs, files, nil)
 	if err != nil {
-		fatal(err)
+		return nil, err
 	}
-	return tpkg
+	return tpkg, nil
 }
 
-func makeMarshalingCode(fs *token.FileSet, pkg *types.Package, typename, otypename string) (packageBody []byte) {
+func genPackage(mtyp *marshalerType) []byte {
-	typ, err := lookupStructType(pkg.Scope(), typename)
-	if err != nil {
-		fatal(fmt.Sprintf("can't find %s: %v", typename, err))
-	}
-	mtyp := newMarshalerType(fs, pkg, typ)
-	if otypename != "" {
-		otyp, err := lookupStructType(pkg.Scope(), otypename)
-		if err != nil {
-			fatal(fmt.Sprintf("can't find field replacement type %s: %v", otypename, err))
-		}
-		mtyp.loadOverrides(otypename, otyp.Underlying().(*types.Struct))
-	}
-
 	w := new(bytes.Buffer)
 	fmt.Fprintln(w, "// generated by gencodec, do not edit.\n")
-	fmt.Fprintln(w, "package ", pkg.Name())
+	fmt.Fprintln(w, "package", mtyp.orig.Obj().Pkg().Name())
-	fmt.Fprintln(w, render(mtyp.computeImports(), `
-import (
-{{- range $name, $path := . }}
-	{{ $name }} "{{ $path }}"
-{{- end }}
-)`))
 	fmt.Fprintln(w)
-	fmt.Fprintln(w, mtyp.JSONMarshalMethod())
+	mtyp.scope.writeImportDecl(w)
 	fmt.Fprintln(w)
-	fmt.Fprintln(w, mtyp.JSONUnmarshalMethod())
+	writeFunction(w, mtyp.fs, genMarshalJSON(mtyp))
 	fmt.Fprintln(w)
-	fmt.Fprintln(w, mtyp.YAMLMarshalMethod())
+	writeFunction(w, mtyp.fs, genUnmarshalJSON(mtyp))
 	fmt.Fprintln(w)
-	fmt.Fprintln(w, mtyp.YAMLUnmarshalMethod())
+	writeFunction(w, mtyp.fs, genMarshalYAML(mtyp))
-
+	fmt.Fprintln(w)
-	// Use goimports to format the source because it separates imports.
+	writeFunction(w, mtyp.fs, genUnmarshalYAML(mtyp))
-	opt := &imports.Options{Comments: true, FormatOnly: true, TabIndent: true, TabWidth: 8}
+	return w.Bytes()
-	body, err := imports.Process("", w.Bytes(), opt)
-	if err != nil {
-		fatal("can't gofmt generated code:", err, "\n"+w.String())
-	}
-	return body
 }
 
 // marshalerType represents the intermediate struct type used during marshaling.
 // This is the input data to all the Go code templates.
 type marshalerType struct {
-	OrigName string
+	name   string
-	Name     string
+	Fields []*marshalerField
-	Fields   []*marshalerField
+	fs     *token.FileSet
-	fs       *token.FileSet
+	orig   *types.Named
-	orig     *types.Named
+	scope  *fileScope
 }
 
 // marshalerField represents a field of the intermediate marshaling type.
 type marshalerField struct {
-	parent *marshalerType
+	name    string
-	field  *types.Var
+	typ     types.Type
-	typ    types.Type
+	origTyp types.Type
-	tag    string
+	tag     string
 }
 
-func newMarshalerType(fs *token.FileSet, pkg *types.Package, typ *types.Named) *marshalerType {
+func newMarshalerType(fs *token.FileSet, imp types.Importer, typ *types.Named) *marshalerType {
-	name := typ.Obj().Name() + "JSON"
+	mtyp := &marshalerType{name: typ.Obj().Name(), fs: fs, orig: typ}
 	styp := typ.Underlying().(*types.Struct)
-	mtyp := &marshalerType{OrigName: typ.Obj().Name(), Name: name, fs: fs, orig: typ}
+	mtyp.scope = newFileScope(imp, typ.Obj().Pkg())
+	mtyp.scope.addReferences(styp)
+
+	// Add packages which are always needed.
+	mtyp.scope.addImport("encoding/json")
+	mtyp.scope.addImport("errors")
+
 	for i := 0; i < styp.NumFields(); i++ {
 		f := styp.Field(i)
 		if !f.Exported() {
 			continue
 		}
-		mf := &marshalerField{parent: mtyp, field: f, typ: ensurePointer(f.Type()), tag: styp.Tag(i)}
+		mf := &marshalerField{
+			name:    f.Name(),
+			typ:     ensurePointer(f.Type()),
+			origTyp: f.Type(),
+			tag:     styp.Tag(i),
+		}
 		if f.Anonymous() {
-			fmt.Fprintln(os.Stderr, mf.errorf("Warning: ignoring embedded field"))
+			fmt.Fprintf(os.Stderr, "Warning: ignoring embedded field %s\n", f.Name())
 			continue
 		}
 		mtyp.Fields = append(mtyp.Fields, mf)
@@ -201,225 +284,34 @@ func newMarshalerType(fs *token.FileSet, pkg *types.Package, typ *types.Named) *
 
 // loadOverrides sets field types of the intermediate marshaling type from
 // matching fields of otyp.
-func (mtyp *marshalerType) loadOverrides(otypename string, otyp *types.Struct) {
+func (mtyp *marshalerType) loadOverrides(otypename string, otyp *types.Struct) error {
 	for i := 0; i < otyp.NumFields(); i++ {
 		of := otyp.Field(i)
 		if of.Anonymous() || !of.Exported() {
-			fatalf("%v: field override type cannot have embedded or unexported fields", mtyp.fs.Position(of.Pos()))
+			return fmt.Errorf("%v: field override type cannot have embedded or unexported fields", mtyp.fs.Position(of.Pos()))
 		}
 		f := mtyp.fieldByName(of.Name())
 		if f == nil {
-			fatalf("%v: no matching field for %s in original type %s", mtyp.fs.Position(of.Pos()), of.Name(), mtyp.OrigName)
+			return fmt.Errorf("%v: no matching field for %s in original type %s", mtyp.fs.Position(of.Pos()), of.Name(), mtyp.name)
 		}
-		if !types.ConvertibleTo(of.Type(), f.field.Type()) {
+		if err := checkConvertible(of.Type(), f.origTyp); err != nil {
-			fatalf("%v: field override type %s is not convertible to %s", mtyp.fs.Position(of.Pos()), mtyp.typeString(of.Type()), mtyp.typeString(f.field.Type()))
+			return fmt.Errorf("%v: invalid field override: %v", mtyp.fs.Position(of.Pos()), err)
 		}
 		f.typ = ensurePointer(of.Type())
 	}
+	mtyp.scope.addReferences(otyp)
+	return nil
 }
 
 func (mtyp *marshalerType) fieldByName(name string) *marshalerField {
 	for _, f := range mtyp.Fields {
-		if f.field.Name() == name {
+		if f.name == name {
 			return f
 		}
 	}
 	return nil
 }
 
-// computeImports returns the import paths of all referenced types.
-// computeImports must be called before generating any code because it
-// renames packages to avoid name clashes.
-func (mtyp *marshalerType) computeImports() map[string]string {
-	seen := make(map[string]string)
-	counter := 0
-	add := func(name string, path string, pkg *types.Package) {
-		if seen[name] != path {
-			if pkg != nil {
-				name = "_" + name
-				pkg.SetName(name)
-			}
-			if seen[name] != "" {
-				// Name clash, add counter.
-				name += "_" + strconv.Itoa(counter)
-				counter++
-				pkg.SetName(name)
-			}
-			seen[name] = path
-		}
-	}
-	addNamed := func(typ *types.Named) {
-		if pkg := typ.Obj().Pkg(); pkg != mtyp.orig.Obj().Pkg() {
-			add(pkg.Name(), pkg.Path(), pkg)
-		}
-	}
-
-	// Add packages which always referenced by the generated code.
-	add("json", "encoding/json", nil)
-	add("errors", "errors", nil)
-	for _, f := range mtyp.Fields {
-		// Add field types of the intermediate struct.
-		walkNamedTypes(f.typ, addNamed)
-		// Add field types of the original struct. Note that this won't generate unused
-		// imports because all fields are either referenced by a conversion or by fields
-		// of the intermediate struct (if no conversion is needed).
-		walkNamedTypes(f.field.Type(), addNamed)
-	}
-	return seen
-}
-
-// JSONMarshalMethod generates MarshalJSON.
-func (mtyp *marshalerType) JSONMarshalMethod() string {
-	return render(mtyp, `
-// MarshalJSON implements json.Marshaler.
-func (x *{{.OrigName}}) MarshalJSON() ([]byte, error) {
-	{{.TypeDecl}}
-
-	return json.Marshal(&{{.Name}}{
-		{{- range .Fields}}
-			{{.Name}}: {{.Convert "x"}},
-		{{- end}}
-	})
-}`)
-}
-
-// YAMLMarsalMethod generates MarshalYAML.
-func (mtyp *marshalerType) YAMLMarshalMethod() string {
-	return render(mtyp, `
-// MarshalYAML implements yaml.Marshaler
-func (x *{{.OrigName}}) MarshalYAML() (interface{}, error) {
-	{{.TypeDecl}}
-
-	return &{{.Name}}{
-		{{- range .Fields}}
-			{{.Name}}: {{.Convert "x"}},
-		{{- end}}
-	}, nil
-}`)
-}
-
-// JSONUnmarshalMethod generates UnmarshalJSON.
-func (mtyp *marshalerType) JSONUnmarshalMethod() string {
-	return render(mtyp, `
-// UnmarshalJSON implements json.Unmarshaler.
-func (x *{{.OrigName}}) UnmarshalJSON(input []byte) error {
-	{{.TypeDecl}}
-
-	var dec {{.Name}}
-	if err := json.Unmarshal(input, &dec); err != nil {
-		return err
-	}
-	var v {{.OrigName}}
-	{{.UnmarshalConversions "json"}}
-	*x = v
-	return nil
-}`)
-}
-
-// YAMLUnmarshalMethod generates UnmarshalYAML.
-func (mtyp *marshalerType) YAMLUnmarshalMethod() string {
-	return render(mtyp, `
-// UnmarshalYAML implements yaml.Unmarshaler.
-func (x *{{.OrigName}}) UnmarshalYAML(fn func (interface{}) error) error {
-	{{.TypeDecl}}
-
-	var dec {{.Name}}
-	if err := fn(&dec); err != nil {
-		return err
-	}
-	var v {{.OrigName}}
-	{{.UnmarshalConversions "yaml"}}
-	*x = v
-	return nil
-}`)
-}
-
-// TypeDecl genereates the declaration of the intermediate marshaling type.
-func (mtyp *marshalerType) TypeDecl() string {
-	return render(mtyp, `
-	type {{.Name}} struct{
-		{{- range .Fields}}
-			{{.Name}} {{.Type}} {{.StructTag}}
-		{{- end}}
-	}`)
-}
-
-// UnmarshalConversion genereates field conversions and presence checks.
-func (mtyp *marshalerType) UnmarshalConversions(formatTag string) (s string) {
-	type fieldContext struct{ Typ, Name, EncName, Conv string }
-
-	for _, mf := range mtyp.Fields {
-		ctx := fieldContext{
-			Typ:     strings.ToUpper(formatTag) + " " + mtyp.OrigName,
-			Name:    mf.Name(),
-			EncName: mf.encodedName(formatTag),
-			Conv:    mf.ConvertBack("dec"),
-		}
-		if mf.isOptional(formatTag) {
-			s += render(ctx, `
-				if dec.{{.Name}} != nil {
-					v.{{.Name}} = {{.Conv}}
-				}`)
-		} else {
-			s += render(ctx, `
-				if dec.{{.Name}} == nil {
-					return errors.New("missing required field '{{.EncName}}' in {{.Typ}}")
-				}
-				v.{{.Name}} = {{.Conv}}`)
-		}
-		s += "\n"
-	}
-	return s
-}
-
-func (mf *marshalerField) Name() string {
-	return mf.field.Name()
-}
-
-func (mf *marshalerField) Type() string {
-	return mf.parent.typeString(mf.typ)
-}
-
-func (mf *marshalerField) OrigType() string {
-	return mf.parent.typeString(mf.typ)
-}
-
-func (mf *marshalerField) StructTag() string {
-	if mf.tag == "" {
-		return ""
-	}
-	return "`" + mf.tag + "`"
-}
-
-func (mf *marshalerField) Convert(variable string) string {
-	expr := fmt.Sprintf("%s.%s", variable, mf.field.Name())
-	return mf.parent.conversionExpr(expr, mf.field.Type(), mf.typ)
-}
-
-func (mf *marshalerField) ConvertBack(variable string) string {
-	expr := fmt.Sprintf("%s.%s", variable, mf.field.Name())
-	return mf.parent.conversionExpr(expr, mf.typ, mf.field.Type())
-}
-
-func (mtyp *marshalerType) conversionExpr(valueExpr string, from, to types.Type) string {
-	if isPointer(from) && !isPointer(to) {
-		valueExpr = "*" + valueExpr
-		from = from.(*types.Pointer).Elem()
-	} else if !isPointer(from) && isPointer(to) {
-		valueExpr = "&" + valueExpr
-		from = types.NewPointer(from)
-	}
-	if types.AssignableTo(from, to) {
-		return valueExpr
-	}
-	return fmt.Sprintf("(%s)(%s)", mtyp.typeString(to), valueExpr)
-}
-
-func (mf *marshalerField) errorf(format string, args ...interface{}) error {
-	pos := mf.parent.fs.Position(mf.field.Pos()).String()
-	return errors.New(pos + ": (" + mf.parent.OrigName + "." + mf.Name() + ") " + fmt.Sprintf(format, args...))
-}
-
 // isOptional returns whether the field is optional when decoding the given format.
 func (mf *marshalerField) isOptional(format string) bool {
 	rtag := reflect.StructTag(mf.tag)
@@ -437,99 +329,11 @@ func (mf *marshalerField) encodedName(format string) string {
 		val = val[:comma]
 	}
 	if val == "" || val == "-" {
-		return uncapitalize(mf.Name())
+		return uncapitalize(mf.name)
 	}
 	return val
 }
 
-func (mtyp *marshalerType) typeString(typ types.Type) string {
-	return types.TypeString(typ, func(pkg *types.Package) string {
-		if pkg == mtyp.orig.Obj().Pkg() {
-			return ""
-		}
-		return pkg.Name()
-	})
-}
-
-// walkNamedTypes runs the callback for all named types contained in the given type.
-func walkNamedTypes(typ types.Type, callback func(*types.Named)) {
-	switch typ := typ.(type) {
-	case *types.Basic:
-	case *types.Chan:
-		walkNamedTypes(typ.Elem(), callback)
-	case *types.Map:
-		walkNamedTypes(typ.Key(), callback)
-		walkNamedTypes(typ.Elem(), callback)
-	case *types.Named:
-		callback(typ)
-	case *types.Pointer:
-		walkNamedTypes(typ.Elem(), callback)
-	case *types.Slice:
-		walkNamedTypes(typ.Elem(), callback)
-	case *types.Struct:
-		for i := 0; i < typ.NumFields(); i++ {
-			walkNamedTypes(typ.Field(i).Type(), callback)
-		}
-	default:
-		panic(fmt.Errorf("can't walk %T", typ))
-	}
-}
-
-func lookupStructType(scope *types.Scope, name string) (*types.Named, error) {
-	typ, err := lookupType(scope, name)
-	if err != nil {
-		return nil, err
-	}
-	_, ok := typ.Underlying().(*types.Struct)
-	if !ok {
-		return nil, errors.New("not a struct type")
-	}
-	return typ, nil
-}
-
-func lookupType(scope *types.Scope, name string) (*types.Named, error) {
-	obj := scope.Lookup(name)
-	if obj == nil {
-		return nil, errors.New("no such identifier")
-	}
-	typ, ok := obj.(*types.TypeName)
-	if !ok {
-		return nil, errors.New("not a type")
-	}
-	return typ.Type().(*types.Named), nil
-}
-
-func isPointer(typ types.Type) bool {
-	_, ok := typ.(*types.Pointer)
-	return ok
-}
-
-func ensurePointer(typ types.Type) types.Type {
-	if isPointer(typ) {
-		return typ
-	}
-	return types.NewPointer(typ)
-}
-
 func uncapitalize(s string) string {
 	return strings.ToLower(s[:1]) + s[1:]
 }
-
-func render(data interface{}, text string) string {
-	t := template.Must(template.New("").Parse(strings.TrimSpace(text)))
-	out := new(bytes.Buffer)
-	if err := t.Execute(out, data); err != nil {
-		panic(err)
-	}
-	return out.String()
-}
-
-func fatal(args ...interface{}) {
-	fmt.Fprintln(os.Stderr, args...)
-	os.Exit(1)
-}
-
-func fatalf(format string, args ...interface{}) {
-	fmt.Fprintf(os.Stderr, format+"\n", args...)
-	os.Exit(1)
-}

main_test.go

@@ -0,0 +1,46 @@
+// Copyright 2017 Felix Lange <fjl@twurst.com>.
+// Use of this source code is governed by the MIT license,
+// which can be found in the LICENSE file.
+
+package main
+
+import (
+	"io/ioutil"
+	"path/filepath"
+	"testing"
+
+	"github.com/kylelemons/godebug/diff"
+)
+
+// 'golden' tests. These tests compare the output code with the expected
+// code in internal/tests/*/output.go. The expected can be updated using
+//
+//    go generate ./internal/...
+
+func TestMapConv(t *testing.T) {
+	runGoldenTest(t, Config{Dir: "mapconv", Type: "X", FieldOverride: "Xo"})
+}
+
+func TestSliceConv(t *testing.T) {
+	runGoldenTest(t, Config{Dir: "sliceconv", Type: "X", FieldOverride: "Xo"})
+}
+
+func TestNameClash(t *testing.T) {
+	runGoldenTest(t, Config{Dir: "nameclash", Type: "Y", FieldOverride: "Yo"})
+}
+
+func runGoldenTest(t *testing.T, cfg Config) {
+	cfg.Dir = filepath.Join("internal", "tests", cfg.Dir)
+	want, err := ioutil.ReadFile(filepath.Join(cfg.Dir, "output.go"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	code, err := cfg.process()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if d := diff.Diff(string(want), string(code)); d != "" {
+		t.Errorf("output mismatch\n\n%s", d)
+	}
+}

