com.google.javascript.jscomp.Normalize Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of closure-compiler Show documentation
Show all versions of closure-compiler Show documentation
Closure Compiler is a JavaScript optimizing compiler. It parses your
JavaScript, analyzes it, removes dead code and rewrites and minimizes
what's left. It also checks syntax, variable references, and types, and
warns about common JavaScript pitfalls. It is used in many of Google's
JavaScript apps, including Gmail, Google Web Search, Google Maps, and
Google Docs.
/*
* Copyright 2008 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 static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.base.Preconditions;
import com.google.javascript.jscomp.AbstractCompiler.LifeCycleStage;
import com.google.javascript.jscomp.MakeDeclaredNamesUnique.BoilerplateRenamer;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.jscomp.NodeTraversal.Callback;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* The goal with this pass is to simplify the other passes, by making less complex statements.
*
* Starting with statements like: {@code var a = 0, b = foo();}
*
*
Which become: {@code var a = 0; var b = foo();}
*
*
The key here is only to break down things that help the other passes and can be put back
* together in a form that is at least as small when all is said and done.
*
*
This pass currently does the following:
*
*
* - Simplifies the AST by splitting var/let/const statements, moving initializers out of for
* loops, and converting whiles to fors.
*
- Moves hoisted functions to the top of function scopes.
*
- Rewrites unhoisted named function declarations to be var declarations.
*
- Makes all variable names globally unique (extern or otherwise) so that no value is ever
* shadowed (note: "arguments" may require special handling).
*
- Removes duplicate variable declarations.
*
- Marks constants with the IS_CONSTANT_NAME annotation.
*
- Finds properties marked @expose, and rewrites them in [] notation.
*
- Rewrite body of arrow function as a block.
*
- Take var statements out from for-loop initializer. This: for(var a = 0;a<0;a++) {} becomes:
* var a = 0; for(a;a<0;a++) {}
*
*/
class Normalize implements CompilerPass {
private final AbstractCompiler compiler;
private final boolean assertOnChange;
Normalize(AbstractCompiler compiler, boolean assertOnChange) {
this.compiler = compiler;
this.assertOnChange = assertOnChange;
// TODO(nicksantos): assertOnChange should only be true if the tree
// is normalized.
}
static void normalizeSyntheticCode(
AbstractCompiler compiler, Node js, String prefix) {
NodeTraversal.traverse(compiler, js,
new Normalize.NormalizeStatements(compiler, false));
NodeTraversal.traverse(
compiler,
js,
new MakeDeclaredNamesUnique(
new BoilerplateRenamer(
compiler.getCodingConvention(),
compiler.getUniqueNameIdSupplier(),
prefix)));
}
static Node parseAndNormalizeTestCode(
AbstractCompiler compiler, String code) {
Node js = compiler.parseTestCode(code);
NodeTraversal.traverse(compiler, js,
new Normalize.NormalizeStatements(compiler, false));
return js;
}
private void reportCodeChange(String changeDescription, Node n) {
if (assertOnChange) {
throw new IllegalStateException(
"Normalize constraints violated:\n" + changeDescription);
}
compiler.reportChangeToEnclosingScope(n);
}
@Override
public void process(Node externs, Node root) {
MakeDeclaredNamesUnique renamer = new MakeDeclaredNamesUnique();
NodeTraversal.traverseRoots(compiler, renamer, externs, root);
NodeTraversal.traverseRoots(
compiler, new NormalizeStatements(compiler, assertOnChange), externs, root);
removeDuplicateDeclarations(externs, root);
new PropagateConstantAnnotationsOverVars(compiler, assertOnChange)
.process(externs, root);
FindExposeAnnotations findExposeAnnotations = new FindExposeAnnotations();
NodeTraversal.traverse(compiler, root, findExposeAnnotations);
if (!findExposeAnnotations.exposedProperties.isEmpty()) {
NodeTraversal.traverse(compiler, root,
new RewriteExposedProperties(
findExposeAnnotations.exposedProperties));
}
if (!compiler.getLifeCycleStage().isNormalized()) {
compiler.setLifeCycleStage(LifeCycleStage.NORMALIZED);
}
}
/**
* Find all the @expose annotations.
