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Fix integration with async-to-generator
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@nicolo-ribaudo
nicolo-ribaudo committed May 22, 2023
1 parent 29b91df commit 54b6b9f
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340 changes: 183 additions & 157 deletions packages/babel-plugin-proposal-explicit-resource-management/src/index.ts
View file
@@ -1,7 +1,7 @@
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";
import { types as t, template, traverse, type PluginPass } from "@babel/core";
import type { NodePath, Visitor } from "@babel/traverse";

export default declare(api => {
// TOOD: assert version 7.22.0
Expand All @@ -20,178 +20,204 @@ export default declare(api => {
);
}

return {
name: "proposal-explicit-resource-management",
inherits: syntacExplicitResourceManagement,
const transformUsingDeclarationsVisitor: Visitor<PluginPass> = {
ForOfStatement(path: NodePath<t.ForOfStatement>) {
const { left } = path.node;
if (!isUsingDeclaration(left)) 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;
let needsAwait = false;

visitor: {
ForOfStatement(path: NodePath<t.ForOfStatement>) {
const { left } = path.node;
if (!isUsingDeclaration(left)) 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;
let needsAwait = false;

for (const node of path.node.body) {
if (!isUsingDeclaration(node)) continue;
stackId ??= path.scope.generateUidIdentifier("stack");
const isAwaitUsing =
node.kind === "await using" || TOP_LEVEL_AWAIT_USING.has(node);
needsAwait ||= isAwaitUsing;

if (
!TOP_LEVEL_AWAIT_USING.delete(node) &&
!TOP_LEVEL_USING.delete(node)
) {
node.kind = "const";
}
node.declarations.forEach(decl => {
const args = [t.cloneNode(stackId), decl.init];
if (isAwaitUsing) args.push(t.booleanLiteral(true));
decl.init = t.callExpression(state.addHelper("using"), args);
});
}
if (!stackId) return;

const errorId = path.scope.generateUidIdentifier("error");
const hasErrorId = path.scope.generateUidIdentifier("hasError");

let disposeCall: t.Expression = t.callExpression(
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.
template.expression.ast`
typeof SuppressedError !== "undefined" && SuppressedError
`,
],
);
if (needsAwait) disposeCall = t.awaitExpression(disposeCall);

const replacement = template.statement.ast`
try {
var ${stackId} = [];
${path.node.body}
} catch (_) {
var ${errorId} = _;
var ${hasErrorId} = true;
} finally {
${disposeCall}
}
`;
for (const node of path.node.body) {
if (!isUsingDeclaration(node)) continue;
stackId ??= path.scope.generateUidIdentifier("stack");
const isAwaitUsing =
node.kind === "await using" || TOP_LEVEL_AWAIT_USING.has(node);
needsAwait ||= isAwaitUsing;

const { parentPath } = path;
if (
parentPath.isFunction() ||
parentPath.isTryStatement() ||
parentPath.isCatchClause() ||
parentPath.isStaticBlock()
!TOP_LEVEL_AWAIT_USING.delete(node) &&
!TOP_LEVEL_USING.delete(node)
) {
path.replaceWith(t.blockStatement([replacement]));
} else {
path.replaceWith(replacement);
node.kind = "const";
}
node.declarations.forEach(decl => {
const args = [t.cloneNode(stackId), decl.init];
if (isAwaitUsing) args.push(t.booleanLiteral(true));
decl.init = t.callExpression(state.addHelper("using"), args);
});
}
if (!stackId) return;

const errorId = path.scope.generateUidIdentifier("error");
const hasErrorId = path.scope.generateUidIdentifier("hasError");

let disposeCall: t.Expression = t.callExpression(
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.
template.expression.ast`
typeof SuppressedError !== "undefined" && SuppressedError
`,
],
);
if (needsAwait) disposeCall = t.awaitExpression(disposeCall);

const replacement = template.statement.ast`
try {
var ${stackId} = [];
${path.node.body}
} catch (_) {
var ${errorId} = _;
var ${hasErrorId} = true;
} finally {
${disposeCall}
}
`;

const { parentPath } = path;
if (
parentPath.isFunction() ||
parentPath.isTryStatement() ||
parentPath.isCatchClause() ||
parentPath.isStaticBlock()
) {
path.replaceWith(t.blockStatement([replacement]));
} else {
path.replaceWith(replacement);
}
},
};

const transformUsingDeclarationsVisitorSkipFn: Visitor<PluginPass> =
traverse.visitors.merge([
transformUsingDeclarationsVisitor,
{
Function(path) {
path.skip();
},
},
// To transform top-level using declarations, we must wrap the
// module body in a block after hoisting all the exports and imports.
// This might cause some variables to be `undefined` rather than TDZ.
Program(path) {
if (path.node.sourceType !== "module") return;
if (!path.node.body.some(isUsingDeclaration)) return;

const innerBlockBody = [];
for (const stmt of path.get("body")) {
if (stmt.isFunctionDeclaration() || stmt.isImportDeclaration()) {
continue;
}
]);

return {
name: "proposal-explicit-resource-management",
inherits: syntacExplicitResourceManagement,

