Backreferences for NAMED capture groups (v0.1.0)

e.g. /(?<name>foo) \k<name>/.examples
Bumped the version to 0.1.0 as this is a big feature update!

Author: tom-lord

README.md

@@ -29,10 +29,9 @@ or a huge number of possible matches, such as `/.\w/`, then only a subset of the
 * Boolean "Or" groups, e.g. `/a|b|c/`
 * Character sets (inluding ranges and negation!), e.g. `/[abc]/`, `/[A-Z0-9]/`, `/[^a-z]/`
 * Escaped characters, e.g. `/\n/`, `/\w/`, `/\D/` (and so on...)
-* Capture groups, and backreferences(!!), e.g. `/(this|that) \1/`
-* Named capture groups, e.g. `(?<name>bar)/`(Warning: Named capture group backreferences not yet implemented!)
+* Capture groups, including named groups and backreferences(!!), e.g. `/(this|that) \1/` `/(?<name>foo) \k<name>/`
 * Non-capture groups, e.g. `/(?:foo)/`
-* Arbitrarily complex combinations of all the above!
+* '''Arbitrarily complex combinations of all the above!'''
 
 ## Not-Yet-Supported syntax
 

lib/regexp-examples/backreferences.rb

@@ -23,8 +23,8 @@ def substitute_backreferences(full_examples)
           [full_example]
         else
           full_example.map! do |partial_example|
-            partial_example.gsub(/__(\d+)__/) do |match|
-              find_backref_for(full_example, $1.to_i)
+            partial_example.gsub(/__(\w+)__/) do |match|
+              find_backref_for(full_example, $1)
             end
           end
         end

lib/regexp-examples/groups.rb

@@ -109,13 +109,13 @@ def result
   end
 
   class BackReferenceGroup
-    attr_reader :num
-    def initialize(num)
-      @num = num
+    attr_reader :id
+    def initialize(id)
+      @id = id
     end
 
     def result
-      ["__#{@num}__"]
+      ["__#{@id}__"]
     end
   end
 

lib/regexp-examples/parser.rb

@@ -46,7 +46,11 @@ def parse_after_backslash_group
       @current_position += 1
       case
       when rest_of_string =~ /\A(\d+)/
-        group = parse_backreference_group($&)
+        @current_position += ($1.length - 1) # In case of 10+ backrefs!
+        group = parse_backreference_group($1)
+      when rest_of_string =~ /\Ak<([^>]+)>/ # Named capture group
+        @current_position += ($1.length + 2)
+        group = parse_backreference_group($1)
       when BackslashCharMap.keys.include?(regexp_string[@current_position])
         group = CharGroup.new(
           BackslashCharMap[regexp_string[@current_position]])
@@ -83,7 +87,7 @@ def parse_multi_group
       rest_of_string.match(/\A(\?)?(:|!|=|<(!|=|[^!=][^>]*))?/) do |match|
         case
         when match[1].nil? # e.g. /(normal)/
-          group_id = @num_groups
+          group_id = @num_groups.to_s
         when match[2] == ':' # e.g. /(?:nocapture)/
           @current_position += 2
           group_id = nil
@@ -141,7 +145,7 @@ def parse_single_char_group(char)
     end
 
     def parse_backreference_group(match)
-      BackReferenceGroup.new(match.to_i)
+      BackReferenceGroup.new(match)
     end
 
     def parse_star_repeater(group)

lib/regexp-examples/regexp_extensions.rb

@@ -1,16 +1,16 @@
 class Regexp
-module Examples
-  def examples
-    partial_examples =
-      RegexpExamples::Parser.new(source)
-        .parse
-        .map {|repeater| repeater.result}
-    full_examples = RegexpExamples::permutations_of_strings(partial_examples.dup, no_join: true)
-    full_examples_with_backrefs = \
-      RegexpExamples::BackReferenceReplacer.new.substitute_backreferences(full_examples)
-    full_examples_with_backrefs.map(&:join)
+  module Examples
+    def examples
+      partial_examples =
+        RegexpExamples::Parser.new(source)
+      .parse
+      .map {|repeater| repeater.result}
+      full_examples = RegexpExamples::permutations_of_strings(partial_examples.dup, no_join: true)
+      full_examples_with_backrefs = \
+        RegexpExamples::BackReferenceReplacer.new.substitute_backreferences(full_examples)
+      full_examples_with_backrefs.map(&:join)
+    end
   end
-end
   include Examples
 end
 

lib/regexp-examples/version.rb

@@ -1,3 +1,3 @@
 module RegexpExamples
-  VERSION = '0.0.2'
+  VERSION = '0.1.0'
 end

spec/regexp-examples_spec.rb

@@ -56,7 +56,8 @@ def self.examples_exist_and_match(*regexps)
       examples_exist_and_match(
         /(normal)/,
         /(?:nocapture)/,
-        /(?<name>namedgroup)/
+        /(?<name>namedgroup)/,
+        /(?<name>namedgroup) \k<name>/
       )
       # TODO: These are not yet implemented
       # (expect to raise exception)