From b654e0719a6d87f51c8b680e53347e4f5de8a54e Mon Sep 17 00:00:00 2001 From: nobu Date: Sat, 14 Jun 2014 01:55:25 +0000 Subject: array.c: non-recursive rcombinate0 * array.c (rcombinate0): remove recursion, by looping with indexes stored in `p`. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46428 b2dd03c8-39d4-4d8f-98ff-823fe69b080e --- array.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) (limited to 'array.c') diff --git a/array.c b/array.c index 8322c294f2..28fd109285 100644 --- a/array.c +++ b/array.c @@ -5087,18 +5087,25 @@ rb_ary_repeated_permutation(VALUE ary, VALUE num) } static void -rcombinate0(long n, long r, long *p, long index, long rest, VALUE values) +rcombinate0(const long n, const long r, long *const p, const long rest, const VALUE values) { - if (rest > 0) { - for (; index < n; ++index) { - p[r-rest] = index; - rcombinate0(n, r, p, index, rest-1, values); + long i = 0, index = 0; + + p[index] = i; + for (;;) { + if (++index < r-1) { + p[index] = i; + continue; } - } - else { - if (!yield_indexed_values(values, r, p)) { - rb_raise(rb_eRuntimeError, "repeated combination reentered"); + for (; i < n; ++i) { + p[index] = i; + if (!yield_indexed_values(values, r, p)) { + rb_raise(rb_eRuntimeError, "repeated combination reentered"); + } } + do { + if (index <= 0) return; + } while ((i = ++p[--index]) >= n); } } @@ -5163,13 +5170,13 @@ rb_ary_repeated_combination(VALUE ary, VALUE num) /* yield nothing */ } else { - volatile VALUE t0 = tmpbuf(n, sizeof(long)); - long *p = (long*)RSTRING_PTR(t0); + volatile VALUE t0; + long *p = ALLOCV_N(long, t0, n); VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */ RBASIC_CLEAR_CLASS(ary0); - rcombinate0(len, n, p, 0, n, ary0); /* compute and yield repeated combinations */ - tmpbuf_discard(t0); + rcombinate0(len, n, p, n, ary0); /* compute and yield repeated combinations */ + ALLOCV_END(t0); RBASIC_SET_CLASS_RAW(ary0, rb_cArray); } return ary; -- cgit v1.2.3