假设我有一个YAML文件,如下所示：
en:
errors:
# Some comment
format: "%{attribute} %{message}"
# One more comment
messages:
"1": "Message 1"
"2": "Message 2"
long_error_message: |
This is a
multiline message
date:
format: "YYYY-MM-DD"
我怎么能把这个读成像这样的Ruby Hash？
{
'en': {
'errors': {
'format': { value: '%{attribute} %{message}',line: 4 }
'messages': {
'1': { value: 'Message 1',line: 8 },'2': { value: 'Message 2',line: 9 }
}
'long_error_message' : { value: "This is a\nmultiline message",line: 11 }
},'date': {
'format': { value: 'YYYY-MM-DD',line: 16 }
}
}
}
我已经尝试使用YAML: Find line number of key?中提到的提示作为起点并实现了一个Psych :: Handler,但感觉我必须从Psych重写大量代码才能使其工作.
我有什么想法可以解决这个问题？
解决方法
看起来您想要采用任何标量值作为映射值,并将其替换为带有包含原始值的值键的哈希值,以及带有行号的行键.
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