random.c

00001 /*
00002 ** random.c - Random module
00003 **
00004 ** See Copyright Notice in mruby.h
00005 */
00006 
00007 #include "mruby.h"
00008 #include "mruby/variable.h"
00009 #include "mruby/class.h"
00010 #include "mruby/data.h"
00011 #include "mruby/array.h"
00012 #include "mt19937ar.h"
00013 
00014 #include <time.h>
00015 
00016 static char const MT_STATE_KEY[] = "$mrb_i_mt_state";
00017 
00018 static const struct mrb_data_type mt_state_type = {
00019   MT_STATE_KEY, mrb_free,
00020 };
00021 
00022 static mrb_value mrb_random_rand(mrb_state *mrb, mrb_value self);
00023 static mrb_value mrb_random_srand(mrb_state *mrb, mrb_value self);
00024 
00025 static void
00026 mt_srand(mt_state *t, unsigned long seed)
00027 {
00028   mrb_random_init_genrand(t, seed);
00029 }
00030 
00031 static unsigned long
00032 mt_rand(mt_state *t)
00033 {
00034   return mrb_random_genrand_int32(t);
00035 }
00036 
00037 static double
00038 mt_rand_real(mt_state *t)
00039 {
00040   return mrb_random_genrand_real1(t);
00041 }
00042 
00043 static mrb_value
00044 mrb_random_mt_srand(mrb_state *mrb, mt_state *t, mrb_value seed)
00045 {
00046   if (mrb_nil_p(seed)) {
00047     seed = mrb_fixnum_value((mrb_int)(time(NULL) + mt_rand(t)));
00048     if (mrb_fixnum(seed) < 0) {
00049       seed = mrb_fixnum_value(0 - mrb_fixnum(seed));
00050     }
00051   }
00052 
00053   mt_srand(t, (unsigned) mrb_fixnum(seed));
00054 
00055   return seed;
00056 }
00057 
00058 static mrb_value
00059 mrb_random_mt_rand(mrb_state *mrb, mt_state *t, mrb_value max)
00060 {
00061   mrb_value value;
00062 
00063   if (mrb_fixnum(max) == 0) {
00064     value = mrb_float_value(mrb, mt_rand_real(t));
00065   }
00066   else {
00067     value = mrb_fixnum_value(mt_rand(t) % mrb_fixnum(max));
00068   }
00069 
00070   return value;
00071 }
00072 
00073 static mrb_value
00074 get_opt(mrb_state* mrb)
00075 {
00076   mrb_value arg;
00077 
00078   arg = mrb_nil_value();
00079   mrb_get_args(mrb, "|o", &arg);
00080 
00081   if (!mrb_nil_p(arg)) {
00082     if (!mrb_fixnum_p(arg)) {
00083       mrb_raise(mrb, E_ARGUMENT_ERROR, "invalid argument type");
00084     }
00085     arg = mrb_check_convert_type(mrb, arg, MRB_TT_FIXNUM, "Fixnum", "to_int");
00086     if (mrb_fixnum(arg) < 0) {
00087       arg = mrb_fixnum_value(0 - mrb_fixnum(arg));
00088     }
00089   }
00090   return arg;
00091 }
00092 
00093 static mrb_value
00094 get_random(mrb_state *mrb) {
00095   return mrb_const_get(mrb,
00096              mrb_obj_value(mrb_class_get(mrb, "Random")),
00097              mrb_intern_lit(mrb, "DEFAULT"));
00098 }
00099 
00100 static mt_state *
00101 get_random_state(mrb_state *mrb)
00102 {
00103   mrb_value random_val = get_random(mrb);
00104   return DATA_GET_PTR(mrb, random_val, &mt_state_type, mt_state);
00105 }
00106 
00107 static mrb_value
00108 mrb_random_g_rand(mrb_state *mrb, mrb_value self)
00109 {
00110   mrb_value random = get_random(mrb);
00111   return mrb_random_rand(mrb, random);
00112 }
00113 
00114 static mrb_value
00115 mrb_random_g_srand(mrb_state *mrb, mrb_value self)
00116 {
00117   mrb_value random = get_random(mrb);
00118   return mrb_random_srand(mrb, random);
00119 }
00120 
00121 static mrb_value
00122 mrb_random_init(mrb_state *mrb, mrb_value self)
00123 {
00124   mrb_value seed;
00125   mt_state *t;
00126 
00127   /* avoid memory leaks */
