/********************************************
re_cmpl.c
copyright 1991, Michael D. Brennan

This is a source file for mawk, an implementation of
the AWK programming language.

Mawk is distributed without warranty under the terms of
the GNU General Public License, version 2, 1991.
********************************************/

/* $Log: re_cmpl.c,v $
 * Revision 1.6  1994/12/13  00:14:58  mike
 * \\ -> \ on second replacement scan
 *
 * Revision 1.5  1994/10/08  19:15:51  mike
 * remove SM_DOS
 *
 * Revision 1.4  1993/07/21  01:17:53  mike
 * handle "&" as replacement correctly
 *
 * Revision 1.3  1993/07/17  13:23:10  mike
 * indent and general code cleanup
 *
 * Revision 1.2  1993/07/15  23:38:23  mike
 * SIZE_T and indent
 *
 * Revision 1.1.1.1  1993/07/03	 18:58:19  mike
 * move source to cvs
 *
 * Revision 5.2	 1993/01/01  21:30:48  mike
 * split new_STRING() into new_STRING and new_STRING0
 *
 * Revision 5.1	 1991/12/05  07:56:25  brennan
 * 1.1 pre-release
 *
*/


/*  re_cmpl.c  */

#include "mawk.h"
#include "memory.h"
#include "scan.h"
#include "regexp.h"
#include "repl.h"


static CELL *PROTO(REPL_compile, (STRING *)) ;

typedef struct re_node
{
   STRING *sval ;
   PTR re ;
   struct re_node *link ;
} RE_NODE ;

/* a list of compiled regular expressions */
static RE_NODE *re_list ;

static char efmt[] = "regular expression compile failed (%s)\n%s" ;

/* compile a STRING to a regular expression machine.
   Search a list of pre-compiled strings first
*/
PTR
re_compile(sval)
   STRING *sval ;
{
   register RE_NODE *p ;
   RE_NODE *q ;
   char *s ;

   /* search list */
   s = sval->str ;
   p = re_list ;
   q = (RE_NODE *) 0 ;
   while (p)
   {
      if (strcmp(s, p->sval->str) == 0) /* found */
      {
	 if (!q)		/* already at front */
	    goto _return ;
	 else  /* delete from list for move to front */
	 {
	    q->link = p->link ; goto found ; 
	 }

      }
      else
      {
	 q = p ; p = p->link ; 
      }
   }

   /* not found */
   p = ZMALLOC(RE_NODE) ;
   p->sval = sval ;

   sval->ref_cnt++ ;
   if (!(p->re = REcompile(s)))
   {
      if (mawk_state == EXECUTION)
	 rt_error(efmt, REerrlist[REerrno], s) ;
      else  /* compiling */
      {
	 compile_error(efmt, REerrlist[REerrno], s) ;
	 return (PTR) 0 ;
      }
   }


found :
/* insert p at the front of the list */
   p->link = re_list ; re_list = p ;

_return :

#ifdef	DEBUG
   if (dump_RE)	 REmprint(p->re, stderr) ;
#endif
   return p->re ;
}



/* this is only used by da() */


char *
re_uncompile(m)
   PTR m ;
{
   register RE_NODE *p ;

   for (p = re_list; p; p = p->link)
      if (p->re == m)  return p->sval->str ;
#ifdef	DEBUG
   bozo("non compiled machine") ;
#else
   return NULL;
#endif
}



/*=================================================*/
/*  replacement	 operations   */

/* create a replacement CELL from a STRING *  */

static CELL *
REPL_compile(sval)
   STRING *sval ;
{
   int i = 0 ;
   register char *p = sval->str ;
   register char *q ;
   char *xbuff ;
   CELL *cp ;

   q = xbuff = (char *) zmalloc(sval->len + 1) ;

   while (1)
   {
      switch (*p)
      {
	 case 0:
	    *q = 0 ;
	    goto done ;

	 case '\\':
	    if (p[1] == '&'|| p[1] == '\\')
	    {
	       *q++ = p[1] ;
	       p += 2 ;
	       continue ;
	    }
	    else  break ;

	 case '&':
	    /* if empty we don't need to make a node */
	    if (q != xbuff)
	    {
	       *q = 0 ;
	       split_buff[i++] = new_STRING(xbuff) ;
	    }
	    /* and a null node for the '&'  */
	    split_buff[i++] = (STRING *) 0 ;
	    /*	reset  */
	    p++ ;  q = xbuff ;
	    continue ;

	 default:
	    break ;
      }

      *q++ = *p++ ;
   }

done :
   /* if we have one empty string it will get made now */
   if (q > xbuff || i == 0)  split_buff[i++] = new_STRING(xbuff) ;

