commands/yap/machine.h

   1 /* Copyright (c) 1985 Ceriel J.H. Jacobs */
   2
   3 /* $Header$ */
   4
   5 # ifndef _MACHINE_
   6 # define PUBLIC extern
   7 # else
   8 # define PUBLIC
   9 # endif
  10
  11 /*
  12  * Simple minded finite state machine implementation to recognize
  13  * strings.
  14  */
  15
  16 struct state {
  17     char s_char;                /* character to match with */
  18     char s_endstate;            /* flag, 1 if this state is an endstate */
  19     struct state *s_match;      /* new state if matched */
  20     struct state *s_next;       /* other characters to match with */
  21     short s_cnt;                /* if an endstate, this field is filled with
  22                                  * some info, dependant on the machine.
  23                                  */
  24 };
  25
  26 # define FSM_OKE        0
  27 # define FSM_ISPREFIX   -1      /* Must be < 0 */
  28 # define FSM_HASPREFIX  1
  29
  30 int     addstring();
  31 /*
  32  * int addstring(str,cnt,mach)
  33  * char *str;                   The string to be recognized
  34  * int cnt;                     Attribute of the string.
  35  * struct state **mach;         The finite state machine
  36  *
  37  * This routine adds a string to a finite state automaton.
  38  * It returns FSM_ISPREFIX if the added string is a prefix of a string already
  39  * in the automaton, FSM_HASPREFIX if a string, already recognized by the
  40  * automaton, is a prefix of the added string.
  41  * Otherwise it returns FSM_OKE.
  42  */
  43
  44 int     match();
  45 /*
  46  * int match(str,p_int,mach)
  47  * char *str;                   pointer to string
  48  * int *p_int;                  Pointer to an integer
  49  * struct state *mach;          The finite state machine
  50  *
  51  * A match of the string indicated by "str" is tried. If a head of "str"
  52  * is recognized by the finite state automaton, a machine dependant number
  53  * is put in the integer pointed to by "p_int".
  54  * The number of characters that match is returned, so a return value of 0
  55  * means no match.
  56  * A return value of FSM_PREFIX means that the string "str" was a prefix of a
  57  * matched string.
  58  */
  59
  60 # undef PUBLIC