Support block in `PageMatch` strategy.

Library/Homebrew/livecheck/strategy/page_match.rb

@@ -46,21 +46,22 @@ module Homebrew
         # @param regex [Regexp] a regex used for matching versions in the
         #   content
         # @return [Array]
-        def self.page_matches(url, regex)
+        def self.page_matches(url, regex, &block)
           page = Strategy.page_contents(url)
 
-          matches = page.scan(regex)
-
-          regex_names = regex.names.map(&:to_sym)
-
-          if regex_names.count > 1
-            matches.map do |match|
-              match_data = regex_names.zip(match).to_h
-              regex_names.sort.map { |name| match_data[name] }.join(",")
-            end.uniq
-          else
-            matches.map(&:first).uniq
+          if block
+            data = { page: page }
+            case (value = block.call(data))
+            when String
+              return [value]
+            when Array
+              return value
+            else
+              raise TypeError, "Return value of `strategy :page_match` block must be a string or array."
+            end
           end
+
+          page.scan(regex).map(&:first).uniq
         end
 
         # Checks the content at the URL for new versions, using the provided
@@ -69,10 +70,10 @@ module Homebrew
         # @param url [String] the URL of the content to check
         # @param regex [Regexp] a regex used for matching versions in content
         # @return [Hash]
-        def self.find_versions(url, regex)
+        def self.find_versions(url, regex, &block)
           match_data = { matches: {}, regex: regex, url: url }
 
-          page_matches(url, regex).each do |match|
+          page_matches(url, regex, &block).each do |match|
             match_data[:matches][match] = Version.new(match)
           end