merge revision(s) 46417,46418: [Backport #9939]

	* array.c (yield_indexed_values): extract from permute0(),
	  rpermute0(), and rcombinate0().

	* array.c (rb_ary_combination): iterate on a shared copy, and use
	  array of indexes instead of array of chosen objects.
	  [ruby-core:63149] [Bug #9939]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@47332 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 33 insertions, 44 deletions

diff --git a/array.c b/array.c
index 5e95e87685..b302b8a268 100644
--- a/array.c
+++ b/array.c
@@ -4529,6 +4529,25 @@ rb_ary_cycle(int argc, VALUE *argv, VALUE ary)
 #define tmpary_discard(a) (ary_discard(a), RBASIC(a)->klass = rb_cArray)
 
 /*
+ * Build a ruby array of the corresponding values and yield it to the
+ * associated block.
+ * Return the class of +values+ for reentry check.
+ */
+static int
+yield_indexed_values(const VALUE values, const long r, const long *const p)
+{
+    const VALUE result = rb_ary_new2(r);
+    VALUE *const result_array = RARRAY_PTR(result);
+    const VALUE *const values_array = RARRAY_PTR(values);
+    long i;
+
+    for (i = 0; i < r; i++) result_array[i] = values_array[p[i]];
+    ARY_SET_LEN(result, r);
+    rb_yield(result);
+    return !RBASIC(values)->klass;
+}
+
+/*
  * Recursively compute permutations of +r+ elements of the set
  * <code>[0..n-1]</code>.
  *
@@ -4545,7 +4564,7 @@ rb_ary_cycle(int argc, VALUE *argv, VALUE ary)
 static void
 permute0(long n, long r, long *p, long index, char *used, VALUE values)
 {
-    long i,j;
+    long i;
     for (i = 0; i < n; i++) {
 	if (used[i] == 0) {
 	    p[index] = i;
@@ -4556,17 +4575,7 @@ permute0(long n, long r, long *p, long index, char *used, VALUE values)
 		used[i] = 0;               /* index unused */
 	    }
 	    else {
-		/* We have a complete permutation of array indexes */
-		/* Build a ruby array of the corresponding values */
-		/* And yield it to the associated block */
-		VALUE result = rb_ary_new2(r);
-		VALUE *result_array = RARRAY_PTR(result);
-		const VALUE *values_array = RARRAY_PTR(values);
-
-		for (j = 0; j < r; j++) result_array[j] = values_array[p[j]];
-		ARY_SET_LEN(result, r);
-		rb_yield(result);
-		if (RBASIC(values)->klass) {
+		if (!yield_indexed_values(values, r, p)) {
 		    rb_raise(rb_eRuntimeError, "permute reentered");
 		}
 	    }
@@ -4731,21 +4740,19 @@ rb_ary_combination(VALUE ary, VALUE num)
 	}
     }
     else {
-	volatile VALUE t0 = tmpbuf(n+1, sizeof(long));
-	long *stack = (long*)RSTRING_PTR(t0);
-	volatile VALUE cc = tmpary(n);
-	VALUE *chosen = RARRAY_PTR(cc);
+	VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
+	volatile VALUE t0;
+	long *stack = ALLOCV_N(long, t0, n+1);
 	long lev = 0;
 
-	MEMZERO(stack, long, n);
+	RBASIC(ary0)->klass = 0;
+	MEMZERO(stack+1, long, n);
 	stack[0] = -1;
 	for (;;) {
-	    chosen[lev] = RARRAY_PTR(ary)[stack[lev+1]];
 	    for (lev++; lev < n; lev++) {
-		chosen[lev] = RARRAY_PTR(ary)[stack[lev+1] = stack[lev]+1];
+		stack[lev+1] = stack[lev]+1;
 	    }
-	    rb_yield(rb_ary_new4(n, chosen));
-	    if (RBASIC(t0)->klass) {
+	    if (!yield_indexed_values(ary0, n, stack+1)) {
 		rb_raise(rb_eRuntimeError, "combination reentered");
 	    }
 	    do {
@@ -4754,8 +4761,8 @@ rb_ary_combination(VALUE ary, VALUE num)
 	    } while (stack[lev+1]+n == len+lev+1);
 	}
     done:
-	tmpbuf_discard(t0);
-	tmpary_discard(cc);
+	ALLOCV_END(t0);
+	RBASIC(ary0)->klass = rb_cArray;
     }
     return ary;
 }
@@ -4776,24 +4783,14 @@ rb_ary_combination(VALUE ary, VALUE num)
 static void
 rpermute0(long n, long r, long *p, long index, VALUE values)
 {
-    long i, j;
+    long i;
     for (i = 0; i < n; i++) {
 	p[index] = i;
 	if (index < r-1) {              /* if not done yet */
 	    rpermute0(n, r, p, index+1, values); /* recurse */
 	}
 	else {
-	    /* We have a complete permutation of array indexes */
-	    /* Build a ruby array of the corresponding values */
-	    /* And yield it to the associated block */
-	    VALUE result = rb_ary_new2(r);
-	    VALUE *result_array = RARRAY_PTR(result);
-	    const VALUE *values_array = RARRAY_PTR(values);
-
-	    for (j = 0; j < r; j++) result_array[j] = values_array[p[j]];
-	    ARY_SET_LEN(result, r);
-	    rb_yield(result);
-	    if (RBASIC(values)->klass) {
+	    if (!yield_indexed_values(values, r, p)) {
 		rb_raise(rb_eRuntimeError, "repeated permute reentered");
 	    }
 	}
@@ -4872,7 +4869,6 @@ rb_ary_repeated_permutation(VALUE ary, VALUE num)
 static void
 rcombinate0(long n, long r, long *p, long index, long rest, VALUE values)
 {
-    long j;
     if (rest > 0) {
 	for (; index < n; ++index) {
 	    p[r-rest] = index;
@@ -4880,14 +4876,7 @@ rcombinate0(long n, long r, long *p, long index, long rest, VALUE values)
 	}
     }
     else {
-	VALUE result = rb_ary_new2(r);
-	VALUE *result_array = RARRAY_PTR(result);
-	const VALUE *values_array = RARRAY_PTR(values);
-
-	for (j = 0; j < r; ++j) result_array[j] = values_array[p[j]];
-	ARY_SET_LEN(result, r);
-	rb_yield(result);
-	if (RBASIC(values)->klass) {
+	if (!yield_indexed_values(values, r, p)) {
 	    rb_raise(rb_eRuntimeError, "repeated combination reentered");
 	}
     }