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#ifndef __RVLALG_BOOL_TERMINATOR
#define __RVLALG_BOOL_TERMINATOR

#include "alg.hh"

/**  boolterm.H
     All Terminators which manipulate other terminators using boolean logic.

*/

namespace RVLAlg {

  /** A terminator which simply acts as a container for a boolean */
  class BoolTerminator: public Terminator {
  private:
    bool & ans;
  public:
    BoolTerminator(bool & _ans): ans(_ans) {}
    BoolTerminator(BoolTerminator & bt): ans(bt.ans) {}
    ~BoolTerminator() {}
    bool query() { return ans; }
  };

  /** Build a new Terminator by combining the results of two others with 
      a logical AND.

      Currently obeys the short-circuit evaluation behavior in the C++ standard
      for logical operations.  Thus, if the first.query is false (continue looping)
      then the second query never occurs.

      Note that this object does NOT own the other two Terminators,
      and thus deleting one of them will cause nasty results.

      Ideally, it would be nice to have some sort of operator behavior
      so you could write

      term = (A AND B AND C) OR D

      where A,B,C,D were all Terminators, but I don't know how to do this yet.
      Of course, in most cases, one can get the desired results just by 
      combining the query calls with the proper logical operations, but I can
      forsee cases where we might need to pass a single Terminator into 
      an algorithm, in which case being able to build one out of combinations
      of others would be useful.
  */
  class AndTerminator: public Terminator {
  public:
    
    AndTerminator( Terminator &a, Terminator &b): first(a), second(b){}
    ~AndTerminator() {}
    
    virtual bool query() { 
      return (first.query() && second.query());
    }
    
  protected:
    Terminator & first;
    Terminator & second;
    
  };
  
  /** Build a new Terminator by combining the results of two others with 
      a logical OR.
      
      Currently obeys the short-circuit evaluation behavior in the C++ standard
      for logical operations. 
  */
  class OrTerminator: public Terminator {
  public:

    OrTerminator( Terminator &a, Terminator &b): first(a), second(b){}
    ~OrTerminator() {}

    virtual bool query() { 
      return (first.query() || second.query());
    }

  protected:
    Terminator & first;
    Terminator & second;
  };

  /** Build a new Terminator by inverting the result of another with 
      a logical NOT.
  */
  class NotTerminator: public Terminator {
  public:

    NotTerminator( Terminator &a): first(a){}
    ~NotTerminator() {}

    virtual bool query() { 
      return (!first.query()); 
    }

  protected:
    Terminator & first;
  };

  /** Build a new Terminator by combining the results of two others with 
      a logical XOR.

      Currently obeys the short-circuit evaluation behavior in the C++ standard
      for logical operations. 
  */
  class XorTerminator: public Terminator {
  public:

    XorTerminator( Terminator &a, Terminator &b): first(a), second(b){}
    ~XorTerminator() {}

    virtual bool query() {
      bool A = first.query();
      bool B = second.query();

      return ((A || B) && (!(A && B)));
    }

  protected:
    Terminator & first;
    Terminator & second;
  };

}

#endif