00128   t = (mt_state*)DATA_PTR(self);
00129   if (t) {
00130     mrb_free(mrb, t);
00131   }
00132   mrb_data_init(self, NULL, &mt_state_type);
00133 
00134   t = (mt_state *)mrb_malloc(mrb, sizeof(mt_state));
00135   t->mti = N + 1;
00136 
00137   seed = get_opt(mrb);
00138   seed = mrb_random_mt_srand(mrb, t, seed);
00139   if (mrb_nil_p(seed)) {
00140     t->has_seed = FALSE;
00141   }
00142   else {
00143     mrb_assert(mrb_fixnum_p(seed));
00144     t->has_seed = TRUE;
00145     t->seed = mrb_fixnum(seed);
00146   }
00147 
00148   mrb_data_init(self, t, &mt_state_type);
00149 
00150   return self;
00151 }
00152 
00153 static void
00154 mrb_random_rand_seed(mrb_state *mrb, mt_state *t)
00155 {
00156   if (!t->has_seed) {
00157     mrb_random_mt_srand(mrb, t, mrb_nil_value());
00158   }
00159 }
00160 
00161 static mrb_value
00162 mrb_random_rand(mrb_state *mrb, mrb_value self)
00163 {
00164   mrb_value max;
00165   mt_state *t = DATA_GET_PTR(mrb, self, &mt_state_type, mt_state);
00166 
00167   max = get_opt(mrb);
00168   mrb_random_rand_seed(mrb, t);
00169   return mrb_random_mt_rand(mrb, t, max);
00170 }
00171 
00172 static mrb_value
00173 mrb_random_srand(mrb_state *mrb, mrb_value self)
00174 {
00175   mrb_value seed;
00176   mrb_value old_seed;
00177   mt_state *t = DATA_GET_PTR(mrb, self, &mt_state_type, mt_state);
00178 
00179   seed = get_opt(mrb);
00180   seed = mrb_random_mt_srand(mrb, t, seed);
00181   old_seed = t->has_seed? mrb_fixnum_value(t->seed) : mrb_nil_value();
00182   if (mrb_nil_p(seed)) {
00183     t->has_seed = FALSE;
00184   }
00185   else {
00186     mrb_assert(mrb_fixnum_p(seed));
00187     t->has_seed = TRUE;
00188     t->seed = mrb_fixnum(seed);
00189   }
00190 
00191   return old_seed;
00192 }
00193 
00194 /*
00195  *  call-seq:
00196  *     ary.shuffle!   ->   ary
00197  *
00198  *  Shuffles elements in self in place.
00199  */
00200 
00201 static mrb_value
00202 mrb_ary_shuffle_bang(mrb_state *mrb, mrb_value ary)
00203 {
00204   mrb_int i;
00205   mt_state *random = NULL;
00206 
00207   if (RARRAY_LEN(ary) > 1) {
00208     mrb_get_args(mrb, "|d", &random, &mt_state_type);
00209 
00210     if (random == NULL) {
00211       random = get_random_state(mrb);
00212     }
00213     mrb_random_rand_seed(mrb, random);
00214 
00215     mrb_ary_modify(mrb, mrb_ary_ptr(ary));
00216 
00217     for (i = RARRAY_LEN(ary) - 1; i > 0; i--)  {
00218       mrb_int j;
00219       mrb_value tmp;
00220 
00221       j = mrb_fixnum(mrb_random_mt_rand(mrb, random, mrb_fixnum_value(RARRAY_LEN(ary))));
00222 
00223       tmp = RARRAY_PTR(ary)[i];
00224       mrb_ary_ptr(ary)->ptr[i] = RARRAY_PTR(ary)[j];
00225       mrb_ary_ptr(ary)->ptr[j] = tmp;
00226     }
00227   }
00228 
00229   return ary;
00230 }
00231 
00232 /*
00233  *  call-seq:
00234  *     ary.shuffle   ->   new_ary
00235  *
00236  *  Returns a new array with elements of self shuffled.
00237  */
00238 
00239 static mrb_value
00240 mrb_ary_shuffle(mrb_state *mrb, mrb_value ary)
00241 {
00242   mrb_value new_ary = mrb_ary_new_from_values(mrb, RARRAY_LEN(ary), RARRAY_PTR(ary));
00243   mrb_ary_shuffle_bang(mrb, new_ary);
00244 
00245   return new_ary;
00246 }
00247 
00248 /*
00249  *  call-seq:
00250  *     ary.sample      ->   obj
00251  *     ary.sample(n)   ->   new_ary
00252  *
00253  *  Choose a random element or +n+ random elements from the array.
