如何将字符串转换为哈希

Question

This is my string

"{web:{url:http://www.example.com,toke:somevalue},username:person}"

I want to convert it into a hash, like this:

```

{
  'web' =>  {
     'url'  => "http://www.example.com",
     'token' => 'somevalue'
   },
   'username' =>  "person"
}

```

Answer 1

You'll have to write a custom parser. It's almost json, but since the values aren't quoted, it won't parse with a JSON parser, so unless you can get quoted values, you'll have to parse it by hand.

Handling colons, commas, and curly brackets in values is going to be a challenge.

Answer 2

Simple parser, tested only on a few examples.

Usage:

parse_string("{web:{url:http://www.example.com,toke:somevalue},username:person}")
=> {"web"=>{"url"=>"http://www.example.com", "toke"=>"somevalue"}, "username"=>"person"} 

Parser code:

class ParserIterator
  attr_accessor :i, :string
  def initialize string,i=0
    @i=i
    @string=string
  end

  def read_until(*sym)
    res=''
    until sym.include?(s=self.curr)
      throw 'syntax error' if s.nil?
      res+=self.next
    end
    res
  end

  def next
    self.i+=1
    self.string[self.i-1]
  end

  def get_next
    self.string[self.i+1]
  end

  def curr
    self.string[self.i]
  end

  def check(*sym)
    throw 'syntax error' until sym.include?(self.next)
  end

  def check_curr(*sym)
    throw 'syntax error' until sym.include?(self.curr)
  end
end

def parse_string(str)
  parse_hash(ParserIterator.new(str))
end


def parse_hash(it)
  it.check('{')
  res={}
  until it.curr=='}'
    it.next if it.curr==','
    k,v=parse_pair(it)
    res[k]=v
  end
  it.check('}')
  res
end

def parse_pair(it)
   key=it.read_until(':')
   it.check(':')
   value=(it.curr=='{' ? parse_hash(it) : it.read_until(',','}'))
   return key,value   
end

Answer 3

I would recommend using ActiveSupport::JSON.decode assuming you have the gem available or are willing to include it in your gem list.

One gotcha is to have string of json. so if you have hash, you can call #to_json to get json string. for example this works:

str = '{"web":{"url":"http://www.example.com","toke":"somevalue"},"username":"person"}'
ActiveSupport::JSON.decode(str)