Add `Hash#slice` [Ruby 2.5]

parent df68a334
......@@ -72,6 +72,45 @@ hash_compact_bang(mrb_state *mrb, mrb_value hash)
return hash;
}
/*
* call-seq:
* hsh.slice(*keys) -> a_hash
*
* Returns a hash containing only the given keys and their values.
*
* h = { a: 100, b: 200, c: 300 }
* h.slice(:a) #=> {:a=>100}
* h.slice(:b, :c, :d) #=> {:b=>200, :c=>300}
*/
static mrb_value
hash_slice(mrb_state *mrb, mrb_value hash)
{
khash_t(ht) *h = RHASH_TBL(hash);
mrb_value *argv, result;
mrb_int argc, i;
khiter_t k;
int ai;
mrb_get_args(mrb, "*", &argv, &argc);
if (argc == 0 || h == NULL) {
return mrb_hash_new_capa(mrb, argc);
}
result = mrb_hash_new_capa(mrb, argc);
ai = mrb_gc_arena_save(mrb);
for (i = 0; i < argc; i++) {
mrb_value key = argv[i];
k = kh_get(ht, mrb, h, key);
if (k != kh_end(h)) {
mrb_value val = kh_value(h, k).v;
mrb_hash_set(mrb, result, key, val);
}
mrb_gc_arena_restore(mrb, ai);
}
return result;
}
void
mrb_mruby_hash_ext_gem_init(mrb_state *mrb)
{
......@@ -80,6 +119,7 @@ mrb_mruby_hash_ext_gem_init(mrb_state *mrb)
h = mrb->hash_class;
mrb_define_method(mrb, h, "values_at", hash_values_at, MRB_ARGS_ANY());
mrb_define_method(mrb, h, "compact!", hash_compact_bang, MRB_ARGS_NONE());
mrb_define_method(mrb, h, "slice", hash_slice, MRB_ARGS_ANY());
}
void
......
......@@ -292,3 +292,9 @@ assert("Hash#transform_values") do
assert_equal(h, h.transform_values!{|v|v.to_s})
assert_equal({a: "1", b: "2", c: "3"}, h)
end
assert("Hash#slice") do
h = { a: 100, b: 200, c: 300 }
assert_equal({:a=>100}, h.slice(:a))
assert_equal({:b=>200, :c=>300}, h.slice(:b, :c, :d))
end
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment