diff options
author | Nobuyoshi Nakada <nobu@ruby-lang.org> | 2019-06-21 16:28:39 +0900 |
---|---|---|
committer | Nobuyoshi Nakada <nobu@ruby-lang.org> | 2019-06-21 16:28:39 +0900 |
commit | 06a622b76e20b8996cd6d66c11ac7819a0996fae (patch) | |
tree | 4876d7dd948f43d3d0185000034a337bb6cb7e40 /enumerator.c | |
parent | 4149fd60786527121d42e3d6f12d1447505d22fa (diff) | |
download | ruby-06a622b76e20b8996cd6d66c11ac7819a0996fae.tar.gz |
Lazy filter_map
Diffstat (limited to 'enumerator.c')
-rw-r--r-- | enumerator.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/enumerator.c b/enumerator.c index 808ab67de8..983e14c157 100644 --- a/enumerator.c +++ b/enumerator.c @@ -2026,6 +2026,40 @@ lazy_select(VALUE obj) return lazy_add_method(obj, 0, 0, Qnil, Qnil, &lazy_select_funcs); } +static VALUE +lazy_filter_map_proc(RB_BLOCK_CALL_FUNC_ARGLIST(val, m)) +{ + VALUE result = rb_yield_values2(argc - 1, &argv[1]); + if (RTEST(result)) { + rb_funcall(argv[0], idLTLT, 1, result); + } + return Qnil; +} + +/* + * call-seq: + * enum.filter_map { |obj| block } -> an_enumerator + * enum.filter_map -> an_enumerator + * + * Returns an enumerator which will return a new array containing the + * truthy results (everything except +false+ or +nil+) of running the + * +block+ for every element in +enum+. + * + * (1..).lazy.filter_map { |i| i * 2 if i.even? }.take(5) #=> [4, 8, 12, 16, 20] + * + */ +static VALUE +lazy_filter_map(VALUE obj) +{ + if (!rb_block_given_p()) { + rb_raise(rb_eArgError, "tried to call lazy filter_map without a block"); + } + + return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj, + lazy_filter_map_proc, 0), + Qnil, 0); +} + static struct MEMO * lazy_reject_proc(VALUE proc_entry, struct MEMO *result, VALUE memos, long memo_index) { @@ -3555,6 +3589,7 @@ InitVM_Enumerator(void) rb_define_method(rb_cLazy, "select", lazy_select, 0); rb_define_method(rb_cLazy, "find_all", lazy_select, 0); rb_define_method(rb_cLazy, "filter", lazy_select, 0); + rb_define_method(rb_cLazy, "filter_map", lazy_filter_map, 0); rb_define_method(rb_cLazy, "reject", lazy_reject, 0); rb_define_method(rb_cLazy, "grep", lazy_grep, 1); rb_define_method(rb_cLazy, "grep_v", lazy_grep_v, 1); |