libguile/eq.c

   1 /* Copyright (C) 1995,1996,1997,1998,2000,2001,2003 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
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful,
   9  * but 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  16  */
  17
  18 \f
  19 #if HAVE_CONFIG_H
  20 #  include <config.h>
  21 #endif
  22
  23 #include "libguile/_scm.h"
  24 #include "libguile/ramap.h"
  25 #include "libguile/stackchk.h"
  26 #include "libguile/strorder.h"
  27 #include "libguile/async.h"
  28 #include "libguile/root.h"
  29 #include "libguile/smob.h"
  30 #include "libguile/unif.h"
  31 #include "libguile/vectors.h"
  32
  33 #include "libguile/validate.h"
  34 #include "libguile/eq.h"
  35 \f
  36
  37 #ifdef HAVE_STRING_H
  38 #include <string.h>
  39 #endif
  40 \f
  41
  42 SCM_DEFINE1 (scm_eq_p, "eq?", scm_tc7_rpsubr,
  43              (SCM x, SCM y),
  44              "Return @code{#t} iff @var{x} references the same object as @var{y}.\n"
  45              "@code{eq?} is similar to @code{eqv?} except that in some cases it is\n"
  46              "capable of discerning distinctions finer than those detectable by\n"
  47              "@code{eqv?}.")
  48 #define FUNC_NAME s_scm_eq_p
  49 {
  50   return scm_from_bool (scm_is_eq (x, y));
  51 }
  52 #undef FUNC_NAME
  53
  54 /* We compare doubles in a special way for 'eqv?' to be able to
  55    distinguish plus and minus zero and to identify NaNs.
  56 */
  57
  58 static int
  59 real_eqv (double x, double y)
  60 {
  61   return !memcmp (&x, &y, sizeof(double));
  62 }
  63
  64 #include <stdio.h>
  65 SCM_PRIMITIVE_GENERIC_1 (scm_eqv_p, "eqv?", scm_tc7_rpsubr,
  66              (SCM x, SCM y),
  67              "The @code{eqv?} procedure defines a useful equivalence relation on objects.\n"
  68              "Briefly, it returns @code{#t} if @var{x} and @var{y} should normally be\n"
  69              "regarded as the same object.  This relation is left slightly open to\n"
  70              "interpretation, but works for comparing immediate integers, characters,\n"
  71              "and inexact numbers.")
  72 #define FUNC_NAME s_scm_eqv_p
  73 {
  74   if (scm_is_eq (x, y))
  75     return SCM_BOOL_T;
  76   if (SCM_IMP (x))
  77     return SCM_BOOL_F;
  78   if (SCM_IMP (y))
  79     return SCM_BOOL_F;
  80   /* this ensures that types and scm_length are the same. */
  81
  82   if (SCM_CELL_TYPE (x) != SCM_CELL_TYPE (y))
  83     {
  84       /* fractions use 0x10000 as a flag (at the suggestion of Marius Vollmer),
  85          but this checks the entire type word, so fractions may be accidentally
  86          flagged here as unequal.  Perhaps I should use the 4th double_cell word?
  87       */
  88
  89       /* treat mixes of real and complex types specially */
  90       if (SCM_INEXACTP (x))
  91         {
  92           if (SCM_REALP (x))
  93             return scm_from_bool (SCM_COMPLEXP (y)
  94                              && real_eqv (SCM_REAL_VALUE (x),
  95                                           SCM_COMPLEX_REAL (y))
  96                              && SCM_COMPLEX_IMAG (y) == 0.0);
  97           else
  98             return scm_from_bool (SCM_REALP (y)
  99                              && real_eqv (SCM_COMPLEX_REAL (x),
 100                                           SCM_REAL_VALUE (y))
 101                              && SCM_COMPLEX_IMAG (x) == 0.0);
 102         }
 103
 104       if (SCM_FRACTIONP (x) && SCM_FRACTIONP (y))
 105         return scm_i_fraction_equalp (x, y);
 106       return SCM_BOOL_F;
 107     }
 108   if (SCM_NUMP (x))
 109     {
 110       if (SCM_BIGP (x)) {
 111         return scm_from_bool (scm_i_bigcmp (x, y) == 0);
 112       } else if (SCM_REALP (x)) {
 113         return scm_from_bool (real_eqv (SCM_REAL_VALUE (x), SCM_REAL_VALUE (y)));
 114       } else if (SCM_FRACTIONP (x)) {
 115         return scm_i_fraction_equalp (x, y);
 116       } else { /* complex */
 117         return scm_from_bool (real_eqv (SCM_COMPLEX_REAL (x),
 118                                    SCM_COMPLEX_REAL (y))
 119                          && real_eqv (SCM_COMPLEX_IMAG (x),
 120                                       SCM_COMPLEX_IMAG (y)));
 121       }
 122     }
 123   if (SCM_UNPACK (g_scm_eqv_p))
 124     return scm_call_generic_2 (g_scm_eqv_p, x, y);
 125   else
 126     return SCM_BOOL_F;
 127 }
 128 #undef FUNC_NAME
 129
 130
 131 SCM_PRIMITIVE_GENERIC_1 (scm_equal_p, "equal?", scm_tc7_rpsubr,
 132                          (SCM x, SCM y),
 133  "Return @code{#t} iff @var{x} and @var{y} are recursively @code{eqv?} equivalent.\n"
 134  "@code{equal?} recursively compares the contents of pairs,\n"
 135  "vectors, and strings, applying @code{eqv?} on other objects such as\n"
 136  "numbers and symbols.  A rule of thumb is that objects are generally\n"
 137  "@code{equal?}  if they print the same.  @code{equal?} may fail to\n"
 138  "terminate if its arguments are circular data structures.")
