* add Lambda module.

git-svn-id: svn+ssh://svn.dotswitch.net/var/svn/dotswitch/projects/library/plugins/purl@2122 c432a1ab-ec09-0410-8e5f-fb625be92370

lib/purl.rb

@@ -10,6 +10,7 @@ def initialize(options = {})
       load_feature Features::Arithmetic
       load_feature Features::Conversion
       load_feature Features::Stack
+      load_feature Features::Lambda
       load_feature Features::Image
       load_feature Features::Effect
       load_feature Features::Resize

lib/purl/features/lambda.rb

@@ -0,0 +1,33 @@
+module Purl
+  module Features::Lambda
+    class << self
+      include ::Purl::Features::Limit
+
+      def operators
+        [
+          Op.new(:call, 1),
+          Op.new(:times, 2),
+          Op.new(:each, -1),
+        ]
+      end
+
+      def call(macro)
+        Result.new(*macro.dispatch)
+      end
+
+      def times(macro, n)
+        n = [@max_n, n].min
+        Result.new(*(macro.dispatch * n))
+      end
+
+      def each(*stack)
+        n = [@max_n, stack.pop].min
+        macro = stack.pop
+        op = macro.dispatch
+
+        stack.concat stack.slice!(-n, n).map{|v| [v, *op]}.flatten
+        Result.new(*stack)
+      end
+    end
+  end
+end

lib/purl/features/limit.rb

@@ -2,15 +2,17 @@ module Purl
   module Features::Limit
     def self.included(base)
       base.class_eval do
-        attr_reader :max_width, :max_height 
+        attr_reader :max_width, :max_height, :max_n
         def options=(options)
           options = {
             :max_width  => 1024,
-            :max_height => 1024
+            :max_height => 1024,
+            :max_n      => 10,
           }.merge(options)
 
           @max_width  = options[:max_width]
           @max_height = options[:max_height]
+          @max_n = options[:max_n]
         end
       end
     end