Added support for array.find (#730)

Perryvw · web-flow · commit de818bcaf407 · 2019-10-05T18:29:54.000+02:00
* Added support for array.find

* Changed lualib function signature to match TS lib
diff --git a/src/LuaLib.ts b/src/LuaLib.ts
@@ -6,6 +6,7 @@ export enum LuaLibFeature {
     ArrayEvery = "ArrayEvery",
     ArrayFilter = "ArrayFilter",
     ArrayForEach = "ArrayForEach",
+    ArrayFind = "ArrayFind",
     ArrayFindIndex = "ArrayFindIndex",
     ArrayIndexOf = "ArrayIndexOf",
     ArrayMap = "ArrayMap",
diff --git a/src/LuaTransformer.ts b/src/LuaTransformer.ts
@@ -5113,6 +5113,8 @@ export class LuaTransformer {
                 );
             case "forEach":
                 return this.transformLuaLibFunction(LuaLibFeature.ArrayForEach, node, caller, ...params);
+            case "find":
+                return this.transformLuaLibFunction(LuaLibFeature.ArrayFind, node, caller, ...params);
             case "findIndex":
                 return this.transformLuaLibFunction(LuaLibFeature.ArrayFindIndex, node, caller, ...params);
             case "indexOf":
diff --git a/src/lualib/ArrayFind.ts b/src/lualib/ArrayFind.ts
@@ -0,0 +1,18 @@
+// https://www.ecma-international.org/ecma-262/10.0/index.html#sec-array.prototype.find
+function __TS__ArrayFind<T>(
+    this: void,
+    arr: T[],
+    predicate: (value: T, index: number, obj: T[]) => unknown
+): T | undefined {
+    const len = arr.length;
+    let k = 0;
+    while (k < len) {
+        const elem = arr[k];
+        if (predicate(elem, k, arr)) {
+            return elem;
+        }
+        k = k + 1;
+    }
+
+    return undefined;
+}
diff --git a/test/unit/builtins/array.spec.ts b/test/unit/builtins/array.spec.ts
@@ -246,9 +246,25 @@ test("array.forEach (%p)", () => {
     `.expectToMatchJsResult();
 });
 
+test.each([
+    { array: [], predicate: "elem > 3" },
+    { array: [0, 2, 4, 8], predicate: "elem > 10" },
+    { array: [0, 2, 4, 8], predicate: "elem > 7" },
+    { array: [0, 2, 4, 8], predicate: "elem == 0" },
+    { array: [0, 2, 4, 8], predicate: "elem > 7" },
+    { array: [0, 2, 4, 8], predicate: "true" },
+    { array: [0, 2, 4, 8], predicate: "false" },
+])("array.find (%p)", ({ array, predicate }) => {
+    util.testFunction`
+        const array = ${util.valueToString(array)};
+        return array.find((elem, index, arr) => ${predicate} && arr[index] === elem);
+    `.expectToMatchJsResult();
+});
+
 test.each([
     { array: [], searchElement: 3 },
     { array: [0, 2, 4, 8], searchElement: 10 },
+    { array: [0, 2, 4, 8], searchElement: 0 },
     { array: [0, 2, 4, 8], searchElement: 8 },
 ])("array.findIndex (%p)", ({ array, searchElement }) => {
     util.testFunction`
