rails--rails/activesupport
Nick LaMuro a822fc513c Cache regexps generated from acronym_regex
The Problem
-----------

The following line from `String#camelize`:

  string = string.sub(/^(?:#{inflections.acronym_regex}(?=\b|[A-Z_])|\w)/) { |match| match.downcase }

and the following line from `String#camelize`:

  word.gsub!(/(?:(?<=([A-Za-z\d]))|\b)(#{inflections.acronym_regex})(?=\b|[^a-z])/) { "#{$1 && '_'.freeze }#{$2.downcase}" }#{$2.downcase}" }

Both generate the same regexep in the first part of the `.sub`/`.gsub`
method calls every time the function is called, creating an extra object
allocation each time.  The value of `acronym_regex` only changes if the
user decides add an acronym to the current set of inflections and apends
another string on the the regexp generated here, but beyond that it
remains relatively static.

This has been around since acronym support was introduced back in 2011
in PR#1648.

Proposed Solution
-----------------
To avoid re-generating these strings every time these methods are
called, cache the values of these regular expressions in the
`ActiveSupport::Inflector::Inflections` instance, making it so these
regular expressions are only generated once, or when the acronym's are
added to.

Other notable changes is the attr_readers are nodoc'd, as they shouldn't
really be public APIs for users.  Also, the new method,
define_acronym_regex_patterns, is the only method in charge of
manipulating @acronym_regex, and initialize_dup also makes use of that
new change.

** Note about fix for non-deterministic actionpack test **

With the introduction of `@acronym_underscore_regex` and
`@acronym_camelize_regex`, tests that manipulated these for a short
time, then reset them could caused test failures to happen.  This
happened because the previous way we reset the `@acronyms` and
`@acronym_regex` was the set them using #instance_variable_set, which
wouldn't run the #define_acronym_regex_patterns method.

This has now been introduced into the actionpack tests to avoid this
failure.
2017-10-23 16:13:14 -05:00
..
bin Use frozen-string-literal in ActiveSupport 2017-07-09 15:08:29 +03:00
lib Cache regexps generated from acronym_regex 2017-10-23 16:13:14 -05:00
test Fix `to_s(:db)` for range comprising of alphabets. 2017-10-16 18:16:23 +05:30
CHANGELOG.md Let Hash#slice return a Hash 2017-10-21 17:44:26 +09:00
MIT-LICENSE
README.rdoc Update MIT licenses link [ci skip] 2017-08-22 08:46:02 +09:00
Rakefile [Active Support] `rubocop -a --only Layout/EmptyLineAfterMagicComment` 2017-07-11 13:12:32 +09:00
activesupport.gemspec [Active Support] `rubocop -a --only Layout/EmptyLineAfterMagicComment` 2017-07-11 13:12:32 +09:00

README.rdoc

= Active Support -- Utility classes and Ruby extensions from Rails

Active Support is a collection of utility classes and standard library
extensions that were found useful for the Rails framework. These additions
reside in this package so they can be loaded as needed in Ruby projects
outside of Rails.


== Download and installation

The latest version of Active Support can be installed with RubyGems:

  $ gem install activesupport

Source code can be downloaded as part of the Rails project on GitHub:

* https://github.com/rails/rails/tree/master/activesupport


== License

Active Support is released under the MIT license:

* https://opensource.org/licenses/MIT


== Support

API documentation is at:

* http://api.rubyonrails.org

Bug reports can be filed for the Ruby on Rails project here:

* https://github.com/rails/rails/issues

Feature requests should be discussed on the rails-core mailing list here:

* https://groups.google.com/forum/?fromgroups#!forum/rubyonrails-core