以下几乎可以工作,主要问题是多行字符串,其中给出的行号是Yaml中下一个事物的开始.问题是,当调用处理程序标量方法时,解析器已经超出了感兴趣的标量,因此当标识知道标量已经结束时,标记给出位置的行.在大多数情况下,在您的示例中,这无关紧要,但在多行情况下,它会给出错误的值.在没有进入Psych C代码的情况下,我无法看到任何方式从标记开始获取标量信息.

require 'psych'

# Psych's first step is to parse the Yaml into an AST of Node objects
# so we open the Node class and add a way to track the line.
class Psych::Nodes::Node
  attr_accessor :line
end

# We need to provide a handler that will add the line to the node
# as it is parsed. TreeBuilder is the "usual" handler,that
# creates the AST.
class LineNumberHandler < Psych::TreeBuilder

  # The handler needs access to the parser in order to call mark
  attr_accessor :parser

  # We are only interested in scalars,so here we override 
  # the method so that it calls mark and adds the line info
  # to the node.
  def scalar value,anchor,tag,plain,quoted,style
    mark = parser.mark
    s = super
    s.line = mark.line
    s
  end
end

# The next step is to convert the AST to a Ruby object.
# Psych does this using the visitor pattern with the ToRuby
# visitor. Here we patch ToRuby rather than inherit from it
# as it makes the last step a little easier.
class Psych::Visitors::ToRuby

  # This is the method for creating hashes. There may be problems
  # with Yaml mappings that have tags.
  def revive_hash hash,o
    o.children.each_slice(2) { |k,v|
      key = accept(k)
      val = accept(v)

      # This is the important bit. If the value is a scalar,# we replace it with the desired hash.
      if v.is_a? ::Psych::Nodes::Scalar
        val = { "value" => val,"line" => v.line + 1} # line is 0 based,so + 1
      end

      # Code dealing with << (for merging hashes) omitted.
      # If you need this you will probably need to copy it
      # in here. See the method:
      # https://github.com/tenderlove/psych/blob/v2.0.13/lib/psych/visitors/to_ruby.rb#L333-L365

      hash[key] = val
    }
    hash
  end
end

yaml = get_yaml_from_wherever

# Put it all together    
handler = LineNumberHandler.new
parser =  Psych::Parser.new(handler)
# Provide the handler with a reference to the parser
handler.parser = parser

# The actual parsing
parser.parse yaml
# We patched ToRuby rather than inherit so we can use to_ruby here
puts handler.root.to_ruby