Class: RuboCop::AST::Node

Inherits:
Parser::AST::Node
  • Object
show all
Extended by:
RuboCop::AST::NodePattern::Macros
Includes:
Sexp
Defined in:
lib/rubocop/ast/node.rb

Overview

`RuboCop::AST::Node` is a subclass of `Parser::AST::Node`. It provides access to parent nodes and an object-oriented way to traverse an AST with the power of `Enumerable`.

It has predicate methods for every node type, like this:

Examples:

node.send_type?    # Equivalent to: `node.type == :send`
node.op_asgn_type? # Equivalent to: `node.type == :op_asgn`

# Non-word characters (other than a-zA-Z0-9_) in type names are omitted.
node.defined_type? # Equivalent to: `node.type == :defined?`

# Find the first lvar node under the receiver node.
lvar_node = node.each_descendant.find(&:lvar_type?)

Constant Summary collapse

COMPARISON_OPERATORS =

<=> isn't included here, because it doesn't return a boolean.

%i[== === != <= >= > <].freeze
TRUTHY_LITERALS =
%i[str dstr xstr int float sym dsym array
hash regexp true irange erange complex
rational regopt].freeze
FALSEY_LITERALS =
%i[false nil].freeze
LITERALS =
(TRUTHY_LITERALS + FALSEY_LITERALS).freeze
COMPOSITE_LITERALS =
%i[dstr xstr dsym array hash irange
erange regexp].freeze
BASIC_LITERALS =
(LITERALS - COMPOSITE_LITERALS).freeze
MUTABLE_LITERALS =
%i[str dstr xstr array hash
regexp irange erange].freeze
IMMUTABLE_LITERALS =
(LITERALS - MUTABLE_LITERALS).freeze
EQUALS_ASSIGNMENTS =
%i[lvasgn ivasgn cvasgn gvasgn
casgn masgn rasgn mrasgn].freeze
SHORTHAND_ASSIGNMENTS =
%i[op_asgn or_asgn and_asgn].freeze
ASSIGNMENTS =
(EQUALS_ASSIGNMENTS + SHORTHAND_ASSIGNMENTS).freeze
BASIC_CONDITIONALS =
%i[if while until].freeze
CONDITIONALS =
[*BASIC_CONDITIONALS, :case].freeze
POST_CONDITION_LOOP_TYPES =
%i[while_post until_post].freeze
LOOP_TYPES =
(POST_CONDITION_LOOP_TYPES + %i[while until for]).freeze
VARIABLES =
%i[ivar gvar cvar lvar].freeze
REFERENCES =
%i[nth_ref back_ref].freeze
KEYWORDS =
%i[alias and break case class def defs defined?
kwbegin do else ensure for if module next
not or postexe redo rescue retry return self
super zsuper then undef until when while
yield].freeze
OPERATOR_KEYWORDS =
%i[and or].freeze
SPECIAL_KEYWORDS =
%w[__FILE__ __LINE__ __ENCODING__].freeze
ARGUMENT_TYPES =
%i[arg optarg restarg kwarg kwoptarg kwrestarg blockarg].freeze

Instance Method Summary collapse

Methods included from RuboCop::AST::NodePattern::Macros

def_node_matcher, def_node_search

Methods included from Sexp

#s

Constructor Details

#initialize(type, children = [], properties = {}) ⇒ Node

Returns a new instance of Node.


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# File 'lib/rubocop/ast/node.rb', line 61

def initialize(type, children = [], properties = {})
  @mutable_attributes = {}

  # ::AST::Node#initialize freezes itself.
  super

  # #parent= may be invoked multiple times for a node because there are
  # pending nodes while constructing AST and they are replaced later.
  # For example, `lvar` and `send` type nodes are initially created as an
  # `ident` type node and fixed to the appropriate type later.
  # So, the #parent attribute needs to be mutable.
  each_child_node do |child_node|
    child_node.parent = self unless child_node.complete?
  end
end

Instance Method Details

#ancestorsArray<Node>

Returns an array of ancestor nodes. This is a shorthand for `node.each_ancestor.to_a`.

