Can use indexes for comparison queries

lib/datastore.js

@@ -213,6 +213,18 @@ Datastore.prototype.getCandidates = function (query) {
     return this.indexes[usableQueryKeys[0]].getMatching(query[usableQueryKeys[0]].$in);
   }
 
+  // For a comparison match
+  usableQueryKeys = [];
+  Object.keys(query).forEach(function (k) {
+    if (query[k].hasOwnProperty('$lt') || query[k].hasOwnProperty('$lte') || query[k].hasOwnProperty('$gt') || query[k].hasOwnProperty('$gte')) {
+      usableQueryKeys.push(k);
+    }
+  });
+  usableQueryKeys = _.intersection(usableQueryKeys, indexNames);
+  if (usableQueryKeys.length > 0) {
+    return this.indexes[usableQueryKeys[0]].getBetweenBounds(query[usableQueryKeys[0]]);
+  }
+
   // By default, return all the DB data
     return this.getAllData();
 };

lib/indexes.js

@@ -210,6 +210,17 @@ Index.prototype.getMatching = function (value) {
 };
 
 
+/**
+ * Get all documents in index whose key is between bounds are they are defined by query
+ * Documents are sorted by key
+ * @param {Query} query
+ * @return {Array of documents}
+ */
+Index.prototype.getBetweenBounds = function (query) {
+  return this.tree.betweenBounds(query);
+};
+
+
 /**
  * Get all elements in the index
  * @return {Array of documents}

test/db.test.js

@@ -524,6 +524,29 @@ describe('Database', function () {
       });
     });
 
+    it('Can use indexes for comparison matches', function (done) {
+      d.ensureIndex({ fieldName: 'tf' }, function (err) {
+        d.insert({ tf: 4 }, function (err, _doc1) {
+          d.insert({ tf: 6 }, function (err, _doc2) {
+            d.insert({ tf: 4, an: 'other' }, function (err, _doc3) {
+              d.insert({ tf: 9 }, function (err, _doc4) {
+                var data = d.getCandidates({ r: 6, tf: { $lte: 9, $gte: 6 } })
+                  , doc2 = _.find(data, function (d) { return d._id === _doc2._id; })
+                  , doc4 = _.find(data, function (d) { return d._id === _doc4._id; })
+                  ;
+
+                data.length.should.equal(2);
+                assert.deepEqual(doc2, { _id: doc2._id, tf: 6 });
+                assert.deepEqual(doc4, { _id: doc4._id, tf: 9 });
+
+                done();
+              });
+            });
+          });
+        });
+      });
+    });
+
   });   // ==== End of '#getCandidates' ==== //
 
 

test/indexes.test.js

@@ -548,6 +548,26 @@ describe('Indexes', function () {
       assert.deepEqual(idx.getMatching(['nope', 'no']), []);
     });
 
+    it('Can get all documents whose key is between certain bounds', function () {
+      var idx = new Index({ fieldName: 'a' })
+        , doc1 = { a: 5, tf: 'hello' }
+        , doc2 = { a: 2, tf: 'bloup' }
+        , doc3 = { a: 8, tf: 'world' }
+        , doc4 = { a: 7, tf: 'yes' }
+        , doc5 = { a: 10, tf: 'yes' }
+        ;
+
+      idx.insert(doc1);
+      idx.insert(doc2);
+      idx.insert(doc3);
+      idx.insert(doc4);
+      idx.insert(doc5);
+
+      assert.deepEqual(idx.getBetweenBounds({ $lt: 10, $gte: 5 }), [ doc1, doc4, doc3 ]);
+      assert.deepEqual(idx.getBetweenBounds({ $lte: 8 }), [ doc2, doc1, doc4, doc3 ]);
+      assert.deepEqual(idx.getBetweenBounds({ $gt: 7 }), [ doc3, doc5 ]);
+    });
+
   });   // ==== End of 'Get matching documents' ==== //