add support for parameters to {% include %} tags

lib/jekyll/tags/include.rb

@@ -1,9 +1,70 @@
 module Jekyll
   module Tags
     class IncludeTag < Liquid::Tag
-      def initialize(tag_name, file, tokens)
+      def initialize(tag_name, markup, tokens)
         super
-        @file = file.strip
+        markup.strip!
+        if markup.include?(' ')
+          separator = markup.index(' ')
+          @file = markup[0..separator].strip
+          parse_params(markup[separator..-1])
+        else
+          @file = markup
+        end
+      end
+
+      def parse_params(markup)
+        last_space = last_quote = pos = 0
+        last_key = nil
+        in_quotes = false
+        @params = {}
+
+        if !(/^(\s*\b\S+="(?:\\"|.)*?")*\s*$/ =~ markup)
+          raise SyntaxError.new <<-eos
+Syntax error for 'include'  while parsing the following markup:
+
+  #{markup}
+
+Valid syntax: include param="value"
+eos
+        end
+
+        while pos = markup.index(/[=\"\s]/, pos)
+          str = markup[pos, 1]
+          if /\s/ =~ str
+            last_space = pos
+          elsif str == '='
+            if !last_key.nil?
+              raise SyntaxError.new <<-eos
+Syntax Error in tag 'include' (missing value) while parsing the following markup:
+
+  #{markup}
+
+Valid syntax: include param="value"
+eos
+            end
+            last_key = markup[last_space+1..pos-1]
+          elsif str == '"' and markup[pos-1, 1] != '\\'
+            in_quotes = !in_quotes
+            if !in_quotes
+              value = markup[last_quote+1..pos-1].gsub(/\\"/, '"')
+              @params[last_key] = value
+              last_key = nil
+            end
+            last_quote = pos
+          end
+          pos += 1
+        end
+
+        if in_quotes
+          raise SyntaxError.new <<-eos
+Syntax Error in tag 'include' (unterminated value) while parsing the following markup:
+
+  #{markup}
+
+Valid syntax: include param="value"
+eos
+        end
       end
 
       def render(context)
@@ -22,6 +83,7 @@ module Jekyll
           if choices.include?(@file)
             source = File.read(@file)
             partial = Liquid::Template.parse(source)
+            context['include'] = @params
             context.stack do
               partial.render(context)
             end