src/mnemonics.c

   1 /*
   2  * This program is free software; you can redistribute it and/or
   3  * modify it under the terms of the GNU General Public License
   4  * as published by the Free Software Foundation; either version 2
   5  * of the License, or (at your option) any later version.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program; if not, write to the Free Software
  14  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  15  *
  16  * See the COPYING file for license information.
  17  *
  18  * Guillaume Chazarain <guichaz@yahoo.fr>
  19  */
  20
  21 /*****************************************
  22  * Try to add unique mnemonics to labels *
  23  *****************************************/
  24
  25 #include <string.h>             /* strlen(), memcpy() */
  26
  27 #include "gliv.h"
  28 #include "mnemonics.h"
  29 #include "str_utils.h"
  30
  31 static GSList *stack = NULL;
  32 static GHashTable *mnemonics = NULL;
  33
  34 static gint count_underscores(const gchar * str, gint len)
  35 {
  36     gint nb_underscores = 0;
  37     gulong himagic, lomagic, magic_bits;
  38     const gulong *long_ptr;
  39     gulong mask;
  40
  41     while ((gulong) str & (sizeof(gulong) - 1))
  42         switch (*str) {
  43         case '\0':
  44             return nb_underscores;
  45
  46         case '_':
  47             nb_underscores++;
  48             /* Fall through */
  49
  50         default:
  51             str++;
  52             len--;
  53         }
  54
  55     long_ptr = (gulong *) str;
  56     INIT_MAGIC();
  57
  58     /* '_' == 0x5F */
  59     mask = 0x5F5F5F5F;
  60     if (sizeof(gulong) > 4)
  61         /* 64-bit */
  62         mask = ((mask << 16) << 16) | mask;
  63
  64     while (len >= sizeof(gulong)) {
  65         gulong masked;
  66
  67         masked = *long_ptr ^ mask;
  68         if (HAS_ZERO(masked)) {
  69             /* A '_' has been detected. */
  70             gchar *char_ptr = (gchar *) & masked;
  71             nb_underscores += (*char_ptr++ == 0);
  72             nb_underscores += (*char_ptr++ == 0);
  73             nb_underscores += (*char_ptr++ == 0);
  74             nb_underscores += (*char_ptr++ == 0);
  75             if (sizeof(gulong) > 4) {
  76                 /* 64-bit */
  77                 nb_underscores += (*char_ptr++ == 0);
  78                 nb_underscores += (*char_ptr++ == 0);
  79                 nb_underscores += (*char_ptr++ == 0);
  80                 nb_underscores += (*char_ptr++ == 0);
  81             }
  82         }
  83
  84         long_ptr++;
  85         len -= sizeof(gulong);
  86     }
  87
  88     str = (const gchar *) long_ptr;
  89     while (len > 0) {
  90         nb_underscores += (*str == '_');
  91         str++;
  92         len--;
  93     }
  94
  95     return nb_underscores;
  96 }
  97
  98 static const gchar *find_mnemonic_position(const gchar * str)
  99 {
 100     const gchar *ptr;
 101
 102     for (ptr = str; *ptr != '\0'; ptr = g_utf8_next_char(ptr)) {
 103         gunichar ch = g_utf8_get_char(ptr);
 104         gpointer ch_key = GINT_TO_POINTER(ch);
 105
 106         if (g_unichar_isalnum(ch)) {
 107             if (mnemonics == NULL) {
 108                 mnemonics = g_hash_table_new(g_direct_hash, g_direct_equal);
 109                 g_hash_table_insert(mnemonics, ch_key, mnemonics);
 110                 return ptr;
 111             }
 112
 113             if (g_hash_table_lookup(mnemonics, ch_key) == NULL) {
 114                 g_hash_table_insert(mnemonics, ch_key, mnemonics);
 115                 return ptr;
 116             }
 117         }
 118     }
 119
 120     /* No position found, add in front. */
 121     return str;
 122 }
 123
 124 /*
 125  * Underscores in labels are replaced with mnemonics, so we duplicate them.
 126  * The caller has to determine whether the returned string has to be freed.
 127  */
 128 static gchar *duplicate_underscores(const gchar * orig)
 129 {
 130     gint nb_underscores, len;
 131     const gchar *ptr_orig;
 132     gchar *new, *ptr_new;
 133
 134     /* How many underscores? */
 135     len = strlen(orig);
 136     nb_underscores = count_underscores(orig, len);
 137     len += nb_underscores;
 138
 139     if (nb_underscores == 0)
 140         return (gchar *) orig;
 141
 142     ptr_new = new = g_new(gchar, len + 1);
 143
 144     for (ptr_orig = orig; *ptr_orig != '\0'; ptr_orig++) {
 145         *ptr_new = *ptr_orig;
 146         if (*ptr_orig == '_') {
 147             /* Duplicate this one. */
 148             ptr_new++;
 149             *ptr_new = '_';
 150         }
 151         ptr_new++;
 152     }
 153
 154     *ptr_new = '\0';
 155
 156     return new;
 157 }
 158
 159 /*
 160  * The returned string should not be freed.  We keep track of already used
 161  * mnemonics to avoid giving twice the same letter.
 162  */
 163 const gchar *add_mnemonic(const gchar * str)
 164 {
 165     static gchar *result = NULL;
 166     static gint size = 0;
 167     const gchar *mnemonic_pos, *end;
 168     gint new_size, offset;
 169     gchar *work;
 170
 171     work = duplicate_underscores(str);
 172     mnemonic_pos = find_mnemonic_position(work);
 173     end = mnemonic_pos + strlen(mnemonic_pos);
 174
 175     /* + 2: '_' and '\0'. */
 176     new_size = end - work + 2;
 177     if (new_size > size) {
 178         size = new_size;
 179         g_free(result);
 180
 181         result = g_new(gchar, size);
 182     }
 183
 184     offset = mnemonic_pos - work;
 185     memcpy(result, work, offset);
 186     result[offset] = '_';
 187     memcpy(result + offset + 1, mnemonic_pos, end - mnemonic_pos + 1);
 188
 189     if (work != str)
 190         g_free(work);
 191
 192     return result;
 193 }
 194
 195 void reset_mnemonics(void)
 196 {
 197     if (mnemonics != NULL) {
 198         g_hash_table_destroy(mnemonics);
 199         mnemonics = NULL;
 200     }
 201 }
 202
 203 void push_mnemonics(void)
 204 {
 205     stack = g_slist_prepend(stack, mnemonics);
 206     mnemonics = NULL;
 207 }
 208
 209 void pop_mnemonics(void)
 210 {
 211     reset_mnemonics();
 212     mnemonics = g_slist_nth_data(stack, 0);
 213     stack = g_slist_delete_link(stack, stack);
 214 }