[rubygems/rubygems] Expand and comment the regex

ruby/rubygems@0dd0e93bde

Author: luizkowalski

lib/bundler/ruby_dsl.rb

@@ -43,7 +43,16 @@ def ruby(*ruby_version)
     def normalize_ruby_file(filename)
       file_content = Bundler.read_file(gemfile.dirname.join(filename))
       # match "ruby-3.2.2", ruby = "3.2.2" or "ruby   3.2.2" capturing version string up to the first space or comment
-      if /^ruby[\s-]*(?:=\s*)?"?([^\s#"]+)"?/.match(file_content)
+      if /^                    # Start of line
+         ruby                  # Literal "ruby"
+         [\s-]*                # Optional whitespace or hyphens (for "ruby-3.2.2" format)
+         (?:=\s*)?             # Optional equals sign with whitespace (for ruby = "3.2.2" format)
+         "?                    # Optional opening quote
+         (                     # Start capturing group
+           [^\s#"]+            # One or more chars that aren't spaces, #, or quotes
+         )                     # End capturing group
+         "?                    # Optional closing quote
+         /x.match(file_content)
         $1
       else
         file_content.strip