inputstream.h

用于词法分析的词法分析器

/*
  $Id: InputStream.h,v 1.2 1996/05/25 01:37:34 matt Exp $

  Input streams class.
  
  Provides higher-level view of an istream-derived object, including
  line, column information and meta-state information (word boundary,
  line end, etc.)
  
  (c) Jan 96 Matt Phillips.
  */

#ifndef _INPUTSTR_H
#define _INPUTSTR_H

#include <iostream.h>
#include <std/string.h>

class InputStream
{
public:

  enum {EOFChar = -1};

  // bit values for state
  enum {stClear = 0x00, stWdBoundary = 0x01, stBegLine = 0x02,
	stEndLine = 0x04};

  InputStream (istream &s, string &fname);
  InputStream (istream &s);
  InputStream (const InputStream &s);
  virtual ~InputStream () {}

  string filename;
  int line, col;

  int eof () const {return current == EOFChar;}

  int peek () const {return current;}
  int peekPrev () const {return prev;}

  // get next char
  virtual void get ();

  int getLine () const {return line;}
  int getColumn () const {return col;}

  string getFilename () const {return filename;}

  int getPoint () const {return 0;}	// current input point
  void setPoint (int point) {};
  void resetPoint () {};		// flush backtrack buffer

  unsigned getState () const;
  static int inState (unsigned state, unsigned flag)
  {return state & flag;}

protected:

  int doPeek () const {return str.eof () ? EOFChar : str.peek ();}

  istream &str;
  int prev, current;
};

#endif