class Prism::CaseMatchNode

Represents the use of a case statement for pattern matching.

case true
in false
end
^^^^^^^^^

Attributes

conditions[R]

attr_reader conditions: Array

consequent[R]

attr_reader consequent: ElseNode?

predicate[R]

attr_reader predicate: Prism::node?

Public Class Methods

new(source, predicate, conditions, consequent, case_keyword_loc, end_keyword_loc, location) click to toggle source

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

# File lib/prism/node.rb, line 3313
def initialize(source, predicate, conditions, consequent, case_keyword_loc, end_keyword_loc, location)
  @source = source
  @newline = false
  @location = location
  @predicate = predicate
  @conditions = conditions
  @consequent = consequent
  @case_keyword_loc = case_keyword_loc
  @end_keyword_loc = end_keyword_loc
end

type() click to toggle source

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 3423
def self.type
  :case_match_node
end

Public Instance Methods

===(other) click to toggle source

Implements case-equality for the node. This is effectively == but without comparing the value of locations. Locations are checked only for presence.

# File lib/prism/node.rb, line 3429
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

accept(visitor) click to toggle source

def accept: (Visitor visitor) -> void

# File lib/prism/node.rb, line 3325
def accept(visitor)
  visitor.visit_case_match_node(self)
end

case_keyword() click to toggle source

def case_keyword: () -> String

# File lib/prism/node.rb, line 3385
def case_keyword
  case_keyword_loc.slice
end

case_keyword_loc() click to toggle source

attr_reader case_keyword_loc: Location

# File lib/prism/node.rb, line 3371
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

child_nodes() click to toggle source

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

# File lib/prism/node.rb, line 3330
def child_nodes
  [predicate, *conditions, consequent]
end

Also aliased as: deconstruct

comment_targets() click to toggle source

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

# File lib/prism/node.rb, line 3344
def comment_targets
  [*predicate, *conditions, *consequent, case_keyword_loc, end_keyword_loc] #: Array[Prism::node | Location]
end

compact_child_nodes() click to toggle source

def compact_child_nodes: () -> Array

# File lib/prism/node.rb, line 3335
def compact_child_nodes
  compact = [] #: Array[Prism::node]
  compact << predicate if predicate
  compact.concat(conditions)
  compact << consequent if consequent
  compact
end

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) click to toggle source

def copy: (?predicate: Prism::node?, ?conditions: Array, ?consequent: ElseNode?, ?case_keyword_loc: Location, ?end_keyword_loc: Location, ?location: Location) -> CaseMatchNode

# File lib/prism/node.rb, line 3349
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

deconstruct()

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

Alias for: child_nodes

deconstruct_keys(keys) click to toggle source

def deconstruct_keys: (Array keys) -> { predicate: Prism::node?, conditions: Array, consequent: ElseNode?, case_keyword_loc: Location, end_keyword_loc: Location, location: Location }

# File lib/prism/node.rb, line 3357
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

end_keyword() click to toggle source

def end_keyword: () -> String

# File lib/prism/node.rb, line 3390
def end_keyword
  end_keyword_loc.slice
end

end_keyword_loc() click to toggle source

attr_reader end_keyword_loc: Location

# File lib/prism/node.rb, line 3378
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

inspect() click to toggle source

def inspect -> String

# File lib/prism/node.rb, line 3395
def inspect
  InspectVisitor.compose(self)
end

type() click to toggle source

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 3413
def type
  :case_match_node
end