com.android.ide.eclipse.apt.internal.analysis.EnhancedForLoopAnalyzer.java Source code

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Here is the source code for com.android.ide.eclipse.apt.internal.analysis.EnhancedForLoopAnalyzer.java

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/**
 * Copyright (C) Mattia Gustarini
 * 
 * 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.android.ide.eclipse.apt.internal.analysis;

import java.util.Collection;
import java.util.LinkedList;

import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.InsnList;
import org.objectweb.asm.tree.MethodInsnNode;
import org.objectweb.asm.tree.MethodNode;

/**
 * This analyzer checks if there are uses of for each loops with iterable objects
 * following the guideline:<br/>
 * @see <a href="http://developer.android.com/guide/practices/design/performance.html#foreach">Use Enhanced For Loop Syntax With Caution</a>
 * @author Mattia Gustarini
 */
public final class EnhancedForLoopAnalyzer extends SpecificAnalyzer {
    private static final String ITERATOR_CLASS = "java/util/Iterator";

    public EnhancedForLoopAnalyzer() {
        super("Enhanced For Loop",
                "Use for each loops with caution, because it creates additional objects (i.e. Iterator)");
    }

    /* (non-Javadoc)
     * @see ch.usi.inf.gustarim.apt.analysis.SpecificAnalyzer#analyzeMethod(org.objectweb.asm.tree.MethodNode)
     */
    @Override
    protected Collection<Problem> analyzeMethod(MethodNode methodNode) {
        final LinkedList<Problem> problems = new LinkedList<Problem>();
        final LinkedList<Problem> iterators = new LinkedList<Problem>();
        final InsnList instructions = methodNode.instructions;
        for (int i = 0; i < instructions.size(); i++) {
            final AbstractInsnNode insnNode = instructions.get(i);
            if (insnNode.getOpcode() == Opcodes.INVOKEINTERFACE) {
                final MethodInsnNode interfaceInst = (MethodInsnNode) insnNode;
                if (interfaceInst.owner.equals(ITERATOR_CLASS)) {
                    final Problem problem = new Problem(insnNode);
                    if (iterators.contains(problem)) {
                        iterators.remove(problem);
                        problems.add(problem);
                    } else {
                        iterators.add(problem);
                    }
                }
            }
        }
        return problems;
    }

}