Returns:

  • (Array<Node>)

    an array of ancestor nodes


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# File 'lib/rubocop/ast/node.rb', line 200

def ancestors
  each_ancestor.to_a
end

#argument?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 505

def argument?
  parent&.send_type? && parent.arguments.include?(self)
end

#argument_type?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 509

def argument_type?
  ARGUMENT_TYPES.include?(type)
end

#assignment?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 457

def assignment?
  ASSIGNMENTS.include?(type)
end

#basic_conditional?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 461

def basic_conditional?
  BASIC_CONDITIONALS.include?(type)
end

#basic_literal?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 404

def basic_literal?
  BASIC_LITERALS.include?(type)
end

#boolean_type?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 513

def boolean_type?
  true_type? || false_type?
end

#call_type?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 497

def call_type?
  send_type? || csend_type?
end

#chained?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 501

def chained?
  parent&.call_type? && eql?(parent.receiver)
end

#child_nodesArray<Node>

Returns an array of child nodes. This is a shorthand for `node.each_child_node.to_a`.

Returns:

  • (Array<Node>)

    an array of child nodes


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# File 'lib/rubocop/ast/node.rb', line 238

def child_nodes
  each_child_node.to_a
end

#complete!Object


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# File 'lib/rubocop/ast/node.rb', line 95

def complete!
  @mutable_attributes.freeze
  each_child_node(&:complete!)
end

#complete?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 100

def complete?
  @mutable_attributes.frozen?
end

#conditional?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 465

def conditional?
  CONDITIONALS.include?(type)
end

#const_nameObject


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# File 'lib/rubocop/ast/node.rb', line 340

def const_name
  return unless const_type?

  namespace, name = *self
  if namespace && !namespace.cbase_type?
    "#{namespace.const_name}::#{name}"
  else
    name.to_s
  end
end

#defined_moduleObject


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# File 'lib/rubocop/ast/node.rb', line 360

def defined_module
  namespace, name = *defined_module0
  s(:const, namespace, name) if name
end

#defined_module_nameObject


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# File 'lib/rubocop/ast/node.rb', line 365

def defined_module_name
  (const = defined_module) && const.const_name
end

#descendantsArray<Node>

Returns an array of descendant nodes. This is a shorthand for `node.each_descendant.to_a`.

Returns:

  • (Array<Node>)

    an array of descendant nodes


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# File 'lib/rubocop/ast/node.rb', line 269

def descendants
  each_descendant.to_a
end

#each_ancestorself, Enumerator #each_ancestor(type) ⇒ self, Enumerator #each_ancestor(type_a, type_b, ...) ⇒ self, Enumerator

Calls the given block for each ancestor node from parent to root. If no block is given, an `Enumerator` is returned.

Overloads:

  • #each_ancestorself, Enumerator

    Yield all nodes.

  • #each_ancestor(type) ⇒ self, Enumerator

    Yield only nodes matching the type.

    Parameters:

    • type (Symbol)

      a node type

  • #each_ancestor(type_a, type_b, ...) ⇒ self, Enumerator

    Yield only nodes matching any of the types.

    Parameters:

    • type_a (Symbol)

      a node type

    • type_b (Symbol)

      a node type

Yield Parameters:

  • node (Node)

    each ancestor node

Returns:

  • (self)

    if a block is given

  • (Enumerator)

    if no block is given


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# File 'lib/rubocop/ast/node.rb', line 188

def each_ancestor(*types, &block)
  return to_enum(__method__, *types) unless block_given?

  visit_ancestors(types, &block)

  self
end

#each_child_nodeself, Enumerator #each_child_node(type) ⇒ self, Enumerator #each_child_node(type_a, type_b, ...) ⇒ self, Enumerator

Calls the given block for each child node. If no block is given, an `Enumerator` is returned.

Note that this is different from `node.children.each { |child| … }` which yields all children including non-node elements.

Overloads:

  • #each_child_nodeself, Enumerator

    Yield all nodes.

