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Wed, Sep 11, 23:15

index.js
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"use strict";
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.default = void 0;
var _helperPluginUtils = require("@babel/helper-plugin-utils");
var _tdz = require("./tdz");
var _core = require("@babel/core");
const DONE = new WeakSet();
var _default = (0, _helperPluginUtils.declare)((api, opts) => {
api.assertVersion(7);
const {
throwIfClosureRequired = false,
tdz: tdzEnabled = false
} = opts;
if (typeof throwIfClosureRequired !== "boolean") {
throw new Error(`.throwIfClosureRequired must be a boolean, or undefined`);
}
if (typeof tdzEnabled !== "boolean") {
throw new Error(`.tdz must be a boolean, or undefined`);
}
return {
name: "transform-block-scoping",
visitor: {
VariableDeclaration(path) {
const {
node,
parent,
scope
} = path;
if (!isBlockScoped(node)) return;
convertBlockScopedToVar(path, null, parent, scope, true);
if (node._tdzThis) {
const nodes = [node];
for (let i = 0; i < node.declarations.length; i++) {
const decl = node.declarations[i];
const assign = _core.types.assignmentExpression("=", _core.types.cloneNode(decl.id), decl.init || scope.buildUndefinedNode());
assign._ignoreBlockScopingTDZ = true;
nodes.push(_core.types.expressionStatement(assign));
decl.init = this.addHelper("temporalUndefined");
}
node._blockHoist = 2;
if (path.isCompletionRecord()) {
nodes.push(_core.types.expressionStatement(scope.buildUndefinedNode()));
}
path.replaceWithMultiple(nodes);
}
},
Loop(path, state) {
const {
parent,
scope
} = path;
path.ensureBlock();
const blockScoping = new BlockScoping(path, path.get("body"), parent, scope, throwIfClosureRequired, tdzEnabled, state);
const replace = blockScoping.run();
if (replace) path.replaceWith(replace);
},
CatchClause(path, state) {
const {
parent,
scope
} = path;
const blockScoping = new BlockScoping(null, path.get("body"), parent, scope, throwIfClosureRequired, tdzEnabled, state);
blockScoping.run();
},
"BlockStatement|SwitchStatement|Program"(path, state) {
if (!ignoreBlock(path)) {
const blockScoping = new BlockScoping(null, path, path.parent, path.scope, throwIfClosureRequired, tdzEnabled, state);
blockScoping.run();
}
}
}
};
});
exports.default = _default;
function ignoreBlock(path) {
return _core.types.isLoop(path.parent) || _core.types.isCatchClause(path.parent);
}
const buildRetCheck = (0, _core.template)(`
if (typeof RETURN === "object") return RETURN.v;
`);
function isBlockScoped(node) {
if (!_core.types.isVariableDeclaration(node)) return false;
if (node[_core.types.BLOCK_SCOPED_SYMBOL]) return true;
if (node.kind !== "let" && node.kind !== "const") return false;
return true;
}
function isInLoop(path) {
const loopOrFunctionParent = path.find(path => path.isLoop() || path.isFunction());
return loopOrFunctionParent == null ? void 0 : loopOrFunctionParent.isLoop();
}
function convertBlockScopedToVar(path, node, parent, scope, moveBindingsToParent = false) {
if (!node) {
node = path.node;
}
if (isInLoop(path) && !_core.types.isFor(parent)) {
for (let i = 0; i < node.declarations.length; i++) {
const declar = node.declarations[i];
declar.init = declar.init || scope.buildUndefinedNode();
}
}
node[_core.types.BLOCK_SCOPED_SYMBOL] = true;
node.kind = "var";
if (moveBindingsToParent) {
const parentScope = scope.getFunctionParent() || scope.getProgramParent();
for (const name of Object.keys(path.getBindingIdentifiers())) {