*/
private static class FindExposeAnnotations extends AbstractPostOrderCallback {
private final Set exposedProperties = new HashSet<>();
@Override public void visit(NodeTraversal t, Node n, Node parent) {
if (NodeUtil.isExprAssign(n)) {
Node assign = n.getFirstChild();
Node lhs = assign.getFirstChild();
if (lhs.isGetProp() && isMarkedExpose(assign)) {
exposedProperties.add(lhs.getLastChild().getString());
}
} else if (n.isStringKey() && isMarkedExpose(n)) {
exposedProperties.add(n.getString());
} else if (n.isGetProp() && n.getParent().isExprResult()
&& isMarkedExpose(n)) {
exposedProperties.add(n.getLastChild().getString());
}
}
private static boolean isMarkedExpose(Node n) {
JSDocInfo info = n.getJSDocInfo();
return info != null && info.isExpose();
}
}
/**
* Rewrite all exposed properties in [] form.
*/
private class RewriteExposedProperties
extends AbstractPostOrderCallback {
private final Set exposedProperties;
RewriteExposedProperties(Set exposedProperties) {
this.exposedProperties = exposedProperties;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isGetProp()) {
String propName = n.getLastChild().getString();
if (exposedProperties.contains(propName)) {
Node obj = n.removeFirstChild();
Node prop = n.removeFirstChild();
compiler.reportChangeToEnclosingScope(n);
n.replaceWith(IR.getelem(obj, prop));
}
} else if (n.isStringKey()) {
String propName = n.getString();
if (exposedProperties.contains(propName)) {
if (!n.isQuotedString()) {
compiler.reportChangeToEnclosingScope(n);
n.setQuotedString();
}
}
}
}
}
/**
* Propagate constant annotations over the Var graph.
*/
static class PropagateConstantAnnotationsOverVars
extends AbstractPostOrderCallback
implements CompilerPass {
private final AbstractCompiler compiler;
private final boolean assertOnChange;
PropagateConstantAnnotationsOverVars(
AbstractCompiler compiler, boolean forbidChanges) {
this.compiler = compiler;
this.assertOnChange = forbidChanges;
}
@Override
public void process(Node externs, Node root) {
NodeTraversal.traverseRoots(compiler, this, externs, root);
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
// Note: Constant properties annotations are not propagated.
if (n.isName() || n.isStringKey()) {
if (n.getString().isEmpty()) {
return;
}
JSDocInfo info = null;
// Find the JSDocInfo for a top-level variable.
Var var = t.getScope().getVar(n.getString());
if (var != null) {
info = var.getJSDocInfo();
}
boolean shouldBeConstant =
(info != null && info.isConstant())
|| NodeUtil.isConstantByConvention(compiler.getCodingConvention(), n);
boolean isMarkedConstant = n.getBooleanProp(Node.IS_CONSTANT_NAME);
if (shouldBeConstant && !isMarkedConstant) {
if (assertOnChange) {
String name = n.getString();
throw new IllegalStateException(
"Unexpected const change.\n"
+ " name: " + name + "\n"
+ " parent:" + n.getParent().toStringTree());
}
n.putBooleanProp(Node.IS_CONSTANT_NAME, true);
}
}
}
}
/**
* Walk the AST tree and verify that constant names are used consistently.
*/
static class VerifyConstants extends AbstractPostOrderCallback
implements CompilerPass {
private final AbstractCompiler compiler;
private final boolean checkUserDeclarations;
VerifyConstants(AbstractCompiler compiler, boolean checkUserDeclarations) {
this.compiler = compiler;
this.checkUserDeclarations = checkUserDeclarations;
}
@Override
public void process(Node externs, Node root) {
Node externsAndJs = root.getParent();
checkState(externsAndJs != null);
checkState(externsAndJs.hasChild(externs));
NodeTraversal.traverseRoots(compiler, this, externs, root);
}
private final Map constantMap = new HashMap<>();
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isName()) {
String name = n.getString();
if (n.getString().isEmpty()) {
return;
}
boolean isConst = n.getBooleanProp(Node.IS_CONSTANT_NAME);
if (checkUserDeclarations) {
boolean expectedConst = false;
CodingConvention convention = compiler.getCodingConvention();
if (NodeUtil.isConstantName(n)
|| NodeUtil.isConstantByConvention(convention, n)) {
expectedConst = true;
} else {
expectedConst = false;
JSDocInfo info = null;
Var var = t.getScope().getVar(n.getString());
if (var != null) {
info = var.getJSDocInfo();
}
if (info != null && info.isConstant()) {
expectedConst = true;
} else {
expectedConst = false;
}
}
if (expectedConst) {
Preconditions.checkState(expectedConst == isConst,
"The name %s is not annotated as constant.", name);
} else {
Preconditions.checkState(expectedConst == isConst,
"The name %s should not be annotated as constant.", name);
}
}
Boolean value = constantMap.get(name);
if (value == null) {
constantMap.put(name, isConst);
} else {
Preconditions.checkState(value.booleanValue() == isConst,
"The name %s is not consistently annotated as constant.", name);
}
}
}
}
/**
* Simplify the AST:
* - VAR declarations split, so they represent exactly one child
* declaration.
