From a981aa36754ca08f67e1c5aad9cbc40e71aa57ae Mon Sep 17 00:00:00 2001
From: Louis Chatriot <louis.chatriot@gmail.com>
Date: Sat, 25 Jan 2014 12:59:22 +0100
Subject: [PATCH] Use cursor to find documents

---
 lib/cursor.js    | 54 ++++++++++++++++++++++++++++++++++++++++++++++++
 lib/datastore.js | 47 ++++++++++++-----------------------------
 2 files changed, 67 insertions(+), 34 deletions(-)
 create mode 100644 lib/cursor.js

diff --git a/lib/cursor.js b/lib/cursor.js
new file mode 100644
index 0000000..ea3d7da
--- /dev/null
+++ b/lib/cursor.js
@@ -0,0 +1,54 @@
+/**
+ * Manage access to data, be it to find, update or remove it
+ */
+var model = require('./model');
+
+ 
+
+/**
+ * Create a new cursor for this collection
+ * @param {Datastore} db - The datastore this cursor is bound to
+ * @param {Query} query - The query this cursor will operate on
+ */
+function Cursor (db, query) {
+  this.db = db;
+  this.query = query;
+}
+
+
+/**
+ * Set a limit the number of results
+ */
+Cursor.prototype.limit = function(limit) {
+  this.limit = limit;
+};
+
+
+/**
+ * Get all matching elements
+ * @param {Function} callback - Signature: err, results
+ */
+ Cursor.prototype.exec = function(callback) {
+  var candidates = this.db.getCandidates(this.query)
+    , res = [], added = 0
+    , i
+    ;
+  
+  try {
+    for (i = 0; i < candidates.length; i += 1) {
+      if (model.match(candidates[i], this.query)) {
+        res.push(model.deepCopy(candidates[i]));
+        added += 1;
+        if (this.limit && this.limit <= added) { break; }
+      }
+    }
+  } catch (err) {
+    return callback(err);
+  }
+  
+  return callback(null, res);
+};
+
+
+// Interface
+module.exports = Cursor;
\ No newline at end of file
diff --git a/lib/datastore.js b/lib/datastore.js
index bf5792f..ac7a745 100644
--- a/lib/datastore.js
+++ b/lib/datastore.js
@@ -6,6 +6,7 @@ var customUtils = require('./customUtils')
   , util = require('util')
   , _ = require('underscore')
   , Persistence = require('./persistence')
+  , Cursor = require('./cursor')
   ;
 
 
@@ -374,11 +375,11 @@ Datastore.prototype._count = function(query, callback) {
   }
 
   return callback(null, res);
-}
+};
 
 Datastore.prototype.count = function() {
     this.executor.push({this: this, fn: this._count, arguments: arguments });
-}
+};
 
 /**
  * Find all documents matching the query
@@ -387,23 +388,8 @@ Datastore.prototype.count = function() {
  * @api private Use find
  */
 Datastore.prototype._find = function (query, callback) {
-  var res = []
-    , self = this
-    , candidates = this.getCandidates(query)
-    , i
-    ;
-
-  try {
-    for (i = 0; i < candidates.length; i += 1) {
-      if (model.match(candidates[i], query)) {
-        res.push(model.deepCopy(candidates[i]));
-      }
-    }
-  } catch (err) {
-    return callback(err);
-  }
-
-  return callback(null, res);
+  var cursor = new Cursor(this, query);
+  cursor.exec(callback);
 };
 
 Datastore.prototype.find = function () {
@@ -418,22 +404,15 @@ Datastore.prototype.find = function () {
  * @api private Use findOne
  */
 Datastore.prototype._findOne = function (query, callback) {
-  var self = this
-    , candidates = this.getCandidates(query)
-    , i, found = null
-    ;
-
-  try {
-    for (i = 0; i < candidates.length; i += 1) {
-      if (model.match(candidates[i], query)) {
-        found = model.deepCopy(candidates[i]);
-      }
+  var cursor = new Cursor(this, query);
+  cursor.limit(1);
+  cursor.exec(function (err, docs) {
+    if (err) {
+      return callback(err);
+    } else {
+      return callback(null, docs.length === 1 ? docs[0] : null);
     }
-  } catch (err) {
-    return callback(err);
-  }
-
-  return callback(null, found);
+  });
 };
 
 Datastore.prototype.findOne = function () {