Class: RuboCop::Node

Inherits:
Parser::AST::Node
  • Object
show all
Includes:
Sexp
Defined in:
lib/rubocop/ast_node.rb,
lib/rubocop/ast_node/builder.rb,
lib/rubocop/ast_node/traversal.rb

Overview

‘RuboCop::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?)

Defined Under Namespace

Modules: Traversal Classes: Builder

Constant Summary collapse

COMPARISON_OPERATORS = 
[:!, :==, :===, :!=, :<=, :>=, :>, :<, :<=>].freeze
TRUTHY_LITERALS = 
[:str, :dstr, :xstr, :int, :float, :sym, :dsym, :array,
:hash, :regexp, :true, :irange, :erange, :complex,
:rational, :regopt].freeze
FALSEY_LITERALS = 
[:false, :nil].freeze
LITERALS = 
(TRUTHY_LITERALS + FALSEY_LITERALS).freeze
COMPOSITE_LITERALS = 
[:dstr, :xstr, :dsym, :array, :hash, :irange,
:erange, :regexp].freeze
BASIC_LITERALS = 
(LITERALS - COMPOSITE_LITERALS).freeze
MUTABLE_LITERALS = 
[:str, :dstr, :xstr, :array, :hash].freeze
IMMUTABLE_LITERALS = 
(LITERALS - MUTABLE_LITERALS).freeze
VARIABLES = 
[:ivar, :gvar, :cvar, :lvar].freeze
REFERENCES = 
[:nth_ref, :back_ref].freeze
KEYWORDS = 
[: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 = 
[:and, :or].freeze
SPECIAL_KEYWORDS = 
%w(__FILE__ __LINE__ __ENCODING__).freeze

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Sexp

#s

Constructor Details

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

Returns a new instance of Node.

See Also:



59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
 
# File 'lib/rubocop/ast_node.rb', line 59

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

Class Method Details

.def_matcher(method_name, pattern_str) ⇒ Object 



47
48
49
50
51
52
53
54
55
 
# File 'lib/rubocop/ast_node.rb', line 47

def def_matcher(method_name, pattern_str)
  compiler = RuboCop::NodePattern::Compiler.new(pattern_str, 'self')
  src = "def #{method_name}(" \
        "#{compiler.emit_param_list});" \
        "#{compiler.emit_method_code};end"

  file, lineno = *caller.first.split(':')
  class_eval(src, file, lineno.to_i)
end

Instance Method Details

#ancestors ⇒ Array<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



157
158
159
 
# File 'lib/rubocop/ast_node.rb', line 157

def ancestors
  each_ancestor.to_a
end

#asgn_method_call? ⇒ Boolean

Returns:

  • (Boolean) 


346
347
348
349
 
# File 'lib/rubocop/ast_node.rb', line 346

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

#basic_literal? ⇒ Boolean

Returns:

  • (Boolean) 


359
360
361
 
# File 'lib/rubocop/ast_node.rb', line 359

def basic_literal?
  BASIC_LITERALS.include?(type)
end

#binary_operation? ⇒ Boolean

Returns:

  • (Boolean) 


432
433
434
435
436
 
# File 'lib/rubocop/ast_node.rb', line 432

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

Returns:

  • (Boolean) 


438
439
440
441
442
 
# File 'lib/rubocop/ast_node.rb', line 438

def chained?
  return false if parent.nil? || !parent.send_type?
  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`.

Returns:

  • (Array<Node>) —

    an array of child nodes



197
198
199
 
# File 'lib/rubocop/ast_node.rb', line 197

def child_nodes
  each_child_node.to_a
end

#complete! ⇒ Object 



93
94
95
96
 
# File 'lib/rubocop/ast_node.rb', line 93

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

#complete? ⇒ Boolean

Returns:

  • (Boolean) 


98
99
100
 
# File 'lib/rubocop/ast_node.rb', line 98

def complete?
  @mutable_attributes.frozen?
end

#const_name ⇒ Object 



292
293
294
295
296
297
298
299
300
 
# File 'lib/rubocop/ast_node.rb', line 292

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 



310
311
312
313
 
# File 'lib/rubocop/ast_node.rb', line 310

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

#defined_module_name ⇒ Object 



315
316
317
 
# File 'lib/rubocop/ast_node.rb', line 315

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`.

Returns:

  • (Array<Node>) —

    an array of descendant nodes



235
236
237
 
# File 'lib/rubocop/ast_node.rb', line 235

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.

    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

  • #each_ancestor(types) ⇒ self, Enumerator

    Yield only nodes matching any of types in the array.

    Parameters:

    • types (Array<Symbol>) —

      an array containing node types

Yield Parameters:

  • node (Node) —

    each ancestor node

Returns:

  • (self) —

    if a block is given

  • (Enumerator) —

    if no block is given



141
142
143
144
145
146
147
148
149
150
151
 
# File 'lib/rubocop/ast_node.rb', line 141

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

  if types.empty?
    visit_ancestors(&block)
  else
    visit_ancestors_with_types(types, &block)
  end

  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.

    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

  • #each_child_node(types) ⇒ self, Enumerator

    Yield only nodes matching any of types in the array.

    Parameters:

    • types (Array<Symbol>) —

      an array containing node types

Yield Parameters:

  • node (Node) —

    each child node

Returns:

  • (self) —

    if a block is given

  • (Enumerator) —

    if no block is given



182
183
184
185
186
187
188
189
190
191
 
# File 'lib/rubocop/ast_node.rb', line 182

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.

    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

  • #each_descendant(types) ⇒ self, Enumerator

    Yield only nodes matching any of types in the array.