* - WHILEs are converted to FORs
* - FOR loop are initializers are moved out of the FOR structure
* - LABEL node of children other than LABEL, BLOCK, WHILE, FOR, or DO are
* moved into a block.
* - Add constant annotations based on coding convention.
*/
static class NormalizeStatements implements Callback {
private final AbstractCompiler compiler;
private final boolean assertOnChange;
NormalizeStatements(AbstractCompiler compiler, boolean assertOnChange) {
this.compiler = compiler;
this.assertOnChange = assertOnChange;
}
private void reportCodeChange(String changeDescription, Node n) {
if (assertOnChange) {
throw new IllegalStateException(
"Normalize constraints violated:\n" + changeDescription);
}
compiler.reportChangeToEnclosingScope(n);
}
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
doStatementNormalizations(n);
return true;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
switch (n.getToken()) {
case WHILE:
Node expr = n.getFirstChild();
n.setToken(Token.FOR);
Node empty = IR.empty();
empty.useSourceInfoIfMissingFrom(n);
n.addChildBefore(empty, expr);
n.addChildAfter(empty.cloneNode(), expr);
reportCodeChange("WHILE node", n);
break;
case FUNCTION:
if (visitFunction(n, compiler)) {
reportCodeChange("Function declaration", n);
}
break;
case EXPORT:
splitExportDeclaration(n);
break;
case NAME:
case STRING:
case GETTER_DEF:
case SETTER_DEF:
annotateConstantsByConvention(n, parent);
break;
case CAST:
compiler.reportChangeToEnclosingScope(n);
parent.replaceChild(n, n.removeFirstChild());
break;
default:
break;
}
}
/**
* Mark names and properties that are constants by convention.
*/
private void annotateConstantsByConvention(Node n, Node parent) {
checkState(
n.isName() || n.isString() || n.isStringKey() || n.isGetterDef() || n.isSetterDef());
// Need to check that variables have not been renamed, to determine whether
// coding conventions still apply.
if (compiler.getLifeCycleStage().isNormalizedObfuscated()) {
return;
}
// There are only two cases where a string token
// may be a variable reference: The right side of a GETPROP
// or an OBJECTLIT key.
boolean isObjLitKey = NodeUtil.mayBeObjectLitKey(n);
boolean isProperty = isObjLitKey || (parent.isGetProp() && parent.getLastChild() == n);
if (n.isName() || isProperty) {
boolean isMarkedConstant = n.getBooleanProp(Node.IS_CONSTANT_NAME);
if (!isMarkedConstant
&& NodeUtil.isConstantByConvention(compiler.getCodingConvention(), n)) {
if (assertOnChange) {
String name = n.getString();
throw new IllegalStateException(
"Unexpected const change.\n"
+ " name: "
+ name
+ "\n"
+ " parent:"
+ n.getParent().toStringTree());
}
n.putBooleanProp(Node.IS_CONSTANT_NAME, true);
}
}
}
/**
* Splits ES6 export combined with a variable or function declaration.
*
*/
private void splitExportDeclaration(Node n) {
if (n.getBooleanProp(Node.EXPORT_DEFAULT)) {
return;
}
Node c = n.getFirstChild();
if (NodeUtil.isDeclaration(c)) {
n.removeChild(c);
Node exportSpecs = new Node(Token.EXPORT_SPECS).srcref(n);
n.addChildToFront(exportSpecs);
Iterable names;
if (c.isClass() || c.isFunction()) {
names = Collections.singleton(c.getFirstChild());
n.getParent().addChildBefore(c, n);
} else {
names = NodeUtil.findLhsNodesInNode(c);
// Split up var declarations onto separate lines.
for (Node child : c.children()) {
c.removeChild(child);
Node newDeclaration = new Node(c.getToken(), child).srcref(n);
n.getParent().addChildBefore(newDeclaration, n);
}
}
for (Node name : names) {
Node exportSpec = new Node(Token.EXPORT_SPEC).srcref(name);
exportSpec.addChildToFront(name.cloneNode());
exportSpec.addChildToFront(name.cloneNode());
exportSpecs.addChildToBack(exportSpec);
}
compiler.reportChangeToEnclosingScope(n.getParent());
}
}
/**
* Rewrite named unhoisted functions declarations to a known
* consistent behavior so we don't to different logic paths for the same
* code.
