* array.c (rb_ary_resize): new utility function. [ruby-dev:42912]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@30465 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

array.c

@@ -1308,6 +1308,51 @@ rb_ary_splice(VALUE ary, long beg, long len, VALUE rpl)
     }
 }
 
+/*!
+ * expands or shrinks \a ary to \a len elements.
+ * expanded region will be filled with Qnil.
+ * \param ary  an arrray
+ * \param len  new size
+ * \return     \a ary
+ * \post       the size of \a ary is \a len.
+ */
+VALUE
+rb_ary_resize(VALUE ary, long len)
+{
+    long olen;
+
+    rb_ary_modify(ary);
+    olen = RARRAY_LEN(ary);
+    if (len == olen) return ary;
+    if (len > ARY_MAX_SIZE) {
+	rb_raise(rb_eIndexError, "index %ld too big", len);
+    }
+    if (len > olen) {
+	if (len >= ARY_CAPA(ary)) {
+	    ary_double_capa(ary, len);
+	}
+	rb_mem_clear(RARRAY_PTR(ary) + olen, len - olen);
+        ARY_SET_HEAP_LEN(ary, len);
+    }
+    else if (ARY_EMBED_P(ary)) {
+        ARY_SET_EMBED_LEN(ary, len);
+    }
+    else if (len <= RARRAY_EMBED_LEN_MAX) {
+	VALUE tmp[RARRAY_EMBED_LEN_MAX];
+	MEMCPY(tmp, ARY_HEAP_PTR(ary), VALUE, len);
+	ary_discard(ary);
+	MEMCPY(ARY_EMBED_PTR(ary), tmp, VALUE, len);
+        ARY_SET_EMBED_LEN(ary, len);
+    }
+    else {
+	if (olen > len + ARY_DEFAULT_SIZE) {
+	    REALLOC_N(RARRAY(ary)->as.heap.ptr, VALUE, len);
+	}
+	ARY_SET_HEAP_LEN(ary, len);
+    }
+    return ary;
+}
+
 /*
  *  call-seq:
  *     ary[index]         = obj                      ->  obj

ext/-test-/array/resize/extconf.rb

@@ -0,0 +1 @@
+create_makefile("-test-/array/resize")

ext/-test-/array/resize/resize.c

@@ -0,0 +1,14 @@
+#include "ruby/ruby.h"
+
+static VALUE
+ary_resize(VALUE ary, VALUE len)
+{
+    rb_ary_resize(ary, NUM2LONG(len));
+    return ary;
+}
+
+void
+Init_resize(void)
+{
+    rb_define_method(rb_cArray, "resize", ary_resize, 1);
+}

include/ruby/intern.h

@@ -83,6 +83,7 @@ VALUE rb_ary_includes(VALUE, VALUE);
 VALUE rb_ary_cmp(VALUE, VALUE);
 VALUE rb_ary_replace(VALUE copy, VALUE orig);
 VALUE rb_get_values_at(VALUE, long, int, VALUE*, VALUE(*)(VALUE,long));
+VALUE rb_ary_resize(VALUE ary, long len);
 /* bignum.c */
 VALUE rb_big_new(long, int);
 int rb_bigzero_p(VALUE x);

test/-ext-/array/test_resize.rb

@@ -0,0 +1,29 @@
+require 'test/unit'
+require '-test-/array/resize'
+
+class TestArray < Test::Unit::TestCase
+  class TestResize < Test::Unit::TestCase
+    def test_expand
+      feature = '[ruby-dev:42912]'
+      ary = [*1..10]
+      ary.resize(10)
+      assert_equal(10, ary.size, feature)
+      assert_equal([*1..10], ary, feature)
+      ary.resize(100)
+      assert_equal(100, ary.size, feature)
+      assert_equal([*1..10]+[nil]*90, ary, feature)
+      ary.resize(20)
+      assert_equal(20, ary.size, feature)
+      assert_equal([*1..10]+[nil]*10, ary, feature)
+      ary.resize(2)
+      assert_equal(2, ary.size, feature)
+      assert_equal([1,2], ary, feature)
+      ary.resize(3)
+      assert_equal(3, ary.size, feature)
+      assert_equal([1,2,nil], ary, feature)
+      ary.resize(10)
+      assert_equal(10, ary.size, feature)
+      assert_equal([1,2]+[nil]*8, ary, feature)
+    end
+  end
+end