Query Syntax Parser

parser.rb

require 'pry'

class MagicBullshit
  def self.inherited(subclass)
    subclass.prepare
  end

  def self.prepare
    @words = {}
  end

  def self.parse(s)
    raw = s.scan(/([+-])?(?:(\S+)\:\s?)?(?:(?:"(.+?)")|(\S+))/).map do |m|
      Hash[[:plusminus, :prefix, :phrase, :word].zip(m).select(&:all?)]
    end

    self.new(raw)
  end

  def self.magic_word(word, type)
    @words[word] = type
  end

  def self.magic_words
    @words
  end

  def initialize(raw)
    @raw = raw
    decorate_magic_words
  end

  def decorate_magic_words
    @baked = @raw.map do |r|
      b = r.dup

      if type = self.class.magic_words[r[:prefix]]
        if type == :string
          b[:magic] = b[:word] || b[:phrase]
        elsif type == :date
          matches = b[:word].match(/^(<=|<|>|>=)?(.+)$/)
          b[:magic] = {}
          b[:magic][:sign] = matches[1] if matches[1]
          b[:magic][:date] = Date.parse(matches[2])
        end
      else
        b[:word] || b[:phrase]
      end

      b
    end
  end
end

class MyBullshit < MagicBullshit
  magic_word 'language', :string
end

class MyOtherBullshit < MagicBullshit
  magic_word 'created', :date
end

puts MyBullshit.parse('language:c# created:<2011-01-01 state:open').inspect
puts MyOtherBullshit.parse('language:c# created:<2011-01-01 state:open').inspect