*
* From:
* function f() {}
* to:
* var f = function () {};
* and move it to the top of the block. This actually breaks
* semantics, but the semantics are also not well-defined
* cross-browser.
*
* See #429
*/
static boolean visitFunction(Node n, AbstractCompiler compiler) {
checkState(n.isFunction(), n);
if (NodeUtil.isFunctionDeclaration(n) && !NodeUtil.isHoistedFunctionDeclaration(n)) {
rewriteFunctionDeclaration(n, compiler);
return true;
} else if (n.isFunction() && !NodeUtil.getFunctionBody(n).isBlock()) {
Node returnValue = NodeUtil.getFunctionBody(n);
Node body = IR.block(IR.returnNode(returnValue.detach()));
body.useSourceInfoIfMissingFromForTree(returnValue);
n.addChildToBack(body);
compiler.reportChangeToEnclosingScope(body);
}
return false;
}
/**
* Rewrite the function declaration from:
* function x() {}
* FUNCTION
* NAME x
* PARAM_LIST
* BLOCK
* to:
* var x = function() {};
* VAR
* NAME x
* FUNCTION
* NAME (w/ empty string)
* PARAM_LIST
* BLOCK
*/
private static void rewriteFunctionDeclaration(Node n, AbstractCompiler compiler) {
// Prepare a spot for the function.
Node oldNameNode = n.getFirstChild();
Node fnNameNode = oldNameNode.cloneNode();
Node var = IR.var(fnNameNode).srcref(n);
// Prepare the function
oldNameNode.setString("");
compiler.reportChangeToEnclosingScope(oldNameNode);
// Move the function to the front of the parent
Node parent = n.getParent();
parent.removeChild(n);
parent.addChildToFront(var);
compiler.reportChangeToEnclosingScope(var);
fnNameNode.addChildToFront(n);
}
/**
* Do normalizations that introduce new siblings or parents.
*/
private void doStatementNormalizations(Node n) {
if (n.isLabel()) {
normalizeLabels(n);
}
// Only inspect the children of SCRIPTs, BLOCKs and LABELs, as all these
// are the only legal place for VARs and FOR statements.
if (NodeUtil.isStatementBlock(n) || n.isLabel()) {
extractForInitializer(n, null, null);
}
// Only inspect the children of SCRIPTs, BLOCKs, as all these
// are the only legal place for VARs.
if (NodeUtil.isStatementBlock(n)) {
splitVarDeclarations(n);
}
if (n.isFunction()) {
moveNamedFunctions(n.getLastChild());
}
if (NodeUtil.isCompoundAssignmentOp(n)) {
normalizeAssignShorthand(n);
}
}
// TODO(johnlenz): Move this to NodeTypeNormalizer once the unit tests are
// fixed.
/**
* Limit the number of special cases where LABELs need to be handled. Only
* BLOCK and loops are allowed to be labeled. Loop labels must remain in
* place as the named continues are not allowed for labeled blocks.
*/
private void normalizeLabels(Node n) {
checkArgument(n.isLabel());
Node last = n.getLastChild();
// TODO(moz): Avoid adding blocks for cases like "label: let x;"
switch (last.getToken()) {
case LABEL:
case BLOCK:
case FOR:
case FOR_IN:
case FOR_OF:
case FOR_AWAIT_OF:
case WHILE:
case DO:
return;
default:
Node block = IR.block();
block.useSourceInfoIfMissingFrom(last);
n.replaceChild(last, block);
block.addChildToFront(last);
reportCodeChange("LABEL normalization", n);
return;
}
}
/**
* Bring the initializers out of FOR loops. These need to be placed
* before any associated LABEL nodes. This needs to be done from the top
* level label first so this is called as a pre-order callback (from
* shouldTraverse).
*
* @param n The node to inspect.
* @param before The node to insert the initializer before.
* @param beforeParent The parent of the node before which the initializer
* will be inserted.
