Porting babel-plugin-transform-for-of-as-array into transform-for-of as an option (#6914)

packages/babel-plugin-transform-for-of/src/index.js

@@ -1,7 +1,61 @@
 import { template, types as t } from "@babel/core";
 
 export default function(api, options) {
-  const { loose } = options;
+  const { loose, assumeArray } = options;
+
+  if (loose === true && assumeArray === true) {
+    throw new Error(
+      `The loose and assumeArray options cannot be used together in @babel/plugin-transform-for-of`,
+    );
+  }
+
+  if (assumeArray) {
+    return {
+      visitor: {
+        ForOfStatement(path) {
+          const { scope } = path;
+          const { left, right, body } = path.node;
+          const i = scope.generateUidIdentifier("i");
+          let array = scope.maybeGenerateMemoised(right, true);
+
+          const inits = [t.variableDeclarator(i, t.numericLiteral(0))];
+          if (array) {
+            inits.push(t.variableDeclarator(array, right));
+          } else {
+            array = right;
+          }
+
+          const item = t.memberExpression(array, t.clone(i), true);
+          let assignment;
+          if (t.isVariableDeclaration(left)) {
+            assignment = left;
+            assignment.declarations[0].init = item;
+          } else {
+            assignment = t.expressionStatement(
+              t.assignmentExpression("=", left, item),
+            );
+          }
+
+          const block = t.toBlock(body);
+          block.body.unshift(assignment);
+
+          path.replaceWith(
+            t.forStatement(
+              t.variableDeclaration("let", inits),
+              t.binaryExpression(
+                "<",
+                t.clone(i),
+                t.memberExpression(t.clone(array), t.identifier("length")),
+              ),
+              t.updateExpression("++", t.clone(i)),
+              block,
+            ),
+          );
+        },
+      },
+    };
+  }
+
   const pushComputedProps = loose
     ? pushComputedPropsLoose
     : pushComputedPropsSpec;

packages/babel-plugin-transform-for-of/test/fixtures/error/invalid-option/actual.js

@@ -0,0 +1,4 @@
+let elm;
+for (elm of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/error/invalid-option/options.json

@@ -0,0 +1,4 @@
+{
+  "plugins": [["transform-for-of", { "assumeArray": true, "loose": true}]],
+  "throws": "The loose and assumeArray options cannot be used together in @babel/plugin-transform-for-of"
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-array-pattern/actual.js

@@ -0,0 +1,4 @@
+let elm;
+for ([elm] of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-array-pattern/expected.js

@@ -0,0 +1,6 @@
+let elm;
+
+for (let _i = 0, _array = array; _i < _array.length; _i++) {
+  [elm] = _array[_i];
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-declaration-array-pattern/actual.js

@@ -0,0 +1,3 @@
+for (const [elm] of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-declaration-array-pattern/expected.js

@@ -0,0 +1,4 @@
+for (let _i = 0, _array = array; _i < _array.length; _i++) {
+  const [elm] = _array[_i];
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-declaration/actual.js

@@ -0,0 +1,3 @@
+for (const elm of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-declaration/expected.js

@@ -0,0 +1,4 @@
+for (let _i = 0, _array = array; _i < _array.length; _i++) {
+  const elm = _array[_i];
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-expression-declaration/actual.js

@@ -0,0 +1 @@
+for (const i of items) i;

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-expression-declaration/expected.js

@@ -0,0 +1,4 @@
+for (let _i = 0, _items = items; _i < _items.length; _i++) {
+  const i = _items[_i];
+  i;
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-expression/actual.js

@@ -0,0 +1,2 @@
+let i;
+for (i of items) i;

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-expression/expected.js

@@ -0,0 +1,6 @@
+let i;
+
+for (let _i = 0, _items = items; _i < _items.length; _i++) {
+  i = _items[_i];
+  i;
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-amd/actual.js

@@ -0,0 +1,5 @@
+import { array } from "foo";
+
+for (const elm of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-amd/expected.js

@@ -0,0 +1,8 @@
+define(["foo"], function (_foo) {
+  "use strict";
+
+  for (let _i = 0; _i < _foo.array.length; _i++) {
+    const elm = _foo.array[_i];
+    console.log(elm);
+  }
+});

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-amd/options.json

@@ -0,0 +1,7 @@
+{
+  "plugins": [["transform-for-of", {
+    "assumeArray": true
+    }],
+    ["transform-modules-amd"]
+  ]
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-commonjs/actual.js

@@ -0,0 +1,5 @@
+import { array } from "foo";
+
+for (const elm of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-commonjs/expected.js

@@ -0,0 +1,8 @@
+"use strict";
+
+var _foo = require("foo");
+
+for (let _i = 0; _i < _foo.array.length; _i++) {
+  const elm = _foo.array[_i];
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-commonjs/options.json

@@ -0,0 +1,7 @@
+{
+  "plugins": [["transform-for-of", {
+    "assumeArray": true
+    }],
+    ["transform-modules-commonjs"]
+  ]
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-es2015/actual.js

@@ -0,0 +1,5 @@
+import { array } from "foo";
+
+for (const elm of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-es2015/expected.js

@@ -0,0 +1,6 @@
+import { array } from "foo";
+
+for (let _i = 0; _i < array.length; _i++) {
+  const elm = array[_i];
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-static-declaration/actual.js

@@ -0,0 +1,5 @@
+const array = [];
+
+for (const elm of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-static-declaration/expected.js

@@ -0,0 +1,6 @@
+const array = [];
+
+for (let _i = 0; _i < array.length; _i++) {
+  const elm = array[_i];
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-static/actual.js

@@ -0,0 +1,6 @@
+const array = [];
+let elm;
+
+for (elm of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-static/expected.js

@@ -0,0 +1,7 @@
+const array = [];
+let elm;
+
+for (let _i = 0; _i < array.length; _i++) {
+  elm = array[_i];
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of/actual.js

@@ -0,0 +1,5 @@
+let elm;
+
+for (elm of array) {
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of/expected.js

@@ -0,0 +1,6 @@
+let elm;
+
+for (let _i = 0, _array = array; _i < _array.length; _i++) {
+  elm = _array[_i];
+  console.log(elm);
+}

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [["transform-for-of", {
+    "assumeArray": true
+    }]
+  ]
+}