[wip] Implement transform support for using declarations

packages/babel-helpers/src/helpers-generated.ts

@@ -57,6 +57,10 @@ export default Object.freeze({
     "7.20.7",
     "export default function _defineAccessor(type,obj,key,fn){var desc={configurable:!0,enumerable:!0};return desc[type]=fn,Object.defineProperty(obj,key,desc)}",
   ),
+  dispose: helper(
+    "7.0.0-beta.0",
+    "function dispose_SuppressedError(suppressed,error){return dispose_SuppressedError=function(suppressed,error){this.suppressed=suppressed,this.error=error,this.stack=(new Error).stack},dispose_SuppressedError.prototype=Object.create(Error.prototype,{constructor:{value:dispose_SuppressedError,writable:!0,configurable:!0}}),new dispose_SuppressedError(suppressed,error)}export default function _dispose(stack,error,hasError,SuppressedError){for(;stack.length>0;){const r=stack.pop();try{r.d.call(r.v)}catch(e){error=hasError?new(SuppressedError||dispose_SuppressedError)(e,error):e,hasError=!0}}if(hasError)throw error}",
+  ),
   iterableToArrayLimit: helper(
     "7.0.0-beta.0",
     'export default function _iterableToArrayLimit(arr,i){var _i=null==arr?null:"undefined"!=typeof Symbol&&arr[Symbol.iterator]||arr["@@iterator"];if(null!=_i){var _s,_e,_x,_r,_arr=[],_n=!0,_d=!1;try{if(_x=(_i=_i.call(arr)).next,0===i){if(Object(_i)!==_i)return;_n=!1}else for(;!(_n=(_s=_x.call(_i)).done)&&(_arr.push(_s.value),_arr.length!==i);_n=!0);}catch(err){_d=!0,_e=err}finally{try{if(!_n&&null!=_i.return&&(_r=_i.return(),Object(_r)!==_r))return}finally{if(_d)throw _e}}return _arr}}',
@@ -81,6 +85,10 @@ export default Object.freeze({
     "7.0.0-beta.0",
     'export default function _typeof(obj){"@babel/helpers - typeof";return _typeof="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(obj){return typeof obj}:function(obj){return obj&&"function"==typeof Symbol&&obj.constructor===Symbol&&obj!==Symbol.prototype?"symbol":typeof obj},_typeof(obj)}',
   ),
+  using: helper(
+    "7.0.0-beta.0",
+    'export default function _using(stack,value){if(null!=value){var dispose=value[Symbol.dispose||Symbol.for("Symbol.dispose")];if("function"!=typeof dispose)throw new TypeError("Property [Symbol.dispose] is not a function.");stack.push({v:value,d:dispose})}return value}',
+  ),
   wrapRegExp: helper(
     "7.19.0",
     'import setPrototypeOf from"setPrototypeOf";import inherits from"inherits";export default function _wrapRegExp(){_wrapRegExp=function(re,groups){return new BabelRegExp(re,void 0,groups)};var _super=RegExp.prototype,_groups=new WeakMap;function BabelRegExp(re,flags,groups){var _this=new RegExp(re,flags);return _groups.set(_this,groups||_groups.get(re)),setPrototypeOf(_this,BabelRegExp.prototype)}function buildGroups(result,re){var g=_groups.get(re);return Object.keys(g).reduce((function(groups,name){var i=g[name];if("number"==typeof i)groups[name]=result[i];else{for(var k=0;void 0===result[i[k]]&&k+1<i.length;)k++;groups[name]=result[i[k]]}return groups}),Object.create(null))}return inherits(BabelRegExp,RegExp),BabelRegExp.prototype.exec=function(str){var result=_super.exec.call(this,str);if(result){result.groups=buildGroups(result,this);var indices=result.indices;indices&&(indices.groups=buildGroups(indices,this))}return result},BabelRegExp.prototype[Symbol.replace]=function(str,substitution){if("string"==typeof substitution){var groups=_groups.get(this);return _super[Symbol.replace].call(this,str,substitution.replace(/\\$<([^>]+)>/g,(function(_,name){var group=groups[name];return"$"+(Array.isArray(group)?group.join("$"):group)})))}if("function"==typeof substitution){var _this=this;return _super[Symbol.replace].call(this,str,(function(){var args=arguments;return"object"!=typeof args[args.length-1]&&(args=[].slice.call(args)).push(buildGroups(args,_this)),substitution.apply(this,args)}))}return _super[Symbol.replace].call(this,str,substitution)},_wrapRegExp.apply(this,arguments)}',

