libguile/pairs.c

   1 /* Copyright (C) 1995,1996,2000,2001, 2004, 2005, 2006, 2008, 2009, 2011, 2012 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public License
   5  * as published by the Free Software Foundation; either version 3 of
   6  * the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301 USA
  17  */
  18
  19
  20 \f
  21 #ifdef HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 #include "libguile/_scm.h"
  26 #include "libguile/validate.h"
  27
  28 #include "libguile/pairs.h"
  29
  30 #include "verify.h"
  31
  32 \f
  33
  34 /* {Pairs}
  35  */
  36
  37 /*
  38  * This compile-time test verifies the properties needed for the
  39  * efficient test macro scm_is_null_or_nil defined in pairs.h,
  40  * which is defined in terms of the SCM_MATCHES_BITS_IN_COMMON macro.
  41  *
  42  * See the comments preceeding the definitions of SCM_BOOL_F and
  43  * SCM_MATCHES_BITS_IN_COMMON in tags.h for more information.
  44  */
  45 verify (SCM_BITS_DIFFER_IN_EXACTLY_ONE_BIT_POSITION             \
  46         (SCM_ELISP_NIL_BITS, SCM_EOL_BITS));
  47
  48
  49 #if (SCM_DEBUG_PAIR_ACCESSES == 1)
  50
  51 #include "libguile/ports.h"
  52 #include "libguile/strings.h"
  53
  54 void scm_error_pair_access (SCM non_pair)
  55 {
  56   static unsigned int running = 0;
  57   SCM message = scm_from_locale_string ("Non-pair accessed with SCM_C[AD]R: `~S'\n");
  58
  59   if (!running)
  60     {
  61       running = 1;
  62       scm_simple_format (scm_current_error_port (),
  63                          message, scm_list_1 (non_pair));
  64       abort ();
  65     }
  66 }
  67
  68 #endif
  69
  70 SCM
  71 scm_cons2 (SCM w, SCM x, SCM y)
  72 {
  73   return scm_cons (w, scm_cons (x, y));
  74 }
  75
  76
  77 SCM_DEFINE (scm_pair_p, "pair?", 1, 0, 0,
  78             (SCM x),
  79             "Return @code{#t} if @var{x} is a pair; otherwise return\n"
  80             "@code{#f}.")
  81 #define FUNC_NAME s_scm_pair_p
  82 {
  83   return scm_from_bool (scm_is_pair (x));
  84 }
  85 #undef FUNC_NAME
  86
  87 SCM_DEFINE (scm_set_car_x, "set-car!", 2, 0, 0,
  88             (SCM pair, SCM value),
  89             "Stores @var{value} in the car field of @var{pair}.  The value returned\n"
  90             "by @code{set-car!} is unspecified.")
  91 #define FUNC_NAME s_scm_set_car_x
  92 {
  93   SCM_VALIDATE_CONS (1, pair);
  94   SCM_SETCAR (pair, value);
  95   return SCM_UNSPECIFIED;
  96 }
  97 #undef FUNC_NAME
  98
  99
 100 SCM_DEFINE (scm_set_cdr_x, "set-cdr!", 2, 0, 0,
 101             (SCM pair, SCM value),
 102             "Stores @var{value} in the cdr field of @var{pair}.  The value returned\n"
 103             "by @code{set-cdr!} is unspecified.")
