Fixes dynamic key matching issue with nested #{}

Refs #180

lib/i18n/tasks/key_pattern_matching.rb

@@ -1,3 +1,5 @@
+require 'strscan'
+
 module I18n::Tasks::KeyPatternMatching
   extend self
   MATCH_NOTHING = /\z\A/.freeze
@@ -30,20 +32,45 @@ def key_pattern_re_body(key_pattern)
         gsub(/\{(.*?)}/) { "(#{$1.strip.gsub /\s*,\s*/, '|'.freeze})" }
   end
 
-  def key_match_pattern(k)
+  def key_match_pattern(k, replacement: ':'.freeze)
     @key_match_pattern ||= {}
     @key_match_pattern[k] ||= begin
-      "#{k.gsub(KEY_INTERPOLATION_RE, ':'.freeze)}#{':'.freeze if k.end_with?('.'.freeze)}"
+      "#{replace_key_interpolations(k, replacement)}#{replacement if k.end_with?('.'.freeze)}"
     end
   end
 
   # @return true if the key looks like an expression
-  KEY_INTERPOLATION_RE = /(?:\#{.*?}|\*+|\:+)/.freeze
+  KEY_INTERPOLATION_RE = /\#{/.freeze
   def key_expression?(k)
     @key_is_expr ||= {}
     if @key_is_expr[k].nil?
       @key_is_expr[k] = (k =~ KEY_INTERPOLATION_RE || k.end_with?('.'.freeze))
     end
     @key_is_expr[k]
   end
+
+  private
+
+  # Replace interpolations.
+  # @param key [String]
+  # @param replacement [String]
+  # @return [String]
+  def replace_key_interpolations(key, replacement)
+    scanner = StringScanner.new(key)
+    braces = []
+    result = []
+    while (match_until = scanner.scan_until(/(?:#?\{|})/.freeze) )
+      if scanner.matched == '#{'.freeze
+        braces << scanner.matched
+        result << match_until[0..-3] if braces.length == 1
+      elsif scanner.matched == '}'
+        prev_brace = braces.pop
+        result << replacement if braces.empty? && prev_brace == '#{'.freeze
+      else
+        braces << '{'.freeze
+      end
+    end
+    result << key[scanner.pos..-1] unless scanner.eos?
+    result.join
+  end
 end

spec/key_pattern_matching_spec.rb

@@ -59,5 +59,12 @@
         expect([$1, $2]).to eq(['x', 'c'])
       end
     end
+
+    describe 'key_match_pattern' do
+      it 'handles nested {}' do
+        expect(key_match_pattern('a.#{b.gsub(%r{/{}{}}, x)}.#{c}.title')).to(
+          eq 'a.:.:.title')
+      end
+    end
   end
 end