*/
private void extractForInitializer(
Node n, Node before, Node beforeParent) {
for (Node next, c = n.getFirstChild(); c != null; c = next) {
next = c.getNext();
Node insertBefore = (before == null) ? c : before;
Node insertBeforeParent = (before == null) ? n : beforeParent;
switch (c.getToken()) {
case LABEL:
extractForInitializer(c, insertBefore, insertBeforeParent);
break;
case FOR_IN:
case FOR_OF:
case FOR_AWAIT_OF:
Node first = c.getFirstChild();
if (first.isVar()) {
Node lhs = first.getFirstChild();
if (lhs.isDestructuringLhs()) {
// Transform:
// for (var [a, b = 3] in c) {}
// to:
// var a; var b; for ([a, b = 3] in c) {}
List lhsNodes = NodeUtil.findLhsNodesInNode(lhs);
for (Node name : lhsNodes) {
// Add a declaration outside the for loop for the given name.
checkState(
name.isName(),
"lhs in destructuring declaration should be a simple name.",
name);
Node newName = IR.name(name.getString()).srcref(name);
Node newVar = IR.var(newName).srcref(name);
insertBeforeParent.addChildBefore(newVar, insertBefore);
}
// Transform for (var [a, b]... ) to for ([a, b]...
Node destructuringPattern = lhs.removeFirstChild();
c.replaceChild(first, destructuringPattern);
} else {
// Transform:
// for (var a = 1 in b) {}
// to:
// var a = 1; for (a in b) {};
Node newStatement = first;
// Clone just the node, to remove any initialization.
Node name = newStatement.getFirstChild().cloneNode();
first.replaceWith(name);
insertBeforeParent.addChildBefore(newStatement, insertBefore);
}
reportCodeChange("FOR-IN var declaration", n);
}
break;
case FOR:
if (!c.getFirstChild().isEmpty()) {
Node init = c.getFirstChild();
if (init.isLet() || init.isConst() || init.isClass() || init.isFunction()) {
return;
}
Node empty = IR.empty();
empty.useSourceInfoIfMissingFrom(c);
c.replaceChild(init, empty);
Node newStatement;
// Only VAR statements, and expressions are allowed,
// but are handled differently.
if (init.isVar()) {
newStatement = init;
} else {
newStatement = NodeUtil.newExpr(init);
}
insertBeforeParent.addChildBefore(newStatement, insertBefore);
reportCodeChange("FOR initializer", n);
}
break;
default:
break;
}
}
}
/**
* Split a var (or let or const) node such as:
* var a, b;
* into individual statements:
* var a;
* var b;
* @param n The whose children we should inspect.
*/
private void splitVarDeclarations(Node n) {
for (Node next, c = n.getFirstChild(); c != null; c = next) {
next = c.getNext();
if (NodeUtil.isNameDeclaration(c)) {
if (assertOnChange && !c.hasChildren()) {
throw new IllegalStateException("Empty VAR node.");
}
while (c.getFirstChild() != c.getLastChild()) {
Node name = c.getFirstChild();
c.removeChild(name);
Node newVar = new Node(c.getToken(), name).srcref(n);
n.addChildBefore(newVar, c);
reportCodeChange("VAR with multiple children", n);
}
}
}
}
/**
* Move all the functions that are valid at the execution of the first
* statement of the function to the beginning of the function definition.
*/
private void moveNamedFunctions(Node functionBody) {
checkState(functionBody.getParent().isFunction());
Node insertAfter = null;
Node current = functionBody.getFirstChild();
// Skip any declarations at the beginning of the function body, they
// are already in the right place.
while (current != null && NodeUtil.isFunctionDeclaration(current)) {
insertAfter = current;
current = current.getNext();
}
// Find any remaining declarations and move them.
while (current != null) {
// Save off the next node as the current node maybe removed.
Node next = current.getNext();
if (NodeUtil.isFunctionDeclaration(current)) {
// Remove the declaration from the body.
functionBody.removeChild(current);
// Read the function at the top of the function body (after any
// previous declarations).
insertAfter = addToFront(functionBody, current, insertAfter);
reportCodeChange("Move function declaration not at top of function", functionBody);
}
current = next;
}
}
private void normalizeAssignShorthand(Node shorthand) {
if (shorthand.getFirstChild().isName()) {
Node name = shorthand.getFirstChild();
shorthand.setToken(NodeUtil.getOpFromAssignmentOp(shorthand));
Node parent = shorthand.getParent();
Node insertPoint = IR.empty();
parent.replaceChild(shorthand, insertPoint);
Node assign = IR.assign(name.cloneNode().useSourceInfoFrom(name), shorthand)
.useSourceInfoFrom(shorthand);
assign.setJSDocInfo(shorthand.getJSDocInfo());
shorthand.setJSDocInfo(null);
parent.replaceChild(insertPoint, assign);
compiler.reportChangeToEnclosingScope(assign);
}
}
/**
* @param after The child node to insert the newChild after, or null if
* newChild should be added to the front of parent's child list.