  • #each_child_node(type) ⇒ self, Enumerator

    Yield only nodes matching the type.

    Parameters:

    • type (Symbol)

      a node type

  • #each_child_node(type_a, type_b, ...) ⇒ self, Enumerator

    Yield only nodes matching any of the types.

    Parameters:

    • type_a (Symbol)

      a node type

    • type_b (Symbol)

      a node type

Yield Parameters:

  • node (Node)

    each child node

Returns:

  • (self)

    if a block is given

  • (Enumerator)

    if no block is given


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# File 'lib/rubocop/ast/node.rb', line 222

def each_child_node(*types)
  return to_enum(__method__, *types) unless block_given?

  children.each do |child|
    next unless child.is_a?(Node)

    yield child if types.empty? || types.include?(child.type)
  end

  self
end

#each_descendantself, Enumerator #each_descendant(type) ⇒ self, Enumerator #each_descendant(type_a, type_b, ...) ⇒ self, Enumerator

Calls the given block for each descendant node with depth first order. If no block is given, an `Enumerator` is returned.

Overloads:

  • #each_descendantself, Enumerator

    Yield all nodes.

  • #each_descendant(type) ⇒ self, Enumerator

    Yield only nodes matching the type.

    Parameters:

    • type (Symbol)

      a node type

  • #each_descendant(type_a, type_b, ...) ⇒ self, Enumerator

    Yield only nodes matching any of the types.

    Parameters:

    • type_a (Symbol)

      a node type

    • type_b (Symbol)

      a node type

Yield Parameters:

  • node (Node)

    each descendant node

Returns:

  • (self)

    if a block is given

  • (Enumerator)

    if no block is given


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# File 'lib/rubocop/ast/node.rb', line 257

def each_descendant(*types, &block)
  return to_enum(__method__, *types) unless block_given?

  visit_descendants(types, &block)

  self
end

#each_nodeself, Enumerator #each_node(type) ⇒ self, Enumerator #each_node(type_a, type_b, ...) ⇒ self, Enumerator

Calls the given block for the receiver and each descendant node in depth-first order. If no block is given, an `Enumerator` is returned.

This method would be useful when you treat the receiver node as the root of a tree and want to iterate over all nodes in the tree.

Overloads:

  • #each_nodeself, Enumerator

    Yield all nodes.

  • #each_node(type) ⇒ self, Enumerator

    Yield only nodes matching the type.

    Parameters:

    • type (Symbol)

      a node type

  • #each_node(type_a, type_b, ...) ⇒ self, Enumerator

    Yield only nodes matching any of the types.

    Parameters:

    • type_a (Symbol)

      a node type

    • type_b (Symbol)

      a node type

Yield Parameters:

  • node (Node)

    each node

Returns:

  • (self)

    if a block is given

  • (Enumerator)

    if no block is given


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# File 'lib/rubocop/ast/node.rb', line 292

def each_node(*types, &block)
  return to_enum(__method__, *types) unless block_given?

  yield self if types.empty? || types.include?(type)

  visit_descendants(types, &block)

  self
end

#empty_source?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 391

def empty_source?
  source_length.zero?
end

#equals_asgn?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 449

def equals_asgn?
  EQUALS_ASSIGNMENTS.include?(type)
end

#falsey_literal?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 412

def falsey_literal?
  FALSEY_LITERALS.include?(type)
end

#first_lineObject


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# File 'lib/rubocop/ast/node.rb', line 310

def first_line
  loc.line
end

#guard_clause?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 525

def guard_clause?
  node = and_type? || or_type? ? rhs : self

  node.match_guard_clause?
end

#immutable_literal?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 420

def immutable_literal?
  IMMUTABLE_LITERALS.include?(type)
end

#keyword?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 478

def keyword?
  return true if special_keyword? || send_type? && prefix_not?
  return false unless KEYWORDS.include?(type)

  !OPERATOR_KEYWORDS.include?(type) || loc.operator.is?(type.to_s)
end

#last_lineObject


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# File 'lib/rubocop/ast/node.rb', line 314

def last_line
  loc.last_line
end

#left_siblingNode?

