class Prism::WhenNode

Represents the use of the ‘when` keyword within a case statement.

case true
when true
^^^^^^^^^
end

Attributes

conditions[R]

attr_reader conditions: Array

statements[R]

attr_reader statements: StatementsNode?

Public Class Methods

new(source, keyword_loc, conditions, then_keyword_loc, statements, location) click to toggle source

def initialize: (Location keyword_loc, Array conditions, Location? then_keyword_loc, StatementsNode? statements, Location location) -> void

# File lib/prism/node.rb, line 18567
def initialize(source, keyword_loc, conditions, then_keyword_loc, statements, location)
  @source = source
  @newline = false
  @location = location
  @keyword_loc = keyword_loc
  @conditions = conditions
  @then_keyword_loc = then_keyword_loc
  @statements = statements
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 18678
def self.type
  :when_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 18684
def ===(other)
  other.is_a?(WhenNode) &&
    (keyword_loc.nil? == other.keyword_loc.nil?) &&
    (conditions.length == other.conditions.length) &&
    conditions.zip(other.conditions).all? { |left, right| left === right } &&
    (then_keyword_loc.nil? == other.then_keyword_loc.nil?) &&
    (statements === other.statements)
end

accept(visitor) click to toggle source

def accept: (Visitor visitor) -> void

# File lib/prism/node.rb, line 18578
def accept(visitor)
  visitor.visit_when_node(self)
end

child_nodes() click to toggle source

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

# File lib/prism/node.rb, line 18583
def child_nodes
  [*conditions, statements]
end

Also aliased as: deconstruct

comment_targets() click to toggle source

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

# File lib/prism/node.rb, line 18596
def comment_targets
  [keyword_loc, *conditions, *then_keyword_loc, *statements] #: Array[Prism::node | Location]
end

compact_child_nodes() click to toggle source

def compact_child_nodes: () -> Array

# File lib/prism/node.rb, line 18588
def compact_child_nodes
  compact = [] #: Array[Prism::node]
  compact.concat(conditions)
  compact << statements if statements
  compact
end

copy(keyword_loc: self.keyword_loc, conditions: self.conditions, then_keyword_loc: self.then_keyword_loc, statements: self.statements, location: self.location) click to toggle source

def copy: (?keyword_loc: Location, ?conditions: Array, ?then_keyword_loc: Location?, ?statements: StatementsNode?, ?location: Location) -> WhenNode

# File lib/prism/node.rb, line 18601
def copy(keyword_loc: self.keyword_loc, conditions: self.conditions, then_keyword_loc: self.then_keyword_loc, statements: self.statements, location: self.location)
  WhenNode.new(source, keyword_loc, conditions, then_keyword_loc, statements, location)
end

deconstruct()

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

Alias for: child_nodes

deconstruct_keys(keys) click to toggle source

def deconstruct_keys: (Array keys) -> { keyword_loc: Location, conditions: Array, then_keyword_loc: Location?, statements: StatementsNode?, location: Location }

# File lib/prism/node.rb, line 18609
def deconstruct_keys(keys)
  { keyword_loc: keyword_loc, conditions: conditions, then_keyword_loc: then_keyword_loc, statements: statements, location: location }
end

inspect() click to toggle source

def inspect -> String

# File lib/prism/node.rb, line 18650
def inspect
  InspectVisitor.compose(self)
end

keyword() click to toggle source

def keyword: () -> String

# File lib/prism/node.rb, line 18640
def keyword
  keyword_loc.slice
end

keyword_loc() click to toggle source

attr_reader keyword_loc: Location

# File lib/prism/node.rb, line 18614
def keyword_loc
  location = @keyword_loc
  return location if location.is_a?(Location)
  @keyword_loc = Location.new(source, location >> 32, location & 0xFFFFFFFF)
end

then_keyword() click to toggle source

def then_keyword: () -> String?

# File lib/prism/node.rb, line 18645
def then_keyword
  then_keyword_loc&.slice
end

then_keyword_loc() click to toggle source

attr_reader then_keyword_loc: Location?

# File lib/prism/node.rb, line 18624
def then_keyword_loc
  location = @then_keyword_loc
  case location
  when nil
    nil
  when Location
    location
  else
    @then_keyword_loc = Location.new(source, location >> 32, location & 0xFFFFFFFF)
  end
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 18668
def type
  :when_node
end