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Diffstat (limited to 'lib/arel/primitives/expression.rb')
| -rw-r--r-- | lib/arel/primitives/expression.rb | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/lib/arel/primitives/expression.rb b/lib/arel/primitives/expression.rb new file mode 100644 index 0000000000..bf674cc9e1 --- /dev/null +++ b/lib/arel/primitives/expression.rb @@ -0,0 +1,44 @@ +module Arel + class Expression < Attribute + include Sql::Quoting + + attr_reader :attribute, :function_sql + delegate :relation, :to => :attribute + alias_method :name, :alias + + def initialize(attribute, function_sql, aliaz = nil, ancestor = nil) + @attribute, @function_sql, @alias, @ancestor = attribute, function_sql, aliaz, ancestor + end + + module Transformations + def as(aliaz) + Expression.new(attribute, function_sql, aliaz, self) + end + + def bind(new_relation) + new_relation == relation ? self : Expression.new(attribute.bind(new_relation), function_sql, @alias, self) + end + + def to_attribute + Attribute.new(relation, @alias, :ancestor => self) + end + end + include Transformations + + def to_sql(formatter = nil) + "#{function_sql}(#{attribute.to_sql})" + (@alias ? " AS #{quote_column_name(@alias)}" : '') + end + + def aggregation? + true + end + + def ==(other) + self.class == other.class and + attribute == other.attribute and + function_sql == other.function_sql and + ancestor == other.ancestor and + @alias == other.alias + end + end +end
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