Added support for captureing transform's when they've been assigned t…

…o a variable

lib/yard-cucumber.rb

@@ -25,6 +25,7 @@
 if RUBY19
   require File.dirname(__FILE__) + "/yard/handlers/step_definition_handler.rb"
   require File.dirname(__FILE__) + "/yard/handlers/step_transform_handler.rb"
+  require File.dirname(__FILE__) + "/yard/handlers/constant_transform_handler.rb"
 end
 
 require File.dirname(__FILE__) + "/yard/handlers/legacy/step_definition_handler.rb"

lib/yard/handlers/constant_transform_handler.rb

@@ -0,0 +1,74 @@
+# There might be a nicer way to decorate this class but with my limited knowledge could only get this handler
+# to be applied after the default constant handler by inheriting from the default constant handler.
+# This is required so that the value assigned from the transform is not overridden in the registry by the
+# default handler
+class YARD::Handlers::Ruby::ConstantTransformHandler < YARD::Handlers::Ruby::ConstantHandler
+  include YARD::Handlers::Ruby::StructHandlerMethods
+  handles :assign
+
+  namespace_only
+
+  process do
+    begin
+      if statement[1][0][0] == "Transform"
+        name = statement[0][0][0]
+        parse_block(statement[1])
+        value = statement[1][1].source
+        value = substitute(value)
+        value = convert_captures(strip_anchors(value))
+        register ConstantObject.new(namespace, name) {|o| o.source = statement; o.value = value }
+      end
+    rescue
+      # This supresses any errors where any of the statement elements are out of bounds. 
+      # In this case the or in cases where the object being assigned is not a Transform
+      # the default constant handler will already have performed the relevant action
+    end
+  end
+
+  private
+
+  # Cucumber's Transform object overrides the to_s function and strips
+  # the anchor tags ^$ and any captures so that id it is interpolated in a step definition
+  # the it can appear anywhere in the step without being effected by position or captures
+  def convert_captures(regexp_source)
+    regexp_source
+      .gsub(/(\()(?!\?[<:=!])/,'(?:')
+      .gsub(/(\(\?<)(?![=!])/,'(?:<')
+  end
+
+  def strip_anchors(regexp_source)
+    regexp_source.
+      gsub(/(^\(\/|\/\)$)/, '').
+      gsub(/(^\^|\$$)/, '')
+  end
+
+  # Support for interpolation in the Transform's Regex
+  def substitute(data)
+    until (nested = constants_from_value(data)).empty?
+      nested.each {|n| data.gsub!(value_regex(n),find_value_for_constant(n)) }
+    end
+    data
+  end
+
+  def constants_from_value(data)
+    escape_pattern = /#\{\s*(\w+)\s*\}/
+    data.scan(escape_pattern).flatten.collect { |value| value.strip }
+  end
+
+  # Return a regex of the value
+  def value_regex(value)
+    /#\{\s*#{value}\s*\}/
+  end
+
+  def find_value_for_constant(name)
+    constant = YARD::Registry.all(:constant).find{|c| c.name == name.to_sym }
+    log.warn "ConstantTransformHandler#find_value_for_constant : Could not find the CONSTANT [#{name}] using the string value." unless constant
+    constant ? strip_regex_from(constant.value) : name
+  end
+
+  # Step the regex starting / and ending / from the value
+  def strip_regex_from(value)
+    value.gsub(/^\/|\/$/,'')
+  end
+
+end