[YAML] load with location info

load_with_location_info.rb

require 'yaml'

src = <<~YAML
name: taro
age: 4
YAML

class Psych::Nodes::Node
  def mapping_key?
    @mapping_key
  end

  attr_writer :mapping_key
end

class MyTreeBuilder < Psych::TreeBuilder
  def scalar(value, anchor, tag, plain, quoted, style)
    node = super
    if @last.mapping? && @last.children.size.odd?
      node.mapping_key = true
    end
    node
  end
end

class MyToRubyVisitor < Psych::Visitors::ToRuby
  def register(node, object)
    if node.scalar? && !node.mapping_key?
      object = [object, [node.start_line, node.start_column]]
    end
    super(node, object)
  end
end

parser = Psych::Parser.new
handler = MyTreeBuilder.new
parser.handler = handler

parser.parse(src)
result = parser.handler.root.children[0]

visitor = MyToRubyVisitor.create
object = visitor.accept(result)

p object # => {"name"=>["taro", [0, 6]], "age"=>[4, [1, 5]]}