1 files changed, 85 insertions, 0 deletions
diff --git a/lib/arel/engines/sql/primitives.rb b/lib/arel/engines/sql/primitives.rb
new file mode 100644
index 0000000000..bb3bed78e6
--- /dev/null
+++ b/lib/arel/engines/sql/primitives.rb
@@ -0,0 +1,85 @@
+module Arel
+  class SqlLiteral < String
+    def relation
+      nil
+    end
+    
+    def to_sql(formatter = nil)
+      self
+    end
+  end
+
+  class Attribute
+    def column
+      original_relation.column_for(self)
+    end
+
+    def type_cast(value)
+      root.relation.format(self, value)
+    end
+
+    def format(object)
+      object.to_sql(Sql::Attribute.new(self))
+    end
+
+    def to_sql(formatter = Sql::WhereCondition.new(relation))
+      formatter.attribute self
+    end
+  end
+
+  class Value
+    delegate :inclusion_predicate_sql, :equality_predicate_sql, :to => :value
+
+    def to_sql(formatter = Sql::WhereCondition.new(relation))
+      formatter.value value
+    end
+
+    def format(object)
+      object.to_sql(Sql::Value.new(relation))
+    end
+  end
+
+  class Ordering
+    def to_sql(formatter = Sql::OrderClause.new(relation))
+      formatter.ordering self
+    end
+  end
+
+  class Ascending < Ordering
+    def direction_sql; 'ASC' end
+  end
+
+  class Descending < Ordering
+    def direction_sql; 'DESC' end
+  end
+
+  class Expression < Attribute
+    def to_sql(formatter = Sql::SelectClause.new(relation))
+      formatter.expression self
+    end
+  end
+
+  class Count < Expression
+    def function_sql; 'COUNT' end
+  end
+
+  class Distinct < Expression
+    def function_sql; 'DISTINCT' end
+  end
+
+  class Sum < Expression
+    def function_sql; 'SUM' end
+  end
+
+  class Maximum < Expression
+    def function_sql; 'MAX' end
+  end
+
+  class Minimum < Expression
+    def function_sql; 'MIN' end
+  end
+
+  class Average < Expression
+    def function_sql; 'AVG' end
+  end
+end