const binding = scope.getOwnBinding(name);
if (binding) binding.kind = "var";
scope.moveBindingTo(name, parentScope);
}
}
}
function isVar(node) {
return _core.types.isVariableDeclaration(node, {
kind: "var"
}) && !isBlockScoped(node);
}
const letReferenceBlockVisitor = _core.traverse.visitors.merge([{
Loop: {
enter(path, state) {
state.loopDepth++;
},
exit(path, state) {
state.loopDepth--;
}
},
Function(path, state) {
if (state.loopDepth > 0) {
path.traverse(letReferenceFunctionVisitor, state);
} else {
path.traverse(_tdz.visitor, state);
}
return path.skip();
}
}, _tdz.visitor]);
const letReferenceFunctionVisitor = _core.traverse.visitors.merge([{
ReferencedIdentifier(path, state) {
const ref = state.letReferences.get(path.node.name);
if (!ref) return;
const localBinding = path.scope.getBindingIdentifier(path.node.name);
if (localBinding && localBinding !== ref) return;
state.closurify = true;
}
}, _tdz.visitor]);
const hoistVarDeclarationsVisitor = {
enter(path, self) {
const {
node,
parent
} = path;
if (path.isForStatement()) {
if (isVar(node.init, node)) {
const nodes = self.pushDeclar(node.init);
if (nodes.length === 1) {
node.init = nodes[0];
} else {
node.init = _core.types.sequenceExpression(nodes);
}
}
} else if (path.isFor()) {
if (isVar(node.left, node)) {
self.pushDeclar(node.left);
node.left = node.left.declarations[0].id;
}
} else if (isVar(node, parent)) {
path.replaceWithMultiple(self.pushDeclar(node).map(expr => _core.types.expressionStatement(expr)));
} else if (path.isFunction()) {
return path.skip();
}
}
};
const loopLabelVisitor = {
LabeledStatement({
node
}, state) {
state.innerLabels.push(node.label.name);
}
};
const continuationVisitor = {
enter(path, state) {
if (path.isAssignmentExpression() || path.isUpdateExpression()) {
for (const name of Object.keys(path.getBindingIdentifiers())) {
if (state.outsideReferences.get(name) !== path.scope.getBindingIdentifier(name)) {
continue;
}
state.reassignments[name] = true;
}
} else if (path.isReturnStatement()) {
state.returnStatements.push(path);
}
}
};
function loopNodeTo(node) {
if (_core.types.isBreakStatement(node)) {
return "break";
} else if (_core.types.isContinueStatement(node)) {
return "continue";
}
}
const loopVisitor = {
Loop(path, state) {
const oldIgnoreLabeless = state.ignoreLabeless;
state.ignoreLabeless = true;
path.traverse(loopVisitor, state);
state.ignoreLabeless = oldIgnoreLabeless;
path.skip();
},
Function(path) {
path.skip();
},
SwitchCase(path, state) {
const oldInSwitchCase = state.inSwitchCase;
state.inSwitchCase = true;
path.traverse(loopVisitor, state);
state.inSwitchCase = oldInSwitchCase;
path.skip();
},
"BreakStatement|ContinueStatement|ReturnStatement"(path, state) {
const {
node,
scope
} = path;
if (node[this.LOOP_IGNORE]) return;
let replace;
let loopText = loopNodeTo(node);
if (loopText) {
if (node.label) {
if (state.innerLabels.indexOf(node.label.name) >= 0) {
return;
}
loopText = `${loopText}|${node.label.name}`;
} else {
if (state.ignoreLabeless) return;
if (_core.types.isBreakStatement(node) && state.inSwitchCase) return;
}
state.hasBreakContinue = true;
state.map[loopText] = node;
replace = _core.types.stringLiteral(loopText);
}
if (path.isReturnStatement()) {
state.hasReturn = true;
replace = _core.types.objectExpression([_core.types.objectProperty(_core.types.identifier("v"), node.argument || scope.buildUndefinedNode())]);
}
if (replace) {
replace = _core.types.returnStatement(replace);
