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hash.c: Add Hash#slice

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* hash.c (rb_hash_slice): add Hash#slice [Feature #8499]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60229 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
glass 2017-10-21 06:08:33 +00:00
parent d83f9745f5
commit 6c50bdda0b
2 changed files with 41 additions and 0 deletions
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33
hash.c
View file

@ -1324,6 +1324,38 @@ rb_hash_reject(VALUE hash)
return result;
}
/*
* call-seq:
* hsh.slice -> a_hash
*
* Slices a hash to include only the given keys.
* Returns a hash containing the given keys.
*
* h = { "a" => 100, "b" => 200, "c" => 300 }
* h.slice("a") #=> {"a" => 100}
*/
static VALUE
rb_hash_slice(int argc, VALUE *argv, VALUE hash)
{
int i;
VALUE key, value, result;
if (argc == 0 || RHASH_EMPTY_P(hash)) {
return rb_hash_new();
}
result = rb_hash_new_with_size(argc);
for (i = 0; i < argc; i++) {
key = argv[i];
value = rb_hash_lookup2(hash, key, Qundef);
if (value != Qundef)
rb_hash_aset(result, key, value);
}
return result;
}
/*
* call-seq:
* hsh.values_at(key, ...) -> array
@ -4585,6 +4617,7 @@ Init_Hash(void)
rb_define_method(rb_cHash, "select!", rb_hash_select_bang, 0);
rb_define_method(rb_cHash, "reject", rb_hash_reject, 0);
rb_define_method(rb_cHash, "reject!", rb_hash_reject_bang, 0);
rb_define_method(rb_cHash, "slice", rb_hash_slice, -1);
rb_define_method(rb_cHash, "clear", rb_hash_clear, 0);
rb_define_method(rb_cHash, "invert", rb_hash_invert, 0);
rb_define_method(rb_cHash, "update", rb_hash_update, 1);

8
test/ruby/test_hash.rb
View file

@ -1006,6 +1006,14 @@ class TestHash < Test::Unit::TestCase
assert_equal(nil, h.select!{true})
end
def test_slice
h = @cls[1=>2,3=>4,5=>6]
assert_equal({1=>2, 3=>4}, h.slice(1, 3))
assert_equal({}, h.slice(7))
assert_equal({}, h.slice)
assert_equal({}, {}.slice)
end
def test_clear2
assert_equal({}, @cls[1=>2,3=>4,5=>6].clear)
h = @cls[1=>2,3=>4,5=>6]