   /* This will never happen */
   if (i > MAX_SPLIT)  overflow("replacement pieces", MAX_SPLIT) ;

   cp = ZMALLOC(CELL) ;
   if (i == 1 && split_buff[0])
   {
      cp->type = C_REPL ;
      cp->ptr = (PTR) split_buff[0] ;
   }
   else
   {
      STRING **sp = (STRING **)
      (cp->ptr = zmalloc(sizeof(STRING *) * i)) ;
      int j = 0 ;

      while (j < i)  *sp++ = split_buff[j++] ;

      cp->type = C_REPLV ;
      cp->vcnt = i ;
   }
   zfree(xbuff, sval->len + 1) ;
   return cp ;
}

/* free memory used by a replacement CELL  */

void
repl_destroy(cp)
   register CELL *cp ;
{
   register STRING **p ;
   unsigned cnt ;

   if (cp->type == C_REPL)  free_STRING(string(cp)) ;
   else	 /* an C_REPLV	      */
   {
      p = (STRING **) cp->ptr ;
      for (cnt = cp->vcnt; cnt; cnt--)
      {
	 if (*p) { free_STRING(*p) ; }
	 p++ ;
      }
      zfree(cp->ptr, cp->vcnt * sizeof(STRING *)) ;
   }
}

/* copy a C_REPLV cell to another CELL */

CELL *
replv_cpy(target, source)
   CELL *target, *source ;
{
   STRING **t, **s ;
   unsigned cnt ;

   target->type = C_REPLV ;
   cnt = target->vcnt = source->vcnt ;
   target->ptr = (PTR) zmalloc(cnt * sizeof(STRING *)) ;

   t = (STRING **) target->ptr ;
   s = (STRING **) source->ptr ;
   while (cnt)
   {
      cnt-- ;
      if ( *s ) (*s)->ref_cnt++ ;
      *t++ = *s++ ;
   }
   return target ;
}


/* here's our old friend linked linear list with move to the front
   for compilation of replacement CELLs	 */

typedef struct repl_node
{
   struct repl_node *link ;
   STRING *sval ;		 /* the input */
   CELL *cp ;			 /* the output */
} REPL_NODE ;

static REPL_NODE *repl_list ;

/* search the list (with move to the front) for a compiled
   separator.
   return a ptr to a CELL (C_REPL or C_REPLV)
*/

CELL *
repl_compile(sval)
   STRING *sval ;
{
   register REPL_NODE *p ;
   REPL_NODE *q ;
   char *s ;

   /* search the list */
   s = sval->str ;
   p = repl_list ;
   q = (REPL_NODE *) 0 ;
   while (p)
   {
      if (strcmp(s, p->sval->str) == 0) /* found */
      {
	 if (!q)		/* already at front */
	    return p->cp ;
	 else  /* delete from list for move to front */
	 {
	    q->link = p->link ;
	    goto found ;
	 }

      }
      else
      {
	 q = p ; p = p->link ; 
      }
   }

   /* not found */
   p = ZMALLOC(REPL_NODE) ;
   p->sval = sval ;
   sval->ref_cnt++ ;
   p->cp = REPL_compile(sval) ;

found :
/* insert p at the front of the list */
   p->link = repl_list ; repl_list = p ;
   return p->cp ;
}

/* return the string for a CELL or type REPL or REPLV,
   this is only used by da()  */


char *
repl_uncompile(cp)
   CELL *cp ;
{
   register REPL_NODE *p = repl_list ;

   if (cp->type == C_REPL)
   {
      while (p)
      {
	 if (p->cp->type == C_REPL && p->cp->ptr == cp->ptr)
	    return p->sval->str ;
	 else  p = p->link ;
      }
   }
   else
   {
      while (p)
      {
	 if (p->cp->type == C_REPLV &&
	     memcmp(cp->ptr, p->cp->ptr, cp->vcnt * sizeof(STRING *))
	     == 0)
	    return p->sval->str ;
	 else  p = p->link ;
      }
   }

#if  DEBUG
   bozo("unable to uncompile an repl") ;
#else
   return NULL;
#endif
}

/*
  convert a C_REPLV to	C_REPL
     replacing the &s with sval
*/

CELL *
replv_to_repl(cp, sval)
CELL *cp ; STRING *sval ;
{
   register STRING **p ;
   STRING **sblock = (STRING **) cp->ptr ;
   unsigned cnt, vcnt = cp->vcnt ;
   unsigned len ;
   char *target ;

#ifdef	DEBUG
   if (cp->type != C_REPLV)  bozo("not replv") ;
#endif

   p = sblock ; cnt = vcnt ; len = 0 ;
   while (cnt--)
   {
      if (*p)  len += (*p++)->len ;
      else
      {
	 *p++ = sval ;
	 sval->ref_cnt++ ;
	 len += sval->len ;
      }
   }
   cp->type = C_REPL ;
   cp->ptr = (PTR) new_STRING0(len) ;

   p = sblock ; cnt = vcnt ; target = string(cp)->str ;
   while (cnt--)
   {
      memcpy(target, (*p)->str, (*p)->len) ;
      target += (*p)->len ;
      free_STRING(*p) ;
      p++ ;
   }

   zfree(sblock, vcnt * sizeof(STRING *)) ;
   return cp ;
}