/*
* Copyright 2013 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.jjs.impl;
import com.google.gwt.dev.jjs.SourceInfo;
import com.google.gwt.dev.jjs.ast.Context;
import com.google.gwt.dev.jjs.ast.JDeclarationStatement;
import com.google.gwt.dev.jjs.ast.JLocal;
import com.google.gwt.dev.jjs.ast.JLocalRef;
import com.google.gwt.dev.jjs.ast.JMethodBody;
import com.google.gwt.dev.jjs.ast.JModVisitor;
import com.google.gwt.dev.jjs.ast.JProgram;
import com.google.gwt.dev.jjs.ast.JStatement;
import com.google.gwt.dev.jjs.ast.JType;
import com.google.gwt.thirdparty.guava.common.collect.Queues;
import java.util.Deque;
/**
* A JModVisitor capable of creating temporary local variables and placing their declarations in an
* appropriate preceding place.
*/
public abstract class JModVisitorWithTemporaryVariableCreation extends JModVisitor {
/**
* Stack to keep track of where to insert the new variable declaration.
* The top of the stack is the statement where declarations will be inserted.
*/
private final Deque<Context> currentDeclarationInsertionPoint = Queues.newArrayDeque();
private JMethodBody currentMethodBody = null;
@Override
public void endVisit(JMethodBody body, Context ctx) {
assert currentMethodBody == body;
currentMethodBody = null;
}
@Override
public final void endVisit(JStatement x, Context ctx) {
if (ctx.canInsert()) {
Context popped = currentDeclarationInsertionPoint.pop();
assert popped == ctx;
}
super.endVisit(x, ctx);
}
@Override
public boolean visit(JMethodBody body, Context ctx) {
assert currentMethodBody == null;
currentMethodBody = body;
return true;
}
@Override
public final boolean visit(JStatement x, Context ctx) {
if (ctx.canInsert()) {
currentDeclarationInsertionPoint.push(ctx);
}
return super.visit(x, ctx);
}
protected JLocal createTempLocal(SourceInfo info, JType type) {
assert currentMethodBody != null;
String temporaryLocalName = newTemporaryLocalName(info, type, currentMethodBody);
JLocal local = JProgram.createLocal(info, temporaryLocalName, type, false, currentMethodBody);
JDeclarationStatement declarationStatement =
new JDeclarationStatement(info, new JLocalRef(info, local), null);
currentDeclarationInsertionPoint.peek().insertBefore(declarationStatement);
return local;
}
protected abstract String newTemporaryLocalName(SourceInfo info, JType type,
JMethodBody methodBody);
}