glibc/string/strxfrm.c

/* Copyright (C) 1995, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#ifndef STRING_TYPE
# define STRING_TYPE char
# define USTRING_TYPE unsigned char
# define STRXFRM strxfrm
# define STRLEN strlen
# define STPNCPY __stpncpy
#endif

/* Include the shared helper functions.  `strxfrm'/`wcsxfrm' also use
   these functions.  */
#include "../locale/weight.h"


/* Write 32 bit value UTF-8 encoded but only if enough space is left.  */
static __inline size_t
print_val (u_int32_t value, STRING_TYPE *dest, size_t max, size_t act)
{
  char tmp[6];
  int idx = 0;

  if (value < 0x80)
    tmp[idx++] = (char) value;
  else
    {
      tmp[idx++] = '\x80' + (char) (value & 0x3f);
      value >>= 6;

      if (value < 0x20)
	tmp[idx++] = '\xc0' + (char) value;
      else
	{
	  tmp[idx++] = '\x80' + (char) (value & 0x3f);
	  value >>= 6;

	  if (value < 0x10)
	    tmp[idx++] = '\xe0' + (char) value;
	  else
	    {
	      tmp[idx++] = '\x80' + (char) (value & 0x3f);
	      value >>= 6;

	      if (value < 0x08)
		tmp[idx++] = '\xf0' + (char) value;
	      else
		{
		  tmp[idx++] = '\x80' + (char) (value & 0x3f);
		  value >>= 6;

		  if (value < 0x04)
		    tmp[idx++] = '\xf8' + (char) value;
		  else
		    {
		      tmp[idx++] = '\x80' + (char) (value & 0x3f);
		      tmp[idx++] = '\xfc' + (char) (value >> 6);
		    }
		}
	    }
	}
    }

  while (idx-- > 0)
    {
      if (act < max)
	dest[act] = tmp[idx];
      ++act;
    }

  return act;
}


/* Transform SRC into a form such that the result of strcmp
   on two strings that have been transformed by strxfrm is
   the same as the result of strcoll on the two strings before
   their transformation.  The transformed string is put in at
   most N characters of DEST and its length is returned.  */
size_t
STRXFRM (STRING_TYPE *dest, const STRING_TYPE *src, size_t n)
{
  weight_t *forw = NULL;
  weight_t *backw = NULL;
  size_t pass;
  size_t written;

  /* If the current locale does not specify locale data we use normal
     8-bit string comparison.  */
  if (collate_nrules == 0)
    {
      if (n != 0)
	STPNCPY (dest, src, n);

      return STRLEN (src);
    }

  /* Get full information about the string.  This means we get
     information for all passes in a special data structure.  */
  get_string (src, forw, backw);

  /* Now we have all the information.  In at most the given number of
     passes we can finally decide about the order.  */
  written = 0;
  for (pass = 0; pass < collate_nrules; ++pass)
    {
      int forward = (collate_rules[pass] & sort_forward) != 0;
      const weight_t *run = forward ? forw : backw;
      int idx = forward ? 0 : run->data[pass].number - 1;

      do
	{
	  int ignore = 0;
	  u_int32_t w;

	  /* Here we have to check for IGNORE entries.  If these are
	     found we count them and go on witht he next value.  */
	  while ((w = run->data[pass].value[idx]) == IGNORE_CHAR)
	    {
	      ++ignore;
	      if ((forward && ++idx >= run->data[pass].number)
		  || (!forward && --idx < 0))
		{
		  weight_t *nextp = forward ? run->next : run->prev;
		  if (nextp == NULL)
		    {
		      w = 0;
		      break;
		    }
		  run = nextp;
		  idx = forward ? 0 : run->data[pass].number - 1;
		}
	    }

	  /* Now we have information of the number of ignored weights
	     and the value of the next weight.  We have to add 2
	     because 0 means EOS and 1 is the intermediate string end.  */
	  if ((collate_rules[pass] & sort_position) != 0)
	    written = print_val (ignore + 2, dest, n, written);

	  if (w != 0)
	    written = print_val (w, dest, n, written);

	  /* We have to increment the index counters.  */
	  if ((forward && ++idx >= run->data[pass].number)
	      || (!forward && --idx < 0))
	    if (forward)
	      {
		run = run->next;
		idx = 0;
	      }
	    else
	      {
		run = run->prev;
		if (run != NULL)
		  idx = run->data[pass].number - 1;
	      }
	}
      while (run != NULL);

      /* Write marker for end of word.  */
      if (pass + 1 < collate_nrules)
	written = print_val (1, dest, n, written);
    }

  /* Terminate string.  */
  return print_val (0, dest, n, written);
}