# class Prism::SingletonClassNode

Represents a singleton class declaration involving the ‘class` keyword.

    class << self end
    ^^^^^^^^^^^^^^^^^

### Attributes

body[R]

attr_reader body: `Node`?

class_keyword_loc[R]

attr_reader `class_keyword_loc`: `Location`

end_keyword_loc[R]

attr_reader `end_keyword_loc`: `Location`

expression[R]

attr_reader expression: `Node`

locals[R]

attr_reader locals: Array

operator_loc[R]

attr_reader `operator_loc`: `Location`

### Public Class Methods

new(locals, class_keyword_loc, operator_loc, expression, body, end_keyword_loc, location) click to toggle source

def initialize: (locals: Array, `class_keyword_loc`: `Location`, `operator_loc`: `Location`, expression: `Node`, body: `Node`?, `end_keyword_loc`: `Location`, location: `Location`) -> void

    # File lib/prism/node.rb, line 15302
    def initialize(locals, class_keyword_loc, operator_loc, expression, body, end_keyword_loc, location)
      @locals = locals
      @class_keyword_loc = class_keyword_loc
      @operator_loc = operator_loc
      @expression = expression
      @body = body
      @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 15413
    def self.type
      :singleton_class_node
    end

### Public Instance Methods

accept(visitor) click to toggle source

def accept: (visitor: `Visitor`) -> void

    # File lib/prism/node.rb, line 15313
    def accept(visitor)
      visitor.visit_singleton_class_node(self)
    end

child_nodes() click to toggle source

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

    # File lib/prism/node.rb, line 15318
    def child_nodes
      [expression, body]
    end

Also aliased as: deconstruct
class_keyword() click to toggle source

def `class_keyword`: () -> `String`

    # File lib/prism/node.rb, line 15357
    def class_keyword
      class_keyword_loc.slice
    end

comment_targets() click to toggle source

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

    # File lib/prism/node.rb, line 15331
    def comment_targets
      [class_keyword_loc, operator_loc, expression, *body, end_keyword_loc]
    end

compact_child_nodes() click to toggle source

def `compact_child_nodes`: () -> Array

    # File lib/prism/node.rb, line 15323
    def compact_child_nodes
      compact = []
      compact << expression
      compact << body if body
      compact
    end

copy(**params) click to toggle source

def copy: (**params) -> `SingletonClassNode`

    # File lib/prism/node.rb, line 15336
    def copy(**params)
      SingletonClassNode.new(
        params.fetch(:locals) { locals },
        params.fetch(:class_keyword_loc) { class_keyword_loc },
        params.fetch(:operator_loc) { operator_loc },
        params.fetch(:expression) { expression },
        params.fetch(:body) { body },
        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

def `deconstruct_keys`: (keys: Array) -> Hash[Symbol, nil | `Node` | Array | `String` | `Token` | Array | Location]

    # File lib/prism/node.rb, line 15352
    def deconstruct_keys(keys)
      { locals: locals, class_keyword_loc: class_keyword_loc, operator_loc: operator_loc, expression: expression, body: body, 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 15367
    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 15372
    def inspect(inspector = NodeInspector.new)
      inspector << inspector.header(self)
      inspector << "├── locals: #{locals.inspect}\n"
      inspector << "├── class_keyword_loc: #{inspector.location(class_keyword_loc)}\n"
      inspector << "├── operator_loc: #{inspector.location(operator_loc)}\n"
      inspector << "├── expression:\n"
      inspector << inspector.child_node(expression, "│   ")
      if (body = self.body).nil?
        inspector << "├── body: ∅\n"
      else
        inspector << "├── body:\n"
        inspector << body.inspect(inspector.child_inspector("│   ")).delete_prefix(inspector.prefix)
      end
      inspector << "└── end_keyword_loc: #{inspector.location(end_keyword_loc)}\n"
      inspector.to_str
    end

operator() click to toggle source

def operator: () -> `String`

    # File lib/prism/node.rb, line 15362
    def operator
      operator_loc.slice
    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 15403
    def type
      :singleton_class_node
    end