Remove usage of lodash _.uniq.

Relates to #68

src/parse/gast_builder.ts

@@ -296,7 +296,7 @@ namespace chevrotain.gastBuilder {
             orPartRanges = orPartRanges.concat(currOrParts)
         })
 
-        let uniqueOrPartRanges = _.uniq(orPartRanges, (prodRange:IProdRange) => {
+        let uniqueOrPartRanges = utils.uniq(orPartRanges, (prodRange:IProdRange) => {
             // using "~" as a separator for the identify function as its not a valid char in javascript
             return prodRange.type + "~" + prodRange.range.start + "~" + prodRange.range.end + "~" + prodRange.text
         })

src/parse/grammar/first.ts

@@ -47,14 +47,14 @@ namespace chevrotain.first {
             hasInnerProdsRemaining = seq.length > nextSubProdIdx
         }
 
-        return _.uniq(firstSet)
+        return utils.uniq(firstSet)
     }
 
     export function firstForBranching(prod:gast.AbstractProduction):Function[] {
         let allAlternativesFirsts:Function[][] = utils.map(prod.definition, (innerProd) => {
             return first(innerProd)
         })
-        return _.uniq(utils.flatten<Function>(allAlternativesFirsts))
+        return utils.uniq(utils.flatten<Function>(allAlternativesFirsts))
     }
 
     export function firstForTerminal(terminal:gast.Terminal):Function[] {

src/parse/grammar/lookahead.ts

@@ -112,7 +112,7 @@ namespace chevrotain.lookahead {
     export function checkAlternativesAmbiguities(alternativesTokens:Function[][]):IAmbiguityDescriptor[] {
 
         let allTokensFlat = utils.flatten(alternativesTokens)
-        let uniqueTokensFlat = _.uniq(allTokensFlat)
+        let uniqueTokensFlat = utils.uniq(allTokensFlat)
 
         let tokensToAltsIndicesItAppearsIn = utils.map(uniqueTokensFlat, (seekToken) => {
             let altsCurrTokenAppearsIn = _.pick(alternativesTokens, (altToLookIn) => {

src/utils/utils.ts

@@ -164,4 +164,18 @@ namespace chevrotain.utils {
     export function compact<T>(arr:T[]):T[] {
         return reject(arr, (item) => item === null || item === undefined)
     }
+
+    export function uniq<T>(arr:T[], identity:(item:T) => any = (item) => item):T[] {
+        let identities = []
+        return reduce(arr, (result, currItem) => {
+            let currIdentity = identity(currItem)
+            if (contains(identities, currIdentity)) {
+                return result
+            }
+            else {
+                identities.push(currIdentity)
+                return result.concat(currItem)
+            }
+        }, [])
+    }
 }

test/utils/utils_spec.ts

@@ -113,6 +113,12 @@ namespace chevrotain.utils.spec {
             expect(compact([])).to.deep.equal([])
             expect(compact([1, 2, 3])).to.deep.equal([1, 2, 3])
         })
+
+        it("exports a uniq utility", () => {
+            expect(uniq([1, 2, 3, 2])).to.contain.members([1, 2, 3])
+            expect(uniq([2, 2, 4, 2], (item) => { return 666 })).to.have.length(1)
+            expect(uniq([])).to.deep.equal([])
+        })
     })
 }