typeutil.go

@@ -0,0 +1,244 @@
+// Copyright 2017 Felix Lange <fjl@twurst.com>.
+// Use of this source code is governed by the MIT license,
+// which can be found in the LICENSE file.
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"go/types"
+	"io"
+	"sort"
+	"strconv"
+)
+
+// walkNamedTypes runs the callback for all named types contained in the given type.
+func walkNamedTypes(typ types.Type, callback func(*types.Named)) {
+	switch typ := typ.(type) {
+	case *types.Basic:
+	case *types.Chan:
+		walkNamedTypes(typ.Elem(), callback)
+	case *types.Map:
+		walkNamedTypes(typ.Key(), callback)
+		walkNamedTypes(typ.Elem(), callback)
+	case *types.Named:
+		callback(typ)
+	case *types.Pointer:
+		walkNamedTypes(typ.Elem(), callback)
+	case *types.Slice:
+		walkNamedTypes(typ.Elem(), callback)
+	case *types.Struct:
+		for i := 0; i < typ.NumFields(); i++ {
+			walkNamedTypes(typ.Field(i).Type(), callback)
+		}
+	default:
+		panic(fmt.Errorf("can't walk %T", typ))
+	}
+}
+
+func lookupStructType(scope *types.Scope, name string) (*types.Named, error) {
+	typ, err := lookupType(scope, name)
+	if err != nil {
+		return nil, err
+	}
+	_, ok := typ.Underlying().(*types.Struct)
+	if !ok {
+		return nil, errors.New("not a struct type")
+	}
+	return typ, nil
+}
+
+func lookupType(scope *types.Scope, name string) (*types.Named, error) {
+	obj := scope.Lookup(name)
+	if obj == nil {
+		return nil, errors.New("no such identifier")
+	}
+	typ, ok := obj.(*types.TypeName)
+	if !ok {
+		return nil, errors.New("not a type")
+	}
+	return typ.Type().(*types.Named), nil
+}
+
+func isPointer(typ types.Type) bool {
+	_, ok := typ.(*types.Pointer)
+	return ok
+}
+
+func isSlice(typ types.Type) bool {
+	_, ok := typ.(*types.Slice)
+	return ok
+}
+
+func isMap(typ types.Type) bool {
+	_, ok := typ.(*types.Map)
+	return ok
+}
+
+func ensurePointer(typ types.Type) types.Type {
+	if isPointer(typ) || isSlice(typ) || isMap(typ) {
+		return typ
+	}
+	return types.NewPointer(typ)
+}
+
+// checkConvertible determines whether values of type from can be converted to type to. It
+// returns nil if convertible and a descriptive error otherwise.
+func checkConvertible(from, to types.Type) error {
+	if types.ConvertibleTo(from, to) {
+		return nil
+	}
+	// Slices.
+	sfrom, fromIsSlice := from.(*types.Slice)
+	sto, toIsSlice := to.(*types.Slice)
+	if fromIsSlice && toIsSlice {
+		if !types.ConvertibleTo(sfrom.Elem(), sto.Elem()) {
+			return fmt.Errorf("slice element type %s is not convertible to %s", sfrom.Elem(), sto.Elem())
+		}
+		return nil
+	}
+	// Maps.
+	mfrom, fromIsMap := from.(*types.Map)
+	mto, toIsMap := to.(*types.Map)
+	if fromIsMap && toIsMap {
+		if !types.ConvertibleTo(mfrom.Key(), mto.Key()) {
+			return fmt.Errorf("map key type %s is not convertible to %s", mfrom.Key(), mto.Key())
+		}
+		if !types.ConvertibleTo(mfrom.Elem(), mto.Elem()) {
+			return fmt.Errorf("map element type %s is not convertible to %s", mfrom.Elem(), mto.Elem())
+		}
+		return nil
+	}
+	return fmt.Errorf("type %s is not convertible to %s", from, to)
+}
+
+// fileScope tracks imports and other names at file scope.
+type fileScope struct {
+	imports       []*types.Package
+	importsByName map[string]*types.Package
+	importNames   map[string]string
+	otherNames    map[string]bool // non-package identifiers
+	pkg           *types.Package
+	imp           types.Importer
+}
+
+func newFileScope(imp types.Importer, pkg *types.Package) *fileScope {
+	return &fileScope{otherNames: make(map[string]bool), pkg: pkg, imp: imp}
+}
+
+func (s *fileScope) writeImportDecl(w io.Writer) {
+	fmt.Fprintln(w, "import (")
+	for _, pkg := range s.imports {
+		if s.importNames[pkg.Path()] != pkg.Name() {
+			fmt.Fprintf(w, "\t%s %q\n", s.importNames[pkg.Path()], pkg.Path())
+		} else {
+			fmt.Fprintf(w, "\t%q\n", pkg.Path())
+		}
+	}
+	fmt.Fprintln(w, ")")
+}
+
+// addImport loads a package and adds it to the import set.
+func (s *fileScope) addImport(path string) {
+	pkg, err := s.imp.Import(path)
+	if err != nil {
+		panic(fmt.Errorf("can't import %q: %v", path, err))
+	}
+	s.insertImport(pkg)
+	s.rebuildImports()
+}
+
+// addReferences marks all names referenced by typ as used.
+func (s *fileScope) addReferences(typ types.Type) {
+	walkNamedTypes(typ, func(nt *types.Named) {
+		if nt.Obj().Pkg() == s.pkg {
+			s.otherNames[nt.Obj().Name()] = true
+		} else {
+			s.insertImport(nt.Obj().Pkg())
+		}
+	})
+	s.rebuildImports()
+}
+
+// insertImport adds pkg to the list of known imports.
+// This method should not be used directly because it doesn't
+// rebuild the import name cache.
+func (s *fileScope) insertImport(pkg *types.Package) {
+	i := sort.Search(len(s.imports), func(i int) bool {
+		return s.imports[i].Path() > pkg.Path()
+	})
+	if i < len(s.imports) && s.imports[i] == pkg {
+		return
+	}
+	s.imports = append(s.imports[:i], append([]*types.Package{pkg}, s.imports[i:]...)...)
+}
+
+// rebuildImports caches the names of imported packages.
+func (s *fileScope) rebuildImports() {
+	s.importNames = make(map[string]string)
+	s.importsByName = make(map[string]*types.Package)
+	for _, pkg := range s.imports {
+		s.maybeRenameImport(pkg)
+	}
+}
+
+func (s *fileScope) maybeRenameImport(pkg *types.Package) {
+	name := pkg.Name()
+	for i := 0; s.isNameTaken(name); i++ {
+		name = pkg.Name()
+		if i > 0 {
+			name += strconv.Itoa(i - 1)
+		}
+	}
+	s.importNames[pkg.Path()] = name
+	s.importsByName[name] = pkg
+}
+
+// isNameTaken reports whether the given name is used by an import or other identifier.
+func (s *fileScope) isNameTaken(name string) bool {
+	return s.importsByName[name] != nil || s.otherNames[name] || types.Universe.Lookup(name) != nil
+}
+
+// qualify is a types.Qualifier that prepends the (possibly renamed) package name of
+// imported types to a type name.
+func (s *fileScope) qualify(pkg *types.Package) string {
+	if pkg == s.pkg {
+		return ""
+	}
+	return s.packageName(pkg.Path())
+}
+
+func (s *fileScope) packageName(path string) string {
+	name, ok := s.importNames[path]
+	if !ok {
+		panic("BUG: missing package " + path)
+	}
+	return name
+}
+
+// funcScope tracks used identifiers in a function. It can create new identifiers that do
+// not clash with the parent scope.
+type funcScope struct {
+	used   map[string]bool
+	parent *fileScope
+}
+
+func newFuncScope(parent *fileScope) *funcScope {
+	return &funcScope{make(map[string]bool), parent}
+}
+
+// newIdent creates a new identifier that doesn't clash with any name
+// in the scope or its parent file scope.
+func (s *funcScope) newIdent(base string) string {
+	for i := 0; ; i++ {
+		name := base
+		if i > 0 {
+			name += strconv.Itoa(i - 1)
+		}
+		if !s.parent.isNameTaken(name) && !s.used[name] {
+			s.used[name] = true
+			return name
+		}
+	}
+}

vendor/github.com/garslo/gogen/README.md

@@ -0,0 +1,78 @@
+# gogen
+
+A simplification of Go's `go/ast` package that allows for some
+interesting code generation. Currently very rough.
+
+# Examples
+
+## Hello World
+```go
+package main
+
+import (
+	"os"
+	. "github.com/garslo/gogen"
+)
+
+func main() {
+	pkg := Package{Name: "main"}
+	pkg.Declare(Import{"fmt"})
+	pkg.Declare(Function{
+		Name: "main",
+		Body: []Statement{
+			CallFunction{
+				Func:   Dotted{Var{"fmt"}, "Println"},
+				Params: []Expression{Var{`"Hello World!"`}},
+			},
+		},
+	})
+	pkg.WriteTo(os.Stdout)
+}
+```
+
+Output:
+
+```go
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("Hello World!")
+}
+```
+
+## More
+See the
+[examples](https://github.com/garslo/gogen/tree/master/examples)
+directory for more examples and a build/run script.
+
+```sh
+$ ./run-example.sh for_loop.go
+CODE:
+package main
+
+import "os"
+import "fmt"
+
+func main() {
+	var i int
+	for i = 0; i <= 10; i++ {
+		fmt.Println(i)
+	}
+	os.Exit(i)
+}
+RUN RESULT:
+0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
+exit status 11
+```

vendor/github.com/garslo/gogen/assign.go

@@ -0,0 +1,19 @@
+package gogen
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+type Assign struct {
+	Lhs Expression
+	Rhs Expression
+}
+
+func (me Assign) Statement() ast.Stmt {
+	return &ast.AssignStmt{
+		Tok: token.ASSIGN,
+		Lhs: []ast.Expr{me.Lhs.Expression()},
+		Rhs: []ast.Expr{me.Rhs.Expression()},
+	}
+}

vendor/github.com/garslo/gogen/binary_op.go

@@ -0,0 +1,84 @@
+package gogen
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+type LessThan struct {
+	Lhs Expression
+	Rhs Expression
+}
+
+func (me LessThan) Expression() ast.Expr {
+	return &ast.BinaryExpr{
+		Op: token.LSS,
+		X:  me.Lhs.Expression(),
+		Y:  me.Rhs.Expression(),
+	}
+}
+
+type LessThanOrEqual struct {
+	Lhs Expression
+	Rhs Expression
+}
+
+func (me LessThanOrEqual) Expression() ast.Expr {
+	return &ast.BinaryExpr{
+		Op: token.LEQ,
+		X:  me.Lhs.Expression(),
+		Y:  me.Rhs.Expression(),
+	}
+}
+
+type GreaterThan struct {
+	Lhs Expression
+	Rhs Expression
+}
+
+func (me GreaterThan) Expression() ast.Expr {
+	return &ast.BinaryExpr{
+		Op: token.GTR,
+		X:  me.Lhs.Expression(),
+		Y:  me.Rhs.Expression(),
+	}
+}
+
+type GreaterThanOrEqual struct {
+	Lhs Expression
+	Rhs Expression
+}
+
+func (me GreaterThanOrEqual) Expression() ast.Expr {
+	return &ast.BinaryExpr{
+		Op: token.GEQ,
+		X:  me.Lhs.Expression(),
+		Y:  me.Rhs.Expression(),
+	}
+}
+
+type Equals struct {
+	Lhs Expression
+	Rhs Expression
+}
+
+func (me Equals) Expression() ast.Expr {
+	return &ast.BinaryExpr{
+		Op: token.EQL,
+		X:  me.Lhs.Expression(),
+		Y:  me.Rhs.Expression(),
+	}
+}
+
+type NotEqual struct {
+	Lhs Expression
+	Rhs Expression
+}
+
+func (me NotEqual) Expression() ast.Expr {
+	return &ast.BinaryExpr{
+		Op: token.NEQ,
+		X:  me.Lhs.Expression(),
+		Y:  me.Rhs.Expression(),
+	}
+}

vendor/github.com/garslo/gogen/builtins.go

@@ -0,0 +1,25 @@
+package gogen
+
+var BuiltinTypes = [...]string{
+	"int",
+	"int8",
+	"int16",
+	"int32",
+	"int64",
+	"uint",
+	"uint8",
+	"uint16",
+	"uint32",
+	"uint64",
+	"uintptr",
+	"float",
+	"float32",
+	"float64",
+	"string",
+	"bool",
+	"byte",
+	"complex128",
+	"complex64",
+	"error",
+	"rune",
+}

vendor/github.com/garslo/gogen/declaration.go

@@ -0,0 +1,7 @@
+package gogen
+
+import "go/ast"
+
+type Declaration interface {
+	Declaration() ast.Decl
+}

vendor/github.com/garslo/gogen/declare.go

@@ -0,0 +1,35 @@
+package gogen
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+type Declare struct {
+	Name     string
+	TypeName string
+}
+
+func (me Declare) Statement() ast.Stmt {
+	return &ast.DeclStmt{
+		Decl: &ast.GenDecl{
+			Tok: token.VAR,
+			Specs: []ast.Spec{
+				&ast.ValueSpec{
+					Names: []*ast.Ident{
+						&ast.Ident{
+							Name: me.Name,
+							Obj: &ast.Object{
+								Kind: ast.Var,
+								Name: me.Name,
+							},
+						},
+					},
+					Type: &ast.Ident{
+						Name: me.TypeName,
+					},
+				},
+			},
+		},
+	}
+}

vendor/github.com/garslo/gogen/declare_and_assign.go

@@ -0,0 +1,19 @@
+package gogen
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+type DeclareAndAssign struct {
+	Lhs Expression
+	Rhs Expression
+}
+
+func (me DeclareAndAssign) Statement() ast.Stmt {
+	return &ast.AssignStmt{
+		Tok: token.DEFINE,
+		Lhs: []ast.Expr{me.Lhs.Expression()},
+		Rhs: []ast.Expr{me.Rhs.Expression()},
+	}
+}

vendor/github.com/garslo/gogen/dotted.go

@@ -0,0 +1,17 @@
+package gogen
+
+import "go/ast"
+
+type Dotted struct {
+	Receiver Expression
+	Name     string
+}
+
+func (me Dotted) Expression() ast.Expr {
+	return &ast.SelectorExpr{
+		X: me.Receiver.Expression(),
+		Sel: &ast.Ident{
+			Name: me.Name,
+		},
+	}
+}

vendor/github.com/garslo/gogen/expression.go

@@ -0,0 +1,7 @@
+package gogen
+
+import "go/ast"
+
+type Expression interface {
+	Expression() ast.Expr
+}

vendor/github.com/garslo/gogen/for.go

@@ -0,0 +1,40 @@
+package gogen
+
+import "go/ast"
+
+type For struct {
+	Init      Statement
+	Condition Expression
+	Post      Statement
+	Body      []Statement
+}
+
+func (me For) Statement() ast.Stmt {
+	body := make([]ast.Stmt, len(me.Body))
+	for i, bodyPart := range me.Body {
+		body[i] = bodyPart.Statement()
+	}
+	var (
+		init ast.Stmt
+		cond ast.Expr
+		post ast.Stmt
+	)
+	if me.Init != nil {
+		init = me.Init.Statement()
+	}
+	if me.Condition != nil {
+		cond = me.Condition.Expression()
+	}
+	if me.Post != nil {
+		post = me.Post.Statement()
+	}
+
+	return &ast.ForStmt{
+		Init: init,
+		Cond: cond,
+		Post: post,
+		Body: &ast.BlockStmt{
+			List: body,
+		},
+	}
+}

vendor/github.com/garslo/gogen/function.go

@@ -0,0 +1,127 @@
+package gogen
+
+import "go/ast"
+
+type Receiver struct {
+	Name string
+	Type Expression
+}
+
+func (me Receiver) Ast() *ast.FieldList {
+	if me.Type == nil {
+		return nil
+	}
+	return &ast.FieldList{
+		List: []*ast.Field{
+			&ast.Field{
+				Names: []*ast.Ident{
+					&ast.Ident{
+						Name: me.Name,
+						Obj: &ast.Object{
+							Kind: ast.Var,
+							Name: me.Name,
+						},
+					},
+				},
+				Type: me.Type.Expression(),
+			},
+		},
+	}
+}
+
+type Function struct {
+	Receiver    Receiver
+	Name        string
+	ReturnTypes Types
+	Parameters  Types
+	Body        []Statement
+}
+
+func (me Function) Declare(pkg *Package) Function {
+	pkg.Declare(me)
+	return me
+}
+
+func (me Function) Declaration() ast.Decl {
+	paramFields := make([]*ast.Field, len(me.Parameters))
+	for j, param := range me.Parameters {
+		var names []*ast.Ident
+		if param.Name != "" {
+			names = []*ast.Ident{
+				&ast.Ident{
+					Name: param.Name,
+					Obj: &ast.Object{
+						Kind: ast.Var,
+						Name: param.Name,
+					},
+				},
+			}
+		}
+		paramFields[j] = &ast.Field{
+			Names: names,
+			Type: &ast.Ident{
+				Name: param.TypeName,
+			},
+		}
+	}
+	returnFields := make([]*ast.Field, len(me.ReturnTypes))
+	for j, ret := range me.ReturnTypes {
+		var names []*ast.Ident
+		if ret.Name != "" {
+			names = []*ast.Ident{
+				&ast.Ident{
+					Name: ret.Name,
+					Obj: &ast.Object{
+						Kind: ast.Var,
+						Name: ret.Name,
+					},
+				},
+			}
+		}
+		returnFields[j] = &ast.Field{
+			Names: names,
+			Type: &ast.Ident{
+				Name: ret.TypeName,
+			},
+		}
+	}
+	stmts := make([]ast.Stmt, len(me.Body))
+	for j, stmt := range me.Body {
+		stmts[j] = stmt.Statement()
+	}
+	return &ast.FuncDecl{
+		Recv: me.Receiver.Ast(),
+		Name: &ast.Ident{
+			Name: me.Name,
+			Obj: &ast.Object{
+				Kind: ast.Fun,
+				Name: me.Name,
+			},
+		},
+		Type: &ast.FuncType{
+			Params: &ast.FieldList{
+				List: paramFields,
+			},
+			Results: &ast.FieldList{
+				List: returnFields,
+			},
+		},
+		Body: &ast.BlockStmt{
+			List: stmts,
+		},
+	}
+}
+
+func (me Function) Call(params ...Expression) CallFunction {
+	// TODO: what if this is a method?
+	return CallFunction{
+		Func:   Var{me.Name},
+		Params: params,
+	}
+}
+
+type Functions []Function
+
+func (me *Functions) Add(fn Function) {
+	*me = append(*me, fn)
+}

vendor/github.com/garslo/gogen/function_call.go

@@ -0,0 +1,37 @@
+package gogen
+
+import "go/ast"
+
+type CallFunction struct {
+	Func   Expression
+	Params []Expression
+}
+
+func (me CallFunction) Statement() ast.Stmt {
+	return &ast.ExprStmt{
+		X: me.Expression(),
+	}
+}
+
+func (me CallFunction) Expression() ast.Expr {
+	params := make([]ast.Expr, len(me.Params))
+	for i, param := range me.Params {
+		params[i] = param.Expression()
+	}
+	return &ast.CallExpr{
+		Fun:  me.Func.Expression(),
+		Args: params,
+	}
+}
+
+// TODO: Bad name, change it
+type Functor struct {
+	Func Expression
+}
+
+func (me Functor) Call(params ...Expression) CallFunction {
+	return CallFunction{
+		Func:   me.Func,
+		Params: params,
+	}
+}

