FindFieldSelfAssignment.java :  » Code-Analyzer » findbugs-1.3.9 » edu » umd » cs » findbugs » detect » Java Open Source

/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2003-2005 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 java.util.HashSet;
import java.util.Set;

import org.apache.bcel.classfile.Code;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.LocalVariableAnnotation;
import edu.umd.cs.findbugs.OpcodeStack;
import edu.umd.cs.findbugs.StatelessDetector;
import edu.umd.cs.findbugs.ba.XField;
import edu.umd.cs.findbugs.bcel.OpcodeStackDetector;

public class FindFieldSelfAssignment extends OpcodeStackDetector implements StatelessDetector {
  private BugReporter bugReporter;

  int state;

  public FindFieldSelfAssignment(BugReporter bugReporter) {
    this.bugReporter = bugReporter;
  }

  @Override
  public void visit(Code obj) {
    state = 0;
    super.visit(obj);
    initializedFields.clear();
  }

  int register;

  Set<String> initializedFields = new HashSet<String>();

  @Override
  public void sawOpcode(int seen) {

    if (seen == PUTFIELD) {
      OpcodeStack.Item top = stack.getStackItem(0);
      OpcodeStack.Item next = stack.getStackItem(1);
      
      
      XField f = top.getXField();
      int registerNumber = next.getRegisterNumber();
      if (f != null && f.equals(getXFieldOperand()) 
          && registerNumber >= 0 && registerNumber == top.getFieldLoadedFromRegister()) {
        int priority = NORMAL_PRIORITY;

        LocalVariableAnnotation possibleMatch = LocalVariableAnnotation.findMatchingIgnoredParameter(getClassContext(),
                getMethod(), getNameConstantOperand(), getSigConstantOperand());
        if (possibleMatch == null)
          possibleMatch = LocalVariableAnnotation.findUniqueBestMatchingParameter(getClassContext(), getMethod(),
                  getNameConstantOperand(), getSigConstantOperand());
        if (possibleMatch != null)
          priority--;
        else {
          String signature = stack.getLVValue(registerNumber).getSignature();
          for(int i = 0; i < stack.getNumLocalValues(); i++) if (i != register) {
            if (stack.getLVValue(i).getSignature().equals(signature)) {
              priority--;
              break;
            }
          }
        }
          
          
          
        
        bugReporter.reportBug(new BugInstance(this, "SA_FIELD_SELF_ASSIGNMENT", priority).addClassAndMethod(this)
                .addReferencedField(this).addOptionalAnnotation(possibleMatch).addSourceLine(this));
        
      }
    }
    switch (state) {
    case 0:
      if (seen == DUP)
        state = 6;
      break;
    case 6:
      if (isRegisterStore()) {
        state = 7;
        register = getRegisterOperand();
      } else
        state = 0;
      break;
    case 7:
      if (isRegisterStore() && register == getRegisterOperand()) {
        bugReporter.reportBug(new BugInstance(this, "SA_LOCAL_DOUBLE_ASSIGNMENT", NORMAL_PRIORITY)
                .addClassAndMethod(this).add(
                        LocalVariableAnnotation.getLocalVariableAnnotation(getMethod(), register, getPC(), getPC() - 1))
                .addSourceLine(this));
      }
      state = 0;
      break;
    }

  }

}