From 466644b72284a955f7ce5972912961070bbfd8ef Mon Sep 17 00:00:00 2001 From: glass Date: Sat, 21 Oct 2017 06:08:33 +0000 Subject: hash.c: Add Hash#slice * 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 --- hash.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'hash.c') diff --git a/hash.c b/hash.c index 878e215dc5..6e9cda954d 100644 --- a/hash.c +++ b/hash.c @@ -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); -- cgit v1.2.3