com.google.javascript.jscomp.Es6RewriteBlockScopedDeclaration Maven / Gradle / Ivy
/*
* Copyright 2014 The Closure Compiler Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.javascript.jscomp;
import com.google.common.base.Predicate;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.LinkedHashMultimap;
import com.google.common.collect.Multimap;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.jscomp.Normalize.NormalizeStatements;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.JSDocInfoBuilder;
import com.google.javascript.rhino.JSTypeExpression;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
/**
* Rewrite "let"s and "const"s as "var"s.
* Rename block-scoped declarations and their references when necessary.
*
* TODO(moz): Try to use MakeDeclaredNamesUnique
*
* @author [email protected] (Michael Zhou)
*/
public final class Es6RewriteBlockScopedDeclaration extends AbstractPostOrderCallback
implements HotSwapCompilerPass {
private final AbstractCompiler compiler;
private final Map> renameMap = new LinkedHashMap<>();
private final Set letConsts = new HashSet<>();
private final Set undeclaredNames = new HashSet<>();
public Es6RewriteBlockScopedDeclaration(AbstractCompiler compiler) {
this.compiler = compiler;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (!n.hasChildren() || !NodeUtil.isBlockScopedDeclaration(n.getFirstChild())) {
return;
}
Scope scope = t.getScope();
Node nameNode = n.getFirstChild();
if (!n.isClass() && !n.isFunction() && !nameNode.hasChildren()
&& (parent == null || !NodeUtil.isEnhancedFor(parent))
&& !n.isCatch()
&& inLoop(n)) {
Node undefined = IR.name("undefined");
if (nameNode.getJSDocInfo() != null || n.getJSDocInfo() != null) {
JSDocInfoBuilder jsDoc = new JSDocInfoBuilder(false);
jsDoc.recordType(new JSTypeExpression(new Node(Token.QMARK), n.getSourceFileName()));
undefined = IR.cast(undefined, jsDoc.build());
}
undefined.useSourceInfoFromForTree(nameNode);
nameNode.addChildToFront(undefined);
}
String oldName = nameNode.getString();
if (n.isLet() || n.isConst()) {
letConsts.add(n);
}
Scope hoistScope = scope.getClosestHoistScope();
boolean doRename = false;
if (scope != hoistScope) {
doRename = hoistScope.isDeclared(oldName, true)
|| undeclaredNames.contains(oldName);
String newName = doRename
? oldName + "$" + compiler.getUniqueNameIdSupplier().get()
: oldName;
Var oldVar = scope.getVar(oldName);
scope.undeclare(oldVar);
hoistScope.declare(newName, nameNode, oldVar.input);
if (doRename) {
nameNode.setString(newName);
Node scopeRoot = scope.getRootNode();
if (!renameMap.containsKey(scopeRoot)) {
renameMap.put(scopeRoot, new HashMap());
}
renameMap.get(scopeRoot).put(oldName, newName);
}
}
if (doRename) {
compiler.reportCodeChange();
}
}
@Override
public void process(Node externs, Node root) {
NodeTraversal.traverseRootsEs6(compiler, new CollectUndeclaredNames(), externs, root);
NodeTraversal.traverseRootsEs6(compiler, this, externs, root);
NodeTraversal.traverseRootsEs6(compiler, new Es6RenameReferences(renameMap), externs, root);
LoopClosureTransformer transformer = new LoopClosureTransformer();
NodeTraversal.traverseRootsEs6(compiler, transformer, externs, root);
transformer.transformLoopClosure();
varify();
NodeTraversal.traverseRootsEs6(
compiler, new RewriteBlockScopedFunctionDeclaration(), externs, root);
}
@Override
public void hotSwapScript(Node scriptRoot, Node originalRoot) {
NodeTraversal.traverseEs6(compiler, scriptRoot, new CollectUndeclaredNames());
NodeTraversal.traverseEs6(compiler, scriptRoot, this);
NodeTraversal.traverseEs6(compiler, scriptRoot, new Es6RenameReferences(renameMap));
LoopClosureTransformer transformer = new LoopClosureTransformer();
NodeTraversal.traverseEs6(compiler, scriptRoot, transformer);
transformer.transformLoopClosure();
varify();
NodeTraversal.traverseEs6(compiler, scriptRoot, new RewriteBlockScopedFunctionDeclaration());
}
/**
* Whether n is inside a loop. If n is inside a function which is inside a loop, we do not
* consider it to be inside a loop.
