Regexp Examples Versions Save

Resolve deprecation warnings when using this gem with ruby 2.7 - See https://github.com/tom-lord/regexp-examples/pull/37

Thanks @taichi-ishitani

• Full ruby v2.6.3 support. (There were a few minor bugs introduced by the unicode version bump from 12.0.0 to 12.1.0.
• Dropped support for ruby v2.0.0 - v2.3.x.
• Fixed ability to generate examples for patterns like: /__xxx__/.
• Added support for unicode range generation, e.g. /[\u4e00-\u9fa5]{2,4}/.random_example (@xiejiangzhi)

Generated unicode 11.0 ranges, as required for ruby v2.6.x compatibility.

This release contains a significant fix to Regexp#random_example, as reported here: https://github.com/tom-lord/regexp-examples/issues/21

There are also some minor additions/bug fixes

• Added (limited) support for the absence operator.
• Fixed back-reference group counter when using non-capture groups or comment groups. (This impacts regex example generation when the back-reference number is after one of the aforementioned group types.)

Generated unicode 10.0 ranges, as required for ruby v2.5.x compatibility.

This ensures code such as:

/\p{Alpha}/.random_example

will generate a matching example under the new ruby version.

//.examples # => ['']
//.random_example # => ''

In previous versions of the gem, running the above commands failed.

This release comes with two significant fixes:

1. /[[:punct:]]/.examples can now return all possible characters for ruby 2.4.0+. (The definition of this character set has changed in the latest minor ruby version.)
2. /foo\Z/.examples will now return "foo" and "foo\n". This fixes a long-standing bug in the library.

Configuration options can now be made globally, e.g.

RegexpExamples::Config.max_repeater_variance = 5
RegexpExamples::Config.max_group_results = 10
RegexpExamples::Config.max_results_limit = 20000

Or within a block, e.g.

RegexpExamples::Config.with_configuration(max_repeater_variance: 5) do
  # ...
end

All forms of configuration are now thread safe.

Following a raised issue, the gem no longer uses symbolic links to simplify cross-version unicode mappings.

There should be no functional change resulting from this release.

Updated the character set definitions, in light of the new v2.4.0 ruby release.