add initial Cache class

lib/rscons.rb

@@ -1,4 +1,5 @@
 require "rscons/builder"
+require "rscons/cache"
 require "rscons/environment"
 require "rscons/version"
 

lib/rscons/cache.rb

@@ -0,0 +1,41 @@
+require 'yaml'
+require 'fileutils'
+require 'digest/md5'
+
+module Rscons
+  class Cache
+    # Constants
+    CACHE_FILE = '.rsconscache'
+
+    # Class Methods
+    def self.clear
+      FileUtils.rm_f(CACHE_FILE)
+    end
+
+    # Instance Methods
+    def initialize
+      @cache = YAML.load(File.read(CACHE_FILE)) rescue {}
+    end
+
+    def write
+      File.open(CACHE_FILE, 'w') do |fh|
+        fh.puts(YAML.dump(@cache))
+      end
+    end
+
+    def up_to_date?(file, deps = nil)
+      # TODO
+    end
+
+    def register_build(target, deps)
+      # TODO
+    end
+
+    # Private Instance Methods
+    private
+
+    def calculate_checksum(file)
+      Digest::MD5.hexdigest(File.read(file)).encode(__ENCODING__)
+    end
+  end
+end

lib/rscons/environment.rb

@@ -57,6 +57,8 @@ module Rscons
     end
 
     def process
+      cache = Cache.new
+      cache.write
     end
 
     alias_method :orig_method_missing, :method_missing