Implement array.entries() (#1031)

Perryvw · web-flow · commit ffde39044407 · 2021-06-12T14:55:07.000+02:00
* Implement array.entries

* Added extra test for indirect use of array.entries()

* Added destructuring test for array.entries

* Fix prettier
diff --git a/src/LuaLib.ts b/src/LuaLib.ts
@@ -3,6 +3,7 @@ import { EmitHost } from "./transpilation";
 
 export enum LuaLibFeature {
     ArrayConcat = "ArrayConcat",
+    ArrayEntries = "ArrayEntries",
     ArrayEvery = "ArrayEvery",
     ArrayFilter = "ArrayFilter",
     ArrayForEach = "ArrayForEach",
diff --git a/src/lualib/ArrayEntries.ts b/src/lualib/ArrayEntries.ts
@@ -0,0 +1,14 @@
+// https://262.ecma-international.org/10.0/#sec-array.prototype.entries
+function __TS__ArrayEntries<T>(this: void, array: T[]): IterableIterator<[number, T]> {
+    let key = 0;
+    return {
+        [Symbol.iterator](): IterableIterator<[number, T]> {
+            return this;
+        },
+        next(): IteratorResult<[number, T]> {
+            const result = { done: array[key] === undefined, value: [key, array[key]] as [number, T] };
+            key++;
+            return result;
+        },
+    };
+}
diff --git a/src/transformation/builtins/array.ts b/src/transformation/builtins/array.ts
@@ -36,6 +36,8 @@ export function transformArrayPrototypeCall(
     switch (expressionName) {
         case "concat":
             return transformLuaLibFunction(context, LuaLibFeature.ArrayConcat, node, caller, ...params);
+        case "entries":
+            return transformLuaLibFunction(context, LuaLibFeature.ArrayEntries, node, caller);
         case "push":
             return transformLuaLibFunction(context, LuaLibFeature.ArrayPush, node, caller, ...params);
         case "reverse":
diff --git a/test/unit/builtins/array.spec.ts b/test/unit/builtins/array.spec.ts
@@ -594,6 +594,35 @@ describe.each(["reduce", "reduceRight"])("array.%s", reduce => {
     });
 });
 
+test.each([{ array: [] }, { array: ["a", "b", "c"] }, { array: [{ foo: "foo" }, { bar: "bar" }] }])(
+    "array.entries (%p)",
+    ({ array }) => {
+        util.testFunction`
+            const array = ${util.formatCode(array)};
+            const result = [];
+            for (const [i, v] of array.entries()) {
+                result.push([i, v]);
+            }
+            return result;
+        `.expectToMatchJsResult();
+    }
+);
+
+test("array.entries indirect use", () => {
+    util.testFunction`
+        const entries = ["a", "b", "c"].entries();
+        const result = [];
+        for (const [i, v] of entries) {
+            result.push([i, v]);
+        }
+        return result;
+    `.expectToMatchJsResult();
+});
+
+test("array.entries destructured", () => {
+    util.testExpression`[...["a", "b", "c"].entries()]`.expectToMatchJsResult();
+});
+
 const genericChecks = [
     "function generic<T extends number[]>(array: T)",
     "function generic<T extends [...number[]]>(array: T)",
