* [ruby-core:99228] [Ruby master Feature#17036] Regexp deconstruction keys to allow pattern matching
@ 2020-07-19 14:21 cottrey
0 siblings, 0 replies; only message in thread
From: cottrey @ 2020-07-19 14:21 UTC (permalink / raw)
To: ruby-core
Issue #17036 has been reported by zechris (Chris Ottrey).
----------------------------------------
Feature #17036: Regexp deconstruction keys to allow pattern matching
https://bugs.ruby-lang.org/issues/17036
* Author: zechris (Chris Ottrey)
* Status: Open
* Priority: Normal
----------------------------------------
This is to allow Regexp matches in Ruby 2.7's new experimental Pattern Matching.
eg.
```ruby
case /(?<a>.)(?<b>.)/.match("xy")
in a: "x", b:
"a was 'x' and b was matched to #{b.inspect}"
end
#=> "a was 'x' and b was matched to 'y'"
```
`MatchData#named_captures` is *close* but not close enough as the Hash required from a `deconstructed_keys()` method that gets used during Pattern Matching requires symbolized keys.
### **NB. This PR ( https://github.com/ruby/ruby/pull/3333) is WIP as the C code hasn't actually been written yet...**
Although, it could be used in the wild now with a refinement of `MatchData` like so:
```ruby
module RegexpDeconstructKeys
refine MatchData do
# Temporary patch in ruby to make tests pass until the code gets re-written in C
def deconstruct_keys(*keys)
h0 = named_captures.transform_keys(&:to_sym)
if keys
keys = keys.flatten.compact
raise TypeError unless keys.all? { |k| k.is_a?(Symbol) }
h0 = h0.slice(*keys) unless keys.empty?
end
h0.inject({}) { |h, (k, v)| h[k] = v if v; h }
end
# Temporary patch in ruby to make tests pass until the code gets re-written in C
end
end
using RegexpDeconstructKeys
case /(?<a>.)(?<b>.)/.match("xy")
in a: "x", b:
puts "a was 'x' and b was #{b.inspect}"
end
#=> "a was 'x' and b was matched to 'y'"
```
(tested in `ruby v2.7.1`)
--
https://bugs.ruby-lang.org/
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