如何在Ruby中遍历YAML树中的所有节点？

Question

我正在加载任意YAML文档,并希望遍历树中的每个节点.我不知道如何预先嵌套树,所以我不能只使用一个简单的每个语句来遍历所有节点.

这是我加载文档的方式:

tree = File.open( "#{RAILS_ROOT}/config/locales/es.yml" ){ |yf| YAML::load (yf)}

Answer 1

def traverse(obj, &blk)
  case obj
  when Hash
    # Forget keys because I don't know what to do with them
    obj.each {|k,v| traverse(v, &blk) }
  when Array
    obj.each {|v| traverse(v, &blk) }
  else
    blk.call(obj)
  end
end

traverse( YAML.load_file(filename) ) do |node|
  puts node
end

编辑:

请注意,这只会产生叶节点.关于什么是完全想要的问题并不是很清楚.

Answer 2

以下是如何解析 YAML 树结构并对每个节点、分支和叶进行操作。它还为您提供所需的每个节点的父节点，例如，从 YAML 文件填充数据库树结构时。这是@sepp2k 优秀答案的一个小补充：

require 'yaml'

def traverse(obj,parent, &blk)
 case obj
 when Hash
   obj.each do |k,v| 
     blk.call(k,parent)
     # Pass hash key as parent
     traverse(v,k, &blk) 
   end
 when Array
   obj.each {|v| traverse(v, parent, &blk) }
 else
   blk.call(obj,parent)
 end
end


# Example, creating a database tree structure, from your YAML file.
# Passing nil to root node(s) as parent

tree_str =<<EOF
  Regions:
    - Asia
    - Europe
    - Americas
  Other:
    - Foo:
      - bar
      - buz
EOF

traverse( YAML.load(tree_str), nil ) do |node,parent|
  puts "Creating node '#{node}' with parent '#{ parent || 'nil' }'"
end