Class PropertiesFileParser
In: lib/rconfig/properties_file_parser.rb
Parent: Object

Copyright (c) 2009 Rahmal Conda <rahmal@gmail.com>

This class parses key/value based properties files used for configuration. It is used by rconfig to import configuration files of the aforementioned format. Unlike yaml, and xml files it can only support three levels. First, it can have root level properties: 

           server_url=host.domain.com
           server_port=8080

Secondly, it can have properties grouped into catagories. The group names must be specified within brackets like [ … ] 

           [server]
           url=host.domain.com
           port=8080

Finally, groups can also be qualified with namespaces, similar to git config files. Group names are same as before, but with namespace in within the brackets like [ <group> "<name>" ] 

           [host "dev"]
           domain=dev.server.com

           [host "prod"]
           domain=www.server.com

These can be retrieved using dot-notation or variable to do it dynamically. 

           RConfig.props.host.dev.domain
                     - or -
           RConfig.props.host[env].domain  (where env is 'dev' or 'prod')

Methods

parse  

Included Modules

Singleton

Constants

COMMENT = /^\#/
KEYVAL = /\s*=\s*/
QUOTES = /^['"](.*)['"]$/
GROUP = /^\[(.+)\]$/
NAMEGRP = /^\[(.+) \"(.+)\"\]$/

Public Class methods

parse(config_file)

Parse config file and import data into hash to be stored in config.

[Source]

# File lib/rconfig/properties_file_parser.rb, line 47
  def self.parse config_file
    raise ArgumentError, 'Invalid config file name.' unless config_file

    config = {}

    # The config is top down.. anything after a [group] gets added as part
    # of that group until a new [group] is found.  
    group, topgrp = nil
    config_file.each do |line|              # for each line in the config file
      line.strip!
      unless (COMMENT.match(line))          # skip comments (lines that state with '#')
        if(KEYVAL.match(line))              # if this line is a config property
          key, val = line.split(KEYVAL, 2)  # parse key and value from line
          key = key.chomp.strip
          val = val.chomp.strip
          if (val)
            if val =~ QUOTES                # if the value is in quotes
              value = $1                    # strip out value from quotes
            else
              value = val                   # otherwise, leave as-is
            end
          else
            value = ''                      # if value was nil, set it to empty string
          end

          if topgrp                         # If there was a top-level named group
            config[topgrp][group][key] =    # then there must be a group.
              value                         # add the prop to the named group
          elsif group                       # if this property is part of a group
            config[group][key] = value      # then add it to the group
          else
            config[key] = value             # otherwise, add it to top-level config
          end

        elsif match = NAMEGRP.match(line)   # This line is a named group (i.e. [env "test"], [env "qa"], [env "production"])
          topgrp, group = match.to_a[1..-1] # There can be multiple groups within a single top-level group
          config[topgrp] ||= {}             # add group to top-level group
          config[topgrp][group] ||= {}      # add name of group as subgroup (properties are added to subgroup)

        elsif match = GROUP.match(line)     # if this line is a config group
          group = match.to_a[1]             # parse the group name from line
          topgrp = nil                      # we got a new group with no namespace, so reset topgrp
          config[group] ||= {}              # add group to top-level config
        end
      end
    end

    config  # return config hash
  end

[Validate]