vendor/github.com/garslo/gogen/if.go

@@ -0,0 +1,29 @@
+package gogen
+
+import "go/ast"
+
+type If struct {
+	Init      Statement
+	Condition Expression
+	Body      []Statement
+}
+
+func (me If) Statement() ast.Stmt {
+	var (
+		init ast.Stmt
+	)
+	if me.Init != nil {
+		init = me.Init.Statement()
+	}
+	body := make([]ast.Stmt, len(me.Body))
+	for j, stmt := range me.Body {
+		body[j] = stmt.Statement()
+	}
+	return &ast.IfStmt{
+		Init: init,
+		Cond: me.Condition.Expression(),
+		Body: &ast.BlockStmt{
+			List: body,
+		},
+	}
+}

vendor/github.com/garslo/gogen/import.go

@@ -0,0 +1,32 @@
+package gogen
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+)
+
+type Import struct {
+	Name string
+}
+
+func (me Import) Declaration() ast.Decl {
+	return &ast.GenDecl{
+		Tok: token.IMPORT,
+		Specs: []ast.Spec{
+			&ast.ImportSpec{
+				Path: &ast.BasicLit{
+					Kind:  token.STRING,
+					Value: fmt.Sprintf(`"%s"`, me.Name),
+				},
+			},
+		},
+	}
+
+}
+
+type Imports []Import
+
+func (me *Imports) Add(imp Import) {
+	*me = append(*me, imp)
+}

vendor/github.com/garslo/gogen/package.go

@@ -0,0 +1,36 @@
+package gogen
+
+import (
+	"go/ast"
+	"go/format"
+	"go/token"
+	"io"
+)
+
+type Package struct {
+	Name         string
+	Declarations []Declaration
+}
+
+func (me *Package) Declare(decl Declaration) *Package {
+	me.Declarations = append(me.Declarations, decl)
+	return me
+}
+
+func (me *Package) Ast() ast.Node {
+	decls := make([]ast.Decl, len(me.Declarations))
+	for i, decl := range me.Declarations {
+		decls[i] = decl.Declaration()
+	}
+	return &ast.File{
+		Name: &ast.Ident{
+			Name: me.Name,
+		},
+		Decls: decls,
+	}
+}
+
+func (me *Package) WriteTo(w io.Writer) error {
+	fset := token.NewFileSet()
+	return format.Node(w, fset, me.Ast())
+}

vendor/github.com/garslo/gogen/range.go

@@ -0,0 +1,46 @@
+package gogen
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+type Range struct {
+	Key          Expression
+	Value        Expression
+	RangeValue   Expression
+	Body         []Statement
+	DoNotDeclare bool
+}
+
+func (me Range) Statement() ast.Stmt {
+	body := make([]ast.Stmt, len(me.Body))
+	for i, bodyPart := range me.Body {
+		body[i] = bodyPart.Statement()
+	}
+	var (
+		key   Expression = Var{"_"}
+		value Expression = Var{"_"}
+	)
+
+	if me.Key != nil {
+		key = me.Key
+	}
+	if me.Value != nil {
+		value = me.Value
+	}
+	tok := token.DEFINE
+	if me.DoNotDeclare || (me.Key == nil && me.Value == nil) {
+		tok = token.ASSIGN
+	}
+
+	return &ast.RangeStmt{
+		Key:   key.Expression(),
+		Value: value.Expression(),
+		X:     me.RangeValue.Expression(),
+		Tok:   tok,
+		Body: &ast.BlockStmt{
+			List: body,
+		},
+	}
+}

vendor/github.com/garslo/gogen/return.go

@@ -0,0 +1,17 @@
+package gogen
+
+import "go/ast"
+
+type Return struct {
+	Values []Expression
+}
+
+func (me Return) Statement() ast.Stmt {
+	ret := make([]ast.Expr, len(me.Values))
+	for i, val := range me.Values {
+		ret[i] = val.Expression()
+	}
+	return &ast.ReturnStmt{
+		Results: ret,
+	}
+}

vendor/github.com/garslo/gogen/star.go

@@ -0,0 +1,13 @@
+package gogen
+
+import "go/ast"
+
+type Star struct {
+	Value Expression
+}
+
+func (me Star) Expression() ast.Expr {
+	return &ast.StarExpr{
+		X: me.Value.Expression(),
+	}
+}

vendor/github.com/garslo/gogen/statement.go

@@ -0,0 +1,7 @@
+package gogen
+
+import "go/ast"
+
+type Statement interface {
+	Statement() ast.Stmt
+}

vendor/github.com/garslo/gogen/stdlib_imports.go

@@ -0,0 +1,141 @@
+package gogen
+
+const (
+	ArchiveTar        = "archive/tar"
+	ArchiveZip        = "archive/zip"
+	Bufio             = "bufio"
+	Builtin           = "builtin"
+	Bytes             = "bytes"
+	CompressBzip2     = "compress/bzip2"
+	CompressFlate     = "compress/flate"
+	CompressGzip      = "compress/gzip"
+	CompressLzw       = "compress/lzw"
+	CompressZlib      = "compress/zlib"
+	ContainerHeap     = "container/heap"
+	ContainerList     = "container/list"
+	ContainerRing     = "container/ring"
+	Crypto            = "crypto"
+	CryptoAes         = "crypto/aes"
+	CryptoCipher      = "crypto/cipher"
+	CryptoDes         = "crypto/des"
+	CryptoDsa         = "crypto/dsa"
+	CryptoEcdsa       = "crypto/ecdsa"
+	CryptoElliptic    = "crypto/elliptic"
+	CryptoHmac        = "crypto/hmac"
+	CryptoMd5         = "crypto/md5"
+	CryptoRand        = "crypto/rand"
+	CryptoRc4         = "crypto/rc4"
+	CryptoRsa         = "crypto/rsa"
+	CryptoSha1        = "crypto/sha1"
+	CryptoSha256      = "crypto/sha256"
+	CryptoSha512      = "crypto/sha512"
+	CryptoSubtle      = "crypto/subtle"
+	CryptoTls         = "crypto/tls"
+	CryptoX509        = "crypto/x509"
+	CryptoX509Pkix    = "crypto/x509/pkix"
+	DatabaseSql       = "database/sql"
+	DatabaseSqlDriver = "database/sql/driver"
+	DebugDwarf        = "debug/dwarf"
+	DebugElf          = "debug/elf"
+	DebugGosym        = "debug/gosym"
+	DebugMacho        = "debug/macho"
+	DebugPe           = "debug/pe"
+	DebugPlan9obj     = "debug/plan9obj"
+	Encoding          = "encoding"
+	EncodingAscii85   = "encoding/ascii85"
+	EncodingAsn1      = "encoding/asn1"
+	EncodingBase32    = "encoding/base32"
+	EncodingBase64    = "encoding/base64"
+	EncodingBinary    = "encoding/binary"
+	EncodingCsv       = "encoding/csv"
+	EncodingGob       = "encoding/gob"
+	EncodingHex       = "encoding/hex"
+	EncodingJson      = "encoding/json"
+	EncodingPem       = "encoding/pem"
+	EncodingXml       = "encoding/xml"
+	Errors            = "errors"
+	Expvar            = "expvar"
+	Flag              = "flag"
+	Fmt               = "fmt"
+	GoAst             = "go/ast"
+	GoBuild           = "go/build"
+	GoDoc             = "go/doc"
+	GoFormat          = "go/format"
+	GoParser          = "go/parser"
+	GoPrinter         = "go/printer"
+	GoScanner         = "go/scanner"
+	GoToken           = "go/token"
+	Hash              = "hash"
+	HashAdler32       = "hash/adler32"
+	HashCrc32         = "hash/crc32"
+	HashCrc64         = "hash/crc64"
+	HashFnv           = "hash/fnv"
+	Html              = "html"
+	HtmlTemplate      = "html/template"
+	Image             = "image"
+	ImageColor        = "image/color"
+	ImageColorPalette = "image/color/palette"
+	ImageDraw         = "image/draw"
+	ImageGif          = "image/gif"
+	ImageJpeg         = "image/jpeg"
+	ImagePng          = "image/png"
+	IndexSuffixarray  = "index/suffixarray"
+	InternalSyscall   = "internal/syscall"
+	Io                = "io"
+	IoIoutil          = "io/ioutil"
+	Log               = "Log"
+	LogSyslog         = "log/syslog"
+	Math              = "math"
+	MathBig           = "math/big"
+	MathCmplx         = "math/cmplx"
+	MathRand          = "math/rand"
+	Mime              = "mime"
+	MimeMultipart     = "mime/multipart"
+	Net               = "net"
+	NetHttp           = "net/http"
+	NetHttpCgi        = "net/http/cgi"
+	NetHttpCookiejar  = "net/http/cookiejar"
+	NetHttpFcgi       = "net/http/fcgi"
+	NetHttpHttptest   = "net/http/httptest"
+	NetHttpHttputil   = "net/http/httputil"
+	NetHttpInternal   = "net/http/internal"
+	NetHttpPprof      = "net/http/pprof"
+	NetMail           = "net/mail"
+	NetRpc            = "net/rpc"
+	NetRpcJsonrpc     = "net/rpc/jsonrpc"
+	NetSmtp           = "net/smtp"
+	NetTextproto      = "net/textproto"
+	NetUrl            = "net/url"
+	Os                = "os"
+	OsExec            = "os/exec"
+	OsSignal          = "os/signal"
+	OsUser            = "os/user"
+	Path              = "path"
+	PathFilepath      = "path/filepath"
+	Reflect           = "reflect"
+	Regexp            = "regexp"
+	RegexpSyntax      = "regexp/syntax"
+	Runtime           = "runtime"
+	RuntimeCgo        = "runtime/cgo"
+	RuntimeDebug      = "runtime/debug"
+	RuntimePprof      = "runtime/pprof"
+	RuntimeRace       = "runtime/race"
+	Sort              = "sort"
+	Strconv           = "strconv"
+	Strings           = "strings"
+	Sync              = "sync"
+	SyncAtomic        = "sync/atomic"
+	Syscall           = "syscall"
+	Testing           = "testing"
+	TestingIotest     = "testing/iotest"
+	TestingQuick      = "testing/quick"
+	TextScanner       = "text/scanner"
+	TextTabwriter     = "text/tabwriter"
+	TextTemplate      = "text/template"
+	TextTemplateParse = "text/template/parse"
+	Time              = "time"
+	Unicode           = "unicode"
+	UnicodeUtf16      = "unicode/utf16"
+	UnicodeUtf8       = "unicode/utf8"
+	Unsafe            = "unsafe"
+)

vendor/github.com/garslo/gogen/struct.go

@@ -0,0 +1,115 @@
+package gogen
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+type Field struct {
+	Name     string
+	TypeName string
+	Tag      string
+}
+
+func (me Field) Ast() *ast.Field {
+	var tag *ast.BasicLit
+	if me.Tag != "" {
+		tag = &ast.BasicLit{
+			Kind:  token.STRING,
+			Value: "`" + me.Tag + "`",
+		}
+	}
+	names := []*ast.Ident{}
+	if me.Name != "" {
+		names = []*ast.Ident{
+			&ast.Ident{
+				Name: me.Name,
+				Obj: &ast.Object{
+					Kind: ast.Var,
+					Name: me.Name,
+				},
+			},
+		}
+	}
+	return &ast.Field{
+		Names: names,
+		Type: &ast.Ident{
+			Name: me.TypeName,
+		},
+		Tag: tag,
+	}
+}
+
+type Fields []Field
+
+func (me Fields) Ast() *ast.FieldList {
+	fields := make([]*ast.Field, len(me))
+	for i, field := range me {
+		fields[i] = field.Ast()
+	}
+	return &ast.FieldList{
+		List: fields,
+	}
+}
+
+type Struct struct {
+	Name        string
+	Fields      Fields
+	Methods     Functions
+	FieldValues map[string]Expression
+}
+
+func (me Struct) Declaration() ast.Decl {
+	return &ast.GenDecl{
+		Tok: token.TYPE,
+		Specs: []ast.Spec{
+			&ast.TypeSpec{
+				Name: &ast.Ident{
+					Name: me.Name,
+					Obj: &ast.Object{
+						Kind: ast.Typ,
+						Name: me.Name,
+					},
+				},
+				Type: &ast.StructType{
+					Fields: me.Fields.Ast(),
+				},
+			},
+		},
+	}
+}
+
+func (me Struct) WithValues(vals map[string]Expression) Struct {
+	return Struct{
+		Name:        me.Name,
+		Fields:      me.Fields,
+		Methods:     me.Methods,
+		FieldValues: vals,
+	}
+}
+
+func (me Struct) Expression() ast.Expr {
+	elts := make([]ast.Expr, len(me.Fields))
+	for i, field := range me.Fields {
+		elts[i] = &ast.KeyValueExpr{
+			Key: &ast.Ident{
+				Name: field.Name,
+			},
+			Value: &ast.Ident{
+			//Value: me.FieldValues[field.Name].Expression(),
+			},
+		}
+	}
+	return &ast.CompositeLit{
+		Type: &ast.Ident{
+			Name: me.Name,
+		},
+		Elts: elts,
+	}
+}
+
+type Structs []Struct
+
+func (me *Structs) Add(st Struct) {
+	*me = append(*me, st)
+}

vendor/github.com/garslo/gogen/thunk.go

@@ -0,0 +1,21 @@
+package gogen
+
+import "go/ast"
+
+type Thunk struct {
+	Expr ast.Expr
+	Stmt ast.Stmt
+	Decl ast.Decl
+}
+
+func (me Thunk) Expression() ast.Expr {
+	return me.Expr
+}
+
+func (me Thunk) Statement() ast.Stmt {
+	return me.Stmt
+}
+
+func (me Thunk) Declaration() ast.Decl {
+	return me.Decl
+}

vendor/github.com/garslo/gogen/type.go

@@ -0,0 +1,9 @@
+package gogen
+
+type Type struct {
+	Name        string // Optional, named type
+	TypeName    string
+	PackageName string // Optional
+}
+
+type Types []Type

vendor/github.com/garslo/gogen/typenames.go

@@ -0,0 +1,6 @@
+package gogen
+
+const (
+	StringT = "string"
+	IntT    = "int"
+)

vendor/github.com/garslo/gogen/unary_op.go

@@ -0,0 +1,61 @@
+package gogen
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+type Increment struct {
+	Value Expression
+}
+
+func (me Increment) Statement() ast.Stmt {
+	return &ast.IncDecStmt{
+		X:   me.Value.Expression(),
+		Tok: token.INC,
+	}
+}
+
+type Decrement struct {
+	Value Expression
+}
+
+func (me Decrement) Statement() ast.Stmt {
+	return &ast.IncDecStmt{
+		X:   me.Value.Expression(),
+		Tok: token.DEC,
+	}
+}
+
+type Not struct {
+	Value Expression
+}
+
+func (me Not) Expression() ast.Expr {
+	return &ast.UnaryExpr{
+		X:  me.Value.Expression(),
+		Op: token.NOT,
+	}
+}
+
+type AddressOf struct {
+	Value Expression
+}
+
+func (me AddressOf) Expression() ast.Expr {
+	return &ast.UnaryExpr{
+		X:  me.Value.Expression(),
+		Op: token.AND,
+	}
+}
+
+type Index struct {
+	Value, Index Expression
+}
+
+func (me Index) Expression() ast.Expr {
+	return &ast.IndexExpr{
+		X:     me.Value.Expression(),
+		Index: me.Index.Expression(),
+	}
+}

vendor/github.com/garslo/gogen/var.go

@@ -0,0 +1,44 @@
+package gogen
+
+import (
+	"fmt"
+	"go/ast"
+	"strconv"
+)
+
+type Var struct {
+	Name string
+}
+
+func (me Var) Expression() ast.Expr {
+	return &ast.Ident{
+		Name: me.Name,
+		Obj: &ast.Object{
+			Kind: ast.Var,
+			Name: me.Name,
+		},
+	}
+}
+
+// Things that are like Var but either deserve their own name, or have
+// slightly different behaviors
+
+type String struct {
+	Value string
+}
+
+func (me String) Expression() ast.Expr {
+	return Var{fmt.Sprintf(`"%s"`, me.Value)}.Expression()
+}
+
+func Int(value int) Var {
+	return Var{strconv.Itoa(value)}
+}
+
+func Pkg(value string) Var {
+	return Var{value}
+}
+
+func Name(value string) Var {
+	return Var{value}
+}

vendor/github.com/kylelemons/godebug/LICENSE

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
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+      Contribution(s) alone or by combination of their Contribution(s)
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+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
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+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
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+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
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+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