    Parameters:

    • types (Array<Symbol>) —

      an array containing node types

Yield Parameters:

  • node (Node) —

    each descendant node

Returns:

  • (self) —

    if a block is given

  • (Enumerator) —

    if no block is given



219
220
221
222
223
224
225
226
227
228
229
 
# File 'lib/rubocop/ast_node.rb', line 219

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

  if types.empty?
    visit_descendants(&block)
  else
    visit_descendants_with_types(types, &block)
  end

  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.

    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

  • #each_node(types) ⇒ self, Enumerator

    Yield only nodes matching any of types in the array.

    Parameters:

    • types (Array<Symbol>) —

      an array containing node types

Yield Parameters:

  • node (Node) —

    each node

Returns:

  • (self) —

    if a block is given

  • (Enumerator) —

    if no block is given



261
262
263
264
265
266
267
268
269
270
271
272
273
 
# File 'lib/rubocop/ast_node.rb', line 261

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

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

  if types.empty?
    visit_descendants(&block)
  else
    visit_descendants_with_types(types, &block)
  end

  self
end

#falsey_literal? ⇒ Boolean

Returns:

  • (Boolean) 


367
368
369
 
# File 'lib/rubocop/ast_node.rb', line 367

def falsey_literal?
  FALSEY_LITERALS.include?(type)
end

#immutable_literal? ⇒ Boolean

Returns:

  • (Boolean) 


375
376
377
 
# File 'lib/rubocop/ast_node.rb', line 375

def immutable_literal?
  IMMUTABLE_LITERALS.include?(type)
end

#keyword? ⇒ Boolean

Returns:

  • (Boolean) 


405
406
407
408
409
410
 
# File 'lib/rubocop/ast_node.rb', line 405

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

Returns:

  • (Boolean) 


421
422
423
424
 
# File 'lib/rubocop/ast_node.rb', line 421

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

#keyword_not? ⇒ Boolean

Returns:

  • (Boolean) 


416
417
418
419
 
# File 'lib/rubocop/ast_node.rb', line 416

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

#literal? ⇒ Boolean

Returns:

  • (Boolean) 


355
356
357
 
# File 'lib/rubocop/ast_node.rb', line 355

def literal?
  LITERALS.include?(type)
end

#modifier_form? ⇒ Boolean

Predicates

Returns:

  • (Boolean) 


333
334
335
 
# File 'lib/rubocop/ast_node.rb', line 333

def modifier_form?
  loc.respond_to?(:end) && loc.end.nil?
end

#multiline? ⇒ Boolean

Returns:

  • (Boolean) 


337
338
339
340
 
# File 'lib/rubocop/ast_node.rb', line 337

def multiline?
  expr = loc.expression
  expr && (expr.first_line != expr.last_line)
end

#mutable_literal? ⇒ Boolean

Returns:

  • (Boolean) 


371
372
373
 
# File 'lib/rubocop/ast_node.rb', line 371

def mutable_literal?
  MUTABLE_LITERALS.include?(type)
end

#parent ⇒ Node?

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

Returns:

  • (Node, nil) —

    the parent node or ‘nil`



85
86
87
 
# File 'lib/rubocop/ast_node.rb', line 85

def parent
  @mutable_attributes[:parent]
end

#parent_module_name ⇒ Object

Searching the AST



321
322
323
324
325
326
327
328
329
 
# File 'lib/rubocop/ast_node.rb', line 321

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?

Returns:

  • (Boolean) 


502
503
504
505
506
507
508
509
510
511
512
513
514
515
 
# File 'lib/rubocop/ast_node.rb', line 502

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



285
 
# File 'lib/rubocop/ast_node.rb', line 285

def_matcher :receiver,    '{(send $_ ...) (block (send $_ ...) ...)}'

#reference? ⇒ Boolean

Returns:

  • (Boolean) 


401
402
403
 
# File 'lib/rubocop/ast_node.rb', line 401

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.)

Returns:

  • (Integer) —

    the index of the receiver node in its siblings



119
120
121
 
# File 'lib/rubocop/ast_node.rb', line 119

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

#single_line? ⇒ Boolean

Returns:

  • (Boolean) 


342
343
344
 
# File 'lib/rubocop/ast_node.rb', line 342

def single_line?
  !multiline?
end

#source ⇒ Object 



275
276
277
 
# File 'lib/rubocop/ast_node.rb', line 275

def source
  loc.expression.source
end

#source_range ⇒ Object 



279
280
281
 
# File 'lib/rubocop/ast_node.rb', line 279

def source_range
  loc.expression
end

#special_keyword? ⇒ Boolean

Returns:

  • (Boolean) 


412
413
414
 
# File 'lib/rubocop/ast_node.rb', line 412

def special_keyword?
  SPECIAL_KEYWORDS.include?(source)
end

#truthy_literal? ⇒ Boolean

Returns:

  • (Boolean) 


363
364
365
 
# File 'lib/rubocop/ast_node.rb', line 363

def truthy_literal?
  TRUTHY_LITERALS.include?(type)
end

#unary_operation? ⇒ Boolean

Returns:

  • (Boolean) 


426
427
428
429
430
 
# File 'lib/rubocop/ast_node.rb', line 426

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.



110
111
112
113
 
# File 'lib/rubocop/ast_node.rb', line 110

def updated(type = nil, children = nil, properties = {})
  properties[:location] ||= @location
  Node.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) 


471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
 
# File 'lib/rubocop/ast_node.rb', line 471

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) 


397
398
399
 
# File 'lib/rubocop/ast_node.rb', line 397

def variable?
  VARIABLES.include?(type)
end