*/
private boolean inLoop(Node n) {
Node enclosingNode = NodeUtil.getEnclosingNode(n, loopPredicate);
return enclosingNode != null && enclosingNode.getType() != Token.FUNCTION;
}
private static final Predicate loopPredicate = new Predicate() {
@Override
public boolean apply(Node n) {
return n.getType() == Token.WHILE
|| n.getType() == Token.FOR
|| n.getType() == Token.FOR_OF
|| n.getType() == Token.DO
|| n.getType() == Token.FUNCTION;
}
};
private static void extractInlineJSDoc(Node srcDeclaration, Node srcName, Node destDeclaration) {
JSDocInfo existingInfo = srcDeclaration.getJSDocInfo();
if (existingInfo == null) {
// Extract inline JSDoc from "src" and add it to the "dest" node.
existingInfo = srcName.getJSDocInfo();
srcName.setJSDocInfo(null);
}
JSDocInfoBuilder builder = JSDocInfoBuilder.maybeCopyFrom(existingInfo);
destDeclaration.setJSDocInfo(builder.build());
}
private static void maybeAddConstJSDoc(Node srcDeclaration, Node srcParent, Node srcName,
Node destDeclaration) {
if (srcDeclaration.isConst()
// Don't add @const for the left side of a for/in. If we do we get warnings from the NTI.
&& !(NodeUtil.isForIn(srcParent) && srcDeclaration == srcParent.getFirstChild())) {
extractInlineJSDoc(srcDeclaration, srcName, destDeclaration);
JSDocInfoBuilder builder = JSDocInfoBuilder.maybeCopyFrom(destDeclaration.getJSDocInfo());
builder.recordConstancy();
destDeclaration.setJSDocInfo(builder.build());
}
}
private static void handleDeclarationList(Node declarationList, Node parent) {
// Normalize: "const i = 0, j = 0;" becomes "/** @const */ var i = 0; /** @const */ var j = 0;"
while (declarationList.hasMoreThanOneChild()) {
Node name = declarationList.getLastChild();
Node newDeclaration = IR.var(name.detachFromParent()).useSourceInfoFrom(declarationList);
maybeAddConstJSDoc(declarationList, parent, name, newDeclaration);
parent.addChildAfter(newDeclaration, declarationList);
}
maybeAddConstJSDoc(declarationList, parent, declarationList.getFirstChild(), declarationList);
declarationList.setType(Token.VAR);
}
private void varify() {
if (!letConsts.isEmpty()) {
for (Node n : letConsts) {
if (n.isConst()) {
handleDeclarationList(n, n.getParent());
}
n.setType(Token.VAR);
}
compiler.reportCodeChange();
}
}
private class RewriteBlockScopedFunctionDeclaration extends
AbstractPostOrderCallback {
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isFunction() && NormalizeStatements.maybeNormalizeFunctionDeclaration(n)) {
compiler.reportCodeChange();
}
}
}
/**
* Record undeclared names and aggressively rename possible references to them.
* Eg: In "{ let inner; } use(inner);", we rename the let declared variable.
*/
private class CollectUndeclaredNames extends AbstractPostOrderCallback {
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isName() && !t.getScope().isDeclared(n.getString(), true)) {
undeclaredNames.add(n.getString());
}
}
}
/**
* Transforms let/const declarations captured by loop closures.