 104 #define FUNC_NAME s_scm_set_cdr_x
 105 {
 106   SCM_VALIDATE_CONS (1, pair);
 107   SCM_SETCDR (pair, value);
 108   return SCM_UNSPECIFIED;
 109 }
 110 #undef FUNC_NAME
 111
 112 \f
 113
 114 /* Every cxr-pattern is made up of pairs of bits, starting with the two least
 115  * significant bits.  If in a pair of bits the least significant of the two
 116  * bits is 0, this means CDR, otherwise CAR.  The most significant bits of the
 117  * two bits is only needed to indicate when cxr-ing is ready.  This is the
 118  * case, when all remaining pairs of bits equal 00.  */
 119
 120 /* The compiler should unroll this. */
 121 #define CHASE_PAIRS(tree, FUNC_NAME, pattern)                           \
 122   scm_t_uint32 pattern_var = pattern;                                   \
 123   do                                                                    \
 124     {                                                                   \
 125       if (!scm_is_pair (tree))                                          \
 126         scm_wrong_type_arg_msg (FUNC_NAME, 0, tree, "pair");            \
 127       tree = (pattern_var & 1) ? SCM_CAR (tree) : SCM_CDR (tree);       \
 128       pattern_var >>= 2;                                                \
 129     }                                                                   \
 130   while (pattern_var);                                                  \
 131   return tree
 132
 133
 134 SCM_DEFINE (scm_cddr, "cddr", 1, 0, 0, (SCM x), "")
 135 {
 136   CHASE_PAIRS (x, "cddr", 0x0a); /* 00001010 */
 137 }
 138 SCM_DEFINE (scm_cdar, "cdar", 1, 0, 0, (SCM x), "")
 139 {
 140   CHASE_PAIRS (x, "cdar", 0x0b); /* 00001011 */
 141 }
 142 SCM_DEFINE (scm_cadr, "cadr", 1, 0, 0, (SCM x), "")
 143 {
 144   CHASE_PAIRS (x, "cadr", 0x0e); /* 00001110 */
 145 }
 146 SCM_DEFINE (scm_caar, "caar", 1, 0, 0, (SCM x), "")
 147 {
 148   CHASE_PAIRS (x, "caar", 0x0f); /* 00001111 */
 149 }
 150 SCM_DEFINE (scm_cdddr, "cdddr", 1, 0, 0, (SCM x), "")
 151 {
 152   CHASE_PAIRS (x, "cdddr", 0x2a); /* 00101010 */
 153 }
 154 SCM_DEFINE (scm_cddar, "cddar", 1, 0, 0, (SCM x), "")
 155 {
 156   CHASE_PAIRS (x, "cddar", 0x2b); /* 00101011 */
 157 }
 158 SCM_DEFINE (scm_cdadr, "cdadr", 1, 0, 0, (SCM x), "")
 159 {
 160   CHASE_PAIRS (x, "cdadr", 0x2e); /* 00101110 */
 161 }
 162 SCM_DEFINE (scm_cdaar, "cdaar", 1, 0, 0, (SCM x), "")
 163 {
 164   CHASE_PAIRS (x, "cdaar", 0x2f); /* 00101111 */
 165 }
 166 SCM_DEFINE (scm_caddr, "caddr", 1, 0, 0, (SCM x), "")
 167 {
 168   CHASE_PAIRS (x, "caddr", 0x3a); /* 00111010 */
 169 }
 170 SCM_DEFINE (scm_cadar, "cadar", 1, 0, 0, (SCM x), "")
 171 {
 172   CHASE_PAIRS (x, "cadar", 0x3b); /* 00111011 */
