/**
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* Copyright (c) 2014-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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"use strict";
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import assert from "assert";
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import { hoist } from "./hoist";
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import { Emitter } from "./emit";
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import replaceShorthandObjectMethod from "./replaceShorthandObjectMethod";
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import * as util from "./util";
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exports.getVisitor = ({ types: t }) => ({
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Method(path, state) {
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let node = path.node;
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if (!shouldRegenerate(node, state)) return;
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const container = t.functionExpression(
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null,
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[],
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t.cloneNode(node.body, false),
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node.generator,
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node.async,
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);
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path.get("body").set("body", [
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t.returnStatement(
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t.callExpression(container, []),
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),
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]);
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// Regardless of whether or not the wrapped function is a an async method
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// or generator the outer function should not be
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node.async = false;
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node.generator = false;
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// Unwrap the wrapper IIFE's environment so super and this and such still work.
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path
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.get("body.body.0.argument.callee")
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.unwrapFunctionEnvironment();
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},
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Function: {
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exit: util.wrapWithTypes(t, function(path, state) {
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let node = path.node;
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if (!shouldRegenerate(node, state)) return;
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// if this is an ObjectMethod, we need to convert it to an ObjectProperty
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path = replaceShorthandObjectMethod(path);
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node = path.node;
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let contextId = path.scope.generateUidIdentifier("context");
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let argsId = path.scope.generateUidIdentifier("args");
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path.ensureBlock();
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let bodyBlockPath = path.get("body");
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if (node.async) {
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bodyBlockPath.traverse(awaitVisitor);
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}
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bodyBlockPath.traverse(functionSentVisitor, {
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context: contextId
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});
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let outerBody = [];
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let innerBody = [];
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bodyBlockPath.get("body").forEach(function(childPath) {
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let node = childPath.node;
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if (t.isExpressionStatement(node) &&
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t.isStringLiteral(node.expression)) {
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// Babylon represents directives like "use strict" as elements
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// of a bodyBlockPath.node.directives array, but they could just
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// as easily be represented (by other parsers) as traditional
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// string-literal-valued expression statements, so we need to
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// handle that here. (#248)
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outerBody.push(node);
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} else if (node && node._blockHoist != null) {
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outerBody.push(node);
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} else {
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innerBody.push(node);
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}
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});
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if (outerBody.length > 0) {
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// Only replace the inner body if we actually hoisted any statements
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// to the outer body.
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bodyBlockPath.node.body = innerBody;
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}
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let outerFnExpr = getOuterFnExpr(path);
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// Note that getOuterFnExpr has the side-effect of ensuring that the
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// function has a name (so node.id will always be an Identifier), even
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// if a temporary name has to be synthesized.
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t.assertIdentifier(node.id);
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let innerFnId = t.identifier(node.id.name + "$");
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// Turn all declarations into vars, and replace the original
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// declarations with equivalent assignment expressions.
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let vars = hoist(path);
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let context = {
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usesThis: false,
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usesArguments: false,
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getArgsId: () => t.clone(argsId),
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};
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path.traverse(argumentsThisVisitor, context);
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if (context.usesArguments) {
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vars = vars || t.variableDeclaration("var", []);
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vars.declarations.push(t.variableDeclarator(
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t.clone(argsId),
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t.identifier("arguments"),
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));
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}
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let emitter = new Emitter(contextId);
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emitter.explode(path.get("body"));
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if (vars && vars.declarations.length > 0) {
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outerBody.push(vars);
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}
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let wrapArgs = [emitter.getContextFunction(innerFnId)];
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let tryLocsList = emitter.getTryLocsList();
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if (node.generator) {
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wrapArgs.push(outerFnExpr);
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} else if (context.usesThis || tryLocsList || node.async) {
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// Async functions that are not generators don't care about the
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// outer function because they don't need it to be marked and don't
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// inherit from its .prototype.
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wrapArgs.push(t.nullLiteral());
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}
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if (context.usesThis) {
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wrapArgs.push(t.thisExpression());
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} else if (tryLocsList || node.async) {
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wrapArgs.push(t.nullLiteral());
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}
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if (tryLocsList) {
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wrapArgs.push(tryLocsList);
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} else if (node.async) {
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wrapArgs.push(t.nullLiteral());
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}
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if (node.async) {
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// Rename any locally declared "Promise" variable,
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// to use the global one.
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let currentScope = path.scope;
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do {
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if (currentScope.hasOwnBinding("Promise")) currentScope.rename("Promise");
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} while (currentScope = currentScope.parent);
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wrapArgs.push(t.identifier("Promise"));
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}
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let wrapCall = t.callExpression(
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util.runtimeProperty(node.async ? "async" : "wrap"),
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wrapArgs
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);
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outerBody.push(t.returnStatement(wrapCall));
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node.body = t.blockStatement(outerBody);
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// We injected a few new variable declarations (for every hoisted var),
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// so we need to add them to the scope.
