Represents the use of a case statement for pattern matching.
case true in false end ^^^^^^^^^
attr_reader conditions: Array
attr_reader consequent: ElseNode?
attr_reader case_keyword_loc: Location
attr_reader end_keyword_loc: Location
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 2948
def initialize(predicate, conditions, consequent, case_keyword_loc, end_keyword_loc, location)
@predicate = predicate
@conditions = conditions
@consequent = consequent
@case_keyword_loc = case_keyword_loc
@end_keyword_loc = end_keyword_loc
@location = location
end
def initialize: (predicate: Node?, conditions: Array, consequent: ElseNode?, case_keyword_loc: Location, end_keyword_loc: Location, location: Location) -> void
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 3056
def self.type
:case_match_node
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 tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 2958
def accept(visitor)
visitor.visit_case_match_node(self)
end
def accept: (visitor: Visitor) -> void
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 3002
def case_keyword
case_keyword_loc.slice
end
def case_keyword: () -> String
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 2963
def child_nodes
[predicate, *conditions, consequent]
end
def child_nodes: () -> Array[nil | Node]
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 2977
def comment_targets
[*predicate, *conditions, *consequent, case_keyword_loc, end_keyword_loc]
end
def comment_targets: () -> Array[Node | Location]
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 2968
def compact_child_nodes
compact = []
compact << predicate if predicate
compact.concat(conditions)
compact << consequent if consequent
compact
end
def compact_child_nodes: () -> Array
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 2982
def copy(**params)
CaseMatchNode.new(
params.fetch(:predicate) { predicate },
params.fetch(:conditions) { conditions },
params.fetch(:consequent) { consequent },
params.fetch(:case_keyword_loc) { case_keyword_loc },
params.fetch(:end_keyword_loc) { end_keyword_loc },
params.fetch(:location) { location },
)
end
def copy: (**params) -> CaseMatchNode
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 2997
def deconstruct_keys(keys)
{ predicate: predicate, conditions: conditions, consequent: consequent, case_keyword_loc: case_keyword_loc, end_keyword_loc: end_keyword_loc, location: location }
end
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 3007
def end_keyword
end_keyword_loc.slice
end
def end_keyword: () -> String
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 3012
def inspect(inspector = NodeInspector.new)
inspector << inspector.header(self)
if (predicate = self.predicate).nil?
inspector << "├── predicate: ∅\n"
else
inspector << "├── predicate:\n"
inspector << predicate.inspect(inspector.child_inspector("│ ")).delete_prefix(inspector.prefix)
end
inspector << "├── conditions: #{inspector.list("#{inspector.prefix}│ ", conditions)}"
if (consequent = self.consequent).nil?
inspector << "├── consequent: ∅\n"
else
inspector << "├── consequent:\n"
inspector << consequent.inspect(inspector.child_inspector("│ ")).delete_prefix(inspector.prefix)
end
inspector << "├── case_keyword_loc: #{inspector.location(case_keyword_loc)}\n"
inspector << "└── end_keyword_loc: #{inspector.location(end_keyword_loc)}\n"
inspector.to_str
end
def inspect(inspector: NodeInspector) -> String
# File tmp/rubies/ruby-3.3.0/lib/prism/node.rb, line 3046
def type
:case_match_node
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