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JavaScript

5 years ago
/**
* Copyright (c) 2014, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* https://raw.github.com/facebook/regenerator/master/LICENSE file. An
* additional grant of patent rights can be found in the PATENTS file in
* the same directory.
*/
"use strict";
var _assert = require("assert");
var _assert2 = _interopRequireDefault(_assert);
var _babelTypes = require("babel-types");
var t = _interopRequireWildcard(_babelTypes);
var _hoist = require("./hoist");
var _emit = require("./emit");
var _replaceShorthandObjectMethod = require("./replaceShorthandObjectMethod");
var _replaceShorthandObjectMethod2 = _interopRequireDefault(_replaceShorthandObjectMethod);
var _util = require("./util");
var util = _interopRequireWildcard(_util);
function _interopRequireWildcard(obj) { if (obj && obj.__esModule) { return obj; } else { var newObj = {}; if (obj != null) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key]; } } newObj.default = obj; return newObj; } }
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
exports.visitor = {
Function: {
exit: function exit(path, state) {
var node = path.node;
if (node.generator) {
if (node.async) {
// Async generator
if (state.opts.asyncGenerators === false) return;
} else {
// Plain generator
if (state.opts.generators === false) return;
}
} else if (node.async) {
// Async function
if (state.opts.async === false) return;
} else {
// Not a generator or async function.
return;
}
// if this is an ObjectMethod, we need to convert it to an ObjectProperty
path = (0, _replaceShorthandObjectMethod2.default)(path);
node = path.node;
var contextId = path.scope.generateUidIdentifier("context");
var argsId = path.scope.generateUidIdentifier("args");
path.ensureBlock();
var bodyBlockPath = path.get("body");
if (node.async) {
bodyBlockPath.traverse(awaitVisitor);
}
bodyBlockPath.traverse(functionSentVisitor, {
context: contextId
});
var outerBody = [];
var innerBody = [];
bodyBlockPath.get("body").forEach(function (childPath) {
var node = childPath.node;
if (t.isExpressionStatement(node) && t.isStringLiteral(node.expression)) {
// Babylon represents directives like "use strict" as elements
// of a bodyBlockPath.node.directives array, but they could just
// as easily be represented (by other parsers) as traditional
// string-literal-valued expression statements, so we need to
// handle that here. (#248)
outerBody.push(node);
} else if (node && node._blockHoist != null) {
outerBody.push(node);
} else {
innerBody.push(node);
}
});
if (outerBody.length > 0) {
// Only replace the inner body if we actually hoisted any statements
// to the outer body.
bodyBlockPath.node.body = innerBody;
}
var outerFnExpr = getOuterFnExpr(path);
// Note that getOuterFnExpr has the side-effect of ensuring that the
// function has a name (so node.id will always be an Identifier), even
// if a temporary name has to be synthesized.
t.assertIdentifier(node.id);
var innerFnId = t.identifier(node.id.name + "$");
// Turn all declarations into vars, and replace the original
// declarations with equivalent assignment expressions.
var vars = (0, _hoist.hoist)(path);
var didRenameArguments = renameArguments(path, argsId);
if (didRenameArguments) {
vars = vars || t.variableDeclaration("var", []);
var argumentIdentifier = t.identifier("arguments");
// we need to do this as otherwise arguments in arrow functions gets hoisted
argumentIdentifier._shadowedFunctionLiteral = path;
vars.declarations.push(t.variableDeclarator(argsId, argumentIdentifier));
}
var emitter = new _emit.Emitter(contextId);
emitter.explode(path.get("body"));
if (vars && vars.declarations.length > 0) {
outerBody.push(vars);
}
var wrapArgs = [emitter.getContextFunction(innerFnId),
// Async functions that are not generators don't care about the
// outer function because they don't need it to be marked and don't
// inherit from its .prototype.
