/*
 * Copyright (c) 2002 - 2014 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
 */

/*
 * This file is part of the Joana IFC project. It is developed at the Programming Paradigms Group of
 * the Karlsruhe Institute of Technology.
 *
 * <p>For further details on licensing please read the information at http://joana.ipd.kit.edu or
 * contact the authors.
 */
package com.ibm.wala.ipa.callgraph.propagation.cfa;

import com.ibm.wala.cfg.ControlFlowGraph;
import com.ibm.wala.classLoader.CallSiteReference;
import com.ibm.wala.classLoader.IClass;
import com.ibm.wala.classLoader.NewSiteReference;
import com.ibm.wala.classLoader.ShrikeCTMethod;
import com.ibm.wala.classLoader.SyntheticMethod;
import com.ibm.wala.ipa.callgraph.CGNode;
import com.ibm.wala.ipa.callgraph.propagation.SSAContextInterpreter;
import com.ibm.wala.ssa.DefUse;
import com.ibm.wala.ssa.IR;
import com.ibm.wala.ssa.IRView;
import com.ibm.wala.ssa.ISSABasicBlock;
import com.ibm.wala.ssa.SSAInstruction;
import com.ibm.wala.types.FieldReference;
import com.ibm.wala.util.collections.EmptyIterator;
import java.util.Iterator;

/**
 * This ContextInterpreter can be used when using another WALA frontend than the shrike frontend.
 * WALA's standard ContextInterpreters, like e.g. DefaultSSAInterpreter delegate to CodeScanner,
 * which assumes, that the provided methods are instances of shrike classes. When using these
 * ContextInterpreter with another frontend than shrike, this leads to ClassCastExceptions. This
 * class can be used to work around this issue. It delegates to a given ContextInterpreter, if the
 * CGNode's IMethod is a Shrike class. Otherwise, it retrieves the required information from the
 * CGNode's IR, which should always work.
 *
 * @author Martin Mohr &lt;martin.mohr@kit.edu&gt;
 *     <p>This class is provided by the JOANA project (joana.ipd.kit.edu).
 */
public class FallbackContextInterpreter implements SSAContextInterpreter {

  private final SSAContextInterpreter shrikeCI;

  public FallbackContextInterpreter(SSAContextInterpreter shrikeCI) {
    this.shrikeCI = shrikeCI;
  }

  /* (non-Javadoc)
   * @see com.ibm.wala.ipa.callgraph.propagation.rta.RTAContextInterpreter#iterateNewSites(com.ibm.wala.ipa.callgraph.CGNode)
   */
  @Override
  public Iterator<NewSiteReference> iterateNewSites(CGNode node) {
    if (node.getMethod() instanceof SyntheticMethod || node.getMethod() instanceof ShrikeCTMethod) {
      return shrikeCI.iterateNewSites(node);
    } else {
      IRView ir = getIR(node);
      if (ir == null) {
        return EmptyIterator.instance();
      } else {
        return ir.iterateNewSites();
      }
    }
  }

  /* (non-Javadoc)
   * @see com.ibm.wala.ipa.callgraph.propagation.rta.RTAContextInterpreter#iterateFieldsRead(com.ibm.wala.ipa.callgraph.CGNode)
   */
  @Override
  public Iterator<FieldReference> iterateFieldsRead(CGNode node) {
    return shrikeCI.iterateFieldsRead(node);
  }

  /* (non-Javadoc)
   * @see com.ibm.wala.ipa.callgraph.propagation.rta.RTAContextInterpreter#iterateFieldsWritten(com.ibm.wala.ipa.callgraph.CGNode)
   */
  @Override
  public Iterator<FieldReference> iterateFieldsWritten(CGNode node) {
    return shrikeCI.iterateFieldsWritten(node);
  }

  /* (non-Javadoc)
   * @see com.ibm.wala.ipa.callgraph.cha.CHAContextInterpreter#iterateCallSites(com.ibm.wala.ipa.callgraph.CGNode)
   */
  @Override
  public Iterator<CallSiteReference> iterateCallSites(CGNode node) {
    if (node.getMethod() instanceof SyntheticMethod || node.getMethod() instanceof ShrikeCTMethod) {
      return shrikeCI.iterateCallSites(node);
    } else {
      IRView ir = getIR(node);
      if (ir == null) {
        return EmptyIterator.instance();
      } else {
        return ir.iterateCallSites();
      }
    }
  }

  /* (non-Javadoc)
   * @see com.ibm.wala.ipa.callgraph.propagation.rta.RTAContextInterpreter#recordFactoryType(com.ibm.wala.ipa.callgraph.CGNode, com.ibm.wala.classLoader.IClass)
   */
  @Override
  public boolean recordFactoryType(CGNode node, IClass klass) {
    return shrikeCI.recordFactoryType(node, klass);
  }

  /* (non-Javadoc)
   * @see com.ibm.wala.ipa.callgraph.cha.CHAContextInterpreter#understands(com.ibm.wala.ipa.callgraph.CGNode)
   */
  @Override
  public boolean understands(CGNode node) {
    return true;
  }

  /* (non-Javadoc)
   * @see com.ibm.wala.ipa.callgraph.propagation.SSAContextInterpreter#getIR(com.ibm.wala.ipa.callgraph.CGNode)
   */
  @Override
  public IR getIR(CGNode node) {
    return shrikeCI.getIR(node);
  }

  @Override
  public IRView getIRView(CGNode node) {
    return getIR(node);
  }

  /* (non-Javadoc)
   * @see com.ibm.wala.ipa.callgraph.propagation.SSAContextInterpreter#getDU(com.ibm.wala.ipa.callgraph.CGNode)
   */
  @Override
  public DefUse getDU(CGNode node) {
    return shrikeCI.getDU(node);
  }

  /* (non-Javadoc)
   * @see com.ibm.wala.ipa.callgraph.propagation.SSAContextInterpreter#getNumberOfStatements(com.ibm.wala.ipa.callgraph.CGNode)
   */
  @Override
  public int getNumberOfStatements(CGNode node) {
    return shrikeCI.getNumberOfStatements(node);
  }

  /* (non-Javadoc)
   * @see com.ibm.wala.ipa.callgraph.propagation.SSAContextInterpreter#getCFG(com.ibm.wala.ipa.callgraph.CGNode)
   */
  @Override
  public ControlFlowGraph<SSAInstruction, ISSABasicBlock> getCFG(CGNode n) {
    return shrikeCI.getCFG(n);
  }
}