*/
private class LoopClosureTransformer extends AbstractPostOrderCallback {
private static final String LOOP_OBJECT_NAME = "$jscomp$loop";
private final Map loopObjectMap = new LinkedHashMap<>();
private final Multimap functionLoopObjectsMap =
LinkedHashMultimap.create();
private final Multimap functionHandledMap = HashMultimap.create();
private final Multimap referenceMap = LinkedHashMultimap.create();
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (!NodeUtil.isReferenceName(n)) {
return;
}
String name = n.getString();
Scope referencedIn = t.getScope();
Var var = referencedIn.getVar(name);
if (var == null) {
return;
}
if (!var.isLet() && !var.isConst()) {
return;
}
if (n.getParent().isLet() || n.getParent().isConst()) {
letConsts.add(n.getParent());
}
// Traverse nodes up from let/const declaration:
// If we hit a function or the root before a loop - Not a loop closure.
// if we hit a loop first - maybe loop closure.
Scope declaredIn = var.getScope();
Node loopNode = null;
for (Scope s = declaredIn;; s = s.getParent()) {
Node scopeRoot = s.getRootNode();
if (NodeUtil.isLoopStructure(s.getRootNode())) {
loopNode = scopeRoot;
break;
} else if (scopeRoot.getParent() != null
&& NodeUtil.isLoopStructure(scopeRoot.getParent())) {
loopNode = scopeRoot.getParent();
break;
} else if (s.isFunctionBlockScope() || s.isGlobal()) {
return;
}
}
referenceMap.put(var, n);
// Traverse scopes from reference scope to declaration scope.
// If we hit a function - loop closure detected.
for (Scope s = referencedIn; s != declaredIn; s = s.getParent()) {
if (s.isFunctionBlockScope()) {
Node function = s.getRootNode().getParent();
if (functionHandledMap.containsEntry(function, name)) {
return;
}
functionHandledMap.put(function, name);
if (!loopObjectMap.containsKey(loopNode)) {
loopObjectMap.put(loopNode,
new LoopObject(
LOOP_OBJECT_NAME + "$" + compiler.getUniqueNameIdSupplier().get()));
}
LoopObject object = loopObjectMap.get(loopNode);
object.vars.add(var);
functionLoopObjectsMap.put(function, object);
return;
}
}
}
private void transformLoopClosure() {
if (loopObjectMap.isEmpty()) {
return;
}
for (Node loopNode : loopObjectMap.keySet()) {
// Introduce objects to reflect the captured scope variables.
// Fields are initially left as undefined to avoid cases like:
// var $jscomp$loop$0 = {i: 0, j: $jscomp$loop$0.i}
// They are initialized lazily by changing declarations into assignments
// later.
LoopObject object = loopObjectMap.get(loopNode);
Node objectLitNextIteration = IR.objectlit();
for (Var var : object.vars) {
objectLitNextIteration.addChildToBack(
IR.stringKey(var.name, IR.getprop(IR.name(object.name), IR.string(var.name))));
}
Node updateLoopObject = IR.assign(IR.name(object.name), objectLitNextIteration);
Node objectLit =
IR.var(IR.name(object.name), IR.objectlit()).useSourceInfoFromForTree(loopNode);
loopNode.getParent().addChildBefore(objectLit, loopNode);
if (NodeUtil.isVanillaFor(loopNode)) { // For
// The initializer is pulled out and placed prior to the loop.