 173 }
 174 SCM_DEFINE (scm_caadr, "caadr", 1, 0, 0, (SCM x), "")
 175 {
 176   CHASE_PAIRS (x, "caadr", 0x3e); /* 00111110 */
 177 }
 178 SCM_DEFINE (scm_caaar, "caaar", 1, 0, 0, (SCM x), "")
 179 {
 180   CHASE_PAIRS (x, "caaar", 0x3f); /* 00111111 */
 181 }
 182 SCM_DEFINE (scm_cddddr, "cddddr", 1, 0, 0, (SCM x), "")
 183 {
 184   CHASE_PAIRS (x, "cddddr", 0xaa); /* 10101010 */
 185 }
 186 SCM_DEFINE (scm_cdddar, "cdddar", 1, 0, 0, (SCM x), "")
 187 {
 188   CHASE_PAIRS (x, "cdddar", 0xab); /* 10101011 */
 189 }
 190 SCM_DEFINE (scm_cddadr, "cddadr", 1, 0, 0, (SCM x), "")
 191 {
 192   CHASE_PAIRS (x, "cddadr", 0xae); /* 10101110 */
 193 }
 194 SCM_DEFINE (scm_cddaar, "cddaar", 1, 0, 0, (SCM x), "")
 195 {
 196   CHASE_PAIRS (x, "cddaar", 0xaf); /* 10101111 */
 197 }
 198 SCM_DEFINE (scm_cdaddr, "cdaddr", 1, 0, 0, (SCM x), "")
 199 {
 200   CHASE_PAIRS (x, "cdaddr", 0xba); /* 10111010 */
 201 }
 202 SCM_DEFINE (scm_cdadar, "cdadar", 1, 0, 0, (SCM x), "")
 203 {
 204   CHASE_PAIRS (x, "cdadar", 0xbb); /* 10111011 */
 205 }
 206 SCM_DEFINE (scm_cdaadr, "cdaadr", 1, 0, 0, (SCM x), "")
 207 {
 208   CHASE_PAIRS (x, "cdaadr", 0xbe); /* 10111110 */
 209 }
 210 SCM_DEFINE (scm_cdaaar, "cdaaar", 1, 0, 0, (SCM x), "")
 211 {
 212   CHASE_PAIRS (x, "cdaaar", 0xbf); /* 10111111 */
 213 }
 214 SCM_DEFINE (scm_cadddr, "cadddr", 1, 0, 0, (SCM x), "")
 215 {
 216   CHASE_PAIRS (x, "cadddr", 0xea); /* 11101010 */
 217 }
 218 SCM_DEFINE (scm_caddar, "caddar", 1, 0, 0, (SCM x), "")
 219 {
 220   CHASE_PAIRS (x, "caddar", 0xeb); /* 11101011 */
 221 }
 222 SCM_DEFINE (scm_cadadr, "cadadr", 1, 0, 0, (SCM x), "")
 223 {
 224   CHASE_PAIRS (x, "cadadr", 0xee); /* 11101110 */
 225 }
 226 SCM_DEFINE (scm_cadaar, "cadaar", 1, 0, 0, (SCM x), "")
 227 {
 228   CHASE_PAIRS (x, "cadaar", 0xef); /* 11101111 */
 229 }
 230 SCM_DEFINE (scm_caaddr, "caaddr", 1, 0, 0, (SCM x), "")
 231 {
 232   CHASE_PAIRS (x, "caaddr", 0xfa); /* 11111010 */
 233 }
 234 SCM_DEFINE (scm_caadar, "caadar", 1, 0, 0, (SCM x), "")
 235 {
 236   CHASE_PAIRS (x, "caadar", 0xfb); /* 11111011 */
 237 }
 238 SCM_DEFINE (scm_caaadr, "caaadr", 1, 0, 0, (SCM x), "")
 239 {
 240   CHASE_PAIRS (x, "caaadr", 0xfe); /* 11111110 */
 241 }
 242 SCM_DEFINE (scm_caaaar, "caaaar", 1, 0, 0, (SCM x), "")
 243 {
 244   CHASE_PAIRS (x, "caaaar", 0xff); /* 11111111 */
 245 }
 246
 247 \f
 248
 249 void
 250 scm_init_pairs ()
 251 {
 252 #include "libguile/pairs.x"
 253   scm_c_define_gsubr ("cons", 2, 0, 0, scm_cons);
 254   scm_c_define_gsubr ("car", 1, 0, 0, scm_car);
 255   scm_c_define_gsubr ("cdr", 1, 0, 0, scm_cdr);
 256 }
 257
 258
 259 /*
 260   Local Variables:
 261   c-file-style: "gnu"
 262   End:
 263 */