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rails--rails/lib/arel/nodes/node.rb
2010-12-14 16:24:36 -08:00

47 lines
1.2 KiB
Ruby

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