lib/standard/symbol.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # Copyright 2005-2008 Jean Privat <jean@pryen.org>
   4 #
   5 # This file is free software, which comes along with NIT.  This software is
   6 # distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
   7 # without  even  the implied warranty of  MERCHANTABILITY or  FITNESS FOR A
   8 # PARTICULAR PURPOSE.  You can modify it is you want,  provided this header
   9 # is kept unaltered, and a notification of the changes is added.
  10 # You  are  allowed  to  redistribute it and sell it, alone or is a part of
  11 # another product.
  12
  13 # This module introduce the Symbol class
  14 package symbol
  15
  16 import string
  17 private import hash
  18
  19 redef class String
  20         # Get the unique corresponding to the string
  21         meth to_symbol: Symbol
  22         do
  23                 var symbol_dictionary = once new HashMap[String, Symbol]
  24                 if symbol_dictionary.has_key(self) then
  25                         return symbol_dictionary[self]
  26                 else
  27                         var symbol = new Symbol(self)
  28                         symbol_dictionary[self] = symbol
  29                         return symbol
  30                 end
  31         end
  32 end
  33
  34 # A symbol is a unique unmutable string
  35 class Symbol
  36         attr _string: String
  37         redef meth to_s do return _string.to_s
  38
  39         # Only used by String::to_symbol
  40         private init(s: String) do _string = s
  41 end