vendor/github.com/kylelemons/godebug/diff/diff.go

@@ -0,0 +1,186 @@
+// Copyright 2013 Google Inc.  All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package diff implements a linewise diff algorithm.
+package diff
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+)
+
+// Chunk represents a piece of the diff.  A chunk will not have both added and
+// deleted lines.  Equal lines are always after any added or deleted lines.
+// A Chunk may or may not have any lines in it, especially for the first or last
+// chunk in a computation.
+type Chunk struct {
+	Added   []string
+	Deleted []string
+	Equal   []string
+}
+
+func (c *Chunk) empty() bool {
+	return len(c.Added) == 0 && len(c.Deleted) == 0 && len(c.Equal) == 0
+}
+
+// Diff returns a string containing a line-by-line unified diff of the linewise
+// changes required to make A into B.  Each line is prefixed with '+', '-', or
+// ' ' to indicate if it should be added, removed, or is correct respectively.
+func Diff(A, B string) string {
+	aLines := strings.Split(A, "\n")
+	bLines := strings.Split(B, "\n")
+
+	chunks := DiffChunks(aLines, bLines)
+
+	buf := new(bytes.Buffer)
+	for _, c := range chunks {
+		for _, line := range c.Added {
+			fmt.Fprintf(buf, "+%s\n", line)
+		}
+		for _, line := range c.Deleted {
+			fmt.Fprintf(buf, "-%s\n", line)
+		}
+		for _, line := range c.Equal {
+			fmt.Fprintf(buf, " %s\n", line)
+		}
+	}
+	return strings.TrimRight(buf.String(), "\n")
+}
+
+// DiffChunks uses an O(D(N+M)) shortest-edit-script algorithm
+// to compute the edits required from A to B and returns the
+// edit chunks.
+func DiffChunks(a, b []string) []Chunk {
+	// algorithm: http://www.xmailserver.org/diff2.pdf
+
+	// We'll need these quantities a lot.
+	alen, blen := len(a), len(b) // M, N
+
+	// At most, it will require len(a) deletions and len(b) additions
+	// to transform a into b.
+	maxPath := alen + blen // MAX
+	if maxPath == 0 {
+		// degenerate case: two empty lists are the same
+		return nil
+	}
+
+	// Store the endpoint of the path for diagonals.
+	// We store only the a index, because the b index on any diagonal
+	// (which we know during the loop below) is aidx-diag.
+	// endpoint[maxPath] represents the 0 diagonal.
+	//
+	// Stated differently:
+	// endpoint[d] contains the aidx of a furthest reaching path in diagonal d
+	endpoint := make([]int, 2*maxPath+1) // V
+
+	saved := make([][]int, 0, 8) // Vs
+	save := func() {
+		dup := make([]int, len(endpoint))
+		copy(dup, endpoint)
+		saved = append(saved, dup)
+	}
+
+	var editDistance int // D
+dLoop:
+	for editDistance = 0; editDistance <= maxPath; editDistance++ {
+		// The 0 diag(onal) represents equality of a and b.  Each diagonal to
+		// the left is numbered one lower, to the right is one higher, from
+		// -alen to +blen.  Negative diagonals favor differences from a,
+		// positive diagonals favor differences from b.  The edit distance to a
+		// diagonal d cannot be shorter than d itself.
+		//
+		// The iterations of this loop cover either odds or evens, but not both,
+		// If odd indices are inputs, even indices are outputs and vice versa.
+		for diag := -editDistance; diag <= editDistance; diag += 2 { // k
+			var aidx int // x
+			switch {
+			case diag == -editDistance:
+				// This is a new diagonal; copy from previous iter
+				aidx = endpoint[maxPath-editDistance+1] + 0
+			case diag == editDistance:
+				// This is a new diagonal; copy from previous iter
+				aidx = endpoint[maxPath+editDistance-1] + 1
+			case endpoint[maxPath+diag+1] > endpoint[maxPath+diag-1]:
+				// diagonal d+1 was farther along, so use that
+				aidx = endpoint[maxPath+diag+1] + 0
+			default:
+				// diagonal d-1 was farther (or the same), so use that
+				aidx = endpoint[maxPath+diag-1] + 1
+			}
+			// On diagonal d, we can compute bidx from aidx.
+			bidx := aidx - diag // y
+			// See how far we can go on this diagonal before we find a difference.
+			for aidx < alen && bidx < blen && a[aidx] == b[bidx] {
+				aidx++
+				bidx++
+			}
+			// Store the end of the current edit chain.
+			endpoint[maxPath+diag] = aidx
+			// If we've found the end of both inputs, we're done!
+			if aidx >= alen && bidx >= blen {
+				save() // save the final path
+				break dLoop
+			}
+		}
+		save() // save the current path
+	}
+	if editDistance == 0 {
+		return nil
+	}
+	chunks := make([]Chunk, editDistance+1)
+
+	x, y := alen, blen
+	for d := editDistance; d > 0; d-- {
+		endpoint := saved[d]
+		diag := x - y
+		insert := diag == -d || (diag != d && endpoint[maxPath+diag-1] < endpoint[maxPath+diag+1])
+
+		x1 := endpoint[maxPath+diag]
+		var x0, xM, kk int
+		if insert {
+			kk = diag + 1
+			x0 = endpoint[maxPath+kk]
+			xM = x0
+		} else {
+			kk = diag - 1
+			x0 = endpoint[maxPath+kk]
+			xM = x0 + 1
+		}
+		y0 := x0 - kk
+
+		var c Chunk
+		if insert {
+			c.Added = b[y0:][:1]
+		} else {
+			c.Deleted = a[x0:][:1]
+		}
+		if xM < x1 {
+			c.Equal = a[xM:][:x1-xM]
+		}
+
+		x, y = x0, y0
+		chunks[d] = c
+	}
+	if x > 0 {
+		chunks[0].Equal = a[:x]
+	}
+	if chunks[0].empty() {
+		chunks = chunks[1:]
+	}
+	if len(chunks) == 0 {
+		return nil
+	}
+	return chunks
+}

vendor/golang.org/x/tools/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/golang.org/x/tools/PATENTS

@@ -0,0 +1,22 @@
+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.

vendor/golang.org/x/tools/go/ast/astutil/enclosing.go

@@ -0,0 +1,627 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package astutil
+
+// This file defines utilities for working with source positions.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"sort"
+)
+
+// PathEnclosingInterval returns the node that encloses the source
+// interval [start, end), and all its ancestors up to the AST root.
+//
+// The definition of "enclosing" used by this function considers
+// additional whitespace abutting a node to be enclosed by it.
+// In this example:
+//
+//              z := x + y // add them
+//                   <-A->
+//                  <----B----->
+//
+// the ast.BinaryExpr(+) node is considered to enclose interval B
+// even though its [Pos()..End()) is actually only interval A.
+// This behaviour makes user interfaces more tolerant of imperfect
+// input.
+//
+// This function treats tokens as nodes, though they are not included
+// in the result. e.g. PathEnclosingInterval("+") returns the
+// enclosing ast.BinaryExpr("x + y").
+//
+// If start==end, the 1-char interval following start is used instead.
+//
+// The 'exact' result is true if the interval contains only path[0]
+// and perhaps some adjacent whitespace.  It is false if the interval
+// overlaps multiple children of path[0], or if it contains only
+// interior whitespace of path[0].
+// In this example:
+//
+//              z := x + y // add them
+//                <--C-->     <---E-->
+//                  ^
+//                  D
+//
+// intervals C, D and E are inexact.  C is contained by the
+// z-assignment statement, because it spans three of its children (:=,
+// x, +).  So too is the 1-char interval D, because it contains only
+// interior whitespace of the assignment.  E is considered interior
+// whitespace of the BlockStmt containing the assignment.
+//
+// Precondition: [start, end) both lie within the same file as root.
+// TODO(adonovan): return (nil, false) in this case and remove precond.
+// Requires FileSet; see loader.tokenFileContainsPos.
+//
+// Postcondition: path is never nil; it always contains at least 'root'.
+//
+func PathEnclosingInterval(root *ast.File, start, end token.Pos) (path []ast.Node, exact bool) {
+	// fmt.Printf("EnclosingInterval %d %d\n", start, end) // debugging
+
+	// Precondition: node.[Pos..End) and adjoining whitespace contain [start, end).
+	var visit func(node ast.Node) bool
+	visit = func(node ast.Node) bool {
+		path = append(path, node)
+
+		nodePos := node.Pos()
+		nodeEnd := node.End()
+
+		// fmt.Printf("visit(%T, %d, %d)\n", node, nodePos, nodeEnd) // debugging
+
+		// Intersect [start, end) with interval of node.
+		if start < nodePos {
+			start = nodePos
+		}
+		if end > nodeEnd {
+			end = nodeEnd
+		}
+
+		// Find sole child that contains [start, end).
+		children := childrenOf(node)
+		l := len(children)
+		for i, child := range children {
+			// [childPos, childEnd) is unaugmented interval of child.
+			childPos := child.Pos()
+			childEnd := child.End()
+
+			// [augPos, augEnd) is whitespace-augmented interval of child.
+			augPos := childPos
+			augEnd := childEnd
+			if i > 0 {
+				augPos = children[i-1].End() // start of preceding whitespace
+			}
+			if i < l-1 {
+				nextChildPos := children[i+1].Pos()
+				// Does [start, end) lie between child and next child?
+				if start >= augEnd && end <= nextChildPos {
+					return false // inexact match
+				}
+				augEnd = nextChildPos // end of following whitespace
+			}
+
+			// fmt.Printf("\tchild %d: [%d..%d)\tcontains interval [%d..%d)?\n",
+			// 	i, augPos, augEnd, start, end) // debugging
+
+			// Does augmented child strictly contain [start, end)?
+			if augPos <= start && end <= augEnd {
+				_, isToken := child.(tokenNode)
+				return isToken || visit(child)
+			}
+
+			// Does [start, end) overlap multiple children?
+			// i.e. left-augmented child contains start
+			// but LR-augmented child does not contain end.
+			if start < childEnd && end > augEnd {
+				break
+			}
+		}
+
+		// No single child contained [start, end),
+		// so node is the result.  Is it exact?
+
+		// (It's tempting to put this condition before the
+		// child loop, but it gives the wrong result in the
+		// case where a node (e.g. ExprStmt) and its sole
+		// child have equal intervals.)
+		if start == nodePos && end == nodeEnd {
+			return true // exact match
+		}
+
+		return false // inexact: overlaps multiple children
+	}
+
+	if start > end {
+		start, end = end, start
+	}
+
+	if start < root.End() && end > root.Pos() {
+		if start == end {
+			end = start + 1 // empty interval => interval of size 1
+		}
+		exact = visit(root)
+
+		// Reverse the path:
+		for i, l := 0, len(path); i < l/2; i++ {
+			path[i], path[l-1-i] = path[l-1-i], path[i]
+		}
+	} else {
+		// Selection lies within whitespace preceding the
+		// first (or following the last) declaration in the file.
+		// The result nonetheless always includes the ast.File.
+		path = append(path, root)
+	}
+
+	return
+}
+
+// tokenNode is a dummy implementation of ast.Node for a single token.
+// They are used transiently by PathEnclosingInterval but never escape
+// this package.
+//
+type tokenNode struct {
+	pos token.Pos
+	end token.Pos
+}
+
+func (n tokenNode) Pos() token.Pos {
+	return n.pos
+}
+
+func (n tokenNode) End() token.Pos {
+	return n.end
+}
+
+func tok(pos token.Pos, len int) ast.Node {
+	return tokenNode{pos, pos + token.Pos(len)}
+}
+
+// childrenOf returns the direct non-nil children of ast.Node n.
+// It may include fake ast.Node implementations for bare tokens.
+// it is not safe to call (e.g.) ast.Walk on such nodes.
+//
+func childrenOf(n ast.Node) []ast.Node {
+	var children []ast.Node
+
+	// First add nodes for all true subtrees.
+	ast.Inspect(n, func(node ast.Node) bool {
+		if node == n { // push n
+			return true // recur
+		}
+		if node != nil { // push child
+			children = append(children, node)
+		}
+		return false // no recursion
+	})
+
+	// Then add fake Nodes for bare tokens.
+	switch n := n.(type) {
+	case *ast.ArrayType:
+		children = append(children,
+			tok(n.Lbrack, len("[")),
+			tok(n.Elt.End(), len("]")))
+
+	case *ast.AssignStmt:
+		children = append(children,
+			tok(n.TokPos, len(n.Tok.String())))
+
+	case *ast.BasicLit:
+		children = append(children,
+			tok(n.ValuePos, len(n.Value)))
+
+	case *ast.BinaryExpr:
+		children = append(children, tok(n.OpPos, len(n.Op.String())))
+
+	case *ast.BlockStmt:
+		children = append(children,
+			tok(n.Lbrace, len("{")),
+			tok(n.Rbrace, len("}")))
+
+	case *ast.BranchStmt:
+		children = append(children,
+			tok(n.TokPos, len(n.Tok.String())))
+
+	case *ast.CallExpr:
+		children = append(children,
+			tok(n.Lparen, len("(")),
+			tok(n.Rparen, len(")")))
+		if n.Ellipsis != 0 {
+			children = append(children, tok(n.Ellipsis, len("...")))
+		}
+
+	case *ast.CaseClause:
+		if n.List == nil {
+			children = append(children,
+				tok(n.Case, len("default")))
+		} else {
+			children = append(children,
+				tok(n.Case, len("case")))
+		}
+		children = append(children, tok(n.Colon, len(":")))
+
+	case *ast.ChanType:
+		switch n.Dir {
+		case ast.RECV:
+			children = append(children, tok(n.Begin, len("<-chan")))
+		case ast.SEND:
+			children = append(children, tok(n.Begin, len("chan<-")))
+		case ast.RECV | ast.SEND:
+			children = append(children, tok(n.Begin, len("chan")))
+		}
+
+	case *ast.CommClause:
+		if n.Comm == nil {
+			children = append(children,
+				tok(n.Case, len("default")))
+		} else {
+			children = append(children,
+				tok(n.Case, len("case")))
+		}
+		children = append(children, tok(n.Colon, len(":")))
+
+	case *ast.Comment:
+		// nop
+
+	case *ast.CommentGroup:
+		// nop
+
+	case *ast.CompositeLit:
+		children = append(children,
+			tok(n.Lbrace, len("{")),
+			tok(n.Rbrace, len("{")))
+
+	case *ast.DeclStmt:
+		// nop
+
+	case *ast.DeferStmt:
+		children = append(children,
+			tok(n.Defer, len("defer")))
+
+	case *ast.Ellipsis:
+		children = append(children,
+			tok(n.Ellipsis, len("...")))
+
+	case *ast.EmptyStmt:
+		// nop
+
+	case *ast.ExprStmt:
+		// nop
+
+	case *ast.Field:
+		// TODO(adonovan): Field.{Doc,Comment,Tag}?
+
+	case *ast.FieldList:
+		children = append(children,
+			tok(n.Opening, len("(")),
+			tok(n.Closing, len(")")))
+
+	case *ast.File:
+		// TODO test: Doc
+		children = append(children,
+			tok(n.Package, len("package")))
+
+	case *ast.ForStmt:
+		children = append(children,
+			tok(n.For, len("for")))
+
+	case *ast.FuncDecl:
+		// TODO(adonovan): FuncDecl.Comment?
+
+		// Uniquely, FuncDecl breaks the invariant that
+		// preorder traversal yields tokens in lexical order:
+		// in fact, FuncDecl.Recv precedes FuncDecl.Type.Func.
+		//
+		// As a workaround, we inline the case for FuncType
+		// here and order things correctly.
+		//
+		children = nil // discard ast.Walk(FuncDecl) info subtrees
+		children = append(children, tok(n.Type.Func, len("func")))
+		if n.Recv != nil {
+			children = append(children, n.Recv)
+		}
+		children = append(children, n.Name)
+		if n.Type.Params != nil {
+			children = append(children, n.Type.Params)
+		}
+		if n.Type.Results != nil {
+			children = append(children, n.Type.Results)
+		}
+		if n.Body != nil {
+			children = append(children, n.Body)
+		}
+
+	case *ast.FuncLit:
+		// nop
+
+	case *ast.FuncType:
+		if n.Func != 0 {
+			children = append(children,
+				tok(n.Func, len("func")))
+		}
+
+	case *ast.GenDecl:
+		children = append(children,
+			tok(n.TokPos, len(n.Tok.String())))
+		if n.Lparen != 0 {
+			children = append(children,
+				tok(n.Lparen, len("(")),
+				tok(n.Rparen, len(")")))
+		}
+
+	case *ast.GoStmt:
+		children = append(children,
+			tok(n.Go, len("go")))
+
+	case *ast.Ident:
+		children = append(children,
+			tok(n.NamePos, len(n.Name)))
+
+	case *ast.IfStmt:
+		children = append(children,
+			tok(n.If, len("if")))
+
+	case *ast.ImportSpec:
+		// TODO(adonovan): ImportSpec.{Doc,EndPos}?
+
+	case *ast.IncDecStmt:
+		children = append(children,
+			tok(n.TokPos, len(n.Tok.String())))
+
+	case *ast.IndexExpr:
+		children = append(children,
+			tok(n.Lbrack, len("{")),
+			tok(n.Rbrack, len("}")))
+
+	case *ast.InterfaceType:
+		children = append(children,
+			tok(n.Interface, len("interface")))
+
+	case *ast.KeyValueExpr:
+		children = append(children,
+			tok(n.Colon, len(":")))
+
+	case *ast.LabeledStmt:
+		children = append(children,
+			tok(n.Colon, len(":")))
+
+	case *ast.MapType:
+		children = append(children,
+			tok(n.Map, len("map")))
+
+	case *ast.ParenExpr:
+		children = append(children,
+			tok(n.Lparen, len("(")),
+			tok(n.Rparen, len(")")))
+
+	case *ast.RangeStmt:
+		children = append(children,
+			tok(n.For, len("for")),
+			tok(n.TokPos, len(n.Tok.String())))
+
+	case *ast.ReturnStmt:
+		children = append(children,
+			tok(n.Return, len("return")))
+
+	case *ast.SelectStmt:
+		children = append(children,
+			tok(n.Select, len("select")))
+
+	case *ast.SelectorExpr:
+		// nop
+
+	case *ast.SendStmt:
+		children = append(children,
+			tok(n.Arrow, len("<-")))
+
+	case *ast.SliceExpr:
+		children = append(children,
+			tok(n.Lbrack, len("[")),
+			tok(n.Rbrack, len("]")))
+
+	case *ast.StarExpr:
+		children = append(children, tok(n.Star, len("*")))
+
+	case *ast.StructType:
+		children = append(children, tok(n.Struct, len("struct")))
+
+	case *ast.SwitchStmt:
+		children = append(children, tok(n.Switch, len("switch")))
+
+	case *ast.TypeAssertExpr:
+		children = append(children,
+			tok(n.Lparen-1, len(".")),
+			tok(n.Lparen, len("(")),
+			tok(n.Rparen, len(")")))
+
+	case *ast.TypeSpec:
+		// TODO(adonovan): TypeSpec.{Doc,Comment}?
+
+	case *ast.TypeSwitchStmt:
+		children = append(children, tok(n.Switch, len("switch")))
+
+	case *ast.UnaryExpr:
+		children = append(children, tok(n.OpPos, len(n.Op.String())))
+
+	case *ast.ValueSpec:
+		// TODO(adonovan): ValueSpec.{Doc,Comment}?
+
+	case *ast.BadDecl, *ast.BadExpr, *ast.BadStmt:
+		// nop
+	}
+
+	// TODO(adonovan): opt: merge the logic of ast.Inspect() into
+	// the switch above so we can make interleaved callbacks for
+	// both Nodes and Tokens in the right order and avoid the need
+	// to sort.
+	sort.Sort(byPos(children))
+
+	return children
+}
+
+type byPos []ast.Node
+
+func (sl byPos) Len() int {
+	return len(sl)
+}
+func (sl byPos) Less(i, j int) bool {
+	return sl[i].Pos() < sl[j].Pos()
+}
+func (sl byPos) Swap(i, j int) {
+	sl[i], sl[j] = sl[j], sl[i]
+}
+
+// NodeDescription returns a description of the concrete type of n suitable
+// for a user interface.
+//
+// TODO(adonovan): in some cases (e.g. Field, FieldList, Ident,
+// StarExpr) we could be much more specific given the path to the AST
+// root.  Perhaps we should do that.
+//
+func NodeDescription(n ast.Node) string {
+	switch n := n.(type) {
+	case *ast.ArrayType:
+		return "array type"
+	case *ast.AssignStmt:
+		return "assignment"
+	case *ast.BadDecl:
+		return "bad declaration"
+	case *ast.BadExpr:
+		return "bad expression"
+	case *ast.BadStmt:
+		return "bad statement"
+	case *ast.BasicLit:
+		return "basic literal"
+	case *ast.BinaryExpr:
+		return fmt.Sprintf("binary %s operation", n.Op)
+	case *ast.BlockStmt:
+		return "block"
+	case *ast.BranchStmt:
+		switch n.Tok {
+		case token.BREAK:
+			return "break statement"
+		case token.CONTINUE:
+			return "continue statement"
+		case token.GOTO:
+			return "goto statement"
+		case token.FALLTHROUGH:
+			return "fall-through statement"
+		}
+	case *ast.CallExpr:
+		if len(n.Args) == 1 && !n.Ellipsis.IsValid() {
+			return "function call (or conversion)"
+		}
+		return "function call"
+	case *ast.CaseClause:
+		return "case clause"
+	case *ast.ChanType:
+		return "channel type"
+	case *ast.CommClause:
+		return "communication clause"
+	case *ast.Comment:
+		return "comment"
+	case *ast.CommentGroup:
+		return "comment group"
+	case *ast.CompositeLit:
+		return "composite literal"
+	case *ast.DeclStmt:
+		return NodeDescription(n.Decl) + " statement"
+	case *ast.DeferStmt:
+		return "defer statement"
+	case *ast.Ellipsis:
+		return "ellipsis"
+	case *ast.EmptyStmt:
+		return "empty statement"
+	case *ast.ExprStmt:
+		return "expression statement"
+	case *ast.Field:
+		// Can be any of these:
+		// struct {x, y int}  -- struct field(s)
+		// struct {T}         -- anon struct field
+		// interface {I}      -- interface embedding
+		// interface {f()}    -- interface method
+		// func (A) func(B) C -- receiver, param(s), result(s)
+		return "field/method/parameter"
+	case *ast.FieldList:
+		return "field/method/parameter list"
+	case *ast.File:
+		return "source file"
+	case *ast.ForStmt:
+		return "for loop"
+	case *ast.FuncDecl:
+		return "function declaration"
+	case *ast.FuncLit:
+		return "function literal"
+	case *ast.FuncType:
+		return "function type"
+	case *ast.GenDecl:
+		switch n.Tok {
+		case token.IMPORT:
+			return "import declaration"
+		case token.CONST:
+			return "constant declaration"
+		case token.TYPE:
+			return "type declaration"
+		case token.VAR:
+			return "variable declaration"
+		}
+	case *ast.GoStmt:
+		return "go statement"
+	case *ast.Ident:
+		return "identifier"
+	case *ast.IfStmt:
+		return "if statement"
+	case *ast.ImportSpec:
+		return "import specification"
+	case *ast.IncDecStmt:
+		if n.Tok == token.INC {
+			return "increment statement"
+		}
+		return "decrement statement"
+	case *ast.IndexExpr:
+		return "index expression"
+	case *ast.InterfaceType:
+		return "interface type"
+	case *ast.KeyValueExpr:
+		return "key/value association"
+	case *ast.LabeledStmt:
+		return "statement label"
+	case *ast.MapType:
+		return "map type"
+	case *ast.Package:
+		return "package"
+	case *ast.ParenExpr:
+		return "parenthesized " + NodeDescription(n.X)
+	case *ast.RangeStmt:
+		return "range loop"
+	case *ast.ReturnStmt:
+		return "return statement"
+	case *ast.SelectStmt:
+		return "select statement"
+	case *ast.SelectorExpr:
+		return "selector"
+	case *ast.SendStmt:
+		return "channel send"
+	case *ast.SliceExpr:
+		return "slice expression"
+	case *ast.StarExpr:
+		return "*-operation" // load/store expr or pointer type
+	case *ast.StructType:
+		return "struct type"
+	case *ast.SwitchStmt:
+		return "switch statement"
+	case *ast.TypeAssertExpr:
+		return "type assertion"
+	case *ast.TypeSpec:
+		return "type specification"
+	case *ast.TypeSwitchStmt:
+		return "type switch"
+	case *ast.UnaryExpr:
+		return fmt.Sprintf("unary %s operation", n.Op)
+	case *ast.ValueSpec:
+		return "value specification"
+
+	}
+	panic(fmt.Sprintf("unexpected node type: %T", n))
+}

