1 files changed, 113 insertions, 0 deletions
diff --git a/lib/arel/engines/sql/formatters.rb b/lib/arel/engines/sql/formatters.rb
new file mode 100644
index 0000000000..ae80feb18e
--- /dev/null
+++ b/lib/arel/engines/sql/formatters.rb
@@ -0,0 +1,113 @@
+module Arel
+  module Sql
+    class Formatter
+      attr_reader :environment
+      delegate :christener, :engine, :to => :environment
+      delegate :name_for, :to => :christener
+      delegate :quote_table_name, :quote_column_name, :quote, :to => :engine
+
+      def initialize(environment)
+        @environment = environment
+      end
+    end
+
+    class SelectClause < Formatter
+      def attribute(attribute)
+        # FIXME this should check that the column exists
+        "#{quote_table_name(name_for(attribute.original_relation))}.#{quote_column_name(attribute.name)}" +
+        (attribute.alias ? " AS #{quote(attribute.alias.to_s)}" : "")
+      end
+
+      def expression(expression)
+        if expression.function_sql == "DISTINCT"
+          "#{expression.function_sql} #{expression.attribute.to_sql(self)}" +
+          (expression.alias ? " AS #{quote_column_name(expression.alias)}" : '')
+        else
+          "#{expression.function_sql}(#{expression.attribute.to_sql(self)})" +
+          (expression.alias ? " AS #{quote_column_name(expression.alias)}" : " AS #{expression.function_sql.to_s.downcase}_id")
+        end
+      end
+
+      def select(select_sql, table)
+        "(#{select_sql}) AS #{quote_table_name(name_for(table))}"
+      end
+
+      def value(value)
+        value
+      end
+    end
+
+    class PassThrough < Formatter
+      def value(value)
+        value
+      end
+    end
+
+    class WhereClause < PassThrough
+    end
+
+    class OrderClause < PassThrough
+      def ordering(ordering)
+        "#{quote_table_name(name_for(ordering.attribute.original_relation))}.#{quote_column_name(ordering.attribute.name)} #{ordering.direction_sql}"
+      end
+    end
+
+    class GroupClause < PassThrough
+      def attribute(attribute)
+        "#{quote_table_name(name_for(attribute.original_relation))}.#{quote_column_name(attribute.name)}"
+      end
+    end
+
+    class WhereCondition < Formatter
+      def attribute(attribute)
+        "#{quote_table_name(name_for(attribute.original_relation))}.#{quote_column_name(attribute.name)}"
+      end
+
+      def expression(expression)
+        "#{expression.function_sql}(#{expression.attribute.to_sql(self)})"
+      end
+
+      def value(value)
+        value.to_sql(self)
+      end
+
+      def scalar(value, column = nil)
+        quote(value, column)
+      end
+
+      def select(select_sql, table)
+        "(#{select_sql})"
+      end
+    end
+
+    class SelectStatement < Formatter
+      def select(select_sql, table)
+        select_sql
+      end
+    end
+
+    class TableReference < Formatter
+      def select(select_sql, table)
+        "(#{select_sql}) AS #{quote_table_name(name_for(table))}"
+      end
+
+      def table(table)
+        quote_table_name(table.name) +
+        (table.name != name_for(table) ? " AS " + quote_table_name(name_for(table)) : '')
+      end
+    end
+
+    class Attribute < WhereCondition
+      def scalar(scalar)
+        quote(scalar, environment.column)
+      end
+
+      def range(left, right)
+        "#{left} AND #{right}"
+      end
+    end
+
+    class Value < WhereCondition
+    end
+  end
+end