replace[this.LOOP_IGNORE] = true;
path.skip();
path.replaceWith(_core.types.inherits(replace, node));
}
}
};
class BlockScoping {
constructor(loopPath, blockPath, parent, scope, throwIfClosureRequired, tdzEnabled, state) {
this.parent = parent;
this.scope = scope;
this.state = state;
this.throwIfClosureRequired = throwIfClosureRequired;
this.tdzEnabled = tdzEnabled;
this.blockPath = blockPath;
this.block = blockPath.node;
this.outsideLetReferences = new Map();
this.hasLetReferences = false;
this.letReferences = new Map();
this.body = [];
if (loopPath) {
this.loopParent = loopPath.parent;
this.loopLabel = _core.types.isLabeledStatement(this.loopParent) && this.loopParent.label;
this.loopPath = loopPath;
this.loop = loopPath.node;
}
}
run() {
const block = this.block;
if (DONE.has(block)) return;
DONE.add(block);
const needsClosure = this.getLetReferences();
this.checkConstants();
if (_core.types.isFunction(this.parent) || _core.types.isProgram(this.block)) {
this.updateScopeInfo();
return;
}
if (!this.hasLetReferences) return;
if (needsClosure) {
this.wrapClosure();
} else {
this.remap();
}
this.updateScopeInfo(needsClosure);
if (this.loopLabel && !_core.types.isLabeledStatement(this.loopParent)) {
return _core.types.labeledStatement(this.loopLabel, this.loop);
}
}
checkConstants() {
const scope = this.scope;
const state = this.state;
for (const name of Object.keys(scope.bindings)) {
const binding = scope.bindings[name];
if (binding.kind !== "const") continue;
for (const violation of binding.constantViolations) {
const readOnlyError = state.addHelper("readOnlyError");
const throwNode = _core.types.callExpression(readOnlyError, [_core.types.stringLiteral(name)]);
if (violation.isAssignmentExpression()) {
violation.get("right").replaceWith(_core.types.sequenceExpression([throwNode, violation.get("right").node]));
} else if (violation.isUpdateExpression()) {
violation.replaceWith(_core.types.sequenceExpression([throwNode, violation.node]));
} else if (violation.isForXStatement()) {
violation.ensureBlock();
violation.node.body.body.unshift(_core.types.expressionStatement(throwNode));
}
}
}
}
updateScopeInfo(wrappedInClosure) {
const blockScope = this.blockPath.scope;
const parentScope = blockScope.getFunctionParent() || blockScope.getProgramParent();
const letRefs = this.letReferences;
for (const key of letRefs.keys()) {
const ref = letRefs.get(key);
const binding = blockScope.getBinding(ref.name);
if (!binding) continue;
if (binding.kind === "let" || binding.kind === "const") {
binding.kind = "var";
if (wrappedInClosure) {
if (blockScope.hasOwnBinding(ref.name)) {
blockScope.removeBinding(ref.name);
}
} else {
blockScope.moveBindingTo(ref.name, parentScope);
}
}
}
}
remap() {
const letRefs = this.letReferences;
const outsideLetRefs = this.outsideLetReferences;
const scope = this.scope;
const blockPathScope = this.blockPath.scope;
for (const key of letRefs.keys()) {
const ref = letRefs.get(key);
if (scope.parentHasBinding(key) || scope.hasGlobal(key)) {
const binding = scope.getOwnBinding(key);
if (binding) {
const parentBinding = scope.parent.getOwnBinding(key);
if (binding.kind === "hoisted" && (!parentBinding || isVar(parentBinding.path.parent))) {
continue;
}
scope.rename(ref.name);
}
if (blockPathScope.hasOwnBinding(key)) {
blockPathScope.rename(ref.name);
}
}
}
for (const key of outsideLetRefs.keys()) {
const ref = letRefs.get(key);
if (isInLoop(this.blockPath) && blockPathScope.hasOwnBinding(key)) {
