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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 2018 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.checkState;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.StaticRef;
import com.google.javascript.rhino.StaticSlot;
import com.google.javascript.rhino.StaticSourceFile;
import com.google.javascript.rhino.Token;
/**
* Used by {@code Scope} to store information about variables.
*/
public class AbstractVar, V extends AbstractVar>
extends ScopedName implements StaticSlot, StaticRef {
final String name;
/** Var node */
final Node nameNode;
/** Input source */
final CompilerInput input;
/**
* The index at which the var is declared. e.g. if it's 0, it's the first
* declared variable in that scope
*/
final int index;
/** The enclosing scope */
final S scope;
AbstractVar(String name, Node nameNode, S scope, int index, CompilerInput input) {
this.name = name;
this.nameNode = nameNode;
this.scope = scope;
this.index = index;
this.input = input;
}
// Non-final for jsdev tests
@Override
public String getName() {
return name;
}
@Override
public final Node getScopeRoot() {
return scope.getRootNode();
}
@Override
public final Node getNode() {
return nameNode;
}
final CompilerInput getInput() {
return input;
}
@Override
public final StaticSourceFile getSourceFile() {
return (nameNode != null ? nameNode : scope.getRootNode()).getStaticSourceFile();
}
@Override
public final V getSymbol() {
return thisVar();
}
@Override
public final V getDeclaration() {
return nameNode == null ? null : thisVar();
}
public final Node getParentNode() {
return nameNode == null ? null : nameNode.getParent();
}
/**
* Whether this is a bleeding function (an anonymous named function
* that bleeds into the inner scope).
*/
public boolean isBleedingFunction() {
Node parent = getParentNode();
return parent != null && NodeUtil.isFunctionExpression(parent);
}
public final S getScope() {
return scope;
}
// Non-final for jsdev tests
public boolean isGlobal() {
return scope.isGlobal();
}
public final boolean isLocal() {
return scope.isLocal();
}
final boolean isExtern() {
return input == null || input.isExtern();
}
/** Returns {@code true} if the variable is declared or inferred to be a constant. */
public final boolean isDeclaredOrInferredConst() {
if (nameNode == null) {
return false;
}
return nameNode.isDeclaredConstantVar()
|| nameNode.isInferredConstantVar()
|| nameNode.getBooleanProp(Node.IS_CONSTANT_NAME);
}
/**
* Returns {@code true} if the variable is declared as a define.
* A variable is a define if it is annotated by {@code @define}.
*/
public final boolean isDefine() {
JSDocInfo info = getJSDocInfo();
return info != null && info.isDefine();
}
public final Node getInitialValue() {
return NodeUtil.getRValueOfLValue(nameNode);
}
// Non-final for jsdev tests
public Node getNameNode() {
return nameNode;
}
// Non-final for jsdev tests
@Override
public JSDocInfo getJSDocInfo() {
return nameNode == null ? null : NodeUtil.getBestJSDocInfo(nameNode);
}
final boolean isVar() {
return declarationType() == Token.VAR;
}
final boolean isCatch() {
return declarationType() == Token.CATCH;
}
final boolean isLet() {
return declarationType() == Token.LET;
}
final boolean isConst() {
return declarationType() == Token.CONST;
}
final boolean isClass() {
return declarationType() == Token.CLASS;
}
final boolean isParam() {
return declarationType() == Token.PARAM_LIST;
}
public final boolean isDefaultParam() {
Node parent = nameNode.getParent();
return parent.getParent().isParamList() && parent.isDefaultValue()
&& parent.getFirstChild() == nameNode;
}
final boolean isImport() {
return declarationType() == Token.IMPORT;
}
public final boolean isArguments() {
return Var.ARGUMENTS.equals(name) && scope.isFunctionScope();
}
final boolean isGoogModuleExports() {
return scope.isModuleScope() && "exports".equals(name) && isImplicit();
}
public final boolean isThis() {
return "this".equals(name) && scope.isFunctionScope();
}
private boolean isImplicit() {
AbstractScope.ImplicitVar var = AbstractScope.ImplicitVar.of(name);
return var != null && var.isMadeByScope(scope);
}
private static final ImmutableSet DECLARATION_TYPES = Sets.immutableEnumSet(
Token.VAR,
Token.LET,
Token.CONST,
Token.FUNCTION,
Token.CLASS,
Token.CATCH,
Token.IMPORT,
Token.PARAM_LIST);
final Token declarationType() {
for (Node current = nameNode; current != null;
current = current.getParent()) {
if (DECLARATION_TYPES.contains(current.getToken())) {
return current.getToken();
}
}
checkState(
isImplicit(),
"The nameNode for %s must be a descendant of one of: %s", this, DECLARATION_TYPES);
return null;
}
// This is safe because any concrete subclass of AbstractVar should be assignable to V.
// While it's theoretically possible to do otherwise, such a class would be very awkward to
// implement, and is therefore not worth worrying about.
@SuppressWarnings("unchecked")
private V thisVar() {
return (V) this;
}
}