vendor/golang.org/x/tools/go/ast/astutil/imports.go

@@ -0,0 +1,450 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package astutil contains common utilities for working with the Go AST.
+package astutil // import "golang.org/x/tools/go/ast/astutil"
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"strconv"
+	"strings"
+)
+
+// AddImport adds the import path to the file f, if absent.
+func AddImport(fset *token.FileSet, f *ast.File, ipath string) (added bool) {
+	return AddNamedImport(fset, f, "", ipath)
+}
+
+// AddNamedImport adds the import path to the file f, if absent.
+// If name is not empty, it is used to rename the import.
+//
+// For example, calling
+//	AddNamedImport(fset, f, "pathpkg", "path")
+// adds
+//	import pathpkg "path"
+func AddNamedImport(fset *token.FileSet, f *ast.File, name, ipath string) (added bool) {
+	if imports(f, ipath) {
+		return false
+	}
+
+	newImport := &ast.ImportSpec{
+		Path: &ast.BasicLit{
+			Kind:  token.STRING,
+			Value: strconv.Quote(ipath),
+		},
+	}
+	if name != "" {
+		newImport.Name = &ast.Ident{Name: name}
+	}
+
+	// Find an import decl to add to.
+	// The goal is to find an existing import
+	// whose import path has the longest shared
+	// prefix with ipath.
+	var (
+		bestMatch  = -1         // length of longest shared prefix
+		lastImport = -1         // index in f.Decls of the file's final import decl
+		impDecl    *ast.GenDecl // import decl containing the best match
+		impIndex   = -1         // spec index in impDecl containing the best match
+	)
+	for i, decl := range f.Decls {
+		gen, ok := decl.(*ast.GenDecl)
+		if ok && gen.Tok == token.IMPORT {
+			lastImport = i
+			// Do not add to import "C", to avoid disrupting the
+			// association with its doc comment, breaking cgo.
+			if declImports(gen, "C") {
+				continue
+			}
+
+			// Match an empty import decl if that's all that is available.
+			if len(gen.Specs) == 0 && bestMatch == -1 {
+				impDecl = gen
+			}
+
+			// Compute longest shared prefix with imports in this group.
+			for j, spec := range gen.Specs {
+				impspec := spec.(*ast.ImportSpec)
+				n := matchLen(importPath(impspec), ipath)
+				if n > bestMatch {
+					bestMatch = n
+					impDecl = gen
+					impIndex = j
+				}
+			}
+		}
+	}
+
+	// If no import decl found, add one after the last import.
+	if impDecl == nil {
+		impDecl = &ast.GenDecl{
+			Tok: token.IMPORT,
+		}
+		if lastImport >= 0 {
+			impDecl.TokPos = f.Decls[lastImport].End()
+		} else {
+			// There are no existing imports.
+			// Our new import goes after the package declaration and after
+			// the comment, if any, that starts on the same line as the
+			// package declaration.
+			impDecl.TokPos = f.Package
+
+			file := fset.File(f.Package)
+			pkgLine := file.Line(f.Package)
+			for _, c := range f.Comments {
+				if file.Line(c.Pos()) > pkgLine {
+					break
+				}
+				impDecl.TokPos = c.End()
+			}
+		}
+		f.Decls = append(f.Decls, nil)
+		copy(f.Decls[lastImport+2:], f.Decls[lastImport+1:])
+		f.Decls[lastImport+1] = impDecl
+	}
+
+	// Insert new import at insertAt.
+	insertAt := 0
+	if impIndex >= 0 {
+		// insert after the found import
+		insertAt = impIndex + 1
+	}
+	impDecl.Specs = append(impDecl.Specs, nil)
+	copy(impDecl.Specs[insertAt+1:], impDecl.Specs[insertAt:])
+	impDecl.Specs[insertAt] = newImport
+	pos := impDecl.Pos()
+	if insertAt > 0 {
+		// If there is a comment after an existing import, preserve the comment
+		// position by adding the new import after the comment.
+		if spec, ok := impDecl.Specs[insertAt-1].(*ast.ImportSpec); ok && spec.Comment != nil {
+			pos = spec.Comment.End()
+		} else {
+			// Assign same position as the previous import,
+			// so that the sorter sees it as being in the same block.
+			pos = impDecl.Specs[insertAt-1].Pos()
+		}
+	}
+	if newImport.Name != nil {
+		newImport.Name.NamePos = pos
+	}
+	newImport.Path.ValuePos = pos
+	newImport.EndPos = pos
+
+	// Clean up parens. impDecl contains at least one spec.
+	if len(impDecl.Specs) == 1 {
+		// Remove unneeded parens.
+		impDecl.Lparen = token.NoPos
+	} else if !impDecl.Lparen.IsValid() {
+		// impDecl needs parens added.
+		impDecl.Lparen = impDecl.Specs[0].Pos()
+	}
+
+	f.Imports = append(f.Imports, newImport)
+
+	if len(f.Decls) <= 1 {
+		return true
+	}
+
+	// Merge all the import declarations into the first one.
+	var first *ast.GenDecl
+	for i := 0; i < len(f.Decls); i++ {
+		decl := f.Decls[i]
+		gen, ok := decl.(*ast.GenDecl)
+		if !ok || gen.Tok != token.IMPORT || declImports(gen, "C") {
+			continue
+		}
+		if first == nil {
+			first = gen
+			continue // Don't touch the first one.
+		}
+		// We now know there is more than one package in this import
+		// declaration. Ensure that it ends up parenthesized.
+		first.Lparen = first.Pos()
+		// Move the imports of the other import declaration to the first one.
+		for _, spec := range gen.Specs {
+			spec.(*ast.ImportSpec).Path.ValuePos = first.Pos()
+			first.Specs = append(first.Specs, spec)
+		}
+		f.Decls = append(f.Decls[:i], f.Decls[i+1:]...)
+		i--
+	}
+
+	return true
+}
+
+// DeleteImport deletes the import path from the file f, if present.
+func DeleteImport(fset *token.FileSet, f *ast.File, path string) (deleted bool) {
+	return DeleteNamedImport(fset, f, "", path)
+}
+
+// DeleteNamedImport deletes the import with the given name and path from the file f, if present.
+func DeleteNamedImport(fset *token.FileSet, f *ast.File, name, path string) (deleted bool) {
+	var delspecs []*ast.ImportSpec
+	var delcomments []*ast.CommentGroup
+
+	// Find the import nodes that import path, if any.
+	for i := 0; i < len(f.Decls); i++ {
+		decl := f.Decls[i]
+		gen, ok := decl.(*ast.GenDecl)
+		if !ok || gen.Tok != token.IMPORT {
+			continue
+		}
+		for j := 0; j < len(gen.Specs); j++ {
+			spec := gen.Specs[j]
+			impspec := spec.(*ast.ImportSpec)
+			if impspec.Name == nil && name != "" {
+				continue
+			}
+			if impspec.Name != nil && impspec.Name.Name != name {
+				continue
+			}
+			if importPath(impspec) != path {
+				continue
+			}
+
+			// We found an import spec that imports path.
+			// Delete it.
+			delspecs = append(delspecs, impspec)
+			deleted = true
+			copy(gen.Specs[j:], gen.Specs[j+1:])
+			gen.Specs = gen.Specs[:len(gen.Specs)-1]
+
+			// If this was the last import spec in this decl,
+			// delete the decl, too.
+			if len(gen.Specs) == 0 {
+				copy(f.Decls[i:], f.Decls[i+1:])
+				f.Decls = f.Decls[:len(f.Decls)-1]
+				i--
+				break
+			} else if len(gen.Specs) == 1 {
+				if impspec.Doc != nil {
+					delcomments = append(delcomments, impspec.Doc)
+				}
+				if impspec.Comment != nil {
+					delcomments = append(delcomments, impspec.Comment)
+				}
+				for _, cg := range f.Comments {
+					// Found comment on the same line as the import spec.
+					if cg.End() < impspec.Pos() && fset.Position(cg.End()).Line == fset.Position(impspec.Pos()).Line {
+						delcomments = append(delcomments, cg)
+						break
+					}
+				}
+
+				spec := gen.Specs[0].(*ast.ImportSpec)
+
+				// Move the documentation right after the import decl.
+				if spec.Doc != nil {
+					for fset.Position(gen.TokPos).Line+1 < fset.Position(spec.Doc.Pos()).Line {
+						fset.File(gen.TokPos).MergeLine(fset.Position(gen.TokPos).Line)
+					}
+				}
+				for _, cg := range f.Comments {
+					if cg.End() < spec.Pos() && fset.Position(cg.End()).Line == fset.Position(spec.Pos()).Line {
+						for fset.Position(gen.TokPos).Line+1 < fset.Position(spec.Pos()).Line {
+							fset.File(gen.TokPos).MergeLine(fset.Position(gen.TokPos).Line)
+						}
+						break
+					}
+				}
+			}
+			if j > 0 {
+				lastImpspec := gen.Specs[j-1].(*ast.ImportSpec)
+				lastLine := fset.Position(lastImpspec.Path.ValuePos).Line
+				line := fset.Position(impspec.Path.ValuePos).Line
+
+				// We deleted an entry but now there may be
+				// a blank line-sized hole where the import was.
+				if line-lastLine > 1 {
+					// There was a blank line immediately preceding the deleted import,
+					// so there's no need to close the hole.
+					// Do nothing.
+				} else {
+					// There was no blank line. Close the hole.
+					fset.File(gen.Rparen).MergeLine(line)
+				}
+			}
+			j--
+		}
+	}
+
+	// Delete imports from f.Imports.
+	for i := 0; i < len(f.Imports); i++ {
+		imp := f.Imports[i]
+		for j, del := range delspecs {
+			if imp == del {
+				copy(f.Imports[i:], f.Imports[i+1:])
+				f.Imports = f.Imports[:len(f.Imports)-1]
+				copy(delspecs[j:], delspecs[j+1:])
+				delspecs = delspecs[:len(delspecs)-1]
+				i--
+				break
+			}
+		}
+	}
+
+	// Delete comments from f.Comments.
+	for i := 0; i < len(f.Comments); i++ {
+		cg := f.Comments[i]
+		for j, del := range delcomments {
+			if cg == del {
+				copy(f.Comments[i:], f.Comments[i+1:])
+				f.Comments = f.Comments[:len(f.Comments)-1]
+				copy(delcomments[j:], delcomments[j+1:])
+				delcomments = delcomments[:len(delcomments)-1]
+				i--
+				break
+			}
+		}
+	}
+
+	if len(delspecs) > 0 {
+		panic(fmt.Sprintf("deleted specs from Decls but not Imports: %v", delspecs))
+	}
+
+	return
+}
+
+// RewriteImport rewrites any import of path oldPath to path newPath.
+func RewriteImport(fset *token.FileSet, f *ast.File, oldPath, newPath string) (rewrote bool) {
+	for _, imp := range f.Imports {
+		if importPath(imp) == oldPath {
+			rewrote = true
+			// record old End, because the default is to compute
+			// it using the length of imp.Path.Value.
+			imp.EndPos = imp.End()
+			imp.Path.Value = strconv.Quote(newPath)
+		}
+	}
+	return
+}
+
+// UsesImport reports whether a given import is used.
+func UsesImport(f *ast.File, path string) (used bool) {
+	spec := importSpec(f, path)
+	if spec == nil {
+		return
+	}
+
+	name := spec.Name.String()
+	switch name {
+	case "<nil>":
+		// If the package name is not explicitly specified,
+		// make an educated guess. This is not guaranteed to be correct.
+		lastSlash := strings.LastIndex(path, "/")
+		if lastSlash == -1 {
+			name = path
+		} else {
+			name = path[lastSlash+1:]
+		}
+	case "_", ".":
+		// Not sure if this import is used - err on the side of caution.
+		return true
+	}
+
+	ast.Walk(visitFn(func(n ast.Node) {
+		sel, ok := n.(*ast.SelectorExpr)
+		if ok && isTopName(sel.X, name) {
+			used = true
+		}
+	}), f)
+
+	return
+}
+
+type visitFn func(node ast.Node)
+
+func (fn visitFn) Visit(node ast.Node) ast.Visitor {
+	fn(node)
+	return fn
+}
+
+// imports returns true if f imports path.
+func imports(f *ast.File, path string) bool {
+	return importSpec(f, path) != nil
+}
+
+// importSpec returns the import spec if f imports path,
+// or nil otherwise.
+func importSpec(f *ast.File, path string) *ast.ImportSpec {
+	for _, s := range f.Imports {
+		if importPath(s) == path {
+			return s
+		}
+	}
+	return nil
+}
+
+// importPath returns the unquoted import path of s,
+// or "" if the path is not properly quoted.
+func importPath(s *ast.ImportSpec) string {
+	t, err := strconv.Unquote(s.Path.Value)
+	if err == nil {
+		return t
+	}
+	return ""
+}
+
+// declImports reports whether gen contains an import of path.
+func declImports(gen *ast.GenDecl, path string) bool {
+	if gen.Tok != token.IMPORT {
+		return false
+	}
+	for _, spec := range gen.Specs {
+		impspec := spec.(*ast.ImportSpec)
+		if importPath(impspec) == path {
+			return true
+		}
+	}
+	return false
+}
+
+// matchLen returns the length of the longest path segment prefix shared by x and y.
+func matchLen(x, y string) int {
+	n := 0
+	for i := 0; i < len(x) && i < len(y) && x[i] == y[i]; i++ {
+		if x[i] == '/' {
+			n++
+		}
+	}
+	return n
+}
+
+// isTopName returns true if n is a top-level unresolved identifier with the given name.
+func isTopName(n ast.Expr, name string) bool {
+	id, ok := n.(*ast.Ident)
+	return ok && id.Name == name && id.Obj == nil
+}
+
+// Imports returns the file imports grouped by paragraph.
+func Imports(fset *token.FileSet, f *ast.File) [][]*ast.ImportSpec {
+	var groups [][]*ast.ImportSpec
+
+	for _, decl := range f.Decls {
+		genDecl, ok := decl.(*ast.GenDecl)
+		if !ok || genDecl.Tok != token.IMPORT {
+			break
+		}
+
+		group := []*ast.ImportSpec{}
+
+		var lastLine int
+		for _, spec := range genDecl.Specs {
+			importSpec := spec.(*ast.ImportSpec)
+			pos := importSpec.Path.ValuePos
+			line := fset.Position(pos).Line
+			if lastLine > 0 && pos > 0 && line-lastLine > 1 {
+				groups = append(groups, group)
+				group = []*ast.ImportSpec{}
+			}
+			group = append(group, importSpec)
+			lastLine = line
+		}
+		groups = append(groups, group)
+	}
+
+	return groups
+}

vendor/golang.org/x/tools/go/ast/astutil/util.go

@@ -0,0 +1,14 @@
+package astutil
+
+import "go/ast"
+
+// Unparen returns e with any enclosing parentheses stripped.
+func Unparen(e ast.Expr) ast.Expr {
+	for {
+		p, ok := e.(*ast.ParenExpr)
+		if !ok {
+			return e
+		}
+		e = p.X
+	}
+}

