Class: Rule

Inherits:
Object
  • Object
show all
Defined in:
lib/zombie_killer/rule.rb

Overview

Rewriting rule

Defined Under Namespace

Classes: Placeholder

Constant Summary collapse

Arg = 
Placeholder.new("Arg")
Arg1 = 
Placeholder.new("Arg1")

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(from:, to:) ⇒ Rule

Returns a new instance of Rule.



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# File 'lib/zombie_killer/rule.rb', line 23

def initialize(from:, to:)
  @from = from
  @to = to
end

Instance Attribute Details

#from ⇒ AST::Node (readonly)

Returns:

  • (AST::Node) 


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# File 'lib/zombie_killer/rule.rb', line 19

def from
  @from
end

#to ⇒ Proc (readonly)

Returns:

  • (Proc) 


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# File 'lib/zombie_killer/rule.rb', line 21

def to
  @to
end

Instance Method Details

#match(node) ⇒ Object 



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# File 'lib/zombie_killer/rule.rb', line 28

def match(node)
  captures = match2(from, node)
  return unless captures
  if to.respond_to? :call
    to.call(*captures)
  else
    to
  end
end

#match2(expected, actual) ⇒ Object

Returns an array of captured values or nil.

Returns:

  • an array of captured values or nil



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# File 'lib/zombie_killer/rule.rb', line 39

def match2(expected, actual)
  # puts "M2 #{expected.inspect} #{actual.inspect}"
  # p expected.class
  # p actual.class
  return [] if expected.nil? && actual.nil?
  return nil if expected.nil? || actual.nil?

  # if we're a node
  case expected
  when AST::Node
    return nil if expected.type != actual.type
    return nil if expected.children.size != actual.children.size

    results = expected.children.zip(actual.children).map do |ec, ac|
      match2(ec, ac)
    end
    # puts "#{results.inspect} for #{expected.inspect}"
    results.flatten(1) if results.all?
  when Rule::Arg
    # puts "ARG #{actual.inspect}"
    [actual]
  else
    expected == actual ? [] : nil
  end
end