fsmedge.h

用于词法分析的词法分析器

/*
  $Id: FsmEdge.h,v 1.3 1997/02/02 01:31:02 matt Exp $

  FSM edge class.
  
  (c) Feb 1995 Matt Phillips.
  */

#ifndef _FSM_EDGE_H
#define _FSM_EDGE_H

#include <util/type.h>
#include <util/Range.h>

// min and max required for Range<uchar>
inline uchar max (uchar c1, const uchar c2)
{
  return c1 > c2 ? c1 : c2;
}

inline uchar min (uchar c1, const uchar c2)
{
  return c1 < c2 ? c1 : c2;
}

class FsmState;			// forward decl

typedef Range<uchar> UCharRange;

class FsmEdge : public UCharRange
{
  friend class FsmState;
  friend ostream &operator << (ostream &os, const FsmEdge &edge);
   
public:

  // normal edge constructors

  FsmEdge (UCharRange rng, FsmState &_target) :
    UCharRange (rng), target (&_target), epsilon (0) {}

  FsmEdge (uchar l, uchar u, FsmState &_target) :
    UCharRange (l, u), target (&_target), epsilon (0) {}

  FsmEdge (const FsmEdge &e) :
    UCharRange (e), target (e.target), epsilon (e.epsilon) {}

  // special copy-with-a-different-target constructor!
  FsmEdge (FsmState &t, const FsmEdge &e) : UCharRange (e), target (&t),
      epsilon (e.epsilon) {}
   
  // epsilon edge constructor
  FsmEdge (FsmState &_target) : target (&_target), epsilon (1) {}

  void operator = (const FsmEdge &e)
  {UCharRange::operator = (e); epsilon = e.epsilon; target = e.target;}

  // an epsilon edge is <= any edge
  int operator <= (const FsmEdge &e) const;

  int operator < (const FsmEdge &e) const;

  int isEpsilon () const {return epsilon;}
  void makeEpsilon () {epsilon = 1; lower = upper = 0;}

  FsmState &getTarget () const {return *target;}

protected:

  void setTarget (FsmState &state) {target = &state;}

  FsmState *target;
  int epsilon;
};

ostream &operator << (ostream &os, const FsmEdge &edge);

#endif