vendor/golang.org/x/tools/imports/fastwalk.go

@@ -0,0 +1,172 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// A faster implementation of filepath.Walk.
+//
+// filepath.Walk's design necessarily calls os.Lstat on each file,
+// even if the caller needs less info. And goimports only need to know
+// the type of each file. The kernel interface provides the type in
+// the Readdir call but the standard library ignored it.
+// fastwalk_unix.go contains a fork of the syscall routines.
+//
+// See golang.org/issue/16399
+
+package imports
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"runtime"
+)
+
+// traverseLink is a sentinel error for fastWalk, similar to filepath.SkipDir.
+var traverseLink = errors.New("traverse symlink, assuming target is a directory")
+
+// fastWalk walks the file tree rooted at root, calling walkFn for
+// each file or directory in the tree, including root.
+//
+// If fastWalk returns filepath.SkipDir, the directory is skipped.
+//
+// Unlike filepath.Walk:
+//   * file stat calls must be done by the user.
+//     The only provided metadata is the file type, which does not include
+//     any permission bits.
+//   * multiple goroutines stat the filesystem concurrently. The provided
+//     walkFn must be safe for concurrent use.
+//   * fastWalk can follow symlinks if walkFn returns the traverseLink
+//     sentinel error. It is the walkFn's responsibility to prevent
+//     fastWalk from going into symlink cycles.
+func fastWalk(root string, walkFn func(path string, typ os.FileMode) error) error {
+	// TODO(bradfitz): make numWorkers configurable? We used a
+	// minimum of 4 to give the kernel more info about multiple
+	// things we want, in hopes its I/O scheduling can take
+	// advantage of that. Hopefully most are in cache. Maybe 4 is
+	// even too low of a minimum. Profile more.
+	numWorkers := 4
+	if n := runtime.NumCPU(); n > numWorkers {
+		numWorkers = n
+	}
+	w := &walker{
+		fn:       walkFn,
+		enqueuec: make(chan walkItem, numWorkers), // buffered for performance
+		workc:    make(chan walkItem, numWorkers), // buffered for performance
+		donec:    make(chan struct{}),
+
+		// buffered for correctness & not leaking goroutines:
+		resc: make(chan error, numWorkers),
+	}
+	defer close(w.donec)
+	// TODO(bradfitz): start the workers as needed? maybe not worth it.
+	for i := 0; i < numWorkers; i++ {
+		go w.doWork()
+	}
+	todo := []walkItem{{dir: root}}
+	out := 0
+	for {
+		workc := w.workc
+		var workItem walkItem
+		if len(todo) == 0 {
+			workc = nil
+		} else {
+			workItem = todo[len(todo)-1]
+		}
+		select {
+		case workc <- workItem:
+			todo = todo[:len(todo)-1]
+			out++
+		case it := <-w.enqueuec:
+			todo = append(todo, it)
+		case err := <-w.resc:
+			out--
+			if err != nil {
+				return err
+			}
+			if out == 0 && len(todo) == 0 {
+				// It's safe to quit here, as long as the buffered
+				// enqueue channel isn't also readable, which might
+				// happen if the worker sends both another unit of
+				// work and its result before the other select was
+				// scheduled and both w.resc and w.enqueuec were
+				// readable.
+				select {
+				case it := <-w.enqueuec:
+					todo = append(todo, it)
+				default:
+					return nil
+				}
+			}
+		}
+	}
+}
+
+// doWork reads directories as instructed (via workc) and runs the
+// user's callback function.
+func (w *walker) doWork() {
+	for {
+		select {
+		case <-w.donec:
+			return
+		case it := <-w.workc:
+			w.resc <- w.walk(it.dir, !it.callbackDone)
+		}
+	}
+}
+
+type walker struct {
+	fn func(path string, typ os.FileMode) error
+
+	donec    chan struct{} // closed on fastWalk's return
+	workc    chan walkItem // to workers
+	enqueuec chan walkItem // from workers
+	resc     chan error    // from workers
+}
+
+type walkItem struct {
+	dir          string
+	callbackDone bool // callback already called; don't do it again
+}
+
+func (w *walker) enqueue(it walkItem) {
+	select {
+	case w.enqueuec <- it:
+	case <-w.donec:
+	}
+}
+
+func (w *walker) onDirEnt(dirName, baseName string, typ os.FileMode) error {
+	joined := dirName + string(os.PathSeparator) + baseName
+	if typ == os.ModeDir {
+		w.enqueue(walkItem{dir: joined})
+		return nil
+	}
+
+	err := w.fn(joined, typ)
+	if typ == os.ModeSymlink {
+		if err == traverseLink {
+			// Set callbackDone so we don't call it twice for both the
+			// symlink-as-symlink and the symlink-as-directory later:
+			w.enqueue(walkItem{dir: joined, callbackDone: true})
+			return nil
+		}
+		if err == filepath.SkipDir {
+			// Permit SkipDir on symlinks too.
+			return nil
+		}
+	}
+	return err
+}
+func (w *walker) walk(root string, runUserCallback bool) error {
+	if runUserCallback {
+		err := w.fn(root, os.ModeDir)
+		if err == filepath.SkipDir {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+	}
+
+	return readDir(root, w.onDirEnt)
+}

vendor/golang.org/x/tools/imports/fastwalk_dirent_fileno.go

@@ -0,0 +1,13 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build freebsd openbsd netbsd
+
+package imports
+
+import "syscall"
+
+func direntInode(dirent *syscall.Dirent) uint64 {
+	return uint64(dirent.Fileno)
+}

vendor/golang.org/x/tools/imports/fastwalk_dirent_ino.go

@@ -0,0 +1,13 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux,!appengine darwin
+
+package imports
+
+import "syscall"
+
+func direntInode(dirent *syscall.Dirent) uint64 {
+	return uint64(dirent.Ino)
+}

vendor/golang.org/x/tools/imports/fastwalk_portable.go

@@ -0,0 +1,29 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build appengine !linux,!darwin,!freebsd,!openbsd,!netbsd
+
+package imports
+
+import (
+	"io/ioutil"
+	"os"
+)
+
+// readDir calls fn for each directory entry in dirName.
+// It does not descend into directories or follow symlinks.
+// If fn returns a non-nil error, readDir returns with that error
+// immediately.
+func readDir(dirName string, fn func(dirName, entName string, typ os.FileMode) error) error {
+	fis, err := ioutil.ReadDir(dirName)
+	if err != nil {
+		return err
+	}
+	for _, fi := range fis {
+		if err := fn(dirName, fi.Name(), fi.Mode()&os.ModeType); err != nil {
+			return err
+		}
+	}
+	return nil
+}

vendor/golang.org/x/tools/imports/fastwalk_unix.go

@@ -0,0 +1,122 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux,!appengine darwin freebsd openbsd netbsd
+
+package imports
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+const blockSize = 8 << 10
+
+// unknownFileMode is a sentinel (and bogus) os.FileMode
+// value used to represent a syscall.DT_UNKNOWN Dirent.Type.
+const unknownFileMode os.FileMode = os.ModeNamedPipe | os.ModeSocket | os.ModeDevice
+
+func readDir(dirName string, fn func(dirName, entName string, typ os.FileMode) error) error {
+	fd, err := syscall.Open(dirName, 0, 0)
+	if err != nil {
+		return err
+	}
+	defer syscall.Close(fd)
+
+	// The buffer must be at least a block long.
+	buf := make([]byte, blockSize) // stack-allocated; doesn't escape
+	bufp := 0                      // starting read position in buf
+	nbuf := 0                      // end valid data in buf
+	for {
+		if bufp >= nbuf {
+			bufp = 0
+			nbuf, err = syscall.ReadDirent(fd, buf)
+			if err != nil {
+				return os.NewSyscallError("readdirent", err)
+			}
+			if nbuf <= 0 {
+				return nil
+			}
+		}
+		consumed, name, typ := parseDirEnt(buf[bufp:nbuf])
+		bufp += consumed
+		if name == "" || name == "." || name == ".." {
+			continue
+		}
+		// Fallback for filesystems (like old XFS) that don't
+		// support Dirent.Type and have DT_UNKNOWN (0) there
+		// instead.
+		if typ == unknownFileMode {
+			fi, err := os.Lstat(dirName + "/" + name)
+			if err != nil {
+				// It got deleted in the meantime.
+				if os.IsNotExist(err) {
+					continue
+				}
+				return err
+			}
+			typ = fi.Mode() & os.ModeType
+		}
+		if err := fn(dirName, name, typ); err != nil {
+			return err
+		}
+	}
+}
+
+func parseDirEnt(buf []byte) (consumed int, name string, typ os.FileMode) {
+	// golang.org/issue/15653
+	dirent := (*syscall.Dirent)(unsafe.Pointer(&buf[0]))
+	if v := unsafe.Offsetof(dirent.Reclen) + unsafe.Sizeof(dirent.Reclen); uintptr(len(buf)) < v {
+		panic(fmt.Sprintf("buf size of %d smaller than dirent header size %d", len(buf), v))
+	}
+	if len(buf) < int(dirent.Reclen) {
+		panic(fmt.Sprintf("buf size %d < record length %d", len(buf), dirent.Reclen))
+	}
+	consumed = int(dirent.Reclen)
+	if direntInode(dirent) == 0 { // File absent in directory.
+		return
+	}
+	switch dirent.Type {
+	case syscall.DT_REG:
+		typ = 0
+	case syscall.DT_DIR:
+		typ = os.ModeDir
+	case syscall.DT_LNK:
+		typ = os.ModeSymlink
+	case syscall.DT_BLK:
+		typ = os.ModeDevice
+	case syscall.DT_FIFO:
+		typ = os.ModeNamedPipe
+	case syscall.DT_SOCK:
+		typ = os.ModeSocket
+	case syscall.DT_UNKNOWN:
+		typ = unknownFileMode
+	default:
+		// Skip weird things.
+		// It's probably a DT_WHT (http://lwn.net/Articles/325369/)
+		// or something. Revisit if/when this package is moved outside
+		// of goimports. goimports only cares about regular files,
+		// symlinks, and directories.
+		return
+	}
+
+	nameBuf := (*[unsafe.Sizeof(dirent.Name)]byte)(unsafe.Pointer(&dirent.Name[0]))
+	nameLen := bytes.IndexByte(nameBuf[:], 0)
+	if nameLen < 0 {
+		panic("failed to find terminating 0 byte in dirent")
+	}
+
+	// Special cases for common things:
+	if nameLen == 1 && nameBuf[0] == '.' {
+		name = "."
+	} else if nameLen == 2 && nameBuf[0] == '.' && nameBuf[1] == '.' {
+		name = ".."
+	} else {
+		name = string(nameBuf[:nameLen])
+	}
+	return
+}