Use is discouraged, this is a potentially slow method and can lead to even slower algorithms

Returns:

  • (Node, nil)

    the left (aka previous) sibling


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# File 'lib/rubocop/ast/node.rb', line 138

def left_sibling
  i = sibling_index
  return if i.nil? || i.zero?

  parent.children[i - 1].freeze
end

#left_siblingsArray<Node>

Use is discouraged, this is a potentially slow method and can lead to even slower algorithms

Returns:

  • (Array<Node>)

    the left (aka previous) siblings


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# File 'lib/rubocop/ast/node.rb', line 148

def left_siblings
  return [].freeze unless parent

  parent.children[0...sibling_index].freeze
end

#line_countObject


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# File 'lib/rubocop/ast/node.rb', line 318

def line_count
  return 0 unless source_range

  source_range.last_line - source_range.first_line + 1
end

#literal?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 400

def literal?
  LITERALS.include?(type)
end

#loop_keyword?Boolean

Note: `loop { }` is a normal method call and thus not a loop keyword.

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 474

def loop_keyword?
  LOOP_TYPES.include?(type)
end

#multiline?Boolean

Predicates

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 383

def multiline?
  line_count > 1
end

#mutable_literal?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 416

def mutable_literal?
  MUTABLE_LITERALS.include?(type)
end

#node_partsArray<Node>

Common destructuring method. This can be used to normalize destructuring for different variations of the node. Some node types override this with their own custom destructuring method.

Returns:

  • (Array<Node>)

    the different parts of the ndde


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# File 'lib/rubocop/ast/node.rb', line 169

def node_parts
  to_a
end

#nonempty_line_countObject


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# File 'lib/rubocop/ast/node.rb', line 324

def nonempty_line_count
  source.lines.grep(/\S/).size
end

#numeric_type?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 517

def numeric_type?
  int_type? || float_type?
end

#operator_keyword?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 489

def operator_keyword?
  OPERATOR_KEYWORDS.include?(type)
end

#parentNode?

Returns the parent node, or `nil` if the receiver is a root node.

Returns:

  • (Node, nil)

    the parent node or `nil`


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# File 'lib/rubocop/ast/node.rb', line 87

def parent
  @mutable_attributes[:parent]
end

#parent_module_nameObject

Searching the AST


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# File 'lib/rubocop/ast/node.rb', line 371

def parent_module_name
  # what class or module is this method/constant/etc definition in?
  # returns nil if answer cannot be determined
  ancestors = each_ancestor(:class, :module, :sclass, :casgn, :block)
  result    = ancestors.map do |ancestor|
    parent_module_name_part(ancestor) { |full_name| return full_name }
  end.compact.reverse.join('::')
  result.empty? ? 'Object' : result
end

#parenthesized_call?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 493

def parenthesized_call?
  loc.respond_to?(:begin) && loc.begin && loc.begin.is?('(')
end

#post_condition_loop?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 469

def post_condition_loop?
  POST_CONDITION_LOOP_TYPES.include?(type)
end

#pure?Boolean

Some expressions are evaluated for their value, some for their side effects, and some for both. If we know that expressions are useful only for their return values, and have no side effects, that means we can reorder them, change the number of times they are evaluated, or replace them with other expressions which are equivalent in value. So, is evaluation of this node free of side effects?

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 606

def pure?
  # Be conservative and return false if we're not sure
  case type
  when :__FILE__, :__LINE__, :const, :cvar, :defined?, :false, :float,
       :gvar, :int, :ivar, :lvar, :nil, :str, :sym, :true, :regopt
    true
  when :and, :array, :begin, :case, :dstr, :dsym, :eflipflop, :ensure,
       :erange, :for, :hash, :if, :iflipflop, :irange, :kwbegin, :not,
       :or, :pair, :regexp, :until, :until_post, :when, :while,
       :while_post
    child_nodes.all?(&:pure?)
  else
    false
  end
end

#range_type?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 521

def range_type?
  irange_type? || erange_type?
end

#receiverObject

Destructuring


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# File 'lib/rubocop/ast/node.rb', line 334

def_node_matcher :receiver, <<~PATTERN
  {(send $_ ...) ({block numblock} (send $_ ...) ...)}
PATTERN

#reference?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 445

def reference?
  REFERENCES.include?(type)
end

#right_siblingNode?