* @return The inserted child node.
*/
private static Node addToFront(Node parent, Node newChild, Node after) {
if (after == null) {
parent.addChildToFront(newChild);
} else {
parent.addChildAfter(newChild, after);
}
return newChild;
}
}
/**
* Remove duplicate VAR declarations.
*/
private void removeDuplicateDeclarations(Node externs, Node root) {
Callback tickler = new ScopeTicklingCallback();
ScopeCreator scopeCreator =
new SyntacticScopeCreator(compiler, new DuplicateDeclarationHandler());
NodeTraversal t = new NodeTraversal(compiler, tickler, scopeCreator);
t.traverseRoots(externs, root);
}
/** ScopeCreator duplicate declaration handler. */
private final class DuplicateDeclarationHandler
implements SyntacticScopeCreator.RedeclarationHandler {
private final Set hasOkDuplicateDeclaration = new HashSet<>();
/**
* Remove duplicate VAR declarations discovered during scope creation.
*/
@Override
public void onRedeclaration(Scope s, String name, Node n, CompilerInput input) {
checkState(n.isName());
Node parent = n.getParent();
Var v = s.getVar(name);
if (s.isGlobal()) {
// We allow variables to be duplicate declared if one
// declaration appears in source and the other in externs.
// This deals with issues where a browser built-in is declared
// in one browser but not in another.
if (v.isExtern() && !input.isExtern()) {
if (hasOkDuplicateDeclaration.add(v)) {
return;
}
}
}
if (parent.isFunction()) {
if (v.getParentNode().isVar()) {
s.undeclare(v);
s.declare(name, n, v.getInput());
replaceVarWithAssignment(v.getNameNode(), v.getParentNode(),
v.getParentNode().getParent());
}
} else if (parent.isVar()) {
checkState(parent.hasOneChild());
replaceVarWithAssignment(n, parent, parent.getParent());
}
}
/**
* Remove the parent VAR. There are three cases that need to be handled:
* 1) "var a = b;" which is replaced with "a = b"
* 2) "label:var a;" which is replaced with "label:;". Ideally, the
* label itself would be removed but that is not possible in the
* context in which "onRedeclaration" is called.
* 3) "for (var a in b) ..." which is replaced with "for (a in b)..."
* Cases we don't need to handle are VARs with multiple children,
* which have already been split into separate declarations, so there
* is no need to handle that here, and "for (var a;;);", which has
* been moved out of the loop.
* The result of this is that in each case the parent node is replaced
* which is generally dangerous in a traversal but is fine here with
* the scope creator, as the next node of interest is the parent's
* next sibling.
*/
private void replaceVarWithAssignment(Node n, Node parent, Node grandparent) {
if (n.hasChildren()) {
// The * is being initialize, preserve the new value.
parent.removeChild(n);
// Convert "var name = value" to "name = value"
Node value = n.getFirstChild();
n.removeChild(value);
Node replacement = IR.assign(n, value);
replacement.setJSDocInfo(parent.getJSDocInfo());
replacement.useSourceInfoIfMissingFrom(parent);
Node statement = NodeUtil.newExpr(replacement);
grandparent.replaceChild(parent, statement);
reportCodeChange("Duplicate VAR declaration", statement);
} else {
// It is an empty reference remove it.
if (NodeUtil.isStatementBlock(grandparent)) {
grandparent.removeChild(parent);
} else if (grandparent.isForIn() || grandparent.isForOf()) {
// This is the "for (var a in b)..." case. We don't need to worry
// about initializers in "for (var a;;)..." as those are moved out
// as part of the other normalizations.
parent.removeChild(n);
grandparent.replaceChild(parent, n);
} else {
// We should never get here. LABELs with a single VAR statement should
// already have been normalized to have a BLOCK.
checkState(grandparent.isLabel(), grandparent);
}
reportCodeChange("Duplicate VAR declaration", grandparent);
}
}
}
/**
* A simple class that causes scope to be created.
*/
private static final class ScopeTicklingCallback implements NodeTraversal.ScopedCallback {
@Override
public void enterScope(NodeTraversal t) {
// Cause the scope to be created, which will cause duplicate
// to be found.
t.getScope();
}
@Override
public void exitScope(NodeTraversal t) {
// Nothing to do.
}
@Override
public boolean shouldTraverse(NodeTraversal nodeTraversal, Node n, Node parent) {
return true;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
// Nothing to do.
}
}
}