class Prism::BackReferenceReadNode
Represents reading a reference to a field in the previous match.
$' ^^
Attributes
The name of the back-reference variable, including the leading ‘$`.
$& # name `:$&` $+ # name `:$+`
Public Class Methods
def initialize: (Symbol name, Location
location) -> void
# File prism/node.rb, line 1297 def initialize(source, name, location) @source = source @location = location @name = name end
Similar to type
, this method returns a symbol that you can use for splitting on the type of the node without having to do a long === chain. Note that like type
, it will still be slower than using == for a single class, but should be faster in a case statement or an array comparison.
def self.type: () -> Symbol
# File prism/node.rb, line 1372 def self.type :back_reference_read_node end
Public Instance Methods
Implements case-equality for the node. This is effectively == but without comparing the value of locations. Locations are checked only for presence.
# File prism/node.rb, line 1378 def ===(other) other.is_a?(BackReferenceReadNode) && (name === other.name) end
def accept: (Visitor
visitor) -> void
# File prism/node.rb, line 1304 def accept(visitor) visitor.visit_back_reference_read_node(self) end
def child_nodes
: () -> Array[nil | Node]
# File prism/node.rb, line 1309 def child_nodes [] end
def comment_targets
: () -> Array[Node | Location]
# File prism/node.rb, line 1319 def comment_targets [] #: Array[Prism::node | Location] end
def compact_child_nodes
: () -> Array
# File prism/node.rb, line 1314 def compact_child_nodes [] end
def copy: (?name: Symbol, ?location: Location
) -> BackReferenceReadNode
# File prism/node.rb, line 1324 def copy(name: self.name, location: self.location) BackReferenceReadNode.new(source, name, location) end
def deconstruct_keys
: (Array keys) -> { name: Symbol, location: Location
}
# File prism/node.rb, line 1332 def deconstruct_keys(keys) { name: name, location: location } end
def inspect -> String
# File prism/node.rb, line 1344 def inspect InspectVisitor.compose(self) end
Sometimes you want to check an instance of a node against a list of classes to see what kind of behavior to perform. Usually this is done by calling ‘[cls1, cls2].include?(node.class)` or putting the node into a case statement and doing `case node; when cls1; when cls2; end`. Both of these approaches are relatively slow because of the constant lookups, method calls, and/or array allocations.
Instead, you can call type
, which will return to you a symbol that you can use for comparison. This is faster than the other approaches because it uses a single integer comparison, but also because if you’re on CRuby you can take advantage of the fact that case statements with all symbol keys will use a jump table.
def type: () -> Symbol
# File prism/node.rb, line 1362 def type :back_reference_read_node end