blockPathScope.rename(ref.name);
}
}
}
wrapClosure() {
if (this.throwIfClosureRequired) {
throw this.blockPath.buildCodeFrameError("Compiling let/const in this block would add a closure " + "(throwIfClosureRequired).");
}
const block = this.block;
const outsideRefs = this.outsideLetReferences;
if (this.loop) {
for (const name of Array.from(outsideRefs.keys())) {
const id = outsideRefs.get(name);
if (this.scope.hasGlobal(id.name) || this.scope.parentHasBinding(id.name)) {
outsideRefs.delete(id.name);
this.letReferences.delete(id.name);
this.scope.rename(id.name);
this.letReferences.set(id.name, id);
outsideRefs.set(id.name, id);
}
}
}
this.has = this.checkLoop();
this.hoistVarDeclarations();
const args = Array.from(outsideRefs.values(), node => _core.types.cloneNode(node));
const params = args.map(id => _core.types.cloneNode(id));
const isSwitch = this.blockPath.isSwitchStatement();
const fn = _core.types.functionExpression(null, params, _core.types.blockStatement(isSwitch ? [block] : block.body));
this.addContinuations(fn);
let call = _core.types.callExpression(_core.types.nullLiteral(), args);
let basePath = ".callee";
const hasYield = _core.traverse.hasType(fn.body, "YieldExpression", _core.types.FUNCTION_TYPES);
if (hasYield) {
fn.generator = true;
call = _core.types.yieldExpression(call, true);
basePath = ".argument" + basePath;
}
const hasAsync = _core.traverse.hasType(fn.body, "AwaitExpression", _core.types.FUNCTION_TYPES);
if (hasAsync) {
fn.async = true;
call = _core.types.awaitExpression(call);
basePath = ".argument" + basePath;
}
let placeholderPath;
let index;
if (this.has.hasReturn || this.has.hasBreakContinue) {
const ret = this.scope.generateUid("ret");
this.body.push(_core.types.variableDeclaration("var", [_core.types.variableDeclarator(_core.types.identifier(ret), call)]));
placeholderPath = "declarations.0.init" + basePath;
index = this.body.length - 1;
this.buildHas(ret);
} else {
this.body.push(_core.types.expressionStatement(call));
placeholderPath = "expression" + basePath;
index = this.body.length - 1;
}
let callPath;
if (isSwitch) {
const {
parentPath,
listKey,
key
} = this.blockPath;
this.blockPath.replaceWithMultiple(this.body);
callPath = parentPath.get(listKey)[key + index];
} else {
block.body = this.body;
callPath = this.blockPath.get("body")[index];
}
const placeholder = callPath.get(placeholderPath);
let fnPath;
if (this.loop) {
const loopId = this.scope.generateUid("loop");
const p = this.loopPath.insertBefore(_core.types.variableDeclaration("var", [_core.types.variableDeclarator(_core.types.identifier(loopId), fn)]));
placeholder.replaceWith(_core.types.identifier(loopId));
fnPath = p[0].get("declarations.0.init");
} else {
placeholder.replaceWith(fn);
fnPath = placeholder;
}
fnPath.unwrapFunctionEnvironment();
}
addContinuations(fn) {
const state = {
reassignments: {},
returnStatements: [],
outsideReferences: this.outsideLetReferences
};
this.scope.traverse(fn, continuationVisitor, state);
for (let i = 0; i < fn.params.length; i++) {
const param = fn.params[i];
if (!state.reassignments[param.name]) continue;
const paramName = param.name;
const newParamName = this.scope.generateUid(param.name);
fn.params[i] = _core.types.identifier(newParamName);
this.scope.rename(paramName, newParamName, fn);
state.returnStatements.forEach(returnStatement => {
returnStatement.insertBefore(_core.types.expressionStatement(_core.types.assignmentExpression("=", _core.types.identifier(paramName), _core.types.identifier(newParamName))));
