Rscons.clean() removes any directories it created if they are empty

lib/rscons.rb

@@ -26,9 +26,16 @@ module Rscons
   # Remove all generated files
   def self.clean
     cache = Cache.new
+    # remove all built files
     cache.targets.each do |target|
       FileUtils.rm_f(target)
     end
+    # remove all created directories if they are empty
+    cache.directories.sort {|a, b| b.size <=> a.size}.each do |directory|
+      if (Dir.entries(directory) - ['.', '..']).empty?
+        Dir.rmdir(directory) rescue nil
+      end
+    end
     Cache.clear
   end
 end

lib/rscons/builder.rb

@@ -24,7 +24,7 @@ module Rscons
     # Return the name of the target or false on failure.
     def standard_build(short_cmd_string, target, command, sources, env, cache)
       unless cache.up_to_date?(target, command, sources)
-        FileUtils.mkdir_p(File.dirname(target))
+        cache.mkdir_p(File.dirname(target))
         FileUtils.rm_f(target)
         return false unless env.execute(short_cmd_string, command)
         cache.register_build(target, command, sources)

lib/rscons/builders/object.rb

@@ -55,7 +55,7 @@ module Rscons
                    end
       command = env.build_command(env["#{com_prefix}COM"], vars)
       unless cache.up_to_date?(target, command, sources)
-        FileUtils.mkdir_p(File.dirname(target))
+        cache.mkdir_p(File.dirname(target))
         FileUtils.rm_f(target)
         return false unless env.execute("#{com_prefix} #{target}", command)
         deps = sources

lib/rscons/cache.rb

@@ -36,6 +36,11 @@ module Rscons
   #         ]
   #       }
   #     }
+  #     directories: {
+  #       'build' => true,
+  #       'build/one' => true,
+  #       'build/two' => true,
+  #     }
   #   }
   class Cache
     #### Constants
@@ -57,6 +62,7 @@ module Rscons
     def initialize
       @cache = YAML.load(File.read(CACHE_FILE)) rescue {
         targets: {},
+        directories: {},
         version: VERSION,
       }
       @lookup_checksums = {}
@@ -137,6 +143,26 @@ module Rscons
       @cache[:targets].keys
     end
 
+    # Make any needed directories and record the ones that are created for
+    # removal upon a "clean" operation.
+    def mkdir_p(path)
+      parts = path.split(/[\\\/]/)
+      (0..parts.size).each do |i|
+        subpath = File.join(*parts[0, i + 1])
+        unless File.exists?(subpath)
+          FileUtils.mkdir(subpath)
+          unless @cache[:directories].include?(subpath)
+            @cache[:directories][subpath] = true
+          end
+        end
+      end
+    end
+
+    # Return a list of directories which were created as a part of the build
+    def directories
+      @cache[:directories].keys
+    end
+
     # Private Instance Methods
     private
 

lib/rscons/environment.rb

@@ -96,7 +96,6 @@ module Rscons
         end
         build_fname.gsub!('\\', '/')
       end
-      FileUtils.mkdir_p(File.dirname(build_fname))
       build_fname
     end