Represents the use of a case statement for pattern matching.
case true in false end ^^^^^^^^^
attr_reader predicate: Prism::node?
attr_reader conditions: Array
attr_reader consequent: ElseNode?
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3325
def initialize(source, predicate, conditions, consequent, case_keyword_loc, end_keyword_loc, location)
@source = source
@location = location
@predicate = predicate
@conditions = conditions
@consequent = consequent
@case_keyword_loc = case_keyword_loc
@end_keyword_loc = end_keyword_loc
end
def initialize: (Prism::node? predicate, Array conditions, ElseNode? consequent, Location case_keyword_loc, Location end_keyword_loc, Location location) -> void
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3434
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-3.4.0-preview1/lib/prism/node.rb, line 3440
def ===(other)
other.is_a?(CaseMatchNode) &&
(predicate === other.predicate) &&
(conditions.length == other.conditions.length) &&
conditions.zip(other.conditions).all? { |left, right| left === right } &&
(consequent === other.consequent) &&
(case_keyword_loc.nil? == other.case_keyword_loc.nil?) &&
(end_keyword_loc.nil? == other.end_keyword_loc.nil?)
end
Implements case-equality for the node. This is effectively == but without comparing the value of locations. Locations are checked only for presence.
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3336
def accept(visitor)
visitor.visit_case_match_node(self)
end
def accept: (Visitor visitor) -> void
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3396
def case_keyword
case_keyword_loc.slice
end
def case_keyword: () -> String
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3382
def case_keyword_loc
location = @case_keyword_loc
return location if location.is_a?(Location)
@case_keyword_loc = Location.new(source, location >> 32, location & 0xFFFFFFFF)
end
attr_reader case_keyword_loc: Location
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3341
def child_nodes
[predicate, *conditions, consequent]
end
def child_nodes: () -> Array[nil | Node]
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3355
def comment_targets
[*predicate, *conditions, *consequent, case_keyword_loc, end_keyword_loc] #: Array[Prism::node | Location]
end
def comment_targets: () -> Array[Node | Location]
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3346
def compact_child_nodes
compact = [] #: Array[Prism::node]
compact << predicate if predicate
compact.concat(conditions)
compact << consequent if consequent
compact
end
def compact_child_nodes: () -> Array
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3360
def copy(predicate: self.predicate, conditions: self.conditions, consequent: self.consequent, case_keyword_loc: self.case_keyword_loc, end_keyword_loc: self.end_keyword_loc, location: self.location)
CaseMatchNode.new(source, predicate, conditions, consequent, case_keyword_loc, end_keyword_loc, location)
end
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3368
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
def deconstruct_keys: (Array keys) -> { predicate: Prism::node?, conditions: Array, consequent: ElseNode?, case_keyword_loc: Location, end_keyword_loc: Location, location: Location }
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3401
def end_keyword
end_keyword_loc.slice
end
def end_keyword: () -> String
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3389
def end_keyword_loc
location = @end_keyword_loc
return location if location.is_a?(Location)
@end_keyword_loc = Location.new(source, location >> 32, location & 0xFFFFFFFF)
end
attr_reader end_keyword_loc: Location
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3406
def inspect
InspectVisitor.compose(self)
end
def inspect -> String
# File tmp/rubies/ruby-3.4.0-preview1/lib/prism/node.rb, line 3424
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