lib/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 # Library for simple interning of strings
  14 module symbol
  15
  16 redef class String
  17         # Get the unique corresponding to the string
  18         fun to_symbol: Symbol
  19         do
  20                 var symbol_dictionary = once new HashMap[String, Symbol]
  21                 if symbol_dictionary.has_key(self) then
  22                         return symbol_dictionary[self]
  23                 else
  24                         var symbol = new Symbol(self)
  25                         symbol_dictionary[self] = symbol
  26                         return symbol
  27                 end
  28         end
  29 end
  30
  31 # A symbol is a unique immutable string
  32 class Symbol
  33         private var string: String
  34         redef fun to_s do return string.to_s
  35 end