add exceptions and storage base abstraction

lib/anemone/core.rb

@@ -2,8 +2,10 @@
 require 'robots'
 require 'anemone/tentacle'
 require 'anemone/page'
+require 'anemone/exceptions'
 require 'anemone/page_store'
 require 'anemone/storage'
+require 'anemone/storage/base'
 
 module Anemone
 
@@ -187,7 +189,8 @@ def run
     def process_options
       @opts = DEFAULT_OPTS.merge @opts
       @opts[:threads] = 1 if @opts[:delay] > 0
-      @pages = PageStore.new(@opts[:storage] || Anemone::Storage.Hash)
+      storage = Anemone::Storage::Base.new(@opts[:storage] || Anemone::Storage.Hash)
+      @pages = PageStore.new(storage)
       @robots = Robots.new(@opts[:user_agent]) if @opts[:obey_robots_txt]
 
       freeze_options

lib/anemone/exceptions.rb

@@ -0,0 +1,5 @@
+module Anemone
+  class Error < ::StandardError
+    attr_accessor :wrapped_exception
+  end
+end

lib/anemone/storage.rb

@@ -2,7 +2,10 @@ module Anemone
   module Storage
 
     def self.Hash(*args)
-      Hash.new(*args)
+      hash = Hash.new(*args)
+      # add close method for compatibility with Storage::Base
+      class << hash; def close; end; end
+      hash
     end
 
     def self.PStore(*args)

lib/anemone/storage/base.rb

@@ -0,0 +1,74 @@
+require 'anemone/storage/exceptions'
+
+module Anemone
+  module Storage
+    class Base
+
+      def initialize(adapter)
+        @adap = adapter
+
+        # verify adapter conforms to this class's methods
+        methods.each do |method|
+          if !@adap.respond_to?(method.to_sym)
+            raise "Storage adapter must support method #{method}"
+          end
+        end
+      end
+
+      def [](key)
+        @adap[key]
+        rescue
+          raise RetrievalError 
+      end
+
+      def []=(key, value)
+        @adap[key] = value
+        rescue
+          raise InsertionError
+      end
+
+      def delete(key)
+        @adap.delete(key)
+        rescue
+          raise DeletionError
+      end
+
+      def each
+        @adap.each { |k, v| yield k, v }
+        rescue
+          raise GenericError
+      end
+
+      def merge!(hash)
+        @adap.merge!(hash)
+        rescue
+          raise GenericError
+      end
+
+      def close
+        @adap.close
+        rescue
+          raise CloseError
+      end
+
+      def size
+        @adap.size
+        rescue
+          raise GenericError
+      end
+
+      def keys
+        @adap.keys
+        rescue
+          raise GenericError
+      end
+
+      def has_key?(key)
+        @adap.has_key?(key)
+        rescue
+          raise GenericError
+      end
+
+    end
+  end
+end

lib/anemone/storage/exceptions.rb

@@ -0,0 +1,15 @@
+module Anemone
+  module Storage
+
+    class GenericError < Error; end;
+
+    class ConnectionError < Error; end
+
+    class RetrievalError < Error; end
+
+    class InsertionError < Error; end
+
+    class CloseError < Error; end
+
+  end
+end

lib/anemone/storage/pstore.rb

@@ -43,6 +43,8 @@ def merge!(hash)
         self
       end
 
+      def close; end
+
     end
   end
 end