Simple parser for my.cnf/ini files without needing an external library.

parse_ini.rb

class Config

  # The path to the config file as a String.
  attr_reader :file

  # Attributes used while config is parsed.
  #
  # Example:
  #   [mysqld]     # group
  #   param = val  # param, val
  #
  attr_accessor :group, :param, :value

  def initialize(file)
    @file = file
  end

  def parse
    config = {}

    File.open(file).each_line do |line|
      line.strip!

      # Skip blank lines and lines starting with # and !
      next if invalid_line?(line)

      # Store which group in the config the line belongs to (e.g. [mysqld])
      # Also create the new Hash for this group if it's nil.
      if set_config_group(line)
        config[group] = {} if config[group].nil?
        next
      end

      # Capture the param/value of this line.
      capture_param_and_value(line)

      # In the rare cases where we're not within a group, add it to the
      # root Hash, just to be safe.
      if group.nil?
        config[param] = value
      else
        config[group][param] = value
      end

      # Reset these attributes back to nil so they can be re-matched
      # next iteration.
      @param, @value = nil
    end

    config
  end

  private

  # Capture param/value in line. If line is a param with no value, set the
  # value to true.
  def capture_param_and_value(line)
    if line.match(/^\s*([\w\-]+)\s*[\s+|=]\s*[\"\']?([\w\-\/\.\:]+)[\s\"\']?\s*$/)
      # Match normal "key = val" lines.
      @param = $1
      @value = $2
    elsif line.match(/^\s*(\w|\-)+\s*$/)
      # Match lines with a param but no value.
      # e.g. federated, quick, skip-locking
      @param = line
      @value = true
    end
  end

  # Set group attribute to match group one if it matches a
  # group block (e.g. [mysqld])
  def set_config_group(line)
    @group = $1 if line.match(/^\[(.+?)\]/)
  end

  # Return true if line matches a blank line or # / (comments).
  def invalid_line?(line)
    line.match(/^\s*$/) or line.match(/^[\#|\!]+.*$/)
  end

end