node.generator ? outerFnExpr : t.nullLiteral(), t.thisExpression()];
var tryLocsList = emitter.getTryLocsList();
if (tryLocsList) {
wrapArgs.push(tryLocsList);
}
var wrapCall = t.callExpression(util.runtimeProperty(node.async ? "async" : "wrap"), wrapArgs);
outerBody.push(t.returnStatement(wrapCall));
node.body = t.blockStatement(outerBody);
var oldDirectives = bodyBlockPath.node.directives;
if (oldDirectives) {
// Babylon represents directives like "use strict" as elements of
// a bodyBlockPath.node.directives array. (#248)
node.body.directives = oldDirectives;
}
var wasGeneratorFunction = node.generator;
if (wasGeneratorFunction) {
node.generator = false;
}
if (node.async) {
node.async = false;
}
if (wasGeneratorFunction && t.isExpression(node)) {
util.replaceWithOrRemove(path, t.callExpression(util.runtimeProperty("mark"), [node]));
path.addComment("leading", "#__PURE__");
}
// Generators are processed in 'exit' handlers so that regenerator only has to run on
// an ES5 AST, but that means traversal will not pick up newly inserted references
// to things like 'regeneratorRuntime'. To avoid this, we explicitly requeue.
path.requeue();
}
}
};
// Given a NodePath for a Function, return an Expression node that can be
// used to refer reliably to the function object from inside the function.
// This expression is essentially a replacement for arguments.callee, with
// the key advantage that it works in strict mode.
function getOuterFnExpr(funPath) {
var node = funPath.node;
t.assertFunction(node);
if (!node.id) {
// Default-exported function declarations, and function expressions may not
// have a name to reference, so we explicitly add one.
node.id = funPath.scope.parent.generateUidIdentifier("callee");
}
if (node.generator && // Non-generator functions don't need to be marked.
t.isFunctionDeclaration(node)) {
// Return the identifier returned by runtime.mark(<node.id>).
return getMarkedFunctionId(funPath);
}
return node.id;
}
var getMarkInfo = require("private").makeAccessor();
function getMarkedFunctionId(funPath) {
var node = funPath.node;
t.assertIdentifier(node.id);
var blockPath = funPath.findParent(function (path) {
return path.isProgram() || path.isBlockStatement();
});
if (!blockPath) {
return node.id;
}
var block = blockPath.node;
_assert2.default.ok(Array.isArray(block.body));
var info = getMarkInfo(block);
if (!info.decl) {
info.decl = t.variableDeclaration("var", []);
blockPath.unshiftContainer("body", info.decl);
info.declPath = blockPath.get("body.0");
}
_assert2.default.strictEqual(info.declPath.node, info.decl);
// Get a new unique identifier for our marked variable.
var markedId = blockPath.scope.generateUidIdentifier("marked");
var markCallExp = t.callExpression(util.runtimeProperty("mark"), [node.id]);
var index = info.decl.declarations.push(t.variableDeclarator(markedId, markCallExp)) - 1;
var markCallExpPath = info.declPath.get("declarations." + index + ".init");
_assert2.default.strictEqual(markCallExpPath.node, markCallExp);
markCallExpPath.addComment("leading", "#__PURE__");
return markedId;
}
function renameArguments(funcPath, argsId) {
var state = {
didRenameArguments: false,
argsId: argsId
};
funcPath.traverse(argumentsVisitor, state);
// If the traversal replaced any arguments references, then we need to
// alias the outer function's arguments binding (be it the implicit
// arguments object or some other parameter or variable) to the variable
// named by argsId.
return state.didRenameArguments;
}
var argumentsVisitor = {
"FunctionExpression|FunctionDeclaration": function FunctionExpressionFunctionDeclaration(path) {
path.skip();
},
Identifier: function Identifier(path, state) {
if (path.node.name === "arguments" && util.isReference(path)) {
util.replaceWithOrRemove(path, state.argsId);
state.didRenameArguments = true;
}
}
};
var functionSentVisitor = {
MetaProperty: function MetaProperty(path) {
var node = path.node;
if (node.meta.name === "function" && node.property.name === "sent") {
util.replaceWithOrRemove(path, t.memberExpression(this.context, t.identifier("_sent")));
}
}
};
var awaitVisitor = {
Function: function Function(path) {
path.skip(); // Don't descend into nested function scopes.
},
AwaitExpression: function AwaitExpression(path) {
// Convert await expressions to yield expressions.
var argument = path.node.argument;
// Transforming `await x` to `yield regeneratorRuntime.awrap(x)`
// causes the argument to be wrapped in such a way that the runtime
// can distinguish between awaited and merely yielded values.
util.replaceWithOrRemove(path, t.yieldExpression(t.callExpression(util.runtimeProperty("awrap"), [argument]), false));
}
};