From f061d403264013440070df52bba46588f2897148 Mon Sep 17 00:00:00 2001 From: akr Date: Sat, 13 Feb 2016 12:45:59 +0000 Subject: * hash.c (rb_hash_invert): [DOC] more examples. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53818 b2dd03c8-39d4-4d8f-98ff-823fe69b080e --- hash.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'hash.c') diff --git a/hash.c b/hash.c index 7759332a0b..68da110511 100644 --- a/hash.c +++ b/hash.c @@ -2217,6 +2217,22 @@ rb_hash_invert_i(VALUE key, VALUE value, VALUE hash) * h = { "n" => 100, "m" => 100, "y" => 300, "d" => 200, "a" => 0 } * h.invert #=> {0=>"a", 100=>"m", 200=>"d", 300=>"y"} * + * If there is no key with the same value, Hash#invert is involutive. + * + * h = { a: 1, b: 3, c: 4 } + * h.invert.invert == h #=> true + * + * The condition, no key with the same value, can be tested by comparing + * the size of inverted hash. + * + * # no key with the same value + * h = { a: 1, b: 3, c: 4 } + * h.size == h.invert.size #=> true + * + * # two (or more) keys has the same value + * h = { a: 1, b: 3, c: 1 } + * h.size == h.invert.size #=> false + * */ static VALUE -- cgit v1.2.3