module Arel module Nodes ### # Abstract base class for all AST nodes class Node include Arel::FactoryMethods include Enumerable ### # Factory method to create a Nodes::Not node that has the recipient of # the caller as a child. def not Nodes::Not.new Nodes::Grouping.new self end ### # Factory method to create a Nodes::Grouping node that has an Nodes::Or # node as a child. def or right Nodes::Grouping.new Nodes::Or.new(self, right) end ### # Factory method to create an Nodes::And node. def and right Nodes::And.new [self, right] end # FIXME: this method should go away. I don't like people calling # to_sql on non-head nodes. This forces us to walk the AST until we # can find a node that has a "relation" member. # # Maybe we should just use `Table.engine`? :'( def to_sql engine = Table.engine viz = Visitors.for engine viz.accept self end # Iterate through AST, nodes will be yielded depth-first def each &block return enum_for(:each) unless block_given? Visitors::DepthFirst.new(block).accept self end end end end