=begin
  string.rb - Extension for String.

  Copyright (C) 2005-2009 Masao Mutoh
 
  You may redistribute it and/or modify it under the same
  license terms as Ruby.
=end

# Extension for String class. This feature is included in Ruby 1.9 or later but not occur TypeError.
#
# String#% method which accept "named argument". The translator can know 
# the meaning of the msgids using "named argument" instead of %s/%d style.
class String

  unless instance_methods.find {|m| m.to_s == 'bytesize'} 
    # For older ruby (such as ruby-1.8.5)
    alias :bytesize :size
  end

  alias :_old_format_m :% # :nodoc:

  PERCENT_MATCH_RE = Regexp.union(
      /%%/,
      /%\{(\w+)\}/,
      /%<(\w+)>(.*?\d*\.?\d*[bBdiouxXeEfgGcps])/
  )

  # call-seq:
  #  %(arg)
  #  %(hash)
  #
  # Format - Uses str as a format specification, and returns the result of applying it to arg. 
  # If the format specification contains more than one substitution, then arg must be 
  # an Array containing the values to be substituted. See Kernel::sprintf for details of the 
  # format string. This is the default behavior of the String class.
  # * arg: an Array or other class except Hash.
  # * Returns: formatted String
  #
  #  (e.g.) "%s, %s" % ["Masao", "Mutoh"]
  #
  # Also you can use a Hash as the "named argument". This is recommanded way for Ruby-GetText
  # because the translators can understand the meanings of the msgids easily.
  # * hash: {:key1 => value1, :key2 => value2, ... }
  # * Returns: formatted String
  #
  #  (e.g.)
  #         For strings.
  #         "%{firstname}, %{familyname}" % {:firstname => "Masao", :familyname => "Mutoh"}
  #
  #         With field type to specify format such as d(decimal), f(float),...
  #         "%<age>d, %<weight>.1f" % {:age => 10, :weight => 43.4}
  def %(args)
    if args.kind_of?(Hash)
      ret = dup
      ret.gsub!(PERCENT_MATCH_RE) {|match|
        if match == '%%'
          '%'
        elsif $1
          key = $1.to_sym
          args.has_key?(key) ? args[key] : match
        elsif $2
          key = $2.to_sym
          args.has_key?(key) ? sprintf("%#{$3}", args[key]) : match
        end
      }
      ret
    else
      ret = gsub(/%([{<])/, '%%\1')
      begin
        ret._old_format_m(args)
      rescue ArgumentError => e
        if $DEBUG
          $stderr.puts "  The string:#{ret}"
          $stderr.puts "  args:#{args.inspect}"
          puts e.backtrace
        else
          raise ArgumentError, e.message
        end
      end
    end
  end
end

