Module: RuboCop::NodePattern::Macros

Overview

Helpers for defining methods based on a pattern string

Instance Method Summary collapse

Instance Method Details

#def_node_matcher(method_name, pattern_str) ⇒ Object

Define a method which applies a pattern to an AST node

The new method will return nil if the node does not match If the node matches, and a block is provided, the new method will yield to the block (passing any captures as block arguments). If the node matches, and no block is provided, the new method will return the captures, or `true` if there were none.


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# File 'lib/rubocop/node_pattern.rb', line 773

def def_node_matcher(method_name, pattern_str)
  compiler = Compiler.new(pattern_str, 'node')
  src = "def #{method_name}(node = self" \
        "#{compiler.emit_trailing_params});" \
        "#{compiler.emit_method_code};end"

  location = caller_locations(1, 1).first
  class_eval(src, location.path, location.lineno)
end

#def_node_search(method_name, pattern_str) ⇒ Object

Define a method which recurses over the descendants of an AST node, checking whether any of them match the provided pattern

If the method name ends with '?', the new method will return `true` as soon as it finds a descendant which matches. Otherwise, it will yield all descendants which match.


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# File 'lib/rubocop/node_pattern.rb', line 789

def def_node_search(method_name, pattern_str)
  compiler = Compiler.new(pattern_str, 'node')
  called_from = caller(1..1).first.split(':')

  if method_name.to_s.end_with?('?')
    node_search_first(method_name, compiler, called_from)
  else
    node_search_all(method_name, compiler, called_from)
  end
end

#node_search(method_name, compiler, on_match, prelude, called_from) ⇒ Object


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# File 'lib/rubocop/node_pattern.rb', line 812

def node_search(method_name, compiler, on_match, prelude, called_from)
  src = node_search_body(method_name, compiler.emit_trailing_params,
                         prelude, compiler.match_code, on_match)
  filename, lineno = *called_from
  class_eval(src, filename, lineno.to_i)
end

#node_search_all(method_name, compiler, called_from) ⇒ Object


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# File 'lib/rubocop/node_pattern.rb', line 804

def node_search_all(method_name, compiler, called_from)
  yield_code = compiler.emit_yield_capture('node')
  prelude = "return enum_for(:#{method_name}, node0" \
            "#{compiler.emit_trailing_params}) unless block_given?"

  node_search(method_name, compiler, yield_code, prelude, called_from)
end

#node_search_body(method_name, trailing_params, prelude, match_code, on_match) ⇒ Object


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# File 'lib/rubocop/node_pattern.rb', line 819

def node_search_body(method_name, trailing_params, prelude, match_code,
                     on_match)
  <<~RUBY
    def #{method_name}(node0#{trailing_params})
      #{prelude}
      node0.each_node do |node|
        if #{match_code}
          #{on_match}
        end
      end
      nil
    end
  RUBY
end

#node_search_first(method_name, compiler, called_from) ⇒ Object


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# File 'lib/rubocop/node_pattern.rb', line 800

def node_search_first(method_name, compiler, called_from)
  node_search(method_name, compiler, 'return true', '', called_from)
end