remove usage of _.last

relates to #68
Chevrotain · Jan 4, 2016 · 2e7e859 · 2e7e859
1 parent 2be403c
commit 2e7e859
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Showing 4 changed files with 24 additions and 7 deletions.
diff --git a/src/parse/grammar/lookahead.ts b/src/parse/grammar/lookahead.ts
@@ -40,7 +40,7 @@ namespace chevrotain.lookahead {
             checkForOrAmbiguities(alternativesTokens, orOccurrence, ruleGrammar)
         }
 
-        let hasLastAnEmptyAlt = utils.isEmpty(_.last(alternativesTokens))
+        let hasLastAnEmptyAlt = utils.isEmpty(utils.last(alternativesTokens))
         if (hasLastAnEmptyAlt) {
             let lastIdx = alternativesTokens.length - 1
             /**

diff --git a/src/parse/parser_public.ts b/src/parse/parser_public.ts
@@ -1279,7 +1279,7 @@ namespace chevrotain {
             let key = this.getKeyForAutomaticLookahead(prodName, prodKeys, prodOccurrence)
             let firstAfterRepInfo = this.firstAfterRepMap.get(key)
             if (firstAfterRepInfo === undefined) {
-                let currRuleName = _.last(this.RULE_STACK)
+                let currRuleName = utils.last(this.RULE_STACK)
                 let ruleGrammar = this.getGAstProductions().get(currRuleName)
                 let walker:interp.AbstractNextTerminalAfterProductionWalker = new nextToksWalker(ruleGrammar, prodOccurrence)
                 firstAfterRepInfo = walker.startWalking()
@@ -1586,7 +1586,7 @@ namespace chevrotain {
 
         private getKeyForAutomaticLookahead(prodName:string, prodKeys:lang.HashTable<string>[], occurrence:number):string {
             let occuMap = prodKeys[occurrence - 1]
-            let currRule = _.last(this.RULE_STACK)
+            let currRule = utils.last(this.RULE_STACK)
             let key = occuMap[currRule]
             if (key === undefined) {
                 key = prodName + occurrence + IN + currRule
@@ -1630,7 +1630,7 @@ namespace chevrotain {
                                        occurrence:number,
                                        laFuncBuilder:(number, any) => () => T,
                                        extraArgs:any[] = []):() => T {
-            let ruleName = _.last(this.RULE_STACK)
+            let ruleName = utils.last(this.RULE_STACK)
             let condition = <any>this.classLAFuncs.get(key)
             if (condition === undefined) {
                 let ruleGrammar = this.getGAstProductions().get(ruleName)
@@ -1660,7 +1660,7 @@ namespace chevrotain {
         private raiseNoAltException(occurrence:number, errMsgTypes:string):void {
             let errSuffix = " but found: '" + this.NEXT_TOKEN().image + "'"
             if (errMsgTypes === undefined) {
-                let ruleName = _.last(this.RULE_STACK)
+                let ruleName = utils.last(this.RULE_STACK)
                 let ruleGrammar = this.getGAstProductions().get(ruleName)
                 let nextTokens = new interp.NextInsideOrWalker(ruleGrammar, occurrence).startWalking()
                 let nextTokensFlat = utils.flatten(nextTokens)

diff --git a/src/utils/utils.ts b/src/utils/utils.ts
@@ -8,10 +8,10 @@
  considering they will not be invoked in hotspots...
  */
 
-namespace utils {
+namespace chevrotain.utils {
 
     export function isEmpty(arr:any[]):boolean {
-        return arr.length === 0
+        return arr && arr.length === 0
     }
 
     export function keys(obj:any):string[] {
@@ -53,4 +53,9 @@ namespace utils {
     export function first<T>(arr:T[]):T {
         return isEmpty(arr) ? undefined : arr[0]
     }
+
+    export function last<T>(arr:T[]):T {
+        let len = arr && arr.length
+        return len ? arr[len - 1] : undefined
+    }
 }
diff --git a/test/utils/utils_spec.ts b/test/utils/utils_spec.ts
@@ -0,0 +1,12 @@
+namespace chevrotain.utils.spec {
+
+    describe("The Utils functions namespace", () => {
+
+        it("exports a last utility", () => {
+            expect(last([1, 2, 3])).to.equal(3)
+            expect(last([])).to.equal(undefined)
+            expect(last(null)).to.equal(undefined)
+        })
+    })
+
+}