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array.c: use rb_random_ulong_limited

* array.c (rb_ary_sample): use rb_random_ulong_limited, since
  precision of long may be larger than double.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37126 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
nobu 2012-10-09 09:01:40 +00:00
parent 7f8e558464
commit e3efce6df1
5 changed files with 41 additions and 22 deletions

View file

@ -1,4 +1,7 @@
Tue Oct 9 17:59:00 2012 Nobuyoshi Nakada <nobu@ruby-lang.org>
Tue Oct 9 18:01:37 2012 Nobuyoshi Nakada <nobu@ruby-lang.org>
* array.c (rb_ary_sample): use rb_random_ulong_limited, since
precision of long may be larger than double.
* random.c (rb_random_ulong_limited): new function to return a random
value from 0 upto limit as unsigned long, simillary to

5
NEWS
View file

@ -17,6 +17,11 @@ with all sufficient information, see the ChangeLog file.
* builtin classes
* Array
* incompatible changes:
* random parameter of Array#shuffle! and Array#sample now
will be called with one argument, maximum value.
* Enumerable
* added method:
* added Enumerable#lazy method for lazy enumeration.

40
array.c
View file

@ -3996,7 +3996,7 @@ rb_ary_flatten(int argc, VALUE *argv, VALUE ary)
(argc > 0 && !NIL_P((opts) = rb_check_hash_type(argv[argc-1])) && (--argc, 1))
static VALUE sym_random;
#define RAND_UPTO(max) (long)(rb_random_real(randgen)*(max))
#define RAND_UPTO(max) (long)rb_random_ulong_limited((randgen), (max)-1)
/*
* call-seq:
@ -4091,7 +4091,7 @@ rb_ary_sample(int argc, VALUE *argv, VALUE ary)
VALUE nv, result, *ptr;
VALUE opts, randgen = rb_cRandom;
long n, len, i, j, k, idx[10];
double rnds[numberof(idx)];
long rnds[numberof(idx)];
if (OPTHASH_GIVEN_P(opts)) {
randgen = rb_hash_lookup2(opts, sym_random, randgen);
@ -4104,11 +4104,11 @@ rb_ary_sample(int argc, VALUE *argv, VALUE ary)
i = 0;
}
else {
double x = rb_random_real(randgen);
if ((len = RARRAY_LEN(ary)) == 0) return Qnil;
i = (long)(x * len);
i = RAND_UPTO(len);
if ((len = RARRAY_LEN(ary)) <= i) return Qnil;
ptr = RARRAY_PTR(ary);
}
return RARRAY_PTR(ary)[i];
return ptr[i];
}
rb_scan_args(argc, argv, "1", &nv);
n = NUM2LONG(nv);
@ -4116,27 +4116,37 @@ rb_ary_sample(int argc, VALUE *argv, VALUE ary)
if (n > len) n = len;
if (n <= numberof(idx)) {
for (i = 0; i < n; ++i) {
rnds[i] = rb_random_real(randgen);
rnds[i] = RAND_UPTO(len - i);
}
}
k = len;
len = RARRAY_LEN(ary);
ptr = RARRAY_PTR(ary);
if (len < k) {
if (n <= numberof(idx)) {
for (i = 0; i < n; ++i) {
if (rnds[i] >= len) {
return rb_ary_new2(0);
}
}
}
}
if (n > len) n = len;
switch (n) {
case 0:
return rb_ary_new2(0);
case 1:
i = (long)(rnds[0] * len);
i = rnds[0];
return rb_ary_new4(1, &ptr[i]);
case 2:
i = (long)(rnds[0] * len);
j = (long)(rnds[1] * (len-1));
i = rnds[0];
j = rnds[1];
if (j >= i) j++;
return rb_ary_new3(2, ptr[i], ptr[j]);
case 3:
i = (long)(rnds[0] * len);
j = (long)(rnds[1] * (len-1));
k = (long)(rnds[2] * (len-2));
i = rnds[0];
j = rnds[1];
k = rnds[2];
{
long l = j, g = i;
if (j >= i) l = i, g = ++j;
@ -4147,9 +4157,9 @@ rb_ary_sample(int argc, VALUE *argv, VALUE ary)
if (n <= numberof(idx)) {
VALUE *ptr_result;
long sorted[numberof(idx)];
sorted[0] = idx[0] = (long)(rnds[0] * len);
sorted[0] = idx[0] = rnds[0];
for (i=1; i<n; i++) {
k = (long)(rnds[i] * --len);
k = rnds[i];
for (j = 0; j < i; ++j) {
if (k < sorted[j]) break;
++k;

View file

@ -2019,15 +2019,15 @@ class TestArray < Test::Unit::TestCase
def test_sample_random
ary = (0...10000).to_a
assert_raise(ArgumentError) {ary.sample(1, 2, random: nil)}
gen0 = proc do
0.5
gen0 = proc do |max|
(max+1)/2
end
class << gen0
alias rand call
end
gen1 = proc do
gen1 = proc do |max|
ary.replace([])
0.5
(max+1)/2
end
class << gen1
alias rand call

View file

@ -170,8 +170,9 @@ class TestRand < Test::Unit::TestCase
def test_shuffle
srand(0)
assert_equal([1,4,2,5,3], [1,2,3,4,5].shuffle)
assert_equal([1,4,2,5,3], [1,2,3,4,5].shuffle(random: Random.new(0)))
result = [*1..5].shuffle
assert_equal([*1..5], result.sort)
assert_equal(result, [*1..5].shuffle(random: Random.new(0)))
end
def test_big_seed