contrib/less/cvt.c

   1 /*
   2  * Copyright (C) 1984-2009  Mark Nudelman
   3  *
   4  * You may distribute under the terms of either the GNU General Public
   5  * License or the Less License, as specified in the README file.
   6  *
   7  * For more information about less, or for information on how to
   8  * contact the author, see the README file.
   9  */
  10
  11 /*
  12  * Routines to convert text in various ways.  Used by search.
  13  */
  14
  15 #include "less.h"
  16 #include "charset.h"
  17
  18 extern int utf_mode;
  19
  20 /*
  21  * Get the length of a buffer needed to convert a string.
  22  */
  23         public int
  24 cvt_length(len, ops)
  25         int len;
  26         int ops;
  27 {
  28         if (utf_mode)
  29                 /*
  30                  * Just copying a string in UTF-8 mode can cause it to grow
  31                  * in length.
  32                  * Four output bytes for one input byte is the worst case.
  33                  */
  34                 len *= 4;
  35         return (len + 1);
  36 }
  37
  38 /*
  39  * Allocate a chpos array for use by cvt_text.
  40  */
  41         public int *
  42 cvt_alloc_chpos(len)
  43         int len;
  44 {
  45         int i;
  46         int *chpos = (int *) ecalloc(sizeof(int), len);
  47         /* Initialize all entries to an invalid position. */
  48         for (i = 0;  i < len;  i++)
  49                 chpos[i] = -1;
  50         return (chpos);
  51 }
  52
  53 /*
  54  * Convert text.  Perform the transformations specified by ops.
  55  * Returns converted text in odst.  The original offset of each
  56  * odst character (when it was in osrc) is returned in the chpos array.
  57  */
  58         public void
  59 cvt_text(odst, osrc, chpos, lenp, ops)
  60         char *odst;
  61         char *osrc;
  62         int *chpos;
  63         int *lenp;
  64         int ops;
  65 {
  66         char *dst;
  67         char *src;
  68         register char *src_end;
  69         LWCHAR ch;
  70
  71         if (lenp != NULL)
  72                 src_end = osrc + *lenp;
  73         else
  74                 src_end = osrc + strlen(osrc);
  75
  76         for (src = osrc, dst = odst;  src < src_end;  )
  77         {
  78                 int src_pos = src - osrc;
  79                 int dst_pos = dst - odst;
  80                 ch = step_char(&src, +1, src_end);
  81                 if ((ops & CVT_BS) && ch == '\b' && dst > odst)
  82                 {
  83                         /* Delete backspace and preceding char. */
  84                         do {
  85                                 dst--;
  86                         } while (dst > odst &&
  87                                 !IS_ASCII_OCTET(*dst) && !IS_UTF8_LEAD(*dst));
  88                 } else if ((ops & CVT_ANSI) && IS_CSI_START(ch))
  89                 {
  90                         /* Skip to end of ANSI escape sequence. */
  91                         src++;  /* skip the CSI start char */
  92                         while (src < src_end)
  93                                 if (!is_ansi_middle(*src++))
  94                                         break;
  95                 } else
  96                 {
  97                         /* Just copy the char to the destination buffer. */
  98                         if ((ops & CVT_TO_LC) && IS_UPPER(ch))
  99                                 ch = TO_LOWER(ch);
 100                         put_wchar(&dst, ch);
 101                         /*
 102                          * Record the original position of the char.
 103                          * But if we've already recorded a position
 104                          * for this char (due to a backspace), leave
 105                          * it alone; if multiple source chars map to
 106                          * one destination char, we want the position
 107                          * of the first one.
 108                          */
 109                         if (chpos != NULL && chpos[dst_pos] < 0)
 110                                 chpos[dst_pos] = src_pos;
 111                 }
 112         }
 113         if ((ops & CVT_CRLF) && dst > odst && dst[-1] == '\r')
 114                 dst--;
 115         *dst = '\0';
 116         if (lenp != NULL)
 117                 *lenp = dst - odst;
 118         if (chpos != NULL)
 119                 chpos[dst - odst] = src - osrc;
 120 }