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path.get("body.body").forEach(p => p.scope.registerDeclaration(p));
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const oldDirectives = bodyBlockPath.node.directives;
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if (oldDirectives) {
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// Babylon represents directives like "use strict" as elements of
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// a bodyBlockPath.node.directives array. (#248)
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node.body.directives = oldDirectives;
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}
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let wasGeneratorFunction = node.generator;
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if (wasGeneratorFunction) {
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node.generator = false;
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}
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if (node.async) {
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node.async = false;
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}
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if (wasGeneratorFunction && t.isExpression(node)) {
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util.replaceWithOrRemove(path, t.callExpression(util.runtimeProperty("mark"), [node]))
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path.addComment("leading", "#__PURE__");
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}
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const insertedLocs = emitter.getInsertedLocs();
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path.traverse({
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NumericLiteral(path) {
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if (!insertedLocs.has(path.node)) {
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return;
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}
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path.replaceWith(t.numericLiteral(path.node.value));
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},
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})
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// Generators are processed in 'exit' handlers so that regenerator only has to run on
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// an ES5 AST, but that means traversal will not pick up newly inserted references
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// to things like 'regeneratorRuntime'. To avoid this, we explicitly requeue.
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path.requeue();
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})
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}
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});
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// Check if a node should be transformed by regenerator
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function shouldRegenerate(node, state) {
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if (node.generator) {
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if (node.async) {
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// Async generator
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return state.opts.asyncGenerators !== false;
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} else {
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// Plain generator
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return state.opts.generators !== false;
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}
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} else if (node.async) {
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// Async function
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return state.opts.async !== false;
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} else {
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// Not a generator or async function.
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return false;
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}
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}
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// Given a NodePath for a Function, return an Expression node that can be
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// used to refer reliably to the function object from inside the function.
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// This expression is essentially a replacement for arguments.callee, with
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// the key advantage that it works in strict mode.
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function getOuterFnExpr(funPath) {
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const t = util.getTypes();
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let node = funPath.node;
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t.assertFunction(node);
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if (!node.id) {
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// Default-exported function declarations, and function expressions may not
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// have a name to reference, so we explicitly add one.
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node.id = funPath.scope.parent.generateUidIdentifier("callee");
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}
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if (node.generator && // Non-generator functions don't need to be marked.
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t.isFunctionDeclaration(node)) {
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// Return the identifier returned by runtime.mark(<node.id>).
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return getMarkedFunctionId(funPath);
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}
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return t.clone(node.id);
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}
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const markInfo = new WeakMap();
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function getMarkInfo(node) {
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if (!markInfo.has(node)) {
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markInfo.set(node, {});
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}
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return markInfo.get(node);
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}
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function getMarkedFunctionId(funPath) {
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const t = util.getTypes();
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const node = funPath.node;
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t.assertIdentifier(node.id);
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const blockPath = funPath.findParent(function (path) {
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return path.isProgram() || path.isBlockStatement();
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});
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if (!blockPath) {
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return node.id;
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}
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const block = blockPath.node;
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assert.ok(Array.isArray(block.body));
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const info = getMarkInfo(block);
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if (!info.decl) {
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info.decl = t.variableDeclaration("var", []);
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blockPath.unshiftContainer("body", info.decl);
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info.declPath = blockPath.get("body.0");
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}
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assert.strictEqual(info.declPath.node, info.decl);
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// Get a new unique identifier for our marked variable.
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const markedId = blockPath.scope.generateUidIdentifier("marked");
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const markCallExp = t.callExpression(
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util.runtimeProperty("mark"),
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[t.clone(node.id)]
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);
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const index = info.decl.declarations.push(
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t.variableDeclarator(markedId, markCallExp)
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) - 1;
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const markCallExpPath =
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info.declPath.get("declarations." + index + ".init");
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assert.strictEqual(markCallExpPath.node, markCallExp);
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markCallExpPath.addComment("leading", "#__PURE__");
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return t.clone(markedId);
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}
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let argumentsThisVisitor = {
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"FunctionExpression|FunctionDeclaration|Method": function(path) {
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path.skip();
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},
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Identifier: function(path, state) {
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if (path.node.name === "arguments" && util.isReference(path)) {
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util.replaceWithOrRemove(path, state.getArgsId());
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state.usesArguments = true;
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}
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},
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ThisExpression: function(path, state) {
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state.usesThis = true;
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}
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};
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let functionSentVisitor = {
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MetaProperty(path) {
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let { node } = path;
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if (node.meta.name === "function" &&
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node.property.name === "sent") {
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const t = util.getTypes();
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util.replaceWithOrRemove(
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path,
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t.memberExpression(
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t.clone(this.context),
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t.identifier("_sent")
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)
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);
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}
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}
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};
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let awaitVisitor = {
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Function: function(path) {
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path.skip(); // Don't descend into nested function scopes.
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},
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AwaitExpression: function(path) {
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const t = util.getTypes();
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// Convert await expressions to yield expressions.
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let argument = path.node.argument;
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// Transforming `await x` to `yield regeneratorRuntime.awrap(x)`
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// causes the argument to be wrapped in such a way that the runtime
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// can distinguish between awaited and merely yielded values.
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util.replaceWithOrRemove(path, t.yieldExpression(
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t.callExpression(
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util.runtimeProperty("awrap"),
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[argument]
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),
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false
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));
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}
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};
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