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/******************************************************************************/
/* Object REXX Support                                                        */
/*                                                                            */
/* Regular Expression Utility functions - automaton header file               */
/*                                                                            */
/******************************************************************************/

#ifndef AUTOMATON
#define AUTOMATON

#include "dblqueue.hpp"

class automaton {
  public:
    automaton();              // CTOR
    ~automaton();             // DTOR
    int parse(const char*);         // parse regular expression
    int match(const char*, int);    // match a string

    // in case of a parsing error, this can be used
    // to detect the position at which the error
    // occured. on successful parsing it tells the
    // length of the regular expression.
    int getCurrentPos() { return currentPos; }

    void setMinimal(bool);
    bool getMinimal() { return minimal; }

  private:
    // methods to parse a regular expression
    int expression();
    int term();
    int factor();
    int set();
    int letter(int);

    // insert a state into the automaton
    void setState(int, int, int, int);
    // insert a set into the list of sets
    int insertSet(char*, int);
    // helper function for set building
    int checkRange(char*, int, char);

    int *ch;        // characters to match
    int *next1;     // first transition possibility
    int *next2;     // second transition possibility

    int  final;     // the final state position

    const char *regexp;  // pointer to regular expression

    int **setArray; // pointer to array of sets
    int setSize;    // number of sets

    int  size;      // number of states
    int  freeState; // number of next free state
    int  currentPos;// current position in parsing
    bool minimal;   // minimal matching?
};

#endif