/*
* FindBugs - Find bugs in Java programs
* Copyright (C) 2004 Dave Brosius <dbrosius@users.sourceforge.net>
* Copyright (C) 2004 University of Maryland
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package edu.umd.cs.findbugs.detect;
import org.apache.bcel.Repository;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;
import edu.umd.cs.findbugs.BugAccumulator;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.StatelessDetector;
import edu.umd.cs.findbugs.SystemProperties;
import edu.umd.cs.findbugs.ba.AnalysisContext;
import edu.umd.cs.findbugs.ba.ClassContext;
/**
* Find occurrences of collection.toArray( new Foo[0] ); This causes another
* memory allocation through reflection Much better to do collection.toArray(
* new Foo[collection.size()] );
*
* @author Dave Brosius
*/
public class InefficientToArray extends BytecodeScanningDetector implements StatelessDetector {
private static final boolean DEBUG = SystemProperties.getBoolean("ita.debug");
static final int SEEN_NOTHING = 0;
static final int SEEN_ICONST_0 = 1;
static final int SEEN_ANEWARRAY = 2;
private final static JavaClass collectionClass;
private final BugReporter bugReporter;
private final BugAccumulator bugAccumulator;
private int state = SEEN_NOTHING;
static {
JavaClass tmp = null;
try {
tmp = AnalysisContext.lookupSystemClass("java.util.Collection");
} catch (ClassNotFoundException cnfe) {
AnalysisContext.reportMissingClass(cnfe);
}
collectionClass = tmp;
}
public InefficientToArray(BugReporter bugReporter) {
this.bugReporter = bugReporter;
this.bugAccumulator = new BugAccumulator(bugReporter);
}
@Override
public void visitClassContext(ClassContext classContext) {
if (collectionClass != null) {
classContext.getJavaClass().accept(this);
}
}
@Override
public void visit(Method obj) {
if (DEBUG) {
System.out.println("------------------- Analyzing " + obj.getName() + " ----------------");
}
state = SEEN_NOTHING;
super.visit(obj);
}
@Override
public void visit(Code obj) {
super.visit(obj);
bugAccumulator.reportAccumulatedBugs();
}
@Override
public void sawOpcode(int seen) {
if (DEBUG) {
System.out.println("State: " + state + " Opcode: " + OPCODE_NAMES[seen]);
}
switch (state) {
case SEEN_NOTHING:
if (seen == ICONST_0) {
state = SEEN_ICONST_0;
}
break;
case SEEN_ICONST_0:
if (seen == ANEWARRAY) {
state = SEEN_ANEWARRAY;
} else {
state = SEEN_NOTHING;
}
break;
case SEEN_ANEWARRAY:
if (((seen == INVOKEVIRTUAL) || (seen == INVOKEINTERFACE)) && (getNameConstantOperand().equals("toArray"))
&& (getSigConstantOperand().equals("([Ljava/lang/Object;)[Ljava/lang/Object;"))) {
try {
String clsName = getDottedClassConstantOperand();
JavaClass cls = Repository.lookupClass(clsName);
if (cls.implementationOf(collectionClass)) {
bugAccumulator.accumulateBug(
new BugInstance(this, "ITA_INEFFICIENT_TO_ARRAY", LOW_PRIORITY).addClassAndMethod(this), this);
}
} catch (ClassNotFoundException cnfe) {
bugReporter.reportMissingClass(cnfe);
}
}
state = SEEN_NOTHING;
break;
default:
state = SEEN_NOTHING;
break;
}
}
}