1 files changed, 171 insertions, 0 deletions
diff --git a/lib/rack-flash.rb b/lib/rack-flash.rb
new file mode 100644
index 0000000..bc95b21
--- /dev/null
+++ b/lib/rack-flash.rb
@@ -0,0 +1,171 @@
+# 
+# borrowed from http://github.com/nakajima/rack-flash - thanks!
+#
+
+require 'rack/builder'
+
+module Rack
+  class Builder
+    attr :ins
+    def use(middleware, *args, &block)
+      middleware.instance_variable_set "@rack_builder", self
+      def middleware.rack_builder
+        @rack_builder
+      end
+      @ins << lambda { |app|
+        middleware.new(app, *args, &block)
+      }
+    end
+
+    def run(app)
+      klass = app.class
+      klass.instance_variable_set "@rack_builder", self
+      def klass.rack_builder
+        @rack_builder
+      end
+      @ins << app #lambda { |nothing| app }
+    end
+
+    def leaf_app
+      ins.last
+    end
+  end
+end
+
+module Rack
+  class Flash
+    # Raised when the session passed to FlashHash initialize is nil. This
+    # is usually an indicator that session middleware is not in use.
+    class SessionUnavailable < StandardError; end
+
+    # Implements bracket accessors for storing and retrieving flash entries.
+    class FlashHash
+      attr_reader :flagged
+
+      def initialize(store, opts={})
+        raise Rack::Flash::SessionUnavailable \
+          .new('Rack::Flash depends on session middleware.') unless store
+
+        @opts = opts
+        @store = store
+
+        if accessors = @opts[:accessorize]
+          accessors.each { |opt| def_accessor(opt) }
+        end
+      end
+
+      # Remove an entry from the session and return its value. Cache result in
+      # the instance cache.
+      def [](key)
+        key = key.to_sym
+        cache[key] ||= values.delete(key)
+      end
+
+      # Store the entry in the session, updating the instance cache as well.
+      def []=(key,val)
+        key = key.to_sym
+        cache[key] = values[key] = val
+      end
+
+      # Store a flash entry for only the current request, swept regardless of
+      # whether or not it was actually accessed. Useful for AJAX requests, where
+      # you want a flash message, even though you're response isn't redirecting.
+      def now
+        cache
+      end
+
+      # Checks for the presence of a flash entry without retrieving or removing
+      # it from the cache or store.
+      def has?(key)
+        [cache, values].any? { |store| store.keys.include?(key.to_sym) }
+      end
+      alias_method :include?, :has?
+
+      # Mark existing entries to allow for sweeping.
+      def flag!
+        @flagged = values.keys
+      end
+
+      # Remove flagged entries from flash session, clear flagged list.
+      def sweep!
+        Array(flagged).each { |key| values.delete(key) }
+        flagged.clear
+      end
+
+      # Hide the underlying :__FLASH__ session key and only expose values stored
+      # in the flash.
+      def inspect
+        '#<FlashHash @values=%s @cache=%s>' % [values.inspect, cache.inspect]
+      end
+
+      # Human readable for logging.
+      def to_s
+        values.inspect
+      end
+
+      private
+
+      # Maintain an instance-level cache of retrieved flash entries. These
+      # entries will have been removed from the session, but are still available
+      # through the cache.
+      def cache
+        @cache ||= {}
+      end
+
+      # Helper to access flash entries from :__FLASH__ session value. This key
+      # is used to prevent collisions with other user-defined session values.
+      def values
+        @store[:__FLASH__] ||= {}
+      end
+
+      # Generate accessor methods for the given entry key if :accessorize is true.
+      def def_accessor(key)
+        raise ArgumentError.new('Invalid entry type: %s' % key) if respond_to?(key)
+
+        class << self; self end.class_eval do
+          define_method(key) { |*args| val = args.first; val ? (self[key]=val) : self[key] }
+          define_method("#{key}=") { |val| self[key] = val }
+          define_method("#{key}!") { |val| cache[key] = val }
+        end
+      end
+    end
+
+    # -------------------------------------------------------------------------
+    # - Rack Middleware implementation
+
+    def initialize(app, opts={})
+      if klass = app_class(app, opts)
+        klass.class_eval do
+          def flash; env['x-rack.flash'] end
+        end
+      end
+
+      @app, @opts = app, opts
+    end
+
+    def call(env)
+      env['x-rack.flash'] ||= Rack::Flash::FlashHash.new(env['rack.session'], @opts)
+
+      if @opts[:sweep]
+        env['x-rack.flash'].flag!
+      end
+
+      res = @app.call(env)
+
+      if @opts[:sweep]
+        env['x-rack.flash'].sweep!
+      end
+
+      res
+    end
+
+    private
+
+    def app_class(app, opts)
+      return nil if opts.has_key?(:helper) and not opts[:helper]
+      opts[:flash_app_class] ||
+        defined?(Sinatra::Base) && Sinatra::Base ||
+        self.class.rack_builder.leaf_app.class
+    end
+  end
+end