/*
* Copyright 2007 Google Inc.
*
* 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.gwt.dev.js;
import com.google.gwt.dev.jjs.InternalCompilerException;
import com.google.gwt.dev.js.ast.JsContext;
import com.google.gwt.dev.js.ast.JsExprStmt;
import com.google.gwt.dev.js.ast.JsExpression;
import com.google.gwt.dev.js.ast.JsFunction;
import com.google.gwt.dev.js.ast.JsModVisitor;
import com.google.gwt.dev.js.ast.JsName;
import com.google.gwt.dev.js.ast.JsNameRef;
import com.google.gwt.dev.js.ast.JsProgram;
import com.google.gwt.dev.js.ast.JsStatement;
import com.google.gwt.dev.js.ast.JsVisitor;
import java.util.HashMap;
import java.util.Map;
/**
* Removes JsFunctions that are never referenced in the program.
*/
public class JsUnusedFunctionRemover {
/**
* Finds all functions in the program.
*/
private class JsFunctionVisitor extends JsVisitor {
@Override
public void endVisit(JsFunction x, JsContext<JsExpression> ctx) {
// Anonymous function, ignore it
if (x.getName() != null && !x.isArtificiallyRescued()) {
toRemove.put(x.getName(), x);
}
}
}
/**
* Finds all function references in the program.
*/
private class JsNameRefVisitor extends JsVisitor {
@Override
public void endVisit(JsNameRef x, JsContext<JsExpression> ctx) {
toRemove.remove(x.getName());
}
}
private class RemovalVisitor extends JsModVisitor {
@Override
public void endVisit(JsExprStmt x, JsContext<JsStatement> ctx) {
if (!(x.getExpression() instanceof JsFunction)) {
return;
}
JsFunction f = (JsFunction) x.getExpression();
JsName name = f.getName();
if (toRemove.containsKey(name)) {
// Removing a static initializer indicates a problem in
// JsInliner.
if (name.getIdent().equals("$clinit")) {
throw new InternalCompilerException("Tried to remove clinit "
+ name.getStaticRef().toSource());
}
if (!name.isObfuscatable()) {
// This is intended to be used externally (e.g. gwtOnLoad)
return;
}
// Remove the statement
ctx.removeMe();
}
}
}
public static boolean exec(JsProgram program) {
return (new JsUnusedFunctionRemover(program)).execImpl();
}
private final Map<JsName, JsFunction> toRemove = new HashMap<JsName, JsFunction>();
private final JsProgram program;
public JsUnusedFunctionRemover(JsProgram program) {
this.program = program;
}
public boolean execImpl() {
// Find all functions
(new JsFunctionVisitor()).accept(program);
// Remove the functions that are referenced from the hit list
(new JsNameRefVisitor()).accept(program);
// Remove the unused functions from the JsProgram
RemovalVisitor removalVisitor = new RemovalVisitor();
removalVisitor.accept(program);
return removalVisitor.didChange();
}
}