let { node } = stmt;
let shouldRemove = true;

if (stmt.isExportDefaultDeclaration()) {
let { declaration } = stmt.node;
let varId;
if (t.isClassDeclaration(declaration)) {
varId = declaration.id;
declaration.id = null;
declaration = t.toExpression(declaration);
} else if (!t.isExpression(declaration)) {
visitor: traverse.visitors.merge([
transformUsingDeclarationsVisitor,
{
// To transform top-level using declarations, we must wrap the
// module body in a block after hoisting all the exports and imports.
// This might cause some variables to be `undefined` rather than TDZ.
Program(path) {
if (path.node.sourceType !== "module") return;
if (!path.node.body.some(isUsingDeclaration)) return;

const innerBlockBody = [];
for (const stmt of path.get("body")) {
if (stmt.isFunctionDeclaration() || stmt.isImportDeclaration()) {
continue;
}

varId ??= path.scope.generateUidIdentifier("_default");
innerBlockBody.push(
t.variableDeclaration("var", [
t.variableDeclarator(varId, declaration),
]),
);
stmt.replaceWith(
t.exportNamedDeclaration(null, [
t.exportSpecifier(t.cloneNode(varId), t.identifier("default")),
]),
);
continue;
}
let { node } = stmt;
let shouldRemove = true;

if (stmt.isExportDefaultDeclaration()) {
let { declaration } = stmt.node;
let varId;
if (t.isClassDeclaration(declaration)) {
varId = declaration.id;
declaration.id = null;
declaration = t.toExpression(declaration);
} else if (!t.isExpression(declaration)) {
continue;
}

varId ??= path.scope.generateUidIdentifier("_default");
innerBlockBody.push(
t.variableDeclaration("var", [
t.variableDeclarator(varId, declaration),
]),
);
stmt.replaceWith(
t.exportNamedDeclaration(null, [
t.exportSpecifier(
t.cloneNode(varId),
t.identifier("default"),
),
]),
);
continue;
}

if (stmt.isExportNamedDeclaration()) {
node = stmt.node.declaration;
if (!node || t.isFunction(node)) continue;
if (stmt.isExportNamedDeclaration()) {
node = stmt.node.declaration;
if (!node || t.isFunction(node)) continue;

stmt.replaceWith(
t.exportNamedDeclaration(
null,
Object.keys(t.getOuterBindingIdentifiers(node, false)).map(id =>
t.exportSpecifier(t.identifier(id), t.identifier(id)),
stmt.replaceWith(
t.exportNamedDeclaration(
null,
Object.keys(t.getOuterBindingIdentifiers(node, false)).map(
id => t.exportSpecifier(t.identifier(id), t.identifier(id)),
),
),
),
);
shouldRemove = false;
} else if (stmt.isExportDeclaration()) {
continue;
}
);
shouldRemove = false;
} else if (stmt.isExportDeclaration()) {
continue;
}

if (t.isClassDeclaration(node)) {
const { id } = node;
node.id = null;
innerBlockBody.push(
t.variableDeclaration("var", [
t.variableDeclarator(id, t.toExpression(node)),
]),
);
} else if (t.isVariableDeclaration(node)) {
if (node.kind === "using") {
TOP_LEVEL_USING.add(stmt.node);
} else if (node.kind === "await using") {
TOP_LEVEL_AWAIT_USING.add(stmt.node);
if (t.isClassDeclaration(node)) {
const { id } = node;
node.id = null;
innerBlockBody.push(
t.variableDeclaration("var", [
t.variableDeclarator(id, t.toExpression(node)),
]),
);
} else if (t.isVariableDeclaration(node)) {
if (node.kind === "using") {
TOP_LEVEL_USING.add(stmt.node);
} else if (node.kind === "await using") {
TOP_LEVEL_AWAIT_USING.add(stmt.node);
}
node.kind = "var";
innerBlockBody.push(node);
} else {
innerBlockBody.push(stmt.node);
}
node.kind = "var";
innerBlockBody.push(node);
} else {
innerBlockBody.push(stmt.node);
}

if (shouldRemove) stmt.remove();
}
if (shouldRemove) stmt.remove();
}

path.pushContainer("body", t.blockStatement(innerBlockBody));
path.pushContainer("body", t.blockStatement(innerBlockBody));
},
// We must transform `await using` in async functions before that
// async-to-generator will transform `await` expressions into `yield`
Function(path, state) {
if (path.node.async) {
path.traverse(transformUsingDeclarationsVisitorSkipFn, state);
}
},
},
},
]),
};
});
7 changes: 7 additions & 0 deletions ...oposal-explicit-resource-management/test/fixtures/integration/async-to-generator/input.js
View file
@@ -0,0 +1,7 @@
async function fn() {
await 0;
{
await using x = y;
await 1;
}
}
6 changes: 6 additions & 0 deletions ...al-explicit-resource-management/test/fixtures/integration/async-to-generator/options.json
View file
@@ -0,0 +1,6 @@
{
"plugins": [
"proposal-explicit-resource-management",
"transform-async-to-generator"
]
}

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