00254  *
00255  *  The elements are chosen by using random and unique indices into the array
00256  *  in order to ensure that an element doesn't repeat itself unless the array
00257  *  already contained duplicate elements.
00258  *
00259  *  If the array is empty the first form returns +nil+ and the second form
00260  *  returns an empty array.
00261  */
00262 
00263 static mrb_value
00264 mrb_ary_sample(mrb_state *mrb, mrb_value ary)
00265 {
00266   mrb_int n = 0;
00267   mrb_bool given;
00268   mt_state *random = NULL;
00269   mrb_int len = RARRAY_LEN(ary);
00270 
00271   mrb_get_args(mrb, "|i?d", &n, &given, &random, &mt_state_type);
00272   if (random == NULL) {
00273     random = get_random_state(mrb);
00274   }
00275   mrb_random_rand_seed(mrb, random);
00276   mt_rand(random);
00277   if (!given) {                 /* pick one element */
00278     switch (len) {
00279     case 0:
00280       return mrb_nil_value();
00281     case 1:
00282       return RARRAY_PTR(ary)[0];
00283     default:
00284       return RARRAY_PTR(ary)[mt_rand(random) % len];
00285     }
00286   }
00287   else {
00288     mrb_value result;
00289     mrb_int i, j;
00290 
00291     if (n < 0) mrb_raise(mrb, E_ARGUMENT_ERROR, "negative sample number");
00292     if (n > len) n = len;
00293     result = mrb_ary_new_capa(mrb, n);
00294     for (i=0; i<n; i++) {
00295       mrb_int r;
00296 
00297       for (;;) {
00298       retry:
00299         r = mt_rand(random) % len;
00300 
00301         for (j=0; j<i; j++) {
00302           if (mrb_fixnum(RARRAY_PTR(result)[j]) == r) {
00303             goto retry;         /* retry if duplicate */
00304           }
00305         }
00306         break;
00307       }
00308       mrb_ary_push(mrb, result, mrb_fixnum_value(r));
00309     }
00310     for (i=0; i<n; i++) {
00311       mrb_ary_set(mrb, result, i, RARRAY_PTR(ary)[mrb_fixnum(RARRAY_PTR(result)[i])]);
00312     }
00313     return result;
00314   }
00315 }
00316 
00317 
00318 void mrb_mruby_random_gem_init(mrb_state *mrb)
00319 {
00320   struct RClass *random;
00321   struct RClass *array = mrb->array_class;
00322 
00323   mrb_define_method(mrb, mrb->kernel_module, "rand", mrb_random_g_rand, MRB_ARGS_OPT(1));
00324   mrb_define_method(mrb, mrb->kernel_module, "srand", mrb_random_g_srand, MRB_ARGS_OPT(1));
00325 
00326   random = mrb_define_class(mrb, "Random", mrb->object_class);
00327   MRB_SET_INSTANCE_TT(random, MRB_TT_DATA);
00328   mrb_define_class_method(mrb, random, "rand", mrb_random_g_rand, MRB_ARGS_OPT(1));
00329   mrb_define_class_method(mrb, random, "srand", mrb_random_g_srand, MRB_ARGS_OPT(1));
00330 
00331   mrb_define_method(mrb, random, "initialize", mrb_random_init, MRB_ARGS_OPT(1));
00332   mrb_define_method(mrb, random, "rand", mrb_random_rand, MRB_ARGS_OPT(1));
00333   mrb_define_method(mrb, random, "srand", mrb_random_srand, MRB_ARGS_OPT(1));
00334 
00335   mrb_define_method(mrb, array, "shuffle", mrb_ary_shuffle, MRB_ARGS_OPT(1));
00336   mrb_define_method(mrb, array, "shuffle!", mrb_ary_shuffle_bang, MRB_ARGS_OPT(1));
00337   mrb_define_method(mrb, array, "sample", mrb_ary_sample, MRB_ARGS_OPT(2));
00338 
00339   mrb_const_set(mrb, mrb_obj_value(random), mrb_intern_lit(mrb, "DEFAULT"),
00340           mrb_obj_new(mrb, random, 0, NULL));
00341 }
00342 
00343 void mrb_mruby_random_gem_final(mrb_state *mrb)
00344 {
00345 }
00346