add a Directory builder - close #27

lib/rscons/builders/directory.rb

@@ -0,0 +1,31 @@
+module Rscons
+  module Builders
+    # The Directory builder creates a directory.
+    class Directory < Builder
+
+      # Run the builder to produce a build target.
+      #
+      # @param target [String] Target file name.
+      # @param sources [Array<String>] Source file name(s).
+      # @param cache [Cache] The Cache object.
+      # @param env [Environment] The Environment executing the builder.
+      # @param vars [Hash,VarSet] Extra construction variables.
+      #
+      # @return [String,false]
+      #   Name of the target file on success or false on failure.
+      def run(target, sources, cache, env, vars)
+        if File.directory?(target)
+          target
+        elsif File.exists?(target)
+          $stderr.puts "Error: `#{target}' already exists and is not a directory"
+          false
+        else
+          puts "Directory #{target}"
+          cache.mkdir_p(target)
+          target
+        end
+      end
+
+    end
+  end
+end