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package com.ibm.wala.demandpa.alg;

import com.ibm.wala.demandpa.alg.statemachine.StateMachine;
import com.ibm.wala.demandpa.alg.statemachine.StateMachineFactory;
import com.ibm.wala.demandpa.flowgraph.AbstractFlowLabelVisitor;
import com.ibm.wala.demandpa.flowgraph.IFlowLabel;
import com.ibm.wala.demandpa.flowgraph.ParamBarLabel;
import com.ibm.wala.demandpa.flowgraph.ParamLabel;
import com.ibm.wala.demandpa.flowgraph.ReturnBarLabel;
import com.ibm.wala.demandpa.flowgraph.ReturnLabel;

/**
 * State machine that only allows intraprocedural paths. Mainly for testing
 * purposes.
 * 
 * @author Manu Sridharan
 * 
 */
public class IntraProcFilter implements StateMachine<IFlowLabel> {

  private static final State DUMMY = new State() {
  };

  @Override
  public State getStartState() {
    return DUMMY;
  }

  private static class InterprocFilterVisitor extends AbstractFlowLabelVisitor {
    @Override
    public void visitParamBar(ParamBarLabel label, Object dst) {
      interprocEdge = true;
    }

    @Override
    public void visitParam(ParamLabel label, Object dst) {
      interprocEdge = true;
    }

    @Override
    public void visitReturn(ReturnLabel label, Object dst) {
      interprocEdge = true;
    }

    @Override
    public void visitReturnBar(ReturnBarLabel label, Object dst) {
      interprocEdge = true;
    }

    boolean interprocEdge = false;

  }

  @Override
  public State transition(State prevState, IFlowLabel label) throws IllegalArgumentException {
    if (label == null) {
      throw new IllegalArgumentException("label == null");
    }
    // filter out all interprocedural edges
    InterprocFilterVisitor v = new InterprocFilterVisitor();
    label.visit(v, null);
    return v.interprocEdge ? ERROR : DUMMY;
  }

  private IntraProcFilter() {
  }

  public static class Factory implements StateMachineFactory<IFlowLabel> {

    @Override
    public StateMachine<IFlowLabel> make() {
      return new IntraProcFilter();
    }

  }
}
