Represents the use of a case statement for pattern matching.

case true
in false
end
^^^^^^^^^
Attributes
Read

attr_reader predicate: Node?

Read

attr_reader conditions: Array

Read

attr_reader consequent: ElseNode?

Class Methods

def initialize: (predicate: Node?, conditions: Array, consequent: ElseNode?, case_keyword_loc: Location, end_keyword_loc: Location, location: Location) -> void

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

Instance Methods

def accept: (visitor: Visitor) -> void

def case_keyword: () -> String

def child_nodes: () -> Array[nil | Node]

def comment_targets: () -> Array[Node | Location]

def copy: (**params) -> CaseMatchNode

An alias for child_nodes

def deconstruct_keys: (keys: Array) -> Hash[Symbol, nil | Node | Array | String | Token | Array | Location]

def end_keyword: () -> String

def inspect(inspector: NodeInspector) -> String

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