Add experimental Twitter::SqliteIdentityMap

etc/sqlite_identity_map.rb

@@ -0,0 +1,48 @@
+require 'sqlite3'
+
+module Twitter
+  class SqliteIdentityMap
+    include SQLite3
+
+    def initialize
+      @database = Database.new(":memory:")
+    end
+
+    # @param klass
+    # @param key
+    # @return [Object]
+    def fetch(klass, key)
+      table = table_from_class(klass)
+      create_table(table)
+      statement = @database.prepare("SELECT object FROM #{table} WHERE key = :key")
+      row = statement.execute!(:key => key).first
+      Marshal.load(row.first) unless row.nil?
+    end
+
+    # @param key
+    # @param object
+    # @return [Object]
+    def store(key, object)
+      table = table_from_class(object.class)
+      create_table(table)
+      statement = @database.prepare("INSERT INTO #{table}(key, object) VALUES (:key, :object)")
+      statement.execute(:key => key, :object => Blob.new(Marshal.dump(object)))
+      object
+    end
+
+  private
+
+    # @params klass [Class]
+    # @return [String]
+    def table_from_class(klass)
+      klass.to_s.downcase.gsub("::", "__")
+    end
+
+    # @param table [Class]
+    def create_table(table)
+      @database.execute("CREATE TABLE IF NOT EXISTS #{table}(key VARCHAR NOT NULl, object BLOB)")
+      @database.execute("CREATE UNIQUE INDEX IF NOT EXISTS #{table}_unique_key ON #{table}(key)")
+    end
+
+  end
+end