Class: RuboCop::AST::Node

Inherits:
Parser::AST::Node
  • Object
show all
Extended by:
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
ARITHMETIC_OPERATORS = 
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].freeze
IMMUTABLE_LITERALS = 
(LITERALS - MUTABLE_LITERALS).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

Instance Method Summary collapse

Methods included from NodePattern::Macros

def_node_matcher, def_node_search, node_search, node_search_all, node_search_body, node_search_first

Methods included from Sexp

#s

Constructor Details

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

Returns a new instance of Node.

See Also:



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# File 'lib/rubocop/ast/node.rb', line 51

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

#ancestors ⇒ Array<Node>

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



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# File 'lib/rubocop/ast/node.rb', line 144

def ancestors
  each_ancestor.to_a
end

#argument? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 455

def argument?
  parent && parent.send_type?
end

#arithmetic_operation? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 347

def arithmetic_operation?
  ARITHMETIC_OPERATORS.include?(method_name)
end

#asgn_method_call? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 342

def asgn_method_call?
  !COMPARISON_OPERATORS.include?(method_name) &&
    method_name.to_s.end_with?('='.freeze)
end

#basic_literal? ⇒ Boolean 



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

def basic_literal?
  BASIC_LITERALS.include?(type)
end

#binary_operation? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 442

def binary_operation?
  return false unless loc.respond_to?(:selector) && loc.selector
  Cop::Util.operator?(method_name) &&
    source_range.begin_pos != loc.selector.begin_pos
end

#chained? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 448

def chained?
  return false unless argument?

  receiver, _method_name, *_args = *parent
  equal?(receiver)
end

#child_nodes ⇒ Array<Node>

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



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# File 'lib/rubocop/ast/node.rb', line 184

def child_nodes
  each_child_node.to_a
end

#complete! ⇒ Object 



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# File 'lib/rubocop/ast/node.rb', line 85

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

#complete? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 90

def complete?
  @mutable_attributes.frozen?
end

#const_name ⇒ Object 



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# File 'lib/rubocop/ast/node.rb', line 276

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_module ⇒ Object 



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# File 'lib/rubocop/ast/node.rb', line 294

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

#defined_module_name ⇒ Object 



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# File 'lib/rubocop/ast/node.rb', line 299

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

#descendants ⇒ Array<Node>

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



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# File 'lib/rubocop/ast/node.rb', line 218

def descendants
  each_descendant.to_a
end

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

    Yield all nodes.

  • #each_ancestor(type) ⇒ self, Enumerator

    Yield only nodes matching the type.

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

    Yield only nodes matching any of the types.

  • #each_ancestor(types) ⇒ self, Enumerator

    Yield only nodes matching any of types in the array.

Yield Parameters:

  • node (Node) —

    each ancestor node



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# File 'lib/rubocop/ast/node.rb', line 132

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

  visit_ancestors(types, &block)

  self
end

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

    Yield all nodes.

  • #each_child_node(type) ⇒ self, Enumerator

    Yield only nodes matching the type.

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

    Yield only nodes matching any of the types.

  • #each_child_node(types) ⇒ self, Enumerator

    Yield only nodes matching any of types in the array.

Yield Parameters:

  • node (Node) —

    each child node



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

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

    Yield all nodes.

  • #each_descendant(type) ⇒ self, Enumerator

    Yield only nodes matching the type.

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

    Yield only nodes matching any of the types.

  • #each_descendant(types) ⇒ self, Enumerator

    Yield only nodes matching any of types in the array.

Yield Parameters:

  • node (Node) —

    each descendant node



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# File 'lib/rubocop/ast/node.rb', line 206

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

  visit_descendants(types, &block)

  self
end

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

    Yield all nodes.

  • #each_node(type) ⇒ self, Enumerator

    Yield only nodes matching the type.

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

    Yield only nodes matching any of the types.

  • #each_node(types) ⇒ self, Enumerator

    Yield only nodes matching any of types in the array.

Yield Parameters:

  • node (Node) —

    each node



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# File 'lib/rubocop/ast/node.rb', line 244

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? ⇒ Boolean 



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

def empty?
  length.zero?
end

#falsey_literal? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 373

def falsey_literal?
  FALSEY_LITERALS.include?(type)
end

#immutable_literal? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 381

def immutable_literal?
  IMMUTABLE_LITERALS.include?(type)
end

#keyword? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 411

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

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

#keyword_bang? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 431

def keyword_bang?
  _receiver, method_name, *args = *self
  args.empty? && method_name == :! && loc.selector.is?('!'.freeze)
end

#keyword_not? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 426

def keyword_not?
  _receiver, method_name, *args = *self
  args.empty? && method_name == :! && loc.selector.is?('not'.freeze)
end

#length ⇒ Object 



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# File 'lib/rubocop/ast/node.rb', line 338

def length
  source_range ? source_range.size : 0
end

#line_count ⇒ Object 



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# File 'lib/rubocop/ast/node.rb', line 325

def line_count
  return 0 unless source_range
  source_range.last_line - source_range.first_line + 1
end

#literal? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 361

def literal?
  LITERALS.include?(type)
end

#multiline? ⇒ Boolean

Predicates



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# File 'lib/rubocop/ast/node.rb', line 317

def multiline?
  line_count > 1
end

#mutable_literal? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 377

def mutable_literal?
  MUTABLE_LITERALS.include?(type)
end

#nonempty_line_count ⇒ Object 



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# File 'lib/rubocop/ast/node.rb', line 330

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

#numeric_type? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 459

def numeric_type?
  int_type? || float_type?
end

#operator_keyword? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 422

def operator_keyword?
  OPERATOR_KEYWORDS.include?(type)
end

#parent ⇒ Node?

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



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# File 'lib/rubocop/ast/node.rb', line 77

def parent
  @mutable_attributes[:parent]
end

#parent_module_name ⇒ Object

Searching the AST



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# File 'lib/rubocop/ast/node.rb', line 305

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

#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?



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

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

#receiver ⇒ Object

Destructuring



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# File 'lib/rubocop/ast/node.rb', line 264

def_node_matcher :receiver, "  {(send $_ ...) (block (send $_ ...) ...)}\n"

#reference? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 407

def reference?
  REFERENCES.include?(type)
end

#sibling_index ⇒ Integer

Returns the index of the receiver node in its siblings. (Sibling index uses zero based numbering.)



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# File 'lib/rubocop/ast/node.rb', line 110

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

#single_line? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 321

def single_line?
  line_count == 1
end

#source ⇒ Object 



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# File 'lib/rubocop/ast/node.rb', line 254

def source
  loc.expression.source
end

#source_range ⇒ Object 



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# File 'lib/rubocop/ast/node.rb', line 258

def source_range
  loc.expression
end

#special_keyword? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 418

def special_keyword?
  SPECIAL_KEYWORDS.include?(source)
end

#truthy_literal? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 369

def truthy_literal?
  TRUTHY_LITERALS.include?(type)
end

#unary_operation? ⇒ Boolean 



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# File 'lib/rubocop/ast/node.rb', line 436

def unary_operation?
  return false unless loc.respond_to?(:selector) && loc.selector
  Cop::Util.operator?(loc.selector.source.to_sym) &&
    source_range.begin_pos == loc.selector.begin_pos
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 101

def updated(type = nil, children = nil, properties = {})
  properties[:location] ||= @location
  self.class.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, Metrics/CyclomaticComplexity



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# File 'lib/rubocop/ast/node.rb', line 494

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 



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# File 'lib/rubocop/ast/node.rb', line 403

def variable?
  VARIABLES.include?(type)
end