packages/babel-helpers/src/helpers/dispose.js

@@ -0,0 +1,31 @@
+/* @minVersion 7.0.0-beta.0 */
+function dispose_SuppressedError(suppressed, error) {
+  dispose_SuppressedError = function SuppressedError(suppressed, error) {
+    this.suppressed = suppressed;
+    this.error = error;
+    this.stack = new Error().stack;
+  };
+  dispose_SuppressedError.prototype = Object.create(Error.prototype, {
+    constructor: {
+      value: dispose_SuppressedError,
+      writable: true,
+      configurable: true,
+    },
+  });
+  return new dispose_SuppressedError(suppressed, error);
+}
+
+export default function _dispose(stack, error, hasError, SuppressedError) {
+  while (stack.length > 0) {
+    const r = stack.pop();
+    try {
+      r.d.call(r.v);
+    } catch (e) {
+      error = hasError
+        ? new (SuppressedError || dispose_SuppressedError)(e, error)
+        : e;
+      hasError = true;
+    }
+  }
+  if (hasError) throw error;
+}

packages/babel-helpers/src/helpers/using.js

@@ -0,0 +1,13 @@
+/* @minVersion 7.0.0-beta.0 */
+
+export default function _using(stack, value) {
+  if (value !== null && value !== void 0) {
+    // core-js-pure uses Symbol.for("Symbol.dispose").
+    var dispose = value[Symbol.dispose || Symbol.for("Symbol.dispose")];
+    if (typeof dispose !== "function") {
+      throw new TypeError(`Property [Symbol.dispose] is not a function.`);
+    }
+    stack.push({ v: value, d: dispose });
+  }
+  return value;
+}

packages/babel-plugin-proposal-explicit-resource-management/.npmignore

@@ -0,0 +1,3 @@
+src
+test
+*.log

packages/babel-plugin-proposal-explicit-resource-management/README.md

@@ -0,0 +1,19 @@
+# @babel/plugin-proposal-explicit-resource-managements
+
+> Compile `using` declarations to ES2015
+
+See our website [@babel/plugin-proposal-explicit-resource-managements](https://babeljs.io/docs/en/babel-plugin-proposal-explicit-resource-managements) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save-dev @babel/plugin-proposal-explicit-resource-managements
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/plugin-proposal-explicit-resource-managements --dev
+```

packages/babel-plugin-proposal-explicit-resource-management/package.json

@@ -0,0 +1,47 @@
+{
+  "name": "@babel/plugin-proposal-explicit-resource-management",
+  "version": "7.18.6",
+  "description": "Compile `using` declarations to ES2015",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/babel/babel.git",
+    "directory": "packages/babel-plugin-proposal-explicit-resource-management"
+  },
+  "homepage": "https://babel.dev/docs/en/next/babel-plugin-proposal-explicit-resource-management",
+  "license": "MIT",
+  "publishConfig": {
+    "access": "public"
+  },
+  "main": "./lib/index.js",
+  "keywords": [
+    "babel-plugin"
+  ],
+  "dependencies": {
+    "@babel/helper-plugin-utils": "workspace:^",
+    "@babel/plugin-syntax-explicit-resource-management": "workspace:^"
+  },
+  "peerDependencies": {
+    "@babel/core": "^7.0.0-0"
+  },
+  "devDependencies": {
+    "@babel/core": "workspace:^",
+    "@babel/helper-plugin-test-runner": "workspace:^"
+  },
+  "engines": {
+    "node": ">=6.9.0"
+  },
+  "author": "The Babel Team (https://babel.dev/team)",
+  "conditions": {
+    "USE_ESM": [
+      {
+        "type": "module"
+      },
+      null
+    ]
+  },
+  "exports": {
+    ".": "./lib/index.js",
+    "./package.json": "./package.json"
+  },
+  "type": "commonjs"
+}

