Added array.reduce (#604)

Perryvw · web-flow · commit 440ef2776a95 · 2019-05-27T21:27:29.000+02:00
* Added array.reduce

* Removed unused import

* Update src/lualib/ArrayReduce.ts

Co-Authored-By: ark120202 &lt;ark120202@gmail.com&gt;

* Fixed error test

* Updated tests

* Added undefined deleteCount test
diff --git a/src/LuaLib.ts b/src/LuaLib.ts
@@ -10,6 +10,7 @@ export enum LuaLibFeature {
     ArrayIndexOf = "ArrayIndexOf",
     ArrayMap = "ArrayMap",
     ArrayPush = "ArrayPush",
+    ArrayReduce = "ArrayReduce",
     ArrayReverse = "ArrayReverse",
     ArrayShift = "ArrayShift",
     ArrayUnshift = "ArrayUnshift",
diff --git a/src/LuaTransformer.ts b/src/LuaTransformer.ts
@@ -4404,6 +4404,8 @@ export class LuaTransformer {
                 return this.transformLuaLibFunction(LuaLibFeature.ArrayMap, node, caller, ...params);
             case "filter":
                 return this.transformLuaLibFunction(LuaLibFeature.ArrayFilter, node, caller, ...params);
+            case "reduce":
+                return this.transformLuaLibFunction(LuaLibFeature.ArrayReduce, node, caller, ...params);
             case "some":
                 return this.transformLuaLibFunction(LuaLibFeature.ArraySome, node, caller, ...params);
             case "every":
diff --git a/src/lualib/ArrayReduce.ts b/src/lualib/ArrayReduce.ts
@@ -0,0 +1,28 @@
+// https://www.ecma-international.org/ecma-262/9.0/index.html#sec-array.prototype.reduce
+function __TS__ArrayReduce<T>(
+    this: void,
+    arr: T[],
+    callbackFn: (accumulator: T, currentValue: T, index: number, array: T[]) => T,
+    initial?: T
+): T {
+    const len = arr.length;
+
+    if (len === 0 && initial === undefined) {
+        // tslint:disable-next-line: no-string-throw
+        throw "Reduce of empty array with no initial value";
+    }
+
+    let k = 0;
+    let accumulator = initial;
+    if (initial === undefined) {
+        accumulator = arr[0];
+        k++;
+    }
+
+    while (k < len) {
+        accumulator = callbackFn(accumulator, arr[k], k, arr);
+        k = k + 1;
+    }
+
+    return accumulator;
+}
diff --git a/src/lualib/ArraySlice.ts b/src/lualib/ArraySlice.ts
@@ -1,12 +1,14 @@
-// https://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf 22.1.3.23
+// https://www.ecma-international.org/ecma-262/9.0/index.html#sec-array.prototype.slice
 function __TS__ArraySlice<T>(this: void, list: T[], first: number, last: number): T[] {
     const len = list.length;
 
+    const relativeStart = first || 0;
+
     let k: number;
-    if (first < 0) {
-        k = Math.max(len + first, 0);
+    if (relativeStart < 0) {
+        k = Math.max(len + relativeStart, 0);
     } else {
-        k = Math.min(first, len);
+        k = Math.min(relativeStart, len);
     }
 
     let relativeEnd = last;
diff --git a/test/unit/lualib/array.spec.ts b/test/unit/lualib/array.spec.ts
diff --git a/test/unit/lualib/lualib.spec.ts b/test/unit/lualib/lualib.spec.ts