 139 #define FUNC_NAME s_scm_equal_p
 140 {
 141   SCM_CHECK_STACK;
 142  tailrecurse:
 143   SCM_TICK;
 144   if (scm_is_eq (x, y))
 145     return SCM_BOOL_T;
 146   if (SCM_IMP (x))
 147     return SCM_BOOL_F;
 148   if (SCM_IMP (y))
 149     return SCM_BOOL_F;
 150   if (SCM_CONSP (x) && SCM_CONSP (y))
 151     {
 152       if (scm_is_false (scm_equal_p (SCM_CAR (x), SCM_CAR (y))))
 153         return SCM_BOOL_F;
 154       x = SCM_CDR(x);
 155       y = SCM_CDR(y);
 156       goto tailrecurse;
 157     }
 158   if (SCM_TYP7 (x) == scm_tc7_string && SCM_TYP7 (y) == scm_tc7_string)
 159     return scm_string_equal_p (x, y);
 160   /* This ensures that types and scm_length are the same.  */
 161   if (SCM_CELL_TYPE (x) != SCM_CELL_TYPE (y))
 162     {
 163       /* treat mixes of real and complex types specially */
 164       if (SCM_INEXACTP (x) && SCM_INEXACTP (y))
 165         {
 166           if (SCM_REALP (x))
 167             return scm_from_bool (SCM_COMPLEXP (y)
 168                              && SCM_REAL_VALUE (x) == SCM_COMPLEX_REAL (y)
 169                              && SCM_COMPLEX_IMAG (y) == 0.0);
 170           else
 171             return scm_from_bool (SCM_REALP (y)
 172                              && SCM_COMPLEX_REAL (x) == SCM_REAL_VALUE (y)
 173                              && SCM_COMPLEX_IMAG (x) == 0.0);
 174         }
 175
 176       /* should we handle fractions here also? */
 177       else if ((SCM_FRACTIONP (x)) && (SCM_INEXACTP (y)))
 178         {
 179           if (SCM_REALP (y))
 180             return scm_from_bool (scm_i_fraction2double (x) == SCM_REAL_VALUE (y));
 181           else
 182             return scm_from_bool (SCM_COMPLEX_REAL (y) == scm_i_fraction2double (x)
 183                              && SCM_COMPLEX_IMAG (y) == 0.0);
 184         }
 185       else if ((SCM_FRACTIONP (y)) && (SCM_INEXACTP (x)))
 186         {
 187           if (SCM_REALP (x))
 188             return scm_from_bool (scm_i_fraction2double (y) == SCM_REAL_VALUE (x));
 189           else
 190             return scm_from_bool (SCM_COMPLEX_REAL (x) == scm_i_fraction2double (y)
 191                              && SCM_COMPLEX_IMAG (x) == 0.0);
 192         }
 193
 194       return SCM_BOOL_F;
 195     }
 196   switch (SCM_TYP7 (x))
 197     {
 198     default:
 199       break;
 200     case scm_tc7_number:
 201       switch SCM_TYP16 (x)
 202         {
 203         case scm_tc16_big:
 204           return scm_bigequal (x, y);
 205         case scm_tc16_real:
 206           return scm_real_equalp (x, y);
 207         case scm_tc16_complex:
 208           return scm_complex_equalp (x, y);
 209         case scm_tc16_fraction:
 210           return scm_i_fraction_equalp (x, y);
 211         }
 212     case scm_tc7_vector:
 213     case scm_tc7_wvect:
 214       return scm_vector_equal_p (x, y);
 215     case scm_tc7_smob:
 216       {
 217         int i = SCM_SMOBNUM (x);
 218         if (!(i < scm_numsmob))
 219           return SCM_BOOL_F;
 220         if (scm_smobs[i].equalp)
 221           return (scm_smobs[i].equalp) (x, y);
 222         else
 223           break;
 224       }
 225 #if SCM_HAVE_ARRAYS
 226     case scm_tc7_bvect: case scm_tc7_uvect: case scm_tc7_ivect:
 227     case scm_tc7_fvect: case scm_tc7_cvect: case scm_tc7_dvect:
 228     case scm_tc7_svect:
 229 #if SCM_SIZEOF_LONG_LONG != 0
 230     case scm_tc7_llvect:
 231 #endif
 232     case scm_tc7_byvect:
 233       if (scm_tc16_array && scm_smobs[SCM_TC2SMOBNUM (scm_tc16_array)].equalp)
 234         return scm_array_equal_p (x, y);
 235 #endif
 236     }
 237   if (SCM_UNPACK (g_scm_equal_p))
 238     return scm_call_generic_2 (g_scm_equal_p, x, y);
 239   else
 240     return SCM_BOOL_F;
 241 }
 242 #undef FUNC_NAME
 243
 244
 245 \f
 246
 247
 248
 249 void
 250 scm_init_eq ()
 251 {
 252 #include "libguile/eq.x"
 253 }
 254
 255
 256 /*
 257   Local Variables:
 258   c-file-style: "gnu"
 259   End:
 260 */