packages/babel-plugin-proposal-explicit-resource-management/src/index.ts

@@ -0,0 +1,85 @@
+import { declare } from "@babel/helper-plugin-utils";
+import syntacExplicitResourceManagement from "@babel/plugin-syntax-explicit-resource-management";
+import { types as t, template } from "@babel/core";
+import type { NodePath } from "@babel/traverse";
+
+export default declare(api => {
+  // TOOD: assert version 7.22.0
+  api.assertVersion(7);
+
+  return {
+    name: "proposal-explicit-resource-management",
+    inherits: syntacExplicitResourceManagement,
+
+    visitor: {
+      VariableDeclaration(path) {
+        if (path.node.kind === "using") {
+          throw path.buildCodeFrameError(
+            `"using" declaration at the top-level of modules is not supported yet.`,
+          );
+        }
+      },
+      ForOfStatement(path: NodePath<t.ForOfStatement>) {
+        const { left } = path.node;
+        if (!t.isVariableDeclaration(left, { kind: "using" })) return;
+
+        const { id } = left.declarations[0];
+        const tmpId = path.scope.generateUidIdentifierBasedOnNode(id);
+        left.declarations[0].id = tmpId;
+        left.kind = "const";
+
+        path.ensureBlock();
+        path.node.body.body.unshift(
+          t.variableDeclaration("using", [
+            t.variableDeclarator(id, t.cloneNode(tmpId)),
+          ]),
+        );
+      },
+      BlockStatement(path, state) {
+        let stackId: t.Identifier | null = null;
+        for (const node of path.node.body) {
+          if (!t.isVariableDeclaration(node, { kind: "using" })) continue;
+          node.kind = "const";
+          stackId ??= path.scope.generateUidIdentifier("stack");
+
+          node.declarations.forEach(decl => {
+            decl.init = t.callExpression(state.addHelper("using"), [
+              t.cloneNode(stackId),
+              decl.init,
+            ]);
+          });
+        }
+        if (!stackId) return;
+
+        const errorId = path.scope.generateUidIdentifier("error");
+        const hasErrorId = path.scope.generateUidIdentifier("hasError");
+
+        const replacement = template.statement.ast`
+          try {
+            var ${stackId} = [];
+            ${path.node.body}
+          } catch (_) {
+            var ${errorId} = _;
+            var ${hasErrorId} = true;
+          } finally {
+            ${state.addHelper("dispose")}(
+              ${t.cloneNode(stackId)},
+              ${t.cloneNode(errorId)},
+              ${t.cloneNode(hasErrorId)},
+              // Pass SuppressedError so that it can be used with "pure"
+              // polyfills that do not compile the contents of runtime
+              // helpers.
+              typeof SuppressedError !== undefined && SuppressedError
+            );
+          }
+        `;
+
+        if (path.parentPath.isFunction()) {
+          path.replaceWith(t.blockStatement([replacement]));
+        } else {
+          path.replaceWith(replacement);
+        }
+      },
+    },
+  };
+});

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["proposal-explicit-resource-management"]
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/bare-block/input.js

@@ -0,0 +1,4 @@
+{
+  using x = obj;
+  doSomethingWith(x);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/bare-block/output.js

@@ -0,0 +1,10 @@
+try {
+  var _stack = [];
+  const x = babelHelpers.using(_stack, obj);
+  doSomethingWith(x);
+} catch (_) {
+  var _error = _;
+  var _hasError = true;
+} finally {
+  babelHelpers.dispose(_stack, _error, _hasError, typeof SuppressedError !== undefined && SuppressedError);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/for-await-head/input.js

@@ -0,0 +1,3 @@
+for await (using x of y) {
+  doSomethingWith(x);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/for-await-head/options.json

@@ -0,0 +1,3 @@
+{
+  "sourceType": "module"
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/for-await-head/output.mjs

@@ -0,0 +1,10 @@
+for await (const _x of y) try {
+  var _stack = [];
+  const x = babelHelpers.using(_stack, _x);
+  doSomethingWith(x);
+} catch (_) {
+  var _error = _;
+  var _hasError = true;
+} finally {
+  babelHelpers.dispose(_stack, _error, _hasError, typeof SuppressedError !== undefined && SuppressedError);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/for-head/input.js

