added sqlite adapter

lib/foreigner/connection_adapters/sqlite_adapter.rb

@@ -0,0 +1,38 @@
+require 'foreigner/connection_adapters/sql_2003'
+
+module Foreigner
+  module ConnectionAdapters
+    module SQLiteAdapter
+      include Foreigner::ConnectionAdapters::Sql2003
+
+      def foreign_keys(table_name)
+        foreign_keys = []
+        create_table_info = select_value %{
+SELECT sql
+FROM sqlite_master
+WHERE sql LIKE '%FOREIGN KEY%'
+AND name = '#{table_name}'
+}
+      if !create_table_info.nil?
+        fk_columns = create_table_info.scan(/FOREIGN KEY\s*\(\"([^\"]+)\"\)/)
+        fk_tables = create_table_info.scan(/REFERENCES\s*\"([^\"]+)\"/)
+        if fk_columns.size == fk_tables.size
+          fk_columns.each_with_index do |fk_column, index|
+            foreign_keys << ForeignKeyDefinition.new(table_name, fk_tables[index][0], :column => fk_column[0])
+          end
+        end
+      end
+      foreign_keys
+      end
+    end
+  end
+end
+
+module ActiveRecord
+  module ConnectionAdapters
+    SQLiteAdapter.class_eval do
+      include Foreigner::ConnectionAdapters::SQLiteAdapter
+    end
+  end
+end
+