class Prism::CaseMatchNode

Represents the use of a case statement for pattern matching.

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

Attributes

case_keyword_loc[R]

attr_reader case_keyword_loc: Location

conditions[R]

attr_reader conditions: Array

consequent[R]

attr_reader consequent: ElseNode?

end_keyword_loc[R]

attr_reader end_keyword_loc: Location

predicate[R]

attr_reader predicate: Node?

Public Class Methods

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

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

# File 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

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 3056
def self.type
  :case_match_node
end

Public Instance Methods

accept(visitor) click to toggle source

def accept: (visitor: Visitor) -> void

# File lib/prism/node.rb, line 2958
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 3002
def case_keyword
  case_keyword_loc.slice
end

child_nodes() click to toggle source

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

# File lib/prism/node.rb, line 2963
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 2977
def comment_targets
  [*predicate, *conditions, *consequent, case_keyword_loc, end_keyword_loc]
end

compact_child_nodes() click to toggle source

def compact_child_nodes: () -> Array

# File lib/prism/node.rb, line 2968
def compact_child_nodes
  compact = []
  compact << predicate if predicate
  compact.concat(conditions)
  compact << consequent if consequent
  compact
end

copy(**params) click to toggle source

def copy: (**params) -> CaseMatchNode

# File 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

deconstruct()

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

Alias for: child_nodes

deconstruct_keys(keys) click to toggle source

# File 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

end_keyword() click to toggle source

def end_keyword: () -> String

# File lib/prism/node.rb, line 3007
def end_keyword
  end_keyword_loc.slice
end

inspect(inspector = NodeInspector.new) click to toggle source

def inspect(inspector: NodeInspector) -> String

# File 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

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 3046
def type
  :case_match_node
end