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array.c: non-recursive rpermute0

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* array.c (rpermute0): remove recursion, by looping with indexes
  stored in `p`.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46427 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
nobu 2014-06-14 01:55:07 +00:00
parent 9d6b7aede9
commit 4802149e44
3 changed files with 28 additions and 14 deletions
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5
ChangeLog
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@ -1,4 +1,7 @@
Sat Jun 14 10:53:28 2014 Nobuyoshi Nakada <nobu@ruby-lang.org> Sat Jun 14 10:53:49 2014 Nobuyoshi Nakada <nobu@ruby-lang.org>
* array.c (rpermute0): remove recursion, by looping with indexes
stored in `p`.
* array.c (permute0): remove recursion, by looping with indexes * array.c (permute0): remove recursion, by looping with indexes
stored in `p`. [ruby-core:63103] [Bug #9932] stored in `p`. [ruby-core:63103] [Bug #9932]

31
array.c
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@ -4981,7 +4981,7 @@ rb_ary_combination(VALUE ary, VALUE num)
} }
/* /*
* Recursively compute repeated permutations of +r+ elements of the set * Compute repeated permutations of +r+ elements of the set
* <code>[0..n-1]</code>. * <code>[0..n-1]</code>.
* *
* When we have a complete repeated permutation of array indexes, copy the * When we have a complete repeated permutation of array indexes, copy the
@ -4990,23 +4990,28 @@ rb_ary_combination(VALUE ary, VALUE num)
* n: the size of the set * n: the size of the set
* r: the number of elements in each permutation * r: the number of elements in each permutation
* p: the array (of size r) that we're filling in * p: the array (of size r) that we're filling in
* index: what index we're filling in now
* values: the Ruby array that holds the actual values to permute * values: the Ruby array that holds the actual values to permute
*/ */
static void static void
rpermute0(long n, long r, long *p, long index, VALUE values) rpermute0(const long n, const long r, long *const p, const VALUE values)
{ {
long i; long i = 0, index = 0;
for (i = 0; i < n; i++) {
p[index] = i; p[index] = i;
if (index < r-1) { /* if not done yet */ for (;;) {
rpermute0(n, r, p, index+1, values); /* recurse */ if (++index < r-1) {
p[index] = i = 0;
continue;
} }
else { for (i = 0; i < n; ++i) {
p[index] = i;
if (!yield_indexed_values(values, r, p)) { if (!yield_indexed_values(values, r, p)) {
rb_raise(rb_eRuntimeError, "repeated permute reentered"); rb_raise(rb_eRuntimeError, "repeated permute reentered");
} }
} }
do {
if (index <= 0) return;
} while ((i = ++p[--index]) >= n);
} }
} }
@ -5069,13 +5074,13 @@ rb_ary_repeated_permutation(VALUE ary, VALUE num)
} }
} }
else { /* this is the general case */ else { /* this is the general case */
volatile VALUE t0 = tmpbuf(r, sizeof(long)); volatile VALUE t0;
long *p = (long*)RSTRING_PTR(t0); long *p = ALLOCV_N(long, t0, r * sizeof(long));
VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */ VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
RBASIC_CLEAR_CLASS(ary0); RBASIC_CLEAR_CLASS(ary0);
rpermute0(n, r, p, 0, ary0); /* compute and yield repeated permutations */ rpermute0(n, r, p, ary0); /* compute and yield repeated permutations */
tmpbuf_discard(t0); ALLOCV_END(t0);
RBASIC_SET_CLASS_RAW(ary0, rb_cArray); RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
} }
return ary; return ary;

6
test/ruby/test_array.rb
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@ -1780,6 +1780,12 @@ class TestArray < Test::Unit::TestCase
a = @cls[0, 1, 2, 3, 4][1, 4].repeated_permutation(2) a = @cls[0, 1, 2, 3, 4][1, 4].repeated_permutation(2)
assert_empty(a.reject {|x| !x.include?(0)}) assert_empty(a.reject {|x| !x.include?(0)})
assert_separately([], <<-"end;") # do
assert_nothing_raised(SystemStackError) do
assert_equal(:ok, Array.new(100_000, nil).repeated_permutation(500_000) {break :ok})
end
end;
end end
def test_repeated_combination def test_repeated_combination