});
fn.body.body.push(_core.types.expressionStatement(_core.types.assignmentExpression("=", _core.types.identifier(paramName), _core.types.identifier(newParamName))));
}
}
getLetReferences() {
const block = this.block;
let declarators = [];
if (this.loop) {
const init = this.loop.left || this.loop.init;
if (isBlockScoped(init)) {
declarators.push(init);
const names = _core.types.getBindingIdentifiers(init);
for (const name of Object.keys(names)) {
this.outsideLetReferences.set(name, names[name]);
}
}
}
const addDeclarationsFromChild = (path, node) => {
node = node || path.node;
if (_core.types.isClassDeclaration(node) || _core.types.isFunctionDeclaration(node) || isBlockScoped(node)) {
if (isBlockScoped(node)) {
convertBlockScopedToVar(path, node, block, this.scope);
}
declarators = declarators.concat(node.declarations || node);
}
if (_core.types.isLabeledStatement(node)) {
addDeclarationsFromChild(path.get("body"), node.body);
}
};
if (block.body) {
const declarPaths = this.blockPath.get("body");
for (let i = 0; i < block.body.length; i++) {
addDeclarationsFromChild(declarPaths[i]);
}
}
if (block.cases) {
const declarPaths = this.blockPath.get("cases");
for (let i = 0; i < block.cases.length; i++) {
const consequents = block.cases[i].consequent;
for (let j = 0; j < consequents.length; j++) {
const declar = consequents[j];
addDeclarationsFromChild(declarPaths[i], declar);
}
}
}
for (let i = 0; i < declarators.length; i++) {
const declar = declarators[i];
const keys = _core.types.getBindingIdentifiers(declar, false, true);
for (const key of Object.keys(keys)) {
this.letReferences.set(key, keys[key]);
}
this.hasLetReferences = true;
}
if (!this.hasLetReferences) return;
const state = {
letReferences: this.letReferences,
closurify: false,
loopDepth: 0,
tdzEnabled: this.tdzEnabled,
addHelper: name => this.state.addHelper(name)
};
if (isInLoop(this.blockPath)) {
state.loopDepth++;
}
this.blockPath.traverse(letReferenceBlockVisitor, state);
return state.closurify;
}
checkLoop() {
const state = {
hasBreakContinue: false,
ignoreLabeless: false,
inSwitchCase: false,
innerLabels: [],
hasReturn: false,
isLoop: !!this.loop,
map: {},
LOOP_IGNORE: Symbol()
};
this.blockPath.traverse(loopLabelVisitor, state);
this.blockPath.traverse(loopVisitor, state);
return state;
}
hoistVarDeclarations() {
this.blockPath.traverse(hoistVarDeclarationsVisitor, this);
}
pushDeclar(node) {
const declars = [];
const names = _core.types.getBindingIdentifiers(node);
for (const name of Object.keys(names)) {
declars.push(_core.types.variableDeclarator(names[name]));
}
this.body.push(_core.types.variableDeclaration(node.kind, declars));
const replace = [];
for (let i = 0; i < node.declarations.length; i++) {
const declar = node.declarations[i];
if (!declar.init) continue;
const expr = _core.types.assignmentExpression("=", _core.types.cloneNode(declar.id), _core.types.cloneNode(declar.init));
replace.push(_core.types.inherits(expr, declar));
}
return replace;
}
buildHas(ret) {
const body = this.body;
const has = this.has;
if (has.hasBreakContinue) {
for (const key of Object.keys(has.map)) {
body.push(_core.types.ifStatement(_core.types.binaryExpression("===", _core.types.identifier(ret), _core.types.stringLiteral(key)), has.map[key]));
}
}
if (has.hasReturn) {
body.push(buildRetCheck({
RETURN: _core.types.identifier(ret)
}));
}
}
}

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