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A Java Optimization Framework
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package soot.jimple.spark.pag;

/*-
 * #%L
 * Soot - a J*va Optimization Framework
 * %%
 * Copyright (C) 2002 Ondrej Lhotak
 * %%
 * This program 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 program 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 General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * .
 * #L%
 */

import soot.Type;
import soot.jimple.spark.internal.TypeManager;
import soot.jimple.spark.sets.EmptyPointsToSet;
import soot.jimple.spark.sets.PointsToSetInternal;
import soot.jimple.toolkits.pointer.representations.ReferenceVariable;
import soot.options.Options;
import soot.util.Numberable;

/**
 * Represents every node in the pointer assignment graph.
 *
 * @author Ondrej Lhotak
 */
public class Node implements ReferenceVariable, Numberable {
  public final int hashCode() {
    return number;
  }

  public final boolean equals(Object other) {
    return this == other;
  }

  /** Returns the declared type of this node, null for unknown. */
  public Type getType() {
    return type;
  }

  /** Sets the declared type of this node, null for unknown. */
  public void setType(Type type) {
    if (TypeManager.isUnresolved(type) && !Options.v().ignore_resolution_errors()) {
      throw new RuntimeException("Unresolved type " + type);
    }
    this.type = type;
  }

  /**
   * If this node has been merged with another, returns the new node to be used as the representative of this node; returns
   * this if the node has not been merged.
   */
  public Node getReplacement() {
    if (replacement != replacement.replacement) {
      replacement = replacement.getReplacement();
    }
    return replacement;
  }

  /** Merge with the node other. */
  public void mergeWith(Node other) {
    if (other.replacement != other) {
      throw new RuntimeException("Shouldn't happen");
    }
    Node myRep = getReplacement();
    if (other == myRep) {
      return;
    }
    other.replacement = myRep;
    if (other.p2set != p2set && other.p2set != null && !other.p2set.isEmpty()) {
      if (myRep.p2set == null || myRep.p2set.isEmpty()) {
        myRep.p2set = other.p2set;
      } else {
        myRep.p2set.mergeWith(other.p2set);
      }
    }
    other.p2set = null;
    pag.mergedWith(myRep, other);
    if ((other instanceof VarNode) && (myRep instanceof VarNode) && ((VarNode) other).isInterProcTarget()) {
      ((VarNode) myRep).setInterProcTarget();
    }
  }

  /** Returns the points-to set for this node. */
  public PointsToSetInternal getP2Set() {
    if (p2set != null) {
      if (replacement != this) {
        throw new RuntimeException("Node " + this + " has replacement " + replacement + " but has p2set");
      }
      return p2set;
    }
    Node rep = getReplacement();
    if (rep == this) {
      return EmptyPointsToSet.v();
    }
    return rep.getP2Set();
  }

  /** Returns the points-to set for this node, makes it if necessary. */
  public PointsToSetInternal makeP2Set() {
    if (p2set != null) {
      if (replacement != this) {
        throw new RuntimeException("Node " + this + " has replacement " + replacement + " but has p2set");
      }
      return p2set;
    }
    Node rep = getReplacement();
    if (rep == this) {
      p2set = pag.getSetFactory().newSet(type, pag);
    }
    return rep.makeP2Set();
  }

  /** Returns the pointer assignment graph that this node is a part of. */
  public PAG getPag() {
    return pag;
  }

  /** Delete current points-to set and make a new one */
  public void discardP2Set() {
    p2set = null;
  }

  /** Use the specified points-to set to replace current one */
  public void setP2Set(PointsToSetInternal ptsInternal) {
    p2set = ptsInternal;
  }

  /* End of public methods. */

  /** Creates a new node of pointer assignment graph pag, with type type. */
  Node(PAG pag, Type type) {
    if (TypeManager.isUnresolved(type) && !Options.v().ignore_resolution_errors()) {
      throw new RuntimeException("Unresolved type " + type);
    }
    this.type = type;
    this.pag = pag;
    replacement = this;
  }

  /* End of package methods. */

  public final int getNumber() {
    return number;
  }

  public final void setNumber(int number) {
    this.number = number;
  }

  private int number = 0;

  protected Type type;
  protected Node replacement;
  protected PAG pag;
  protected PointsToSetInternal p2set;
}