Use is discouraged, this is a potentially slow method and can lead to even slower algorithms

Returns:

  • (Node, nil)

    the right (aka next) sibling


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# File 'lib/rubocop/ast/node.rb', line 129

def right_sibling
  return unless parent

  parent.children[sibling_index + 1].freeze
end

#right_siblingsArray<Node>

Use is discouraged, this is a potentially slow method and can lead to even slower algorithms

Returns:

  • (Array<Node>)

    the right (aka next) siblings


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# File 'lib/rubocop/ast/node.rb', line 157

def right_siblings
  return [].freeze unless parent

  parent.children[sibling_index + 1..-1].freeze
end

#shorthand_asgn?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 453

def shorthand_asgn?
  SHORTHAND_ASSIGNMENTS.include?(type)
end

#sibling_indexInteger?

Returns the index of the receiver node in its siblings. (Sibling index uses zero based numbering.) Use is discouraged, this is a potentially slow method.

Returns:

  • (Integer, nil)

    the index of the receiver node in its siblings


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# File 'lib/rubocop/ast/node.rb', line 122

def sibling_index
  parent&.children&.index { |sibling| sibling.equal?(self) }
end

#single_line?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 387

def single_line?
  line_count == 1
end

#sourceObject


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# File 'lib/rubocop/ast/node.rb', line 302

def source
  loc.expression.source
end

#source_lengthObject


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# File 'lib/rubocop/ast/node.rb', line 328

def source_length
  source_range ? source_range.size : 0
end

#source_rangeObject


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# File 'lib/rubocop/ast/node.rb', line 306

def source_range
  loc.expression
end

#special_keyword?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 485

def special_keyword?
  SPECIAL_KEYWORDS.include?(source)
end

#truthy_literal?Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 408

def truthy_literal?
  TRUTHY_LITERALS.include?(type)
end

#updated(type = nil, children = nil, properties = {}) ⇒ Object

Override `AST::Node#updated` so that `AST::Processor` does not try to mutate our ASTs. Since we keep references from children to parents and not just the other way around, we cannot update an AST and share identical subtrees. Rather, the entire AST must be copied any time any part of it is changed.


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# File 'lib/rubocop/ast/node.rb', line 111

def updated(type = nil, children = nil, properties = {})
  properties[:location] ||= @location
  klass = RuboCop::AST::Builder::NODE_MAP[type || @type] || Node
  klass.new(type || @type, children || @children, properties)
end

#value_used?Boolean

Some expressions are evaluated for their value, some for their side effects, and some for both If we know that an expression is useful only for its side effects, that means we can transform it in ways which preserve the side effects, but change the return value So, does the return value of this node matter? If we changed it to `(…; nil)`, might that affect anything?

rubocop:disable Metrics/MethodLength

Returns:

  • (Boolean)

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# File 'lib/rubocop/ast/node.rb', line 575

def value_used?
  # Be conservative and return true if we're not sure.
  return false if parent.nil?

  case parent.type
  when :array, :defined?, :dstr, :dsym, :eflipflop, :erange, :float,
       :hash, :iflipflop, :irange, :not, :pair, :regexp, :str, :sym,
       :when, :xstr
    parent.value_used?
  when :begin, :kwbegin
    begin_value_used?
  when :for
    for_value_used?
  when :case, :if
    case_if_value_used?
  when :while, :until, :while_post, :until_post
    while_until_value_used?
  else
    true
  end
end

#variable?Boolean

Returns:

  • (Boolean)

441
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443
# File 'lib/rubocop/ast/node.rb', line 441

def variable?
  VARIABLES.include?(type)
end