Hacklog: Blogamundo — poking holes in the language barrier since approximately 1 month from now

I wrote a new Ruby JSON serializer using Jamis Buck’s Ruby Tokenizer. It’s an order of magnitude safer than my previous attempt. I still use inspect() to create a string representation of the object, but now I’m using the tokenizer to safely replace => by : (properly ignoring => inside strings, that is) instead of that heinous regular expression.

require 'rubygems'
require_gem 'syntax'
	
class RubyJSONSerializer
	
    @@tokenizer = Syntax.load \"ruby\"
	
    def ruby_to_json(obj)
        res = \"\"
        symbol = false
        @@tokenizer.tokenize(obj.inspect) do |token|
            if token.group == :punct
                if symbol
                    res += token.gsub(/>/, '')
                    symbol = false
                else
                    res += token.gsub(/=>/, ': ')
                end
            elsif token.group == :symbol
                res += \"\\"#{token.match(/:(.+)=/)[1]}\\": \"
                symbol = true
            else
                res += token
            end
        end
        res
    end
	
end
	
s = RubyJSONSerializer.new
o = {\"foo\"=>\"foo => bar\", :bar=>\"bar => foo\", \"meh\"=>[1,2,3], :n=>123}
puts s.ruby_to_json(o)

Let me know if you spot anything wrong. Update: since a couple friends asked me about this, I thought I’d clarify it here: I’m using Ruby’s built-in YAML parser (syck, I believe, which is also available for Python) to parse JSON. It’s been flawless so far.

Update 2: I should also point out that this only works for primitive datatypes. If you have an object whose to_s method is not JSON-enabled, beware that the serializer will silently produce invalid JSON. To avoid this, make sure you’re creating a Ruby object from scratch:

# good
obj = ruby_to_json({\"foo\"=>MyActiveRecordInstance.foo, \"bar\"=>MyActiveRecordInstance.bar})
# bad
obj = ruby_to_json(MyActiveRecordInstance)