vendor/golang.org/x/tools/imports/fix.go

@@ -0,0 +1,978 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package imports
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/parser"
+	"go/token"
+	"io/ioutil"
+	"log"
+	"os"
+	"path"
+	"path/filepath"
+	"sort"
+	"strings"
+	"sync"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+// Debug controls verbose logging.
+var Debug = false
+
+var (
+	inTests = false      // set true by fix_test.go; if false, no need to use testMu
+	testMu  sync.RWMutex // guards globals reset by tests; used only if inTests
+)
+
+// If set, LocalPrefix instructs Process to sort import paths with the given
+// prefix into another group after 3rd-party packages.
+var LocalPrefix string
+
+// importToGroup is a list of functions which map from an import path to
+// a group number.
+var importToGroup = []func(importPath string) (num int, ok bool){
+	func(importPath string) (num int, ok bool) {
+		if LocalPrefix != "" && strings.HasPrefix(importPath, LocalPrefix) {
+			return 3, true
+		}
+		return
+	},
+	func(importPath string) (num int, ok bool) {
+		if strings.HasPrefix(importPath, "appengine") {
+			return 2, true
+		}
+		return
+	},
+	func(importPath string) (num int, ok bool) {
+		if strings.Contains(importPath, ".") {
+			return 1, true
+		}
+		return
+	},
+}
+
+func importGroup(importPath string) int {
+	for _, fn := range importToGroup {
+		if n, ok := fn(importPath); ok {
+			return n
+		}
+	}
+	return 0
+}
+
+// packageInfo is a summary of features found in a package.
+type packageInfo struct {
+	Globals map[string]bool // symbol => true
+}
+
+// dirPackageInfo gets information from other files in the package.
+func dirPackageInfo(srcDir, filename string) (*packageInfo, error) {
+	considerTests := strings.HasSuffix(filename, "_test.go")
+
+	// Handle file from stdin
+	if _, err := os.Stat(filename); err != nil {
+		if os.IsNotExist(err) {
+			return &packageInfo{}, nil
+		}
+		return nil, err
+	}
+
+	fileBase := filepath.Base(filename)
+	packageFileInfos, err := ioutil.ReadDir(srcDir)
+	if err != nil {
+		return nil, err
+	}
+
+	info := &packageInfo{Globals: make(map[string]bool)}
+	for _, fi := range packageFileInfos {
+		if fi.Name() == fileBase || !strings.HasSuffix(fi.Name(), ".go") {
+			continue
+		}
+		if !considerTests && strings.HasSuffix(fi.Name(), "_test.go") {
+			continue
+		}
+
+		fileSet := token.NewFileSet()
+		root, err := parser.ParseFile(fileSet, filepath.Join(srcDir, fi.Name()), nil, 0)
+		if err != nil {
+			continue
+		}
+
+		for _, decl := range root.Decls {
+			genDecl, ok := decl.(*ast.GenDecl)
+			if !ok {
+				continue
+			}
+
+			for _, spec := range genDecl.Specs {
+				valueSpec, ok := spec.(*ast.ValueSpec)
+				if !ok {
+					continue
+				}
+				info.Globals[valueSpec.Names[0].Name] = true
+			}
+		}
+	}
+	return info, nil
+}
+
+func fixImports(fset *token.FileSet, f *ast.File, filename string) (added []string, err error) {
+	// refs are a set of possible package references currently unsatisfied by imports.
+	// first key: either base package (e.g. "fmt") or renamed package
+	// second key: referenced package symbol (e.g. "Println")
+	refs := make(map[string]map[string]bool)
+
+	// decls are the current package imports. key is base package or renamed package.
+	decls := make(map[string]*ast.ImportSpec)
+
+	abs, err := filepath.Abs(filename)
+	if err != nil {
+		return nil, err
+	}
+	srcDir := filepath.Dir(abs)
+	if Debug {
+		log.Printf("fixImports(filename=%q), abs=%q, srcDir=%q ...", filename, abs, srcDir)
+	}
+
+	var packageInfo *packageInfo
+	var loadedPackageInfo bool
+
+	// collect potential uses of packages.
+	var visitor visitFn
+	visitor = visitFn(func(node ast.Node) ast.Visitor {
+		if node == nil {
+			return visitor
+		}
+		switch v := node.(type) {
+		case *ast.ImportSpec:
+			if v.Name != nil {
+				decls[v.Name.Name] = v
+				break
+			}
+			ipath := strings.Trim(v.Path.Value, `"`)
+			if ipath == "C" {
+				break
+			}
+			local := importPathToName(ipath, srcDir)
+			decls[local] = v
+		case *ast.SelectorExpr:
+			xident, ok := v.X.(*ast.Ident)
+			if !ok {
+				break
+			}
+			if xident.Obj != nil {
+				// if the parser can resolve it, it's not a package ref
+				break
+			}
+			pkgName := xident.Name
+			if refs[pkgName] == nil {
+				refs[pkgName] = make(map[string]bool)
+			}
+			if !loadedPackageInfo {
+				loadedPackageInfo = true
+				packageInfo, _ = dirPackageInfo(srcDir, filename)
+			}
+			if decls[pkgName] == nil && (packageInfo == nil || !packageInfo.Globals[pkgName]) {
+				refs[pkgName][v.Sel.Name] = true
+			}
+		}
+		return visitor
+	})
+	ast.Walk(visitor, f)
+
+	// Nil out any unused ImportSpecs, to be removed in following passes
+	unusedImport := map[string]string{}
+	for pkg, is := range decls {
+		if refs[pkg] == nil && pkg != "_" && pkg != "." {
+			name := ""
+			if is.Name != nil {
+				name = is.Name.Name
+			}
+			unusedImport[strings.Trim(is.Path.Value, `"`)] = name
+		}
+	}
+	for ipath, name := range unusedImport {
+		if ipath == "C" {
+			// Don't remove cgo stuff.
+			continue
+		}
+		astutil.DeleteNamedImport(fset, f, name, ipath)
+	}
+
+	for pkgName, symbols := range refs {
+		if len(symbols) == 0 {
+			// skip over packages already imported
+			delete(refs, pkgName)
+		}
+	}
+
+	// Search for imports matching potential package references.
+	searches := 0
+	type result struct {
+		ipath string // import path (if err == nil)
+		name  string // optional name to rename import as
+		err   error
+	}
+	results := make(chan result)
+	for pkgName, symbols := range refs {
+		go func(pkgName string, symbols map[string]bool) {
+			ipath, rename, err := findImport(pkgName, symbols, filename)
+			r := result{ipath: ipath, err: err}
+			if rename {
+				r.name = pkgName
+			}
+			results <- r
+		}(pkgName, symbols)
+		searches++
+	}
+	for i := 0; i < searches; i++ {
+		result := <-results
+		if result.err != nil {
+			return nil, result.err
+		}
+		if result.ipath != "" {
+			if result.name != "" {
+				astutil.AddNamedImport(fset, f, result.name, result.ipath)
+			} else {
+				astutil.AddImport(fset, f, result.ipath)
+			}
+			added = append(added, result.ipath)
+		}
+	}
+
+	return added, nil
+}
+
+// importPathToName returns the package name for the given import path.
+var importPathToName func(importPath, srcDir string) (packageName string) = importPathToNameGoPath
+
+// importPathToNameBasic assumes the package name is the base of import path.
+func importPathToNameBasic(importPath, srcDir string) (packageName string) {
+	return path.Base(importPath)
+}
+
+// importPathToNameGoPath finds out the actual package name, as declared in its .go files.
+// If there's a problem, it falls back to using importPathToNameBasic.
+func importPathToNameGoPath(importPath, srcDir string) (packageName string) {
+	// Fast path for standard library without going to disk.
+	if pkg, ok := stdImportPackage[importPath]; ok {
+		return pkg
+	}
+
+	pkgName, err := importPathToNameGoPathParse(importPath, srcDir)
+	if Debug {
+		log.Printf("importPathToNameGoPathParse(%q, srcDir=%q) = %q, %v", importPath, srcDir, pkgName, err)
+	}
+	if err == nil {
+		return pkgName
+	}
+	return importPathToNameBasic(importPath, srcDir)
+}
+
+// importPathToNameGoPathParse is a faster version of build.Import if
+// the only thing desired is the package name. It uses build.FindOnly
+// to find the directory and then only parses one file in the package,
+// trusting that the files in the directory are consistent.
+func importPathToNameGoPathParse(importPath, srcDir string) (packageName string, err error) {
+	buildPkg, err := build.Import(importPath, srcDir, build.FindOnly)
+	if err != nil {
+		return "", err
+	}
+	d, err := os.Open(buildPkg.Dir)
+	if err != nil {
+		return "", err
+	}
+	names, err := d.Readdirnames(-1)
+	d.Close()
+	if err != nil {
+		return "", err
+	}
+	sort.Strings(names) // to have predictable behavior
+	var lastErr error
+	var nfile int
+	for _, name := range names {
+		if !strings.HasSuffix(name, ".go") {
+			continue
+		}
+		if strings.HasSuffix(name, "_test.go") {
+			continue
+		}
+		nfile++
+		fullFile := filepath.Join(buildPkg.Dir, name)
+
+		fset := token.NewFileSet()
+		f, err := parser.ParseFile(fset, fullFile, nil, parser.PackageClauseOnly)
+		if err != nil {
+			lastErr = err
+			continue
+		}
+		pkgName := f.Name.Name
+		if pkgName == "documentation" {
+			// Special case from go/build.ImportDir, not
+			// handled by ctx.MatchFile.
+			continue
+		}
+		if pkgName == "main" {
+			// Also skip package main, assuming it's a +build ignore generator or example.
+			// Since you can't import a package main anyway, there's no harm here.
+			continue
+		}
+		return pkgName, nil
+	}
+	if lastErr != nil {
+		return "", lastErr
+	}
+	return "", fmt.Errorf("no importable package found in %d Go files", nfile)
+}
+
+var stdImportPackage = map[string]string{} // "net/http" => "http"
+
+func init() {
+	// Nothing in the standard library has a package name not
+	// matching its import base name.
+	for _, pkg := range stdlib {
+		if _, ok := stdImportPackage[pkg]; !ok {
+			stdImportPackage[pkg] = path.Base(pkg)
+		}
+	}
+}
+
+// Directory-scanning state.
+var (
+	// scanGoRootOnce guards calling scanGoRoot (for $GOROOT)
+	scanGoRootOnce sync.Once
+	// scanGoPathOnce guards calling scanGoPath (for $GOPATH)
+	scanGoPathOnce sync.Once
+
+	// populateIgnoreOnce guards calling populateIgnore
+	populateIgnoreOnce sync.Once
+	ignoredDirs        []os.FileInfo
+
+	dirScanMu sync.RWMutex
+	dirScan   map[string]*pkg // abs dir path => *pkg
+)
+
+type pkg struct {
+	dir             string // absolute file path to pkg directory ("/usr/lib/go/src/net/http")
+	importPath      string // full pkg import path ("net/http", "foo/bar/vendor/a/b")
+	importPathShort string // vendorless import path ("net/http", "a/b")
+}
+
+// byImportPathShortLength sorts by the short import path length, breaking ties on the
+// import string itself.
+type byImportPathShortLength []*pkg
+
+func (s byImportPathShortLength) Len() int { return len(s) }
+func (s byImportPathShortLength) Less(i, j int) bool {
+	vi, vj := s[i].importPathShort, s[j].importPathShort
+	return len(vi) < len(vj) || (len(vi) == len(vj) && vi < vj)
+
+}
+func (s byImportPathShortLength) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+
+// gate is a semaphore for limiting concurrency.
+type gate chan struct{}
+
+func (g gate) enter() { g <- struct{}{} }
+func (g gate) leave() { <-g }
+
+var visitedSymlinks struct {
+	sync.Mutex
+	m map[string]struct{}
+}
+
+// guarded by populateIgnoreOnce; populates ignoredDirs.
+func populateIgnore() {
+	for _, srcDir := range build.Default.SrcDirs() {
+		if srcDir == filepath.Join(build.Default.GOROOT, "src") {
+			continue
+		}
+		populateIgnoredDirs(srcDir)
+	}
+}
+
+// populateIgnoredDirs reads an optional config file at <path>/.goimportsignore
+// of relative directories to ignore when scanning for go files.
+// The provided path is one of the $GOPATH entries with "src" appended.
+func populateIgnoredDirs(path string) {
+	file := filepath.Join(path, ".goimportsignore")
+	slurp, err := ioutil.ReadFile(file)
+	if Debug {
+		if err != nil {
+			log.Print(err)
+		} else {
+			log.Printf("Read %s", file)
+		}
+	}
+	if err != nil {
+		return
+	}
+	bs := bufio.NewScanner(bytes.NewReader(slurp))
+	for bs.Scan() {
+		line := strings.TrimSpace(bs.Text())
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		full := filepath.Join(path, line)
+		if fi, err := os.Stat(full); err == nil {
+			ignoredDirs = append(ignoredDirs, fi)
+			if Debug {
+				log.Printf("Directory added to ignore list: %s", full)
+			}
+		} else if Debug {
+			log.Printf("Error statting entry in .goimportsignore: %v", err)
+		}
+	}
+}
+
+func skipDir(fi os.FileInfo) bool {
+	for _, ignoredDir := range ignoredDirs {
+		if os.SameFile(fi, ignoredDir) {
+			return true
+		}
+	}
+	return false
+}
+
+// shouldTraverse reports whether the symlink fi should, found in dir,
+// should be followed.  It makes sure symlinks were never visited
+// before to avoid symlink loops.
+func shouldTraverse(dir string, fi os.FileInfo) bool {
+	path := filepath.Join(dir, fi.Name())
+	target, err := filepath.EvalSymlinks(path)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			fmt.Fprintln(os.Stderr, err)
+		}
+		return false
+	}
+	ts, err := os.Stat(target)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		return false
+	}
+	if !ts.IsDir() {
+		return false
+	}
+	if skipDir(ts) {
+		return false
+	}
+
+	realParent, err := filepath.EvalSymlinks(dir)
+	if err != nil {
+		fmt.Fprint(os.Stderr, err)
+		return false
+	}
+	realPath := filepath.Join(realParent, fi.Name())
+	visitedSymlinks.Lock()
+	defer visitedSymlinks.Unlock()
+	if visitedSymlinks.m == nil {
+		visitedSymlinks.m = make(map[string]struct{})
+	}
+	if _, ok := visitedSymlinks.m[realPath]; ok {
+		return false
+	}
+	visitedSymlinks.m[realPath] = struct{}{}
+	return true
+}
+
+var testHookScanDir = func(dir string) {}
+
+var scanGoRootDone = make(chan struct{}) // closed when scanGoRoot is done
+
+func scanGoRoot() {
+	go func() {
+		scanGoDirs(true)
+		close(scanGoRootDone)
+	}()
+}
+
+func scanGoPath() { scanGoDirs(false) }
+
+func scanGoDirs(goRoot bool) {
+	if Debug {
+		which := "$GOROOT"
+		if !goRoot {
+			which = "$GOPATH"
+		}
+		log.Printf("scanning " + which)
+		defer log.Printf("scanned " + which)
+	}
+	dirScanMu.Lock()
+	if dirScan == nil {
+		dirScan = make(map[string]*pkg)
+	}
+	dirScanMu.Unlock()
+
+	for _, srcDir := range build.Default.SrcDirs() {
+		isGoroot := srcDir == filepath.Join(build.Default.GOROOT, "src")
+		if isGoroot != goRoot {
+			continue
+		}
+		testHookScanDir(srcDir)
+		walkFn := func(path string, typ os.FileMode) error {
+			dir := filepath.Dir(path)
+			if typ.IsRegular() {
+				if dir == srcDir {
+					// Doesn't make sense to have regular files
+					// directly in your $GOPATH/src or $GOROOT/src.
+					return nil
+				}
+				if !strings.HasSuffix(path, ".go") {
+					return nil
+				}
+				dirScanMu.Lock()
+				if _, dup := dirScan[dir]; !dup {
+					importpath := filepath.ToSlash(dir[len(srcDir)+len("/"):])
+					dirScan[dir] = &pkg{
+						importPath:      importpath,
+						importPathShort: vendorlessImportPath(importpath),
+						dir:             dir,
+					}
+				}
+				dirScanMu.Unlock()
+				return nil
+			}
+			if typ == os.ModeDir {
+				base := filepath.Base(path)
+				if base == "" || base[0] == '.' || base[0] == '_' ||
+					base == "testdata" || base == "node_modules" {
+					return filepath.SkipDir
+				}
+				fi, err := os.Lstat(path)
+				if err == nil && skipDir(fi) {
+					if Debug {
+						log.Printf("skipping directory %q under %s", fi.Name(), dir)
+					}
+					return filepath.SkipDir
+				}
+				return nil
+			}
+			if typ == os.ModeSymlink {
+				base := filepath.Base(path)
+				if strings.HasPrefix(base, ".#") {
+					// Emacs noise.
+					return nil
+				}
+				fi, err := os.Lstat(path)
+				if err != nil {
+					// Just ignore it.
+					return nil
+				}
+				if shouldTraverse(dir, fi) {
+					return traverseLink
+				}
+			}
+			return nil
+		}
+		if err := fastWalk(srcDir, walkFn); err != nil {
+			log.Printf("goimports: scanning directory %v: %v", srcDir, err)
+		}
+	}
+}
+
+// vendorlessImportPath returns the devendorized version of the provided import path.
+// e.g. "foo/bar/vendor/a/b" => "a/b"
+func vendorlessImportPath(ipath string) string {
+	// Devendorize for use in import statement.
+	if i := strings.LastIndex(ipath, "/vendor/"); i >= 0 {
+		return ipath[i+len("/vendor/"):]
+	}
+	if strings.HasPrefix(ipath, "vendor/") {
+		return ipath[len("vendor/"):]
+	}
+	return ipath
+}
+
+// loadExports returns the set of exported symbols in the package at dir.
+// It returns nil on error or if the package name in dir does not match expectPackage.
+var loadExports func(expectPackage, dir string) map[string]bool = loadExportsGoPath
+
+func loadExportsGoPath(expectPackage, dir string) map[string]bool {
+	if Debug {
+		log.Printf("loading exports in dir %s (seeking package %s)", dir, expectPackage)
+	}
+	exports := make(map[string]bool)
+
+	ctx := build.Default
+
+	// ReadDir is like ioutil.ReadDir, but only returns *.go files
+	// and filters out _test.go files since they're not relevant
+	// and only slow things down.
+	ctx.ReadDir = func(dir string) (notTests []os.FileInfo, err error) {
+		all, err := ioutil.ReadDir(dir)
+		if err != nil {
+			return nil, err
+		}
+		notTests = all[:0]
+		for _, fi := range all {
+			name := fi.Name()
+			if strings.HasSuffix(name, ".go") && !strings.HasSuffix(name, "_test.go") {
+				notTests = append(notTests, fi)
+			}
+		}
+		return notTests, nil
+	}
+
+	files, err := ctx.ReadDir(dir)
+	if err != nil {
+		log.Print(err)
+		return nil
+	}
+
+	fset := token.NewFileSet()
+
+	for _, fi := range files {
+		match, err := ctx.MatchFile(dir, fi.Name())
+		if err != nil || !match {
+			continue
+		}
+		fullFile := filepath.Join(dir, fi.Name())
+		f, err := parser.ParseFile(fset, fullFile, nil, 0)
+		if err != nil {
+			if Debug {
+				log.Printf("Parsing %s: %v", fullFile, err)
+			}
+			return nil
+		}
+		pkgName := f.Name.Name
+		if pkgName == "documentation" {
+			// Special case from go/build.ImportDir, not
+			// handled by ctx.MatchFile.
+			continue
+		}
+		if pkgName != expectPackage {
+			if Debug {
+				log.Printf("scan of dir %v is not expected package %v (actually %v)", dir, expectPackage, pkgName)
+			}
+			return nil
+		}
+		for name := range f.Scope.Objects {
+			if ast.IsExported(name) {
+				exports[name] = true
+			}
+		}
+	}
+
+	if Debug {
+		exportList := make([]string, 0, len(exports))
+		for k := range exports {
+			exportList = append(exportList, k)
+		}
+		sort.Strings(exportList)
+		log.Printf("loaded exports in dir %v (package %v): %v", dir, expectPackage, strings.Join(exportList, ", "))
+	}
+	return exports
+}
+
+// findImport searches for a package with the given symbols.
+// If no package is found, findImport returns ("", false, nil)
+//
+// This is declared as a variable rather than a function so goimports
+// can be easily extended by adding a file with an init function.
+//
+// The rename value tells goimports whether to use the package name as
+// a local qualifier in an import. For example, if findImports("pkg",
+// "X") returns ("foo/bar", rename=true), then goimports adds the
+// import line:
+// 	import pkg "foo/bar"
+// to satisfy uses of pkg.X in the file.
+var findImport func(pkgName string, symbols map[string]bool, filename string) (foundPkg string, rename bool, err error) = findImportGoPath
+
+// findImportGoPath is the normal implementation of findImport.
+// (Some companies have their own internally.)
+func findImportGoPath(pkgName string, symbols map[string]bool, filename string) (foundPkg string, rename bool, err error) {
+	if inTests {
+		testMu.RLock()
+		defer testMu.RUnlock()
+	}
+
+	// Fast path for the standard library.
+	// In the common case we hopefully never have to scan the GOPATH, which can
+	// be slow with moving disks.
+	if pkg, rename, ok := findImportStdlib(pkgName, symbols); ok {
+		return pkg, rename, nil
+	}
+	if pkgName == "rand" && symbols["Read"] {
+		// Special-case rand.Read.
+		//
+		// If findImportStdlib didn't find it above, don't go
+		// searching for it, lest it find and pick math/rand
+		// in GOROOT (new as of Go 1.6)
+		//
+		// crypto/rand is the safer choice.
+		return "", false, nil
+	}
+
+	// TODO(sameer): look at the import lines for other Go files in the
+	// local directory, since the user is likely to import the same packages
+	// in the current Go file.  Return rename=true when the other Go files
+	// use a renamed package that's also used in the current file.
+
+	// Read all the $GOPATH/src/.goimportsignore files before scanning directories.
+	populateIgnoreOnce.Do(populateIgnore)
+
+	// Start scanning the $GOROOT asynchronously, then run the
+	// GOPATH scan synchronously if needed, and then wait for the
+	// $GOROOT to finish.
+	//
+	// TODO(bradfitz): run each $GOPATH entry async. But nobody
+	// really has more than one anyway, so low priority.
+	scanGoRootOnce.Do(scanGoRoot) // async
+	if !fileInDir(filename, build.Default.GOROOT) {
+		scanGoPathOnce.Do(scanGoPath) // blocking
+	}
+	<-scanGoRootDone
+
+	// Find candidate packages, looking only at their directory names first.
+	var candidates []*pkg
+	for _, pkg := range dirScan {
+		if pkgIsCandidate(filename, pkgName, pkg) {
+			candidates = append(candidates, pkg)
+		}
+	}
+
+	// Sort the candidates by their import package length,
+	// assuming that shorter package names are better than long
+	// ones.  Note that this sorts by the de-vendored name, so
+	// there's no "penalty" for vendoring.
+	sort.Sort(byImportPathShortLength(candidates))
+	if Debug {
+		for i, pkg := range candidates {
+			log.Printf("%s candidate %d/%d: %v", pkgName, i+1, len(candidates), pkg.importPathShort)
+		}
+	}
+
+	// Collect exports for packages with matching names.
+
+	done := make(chan struct{}) // closed when we find the answer
+	defer close(done)
+
+	rescv := make([]chan *pkg, len(candidates))
+	for i := range candidates {
+		rescv[i] = make(chan *pkg)
+	}
+	const maxConcurrentPackageImport = 4
+	loadExportsSem := make(chan struct{}, maxConcurrentPackageImport)
+
+	go func() {
+		for i, pkg := range candidates {
+			select {
+			case loadExportsSem <- struct{}{}:
+				select {
+				case <-done:
+				default:
+				}
+			case <-done:
+				return
+			}
+			pkg := pkg
+			resc := rescv[i]
+			go func() {
+				if inTests {
+					testMu.RLock()
+					defer testMu.RUnlock()
+				}
+				defer func() { <-loadExportsSem }()
+				exports := loadExports(pkgName, pkg.dir)
+
+				// If it doesn't have the right
+				// symbols, send nil to mean no match.
+				for symbol := range symbols {
+					if !exports[symbol] {
+						pkg = nil
+						break
+					}
+				}
+				select {
+				case resc <- pkg:
+				case <-done:
+				}
+			}()
+		}
+	}()
+	for _, resc := range rescv {
+		pkg := <-resc
+		if pkg == nil {
+			continue
+		}
+		// If the package name in the source doesn't match the import path's base,
+		// return true so the rewriter adds a name (import foo "github.com/bar/go-foo")
+		needsRename := path.Base(pkg.importPath) != pkgName
+		return pkg.importPathShort, needsRename, nil
+	}
+	return "", false, nil
+}
+
+// pkgIsCandidate reports whether pkg is a candidate for satisfying the
+// finding which package pkgIdent in the file named by filename is trying
+// to refer to.
+//
+// This check is purely lexical and is meant to be as fast as possible
+// because it's run over all $GOPATH directories to filter out poor
+// candidates in order to limit the CPU and I/O later parsing the
+// exports in candidate packages.
+//
+// filename is the file being formatted.
+// pkgIdent is the package being searched for, like "client" (if
+// searching for "client.New")
+func pkgIsCandidate(filename, pkgIdent string, pkg *pkg) bool {
+	// Check "internal" and "vendor" visibility:
+	if !canUse(filename, pkg.dir) {
+		return false
+	}
+
+	// Speed optimization to minimize disk I/O:
+	// the last two components on disk must contain the
+	// package name somewhere.
+	//
+	// This permits mismatch naming like directory
+	// "go-foo" being package "foo", or "pkg.v3" being "pkg",
+	// or directory "google.golang.org/api/cloudbilling/v1"
+	// being package "cloudbilling", but doesn't
+	// permit a directory "foo" to be package
+	// "bar", which is strongly discouraged
+	// anyway. There's no reason goimports needs
+	// to be slow just to accomodate that.
+	lastTwo := lastTwoComponents(pkg.importPathShort)
+	if strings.Contains(lastTwo, pkgIdent) {
+		return true
+	}
+	if hasHyphenOrUpperASCII(lastTwo) && !hasHyphenOrUpperASCII(pkgIdent) {
+		lastTwo = lowerASCIIAndRemoveHyphen(lastTwo)
+		if strings.Contains(lastTwo, pkgIdent) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func hasHyphenOrUpperASCII(s string) bool {
+	for i := 0; i < len(s); i++ {
+		b := s[i]
+		if b == '-' || ('A' <= b && b <= 'Z') {
+			return true
+		}
+	}
+	return false
+}
+
+func lowerASCIIAndRemoveHyphen(s string) (ret string) {
+	buf := make([]byte, 0, len(s))
+	for i := 0; i < len(s); i++ {
+		b := s[i]
+		switch {
+		case b == '-':
+			continue
+		case 'A' <= b && b <= 'Z':
+			buf = append(buf, b+('a'-'A'))
+		default:
+			buf = append(buf, b)
+		}
+	}
+	return string(buf)
+}
+
+// canUse reports whether the package in dir is usable from filename,
+// respecting the Go "internal" and "vendor" visibility rules.
+func canUse(filename, dir string) bool {
+	// Fast path check, before any allocations. If it doesn't contain vendor
+	// or internal, it's not tricky:
+	// Note that this can false-negative on directories like "notinternal",
+	// but we check it correctly below. This is just a fast path.
+	if !strings.Contains(dir, "vendor") && !strings.Contains(dir, "internal") {
+		return true
+	}
+
+	dirSlash := filepath.ToSlash(dir)
+	if !strings.Contains(dirSlash, "/vendor/") && !strings.Contains(dirSlash, "/internal/") && !strings.HasSuffix(dirSlash, "/internal") {
+		return true
+	}
+	// Vendor or internal directory only visible from children of parent.
+	// That means the path from the current directory to the target directory
+	// can contain ../vendor or ../internal but not ../foo/vendor or ../foo/internal
+	// or bar/vendor or bar/internal.
+	// After stripping all the leading ../, the only okay place to see vendor or internal
+	// is at the very beginning of the path.
+	absfile, err := filepath.Abs(filename)
+	if err != nil {
+		return false
+	}
+	absdir, err := filepath.Abs(dir)
+	if err != nil {
+		return false
+	}
+	rel, err := filepath.Rel(absfile, absdir)
+	if err != nil {
+		return false
+	}
+	relSlash := filepath.ToSlash(rel)
+	if i := strings.LastIndex(relSlash, "../"); i >= 0 {
+		relSlash = relSlash[i+len("../"):]
+	}
+	return !strings.Contains(relSlash, "/vendor/") && !strings.Contains(relSlash, "/internal/") && !strings.HasSuffix(relSlash, "/internal")
+}
+
+// lastTwoComponents returns at most the last two path components
+// of v, using either / or \ as the path separator.
+func lastTwoComponents(v string) string {
+	nslash := 0
+	for i := len(v) - 1; i >= 0; i-- {
+		if v[i] == '/' || v[i] == '\\' {
+			nslash++
+			if nslash == 2 {
+				return v[i:]
+			}
+		}
+	}
+	return v
+}
+
+type visitFn func(node ast.Node) ast.Visitor
+
+func (fn visitFn) Visit(node ast.Node) ast.Visitor {
+	return fn(node)
+}
+
+func findImportStdlib(shortPkg string, symbols map[string]bool) (importPath string, rename, ok bool) {
+	for symbol := range symbols {
+		key := shortPkg + "." + symbol
+		path := stdlib[key]
+		if path == "" {
+			if key == "rand.Read" {
+				continue
+			}
+			return "", false, false
+		}
+		if importPath != "" && importPath != path {
+			// Ambiguous. Symbols pointed to different things.
+			return "", false, false
+		}
+		importPath = path
+	}
+	if importPath == "" && shortPkg == "rand" && symbols["Read"] {
+		return "crypto/rand", false, true
+	}
+	return importPath, false, importPath != ""
+}
+
+// fileInDir reports whether the provided file path looks like
+// it's in dir. (without hitting the filesystem)
+func fileInDir(file, dir string) bool {
+	rest := strings.TrimPrefix(file, dir)
+	if len(rest) == len(file) {
+		// dir is not a prefix of file.
+		return false
+	}
+	// Check for boundary: either nothing (file == dir), or a slash.
+	return len(rest) == 0 || rest[0] == '/' || rest[0] == '\\'
+}