Node initializer = loopNode.getFirstChild();
loopNode.replaceChild(initializer, IR.empty());
if (!initializer.isEmpty()) {
if (!NodeUtil.isNameDeclaration(initializer)) {
initializer = IR.exprResult(initializer).useSourceInfoFrom(initializer);
}
loopNode.getParent().addChildBefore(initializer, loopNode);
}
Node increment = loopNode.getChildAtIndex(2);
if (increment.isEmpty()) {
loopNode.replaceChild(
increment,
updateLoopObject.useSourceInfoIfMissingFromForTree(loopNode));
} else {
Node placeHolder = IR.empty();
loopNode.replaceChild(increment, placeHolder);
loopNode.replaceChild(
placeHolder,
IR.comma(updateLoopObject, increment)
.useSourceInfoIfMissingFromForTree(loopNode));
}
} else if (loopNode.isDo()) { // do-while, put at the end of the block
loopNode.getFirstChild().addChildToBack(IR.exprResult(updateLoopObject)
.useSourceInfoIfMissingFromForTree(loopNode));
} else { // For-in, for-of or while, put at the end of the block
loopNode.getLastChild().addChildToBack(IR.exprResult(updateLoopObject)
.useSourceInfoIfMissingFromForTree(loopNode));
}
// For captured variables, change declarations to assignments on the
// corresponding field of the introduced object. Rename all references
// accordingly.
for (Var var : object.vars) {
for (Node reference : referenceMap.get(var)) {
// For-of and for-in declarations are not altered, since they are
// used as temporary variables for assignment.
if (NodeUtil.isEnhancedFor(loopNode)
&& loopNode.getFirstChild() == reference.getParent()) {
loopNode.getLastChild().addChildToFront(
IR.exprResult(IR.assign(
IR.getprop(IR.name(object.name), IR.string(var.name)),
var.getNameNode().cloneNode()))
.useSourceInfoIfMissingFromForTree(reference));
} else {
if (NodeUtil.isNameDeclaration(reference.getParent())) {
Node declaration = reference.getParent();
Node grandParent = declaration.getParent();
handleDeclarationList(declaration, grandParent);
declaration = reference.getParent(); // Might have changed after normalization.
// Change declaration to assignment, or just drop it if there's
// no initial value.
if (reference.hasChildren()) {
Node newReference = reference.cloneNode();
Node assign = IR.assign(newReference, reference.removeFirstChild());
extractInlineJSDoc(declaration, reference, declaration);
maybeAddConstJSDoc(declaration, grandParent, reference, declaration);
assign.setJSDocInfo(declaration.getJSDocInfo());
Node replacement = IR.exprResult(assign)
.useSourceInfoIfMissingFromForTree(declaration);
grandParent.replaceChild(declaration, replacement);
reference = newReference;
} else {
grandParent.removeChild(declaration);
}
letConsts.remove(declaration);
compiler.reportCodeChange();
}
if (reference.getParent().isCall()
&& reference.getParent().getFirstChild() == reference) {
reference.getParent().putBooleanProp(Node.FREE_CALL, false);
}
// Change reference to GETPROP.
reference.getParent().replaceChild(
reference,
IR.getprop(IR.name(object.name), IR.string(var.name))
.useSourceInfoIfMissingFromForTree(reference));
}
}
}
}
// Create wrapper functions and call them.
for (Node function : functionLoopObjectsMap.keySet()) {
Node returnNode = IR.returnNode();
Collection objects = functionLoopObjectsMap.get(function);
Node[] objectNames = new Node[objects.size()];
Node[] objectNamesForCall = new Node[objects.size()];
int i = 0;
for (LoopObject object : objects) {
objectNames[i] = IR.name(object.name);
objectNamesForCall[i] = IR.name(object.name);
i++;
}
Node iife = IR.function(
IR.name(""),
IR.paramList(objectNames),
IR.block(returnNode));
Node call = IR.call(iife, objectNamesForCall);
call.putBooleanProp(Node.FREE_CALL, true);
Node replacement;
if (NodeUtil.isFunctionDeclaration(function)) {
replacement = IR.var(IR.name(function.getFirstChild().getString()), call)
.useSourceInfoIfMissingFromForTree(function);
} else {
replacement = call.useSourceInfoIfMissingFromForTree(function);
}
function.getParent().replaceChild(function, replacement);
returnNode.addChildToFront(function);
}
}
private class LoopObject {
private final String name;
private final Set vars = new LinkedHashSet<>();
private LoopObject(String name) {
this.name = name;
}
}
}
}
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