/*******************************************************************************
 * Copyright (c) 2006 IBM Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package com.ibm.wala.ipa.slicer;

import com.ibm.wala.dataflow.IFDS.IFlowFunction;
import com.ibm.wala.dataflow.IFDS.IPartiallyBalancedFlowFunctions;
import com.ibm.wala.dataflow.IFDS.IUnaryFlowFunction;
import com.ibm.wala.dataflow.IFDS.IdentityFlowFunction;
import com.ibm.wala.util.debug.Assertions;

/**
 * flow functions for flow-sensitive context-sensitive slicer
 */
public class SliceFunctions implements IPartiallyBalancedFlowFunctions<Statement> {

  @Override
  public IUnaryFlowFunction getCallFlowFunction(Statement src, Statement dest, Statement ret) {
    return ReachabilityFunctions.createReachabilityFunctions().getCallFlowFunction(src, dest, ret);
  }

  @Override
  public IUnaryFlowFunction getCallNoneToReturnFlowFunction(Statement src, Statement dest) {
    if (src == null) {
      throw new IllegalArgumentException("src is null");
    }
    Statement s = src;
    switch (s.getKind()) {
    case NORMAL_RET_CALLER:
    case PARAM_CALLER:
    case EXC_RET_CALLER:
      // uh oh. anything that flows into the missing function will be killed.
      return ReachabilityFunctions.KILL_FLOW;
    case HEAP_PARAM_CALLEE:
    case HEAP_PARAM_CALLER:
    case HEAP_RET_CALLEE:
    case HEAP_RET_CALLER:
      if (dest instanceof HeapStatement) {
        HeapStatement hd = (HeapStatement) dest;
        HeapStatement hs = (HeapStatement) src;
        if (hs.getLocation().equals(hd.getLocation())) {
          return IdentityFlowFunction.identity();
        } else {
          return ReachabilityFunctions.KILL_FLOW;
        }
      } else {
        return ReachabilityFunctions.KILL_FLOW;
      }
    case NORMAL:
      // only control dependence flows into the missing function.
      // this control dependence does not flow back to the caller.
      return ReachabilityFunctions.KILL_FLOW;
    default:
      Assertions.UNREACHABLE(s.getKind().toString());
      return null;
    }
  }

  @Override
  public IUnaryFlowFunction getCallToReturnFlowFunction(Statement src, Statement dest) {
    return ReachabilityFunctions.createReachabilityFunctions().getCallToReturnFlowFunction(src, dest);
  }

  @Override
  public IUnaryFlowFunction getNormalFlowFunction(Statement src, Statement dest) {
    return ReachabilityFunctions.createReachabilityFunctions().getNormalFlowFunction(src, dest);
  }

  @Override
  public IFlowFunction getReturnFlowFunction(Statement call, Statement src, Statement dest) {
    return ReachabilityFunctions.createReachabilityFunctions().getReturnFlowFunction(call, src, dest);
  }

  public IFlowFunction getReturnFlowFunction(Statement src, Statement dest) {
    return ReachabilityFunctions.createReachabilityFunctions().getReturnFlowFunction(src, dest);
  }

  @Override
  public IFlowFunction getUnbalancedReturnFlowFunction(Statement src, Statement dest) {
    return getReturnFlowFunction(src, dest);
  }

}