vendor/golang.org/x/tools/imports/imports.go

@@ -0,0 +1,289 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:generate go run mkstdlib.go
+
+// Package imports implements a Go pretty-printer (like package "go/format")
+// that also adds or removes import statements as necessary.
+package imports // import "golang.org/x/tools/imports"
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/format"
+	"go/parser"
+	"go/printer"
+	"go/token"
+	"io"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+// Options specifies options for processing files.
+type Options struct {
+	Fragment  bool // Accept fragment of a source file (no package statement)
+	AllErrors bool // Report all errors (not just the first 10 on different lines)
+
+	Comments  bool // Print comments (true if nil *Options provided)
+	TabIndent bool // Use tabs for indent (true if nil *Options provided)
+	TabWidth  int  // Tab width (8 if nil *Options provided)
+
+	FormatOnly bool // Disable the insertion and deletion of imports
+}
+
+// Process formats and adjusts imports for the provided file.
+// If opt is nil the defaults are used.
+//
+// Note that filename's directory influences which imports can be chosen,
+// so it is important that filename be accurate.
+// To process data ``as if'' it were in filename, pass the data as a non-nil src.
+func Process(filename string, src []byte, opt *Options) ([]byte, error) {
+	if opt == nil {
+		opt = &Options{Comments: true, TabIndent: true, TabWidth: 8}
+	}
+
+	fileSet := token.NewFileSet()
+	file, adjust, err := parse(fileSet, filename, src, opt)
+	if err != nil {
+		return nil, err
+	}
+
+	if !opt.FormatOnly {
+		_, err = fixImports(fileSet, file, filename)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	sortImports(fileSet, file)
+	imps := astutil.Imports(fileSet, file)
+
+	var spacesBefore []string // import paths we need spaces before
+	for _, impSection := range imps {
+		// Within each block of contiguous imports, see if any
+		// import lines are in different group numbers. If so,
+		// we'll need to put a space between them so it's
+		// compatible with gofmt.
+		lastGroup := -1
+		for _, importSpec := range impSection {
+			importPath, _ := strconv.Unquote(importSpec.Path.Value)
+			groupNum := importGroup(importPath)
+			if groupNum != lastGroup && lastGroup != -1 {
+				spacesBefore = append(spacesBefore, importPath)
+			}
+			lastGroup = groupNum
+		}
+
+	}
+
+	printerMode := printer.UseSpaces
+	if opt.TabIndent {
+		printerMode |= printer.TabIndent
+	}
+	printConfig := &printer.Config{Mode: printerMode, Tabwidth: opt.TabWidth}
+
+	var buf bytes.Buffer
+	err = printConfig.Fprint(&buf, fileSet, file)
+	if err != nil {
+		return nil, err
+	}
+	out := buf.Bytes()
+	if adjust != nil {
+		out = adjust(src, out)
+	}
+	if len(spacesBefore) > 0 {
+		out = addImportSpaces(bytes.NewReader(out), spacesBefore)
+	}
+
+	out, err = format.Source(out)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// parse parses src, which was read from filename,
+// as a Go source file or statement list.
+func parse(fset *token.FileSet, filename string, src []byte, opt *Options) (*ast.File, func(orig, src []byte) []byte, error) {
+	parserMode := parser.Mode(0)
+	if opt.Comments {
+		parserMode |= parser.ParseComments
+	}
+	if opt.AllErrors {
+		parserMode |= parser.AllErrors
+	}
+
+	// Try as whole source file.
+	file, err := parser.ParseFile(fset, filename, src, parserMode)
+	if err == nil {
+		return file, nil, nil
+	}
+	// If the error is that the source file didn't begin with a
+	// package line and we accept fragmented input, fall through to
+	// try as a source fragment.  Stop and return on any other error.
+	if !opt.Fragment || !strings.Contains(err.Error(), "expected 'package'") {
+		return nil, nil, err
+	}
+
+	// If this is a declaration list, make it a source file
+	// by inserting a package clause.
+	// Insert using a ;, not a newline, so that the line numbers
+	// in psrc match the ones in src.
+	psrc := append([]byte("package main;"), src...)
+	file, err = parser.ParseFile(fset, filename, psrc, parserMode)
+	if err == nil {
+		// If a main function exists, we will assume this is a main
+		// package and leave the file.
+		if containsMainFunc(file) {
+			return file, nil, nil
+		}
+
+		adjust := func(orig, src []byte) []byte {
+			// Remove the package clause.
+			// Gofmt has turned the ; into a \n.
+			src = src[len("package main\n"):]
+			return matchSpace(orig, src)
+		}
+		return file, adjust, nil
+	}
+	// If the error is that the source file didn't begin with a
+	// declaration, fall through to try as a statement list.
+	// Stop and return on any other error.
+	if !strings.Contains(err.Error(), "expected declaration") {
+		return nil, nil, err
+	}
+
+	// If this is a statement list, make it a source file
+	// by inserting a package clause and turning the list
+	// into a function body.  This handles expressions too.
+	// Insert using a ;, not a newline, so that the line numbers
+	// in fsrc match the ones in src.
+	fsrc := append(append([]byte("package p; func _() {"), src...), '}')
+	file, err = parser.ParseFile(fset, filename, fsrc, parserMode)
+	if err == nil {
+		adjust := func(orig, src []byte) []byte {
+			// Remove the wrapping.
+			// Gofmt has turned the ; into a \n\n.
+			src = src[len("package p\n\nfunc _() {"):]
+			src = src[:len(src)-len("}\n")]
+			// Gofmt has also indented the function body one level.
+			// Remove that indent.
+			src = bytes.Replace(src, []byte("\n\t"), []byte("\n"), -1)
+			return matchSpace(orig, src)
+		}
+		return file, adjust, nil
+	}
+
+	// Failed, and out of options.
+	return nil, nil, err
+}
+
+// containsMainFunc checks if a file contains a function declaration with the
+// function signature 'func main()'
+func containsMainFunc(file *ast.File) bool {
+	for _, decl := range file.Decls {
+		if f, ok := decl.(*ast.FuncDecl); ok {
+			if f.Name.Name != "main" {
+				continue
+			}
+
+			if len(f.Type.Params.List) != 0 {
+				continue
+			}
+
+			if f.Type.Results != nil && len(f.Type.Results.List) != 0 {
+				continue
+			}
+
+			return true
+		}
+	}
+
+	return false
+}
+
+func cutSpace(b []byte) (before, middle, after []byte) {
+	i := 0
+	for i < len(b) && (b[i] == ' ' || b[i] == '\t' || b[i] == '\n') {
+		i++
+	}
+	j := len(b)
+	for j > 0 && (b[j-1] == ' ' || b[j-1] == '\t' || b[j-1] == '\n') {
+		j--
+	}
+	if i <= j {
+		return b[:i], b[i:j], b[j:]
+	}
+	return nil, nil, b[j:]
+}
+
+// matchSpace reformats src to use the same space context as orig.
+// 1) If orig begins with blank lines, matchSpace inserts them at the beginning of src.
+// 2) matchSpace copies the indentation of the first non-blank line in orig
+//    to every non-blank line in src.
+// 3) matchSpace copies the trailing space from orig and uses it in place
+//   of src's trailing space.
+func matchSpace(orig []byte, src []byte) []byte {
+	before, _, after := cutSpace(orig)
+	i := bytes.LastIndex(before, []byte{'\n'})
+	before, indent := before[:i+1], before[i+1:]
+
+	_, src, _ = cutSpace(src)
+
+	var b bytes.Buffer
+	b.Write(before)
+	for len(src) > 0 {
+		line := src
+		if i := bytes.IndexByte(line, '\n'); i >= 0 {
+			line, src = line[:i+1], line[i+1:]
+		} else {
+			src = nil
+		}
+		if len(line) > 0 && line[0] != '\n' { // not blank
+			b.Write(indent)
+		}
+		b.Write(line)
+	}
+	b.Write(after)
+	return b.Bytes()
+}
+
+var impLine = regexp.MustCompile(`^\s+(?:[\w\.]+\s+)?"(.+)"`)
+
+func addImportSpaces(r io.Reader, breaks []string) []byte {
+	var out bytes.Buffer
+	sc := bufio.NewScanner(r)
+	inImports := false
+	done := false
+	for sc.Scan() {
+		s := sc.Text()
+
+		if !inImports && !done && strings.HasPrefix(s, "import") {
+			inImports = true
+		}
+		if inImports && (strings.HasPrefix(s, "var") ||
+			strings.HasPrefix(s, "func") ||
+			strings.HasPrefix(s, "const") ||
+			strings.HasPrefix(s, "type")) {
+			done = true
+			inImports = false
+		}
+		if inImports && len(breaks) > 0 {
+			if m := impLine.FindStringSubmatch(s); m != nil {
+				if m[1] == breaks[0] {
+					out.WriteByte('\n')
+					breaks = breaks[1:]
+				}
+			}
+		}
+
+		fmt.Fprintln(&out, s)
+	}
+	return out.Bytes()
+}

vendor/golang.org/x/tools/imports/sortimports.go

@@ -0,0 +1,212 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Hacked up copy of go/ast/import.go
+
+package imports
+
+import (
+	"go/ast"
+	"go/token"
+	"sort"
+	"strconv"
+)
+
+// sortImports sorts runs of consecutive import lines in import blocks in f.
+// It also removes duplicate imports when it is possible to do so without data loss.
+func sortImports(fset *token.FileSet, f *ast.File) {
+	for i, d := range f.Decls {
+		d, ok := d.(*ast.GenDecl)
+		if !ok || d.Tok != token.IMPORT {
+			// Not an import declaration, so we're done.
+			// Imports are always first.
+			break
+		}
+
+		if len(d.Specs) == 0 {
+			// Empty import block, remove it.
+			f.Decls = append(f.Decls[:i], f.Decls[i+1:]...)
+		}
+
+		if !d.Lparen.IsValid() {
+			// Not a block: sorted by default.
+			continue
+		}
+
+		// Identify and sort runs of specs on successive lines.
+		i := 0
+		specs := d.Specs[:0]
+		for j, s := range d.Specs {
+			if j > i && fset.Position(s.Pos()).Line > 1+fset.Position(d.Specs[j-1].End()).Line {
+				// j begins a new run.  End this one.
+				specs = append(specs, sortSpecs(fset, f, d.Specs[i:j])...)
+				i = j
+			}
+		}
+		specs = append(specs, sortSpecs(fset, f, d.Specs[i:])...)
+		d.Specs = specs
+
+		// Deduping can leave a blank line before the rparen; clean that up.
+		if len(d.Specs) > 0 {
+			lastSpec := d.Specs[len(d.Specs)-1]
+			lastLine := fset.Position(lastSpec.Pos()).Line
+			if rParenLine := fset.Position(d.Rparen).Line; rParenLine > lastLine+1 {
+				fset.File(d.Rparen).MergeLine(rParenLine - 1)
+			}
+		}
+	}
+}
+
+func importPath(s ast.Spec) string {
+	t, err := strconv.Unquote(s.(*ast.ImportSpec).Path.Value)
+	if err == nil {
+		return t
+	}
+	return ""
+}
+
+func importName(s ast.Spec) string {
+	n := s.(*ast.ImportSpec).Name
+	if n == nil {
+		return ""
+	}
+	return n.Name
+}
+
+func importComment(s ast.Spec) string {
+	c := s.(*ast.ImportSpec).Comment
+	if c == nil {
+		return ""
+	}
+	return c.Text()
+}
+
+// collapse indicates whether prev may be removed, leaving only next.
+func collapse(prev, next ast.Spec) bool {
+	if importPath(next) != importPath(prev) || importName(next) != importName(prev) {
+		return false
+	}
+	return prev.(*ast.ImportSpec).Comment == nil
+}
+
+type posSpan struct {
+	Start token.Pos
+	End   token.Pos
+}
+
+func sortSpecs(fset *token.FileSet, f *ast.File, specs []ast.Spec) []ast.Spec {
+	// Can't short-circuit here even if specs are already sorted,
+	// since they might yet need deduplication.
+	// A lone import, however, may be safely ignored.
+	if len(specs) <= 1 {
+		return specs
+	}
+
+	// Record positions for specs.
+	pos := make([]posSpan, len(specs))
+	for i, s := range specs {
+		pos[i] = posSpan{s.Pos(), s.End()}
+	}
+
+	// Identify comments in this range.
+	// Any comment from pos[0].Start to the final line counts.
+	lastLine := fset.Position(pos[len(pos)-1].End).Line
+	cstart := len(f.Comments)
+	cend := len(f.Comments)
+	for i, g := range f.Comments {
+		if g.Pos() < pos[0].Start {
+			continue
+		}
+		if i < cstart {
+			cstart = i
+		}
+		if fset.Position(g.End()).Line > lastLine {
+			cend = i
+			break
+		}
+	}
+	comments := f.Comments[cstart:cend]
+
+	// Assign each comment to the import spec preceding it.
+	importComment := map[*ast.ImportSpec][]*ast.CommentGroup{}
+	specIndex := 0
+	for _, g := range comments {
+		for specIndex+1 < len(specs) && pos[specIndex+1].Start <= g.Pos() {
+			specIndex++
+		}
+		s := specs[specIndex].(*ast.ImportSpec)
+		importComment[s] = append(importComment[s], g)
+	}
+
+	// Sort the import specs by import path.
+	// Remove duplicates, when possible without data loss.
+	// Reassign the import paths to have the same position sequence.
+	// Reassign each comment to abut the end of its spec.
+	// Sort the comments by new position.
+	sort.Sort(byImportSpec(specs))
+
+	// Dedup. Thanks to our sorting, we can just consider
+	// adjacent pairs of imports.
+	deduped := specs[:0]
+	for i, s := range specs {
+		if i == len(specs)-1 || !collapse(s, specs[i+1]) {
+			deduped = append(deduped, s)
+		} else {
+			p := s.Pos()
+			fset.File(p).MergeLine(fset.Position(p).Line)
+		}
+	}
+	specs = deduped
+
+	// Fix up comment positions
+	for i, s := range specs {
+		s := s.(*ast.ImportSpec)
+		if s.Name != nil {
+			s.Name.NamePos = pos[i].Start
+		}
+		s.Path.ValuePos = pos[i].Start
+		s.EndPos = pos[i].End
+		for _, g := range importComment[s] {
+			for _, c := range g.List {
+				c.Slash = pos[i].End
+			}
+		}
+	}
+
+	sort.Sort(byCommentPos(comments))
+
+	return specs
+}
+
+type byImportSpec []ast.Spec // slice of *ast.ImportSpec
+
+func (x byImportSpec) Len() int      { return len(x) }
+func (x byImportSpec) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
+func (x byImportSpec) Less(i, j int) bool {
+	ipath := importPath(x[i])
+	jpath := importPath(x[j])
+
+	igroup := importGroup(ipath)
+	jgroup := importGroup(jpath)
+	if igroup != jgroup {
+		return igroup < jgroup
+	}
+
+	if ipath != jpath {
+		return ipath < jpath
+	}
+	iname := importName(x[i])
+	jname := importName(x[j])
+
+	if iname != jname {
+		return iname < jname
+	}
+	return importComment(x[i]) < importComment(x[j])
+}
+
+type byCommentPos []*ast.CommentGroup
+
+func (x byCommentPos) Len() int           { return len(x) }
+func (x byCommentPos) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
+func (x byCommentPos) Less(i, j int) bool { return x[i].Pos() < x[j].Pos() }

vendor/vendor.json

@@ -0,0 +1,32 @@
+{
+	"comment": "",
+	"ignore": "test ignore",
+	"package": [
+		{
+			"checksumSHA1": "WXQKmdzMj9t4XgMdrghVO8jmKRY=",
+			"origin": "github.com/fjl/gogen",
+			"path": "github.com/garslo/gogen",
+			"revision": "1d203ffc1f61870f13a589286cd21b9fdcaf7755",
+			"revisionTime": "2017-03-06T19:27:44Z"
+		},
+		{
+			"checksumSHA1": "0xjvz/KGzXhAFsnDRvzofE0xNzI=",
+			"path": "github.com/kylelemons/godebug/diff",
+			"revision": "a616ab194758ae0a11290d87ca46ee8c440117b0",
+			"revisionTime": "2017-02-24T01:00:52Z"
+		},
+		{
+			"checksumSHA1": "ikor+YKJu2eKwyFteBWhsb8IGy8=",
+			"path": "golang.org/x/tools/go/ast/astutil",
+			"revision": "6e7ee5a9ec598d425ca86d6aab6e76e21baf328c",
+			"revisionTime": "2017-02-09T19:54:08Z"
+		},
+		{
+			"checksumSHA1": "q7d529ueItc/mhXnJ1J9/FUCYu4=",
+			"path": "golang.org/x/tools/imports",
+			"revision": "6e7ee5a9ec598d425ca86d6aab6e76e21baf328c",
+			"revisionTime": "2017-02-09T19:54:08Z"
+		}
+	],
+	"rootPath": "github.com/fjl/gencodec"
+}