class Prism::CapturePatternNode
Represents assigning to a local variable in pattern matching.
foo => [bar => baz] ^^^^^^^^^^^^
Attributes
attr_reader operator_loc
: Location
attr_reader target: Node
attr_reader value: Node
Public Class Methods
def initialize: (value: Node
, target: Node
, operator_loc
: Location
, location: Location
) -> void
# File prism/node.rb, line 2835 def initialize(value, target, operator_loc, location) @value = value @target = target @operator_loc = operator_loc @location = location 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 2920 def self.type :capture_pattern_node end
Public Instance Methods
def accept: (visitor: Visitor
) -> void
# File prism/node.rb, line 2843 def accept(visitor) visitor.visit_capture_pattern_node(self) end
def child_nodes
: () -> Array[nil | Node]
# File prism/node.rb, line 2848 def child_nodes [value, target] end
def comment_targets
: () -> Array[Node | Location]
# File prism/node.rb, line 2858 def comment_targets [value, target, operator_loc] end
def compact_child_nodes
: () -> Array
# File prism/node.rb, line 2853 def compact_child_nodes [value, target] end
def copy: (**params) -> CapturePatternNode
# File prism/node.rb, line 2863 def copy(**params) CapturePatternNode.new( params.fetch(:value) { value }, params.fetch(:target) { target }, params.fetch(:operator_loc) { operator_loc }, params.fetch(:location) { location }, ) end
def inspect(inspector: NodeInspector) -> String
# File prism/node.rb, line 2886 def inspect(inspector = NodeInspector.new) inspector << inspector.header(self) inspector << "├── value:\n" inspector << inspector.child_node(value, "│ ") inspector << "├── target:\n" inspector << inspector.child_node(target, "│ ") inspector << "└── operator_loc: #{inspector.location(operator_loc)}\n" inspector.to_str end
def operator: () -> String
# File prism/node.rb, line 2881 def operator operator_loc.slice 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 2910 def type :capture_pattern_node end