class Prism::WhenNode
Represents the use of the ‘when` keyword within a case statement.
case true when true ^^^^^^^^^ end
Attributes
attr_reader conditions: Array
attr_reader keyword_loc
: Location
attr_reader statements: StatementsNode
?
Public Class Methods
def initialize: (keyword_loc
: Location
, conditions: Array, statements: StatementsNode
?, location: Location
) -> void
# File lib/prism/node.rb, line 16776 def initialize(keyword_loc, conditions, statements, location) @keyword_loc = keyword_loc @conditions = conditions @statements = statements @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 lib/prism/node.rb, line 16867 def self.type :when_node end
Public Instance Methods
def accept: (visitor: Visitor
) -> void
# File lib/prism/node.rb, line 16784 def accept(visitor) visitor.visit_when_node(self) end
def child_nodes
: () -> Array[nil | Node]
# File lib/prism/node.rb, line 16789 def child_nodes [*conditions, statements] end
def comment_targets
: () -> Array[Node | Location]
# File lib/prism/node.rb, line 16802 def comment_targets [keyword_loc, *conditions, *statements] end
def compact_child_nodes
: () -> Array
# File lib/prism/node.rb, line 16794 def compact_child_nodes compact = [] compact.concat(conditions) compact << statements if statements compact end
def copy: (**params) -> WhenNode
# File lib/prism/node.rb, line 16807 def copy(**params) WhenNode.new( params.fetch(:keyword_loc) { keyword_loc }, params.fetch(:conditions) { conditions }, params.fetch(:statements) { statements }, params.fetch(:location) { location }, ) end
def inspect(inspector: NodeInspector) -> String
# File lib/prism/node.rb, line 16830 def inspect(inspector = NodeInspector.new) inspector << inspector.header(self) inspector << "├── keyword_loc: #{inspector.location(keyword_loc)}\n" inspector << "├── conditions: #{inspector.list("#{inspector.prefix}│ ", conditions)}" if (statements = self.statements).nil? inspector << "└── statements: ∅\n" else inspector << "└── statements:\n" inspector << statements.inspect(inspector.child_inspector(" ")).delete_prefix(inspector.prefix) end inspector.to_str end
def keyword: () -> String
# File lib/prism/node.rb, line 16825 def keyword keyword_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 lib/prism/node.rb, line 16857 def type :when_node end