@@ -0,0 +1,3 @@
+for (using x of y) {
+  doSomethingWith(x);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/for-head/output.js

@@ -0,0 +1,10 @@
+for (const _x of y) try {
+  var _stack = [];
+  const x = babelHelpers.using(_stack, _x);
+  doSomethingWith(x);
+} catch (_) {
+  var _error = _;
+  var _hasError = true;
+} finally {
+  babelHelpers.dispose(_stack, _error, _hasError, typeof SuppressedError !== undefined && SuppressedError);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/function-body/input.js

@@ -0,0 +1,4 @@
+if (test) {
+  using x = obj;
+  doSomethingWith(x);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/function-body/output.js

@@ -0,0 +1,10 @@
+if (test) try {
+  var _stack = [];
+  const x = babelHelpers.using(_stack, obj);
+  doSomethingWith(x);
+} catch (_) {
+  var _error = _;
+  var _hasError = true;
+} finally {
+  babelHelpers.dispose(_stack, _error, _hasError, typeof SuppressedError !== undefined && SuppressedError);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/if-body/input.js

@@ -0,0 +1,4 @@
+function fn() {
+  using x = obj;
+  return doSomethingWith(x);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/if-body/output.js

@@ -0,0 +1,12 @@
+function fn() {
+  try {
+    var _stack = [];
+    const x = babelHelpers.using(_stack, obj);
+    return doSomethingWith(x);
+  } catch (_) {
+    var _error = _;
+    var _hasError = true;
+  } finally {
+    babelHelpers.dispose(_stack, _error, _hasError, typeof SuppressedError !== undefined && SuppressedError);
+  }
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/multiple-nested/input.js

@@ -0,0 +1,11 @@
+{
+  using x = obj;
+  {
+    using y = call(() => {
+      using z = obj;
+      return z;
+    });
+    stmt;
+  }
+  stmt;
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/multiple-nested/output.js

@@ -0,0 +1,31 @@
+try {
+  var _stack = [];
+  const x = babelHelpers.using(_stack, obj);
+  try {
+    var _stack2 = [];
+    const y = babelHelpers.using(_stack2, call(() => {
+      try {
+        var _stack3 = [];
+        const z = babelHelpers.using(_stack3, obj);
+        return z;
+      } catch (_) {
+        var _error3 = _;
+        var _hasError3 = true;
+      } finally {
+        babelHelpers.dispose(_stack3, _error3, _hasError3, typeof SuppressedError !== undefined && SuppressedError);
+      }
+    }));
+    stmt;
+  } catch (_) {
+    var _error2 = _;
+    var _hasError2 = true;
+  } finally {
+    babelHelpers.dispose(_stack2, _error2, _hasError2, typeof SuppressedError !== undefined && SuppressedError);
+  }
+  stmt;
+} catch (_) {
+  var _error = _;
+  var _hasError = true;
+} finally {
+  babelHelpers.dispose(_stack, _error, _hasError, typeof SuppressedError !== undefined && SuppressedError);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/multiple-same-level/input.js

@@ -0,0 +1,9 @@
+{
+  stmt;
+  using x = obj;
+  stmt;
+  using y = obj, z = obj;
+  stmt;
+  using w = obj;
+  doSomethingWith(x, z);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/transform-sync/multiple-same-level/output.js

@@ -0,0 +1,16 @@
+try {
+  var _stack = [];
+  stmt;
+  const x = babelHelpers.using(_stack, obj);
+  stmt;
+  const y = babelHelpers.using(_stack, obj),
+    z = babelHelpers.using(_stack, obj);
+  stmt;
+  const w = babelHelpers.using(_stack, obj);
+  doSomethingWith(x, z);
+} catch (_) {
+  var _error = _;
+  var _hasError = true;
+} finally {
+  babelHelpers.dispose(_stack, _error, _hasError, typeof SuppressedError !== undefined && SuppressedError);
+}

packages/babel-plugin-proposal-explicit-resource-management/test/index.js

@@ -0,0 +1,3 @@
+import runner from "@babel/helper-plugin-test-runner";
+
+runner(import.meta.url);

packages/babel-plugin-proposal-explicit-resource-management/test/package.json

@@ -0,0 +1 @@
+{ "type": "module" }