define Range#match? if Ruby < 2.4

See the rationale in the documentation included in this patch.

We are going to gradually introduce this predicate in the code base.

1 files changed, 18 insertions, 0 deletions

diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md
index e0b6f2f820..27478b21a0 100644
--- a/guides/source/active_support_core_extensions.md
+++ b/guides/source/active_support_core_extensions.md
@@ -2916,6 +2916,24 @@ end
 
 NOTE: Defined in `active_support/core_ext/regexp.rb`.
 
+### `match?`
+
+Rails implements `Regexp#match?` for Ruby versions prior to 2.4:
+
+```ruby
+/oo/.match?('foo')    # => true
+/oo/.match?('bar')    # => false
+/oo/.match?('foo', 1) # => true
+```
+
+The backport has the same interface and lack of side-effects in the caller like
+not setting `$1` and friends, but it does not have the speed benefits. Its
+purpose is to be able to write 2.4 compatible code. Rails itself uses this
+predicate internally for example.
+
+Active Support defines `Regexp#match?` only if not present, so code running
+under 2.4 or later does run the original one and gets the performance boost.
+
 Extensions to `Range`
 ---------------------