lib/standard/range.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # Copyright 2004-2008 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 # Module for range of discrete objects.
  14 package range
  15
  16 import abstract_collection
  17
  18 # Range of discrete objects.
  19 class Range[E: Discrete]
  20 special Collection[E]
  21
  22         redef readable var _first: E
  23
  24         # Get the last element.
  25         readable var _last: E
  26
  27         # Get the element after the last one.
  28         readable var _after: E
  29
  30         redef fun has(item) do return item >= _first and item <= _last
  31
  32         redef fun has_only(item) do return _first == item and item == _last
  33
  34         redef fun count(item)
  35         do
  36                 if has(item) then
  37                         return 1
  38                 else
  39                         return 0
  40                 end
  41         end
  42
  43         redef fun iterator do return new IteratorRange[E](self)
  44
  45         redef fun length
  46         do
  47                 var nb = _first.distance(_after)
  48                 if nb > 0 then
  49                         return nb
  50                 else
  51                         return 0
  52                 end
  53         end
  54
  55         redef fun is_empty do return _first >= _after
  56
  57         # Create a range [`from', `to'].
  58         # The syntax [`from'..`to'[ is equivalent.
  59         init(from: E, to: E)
  60         do
  61                 _first = from
  62                 _last = to
  63                 _after = to.succ
  64         end
  65
  66         # Create a range [`from', `to'[.
  67         # The syntax [`from'..`to'[ is equivalent.
  68         init without_last(from: E, to: E)
  69         do
  70                 _first = from
  71                 _last = to.prec
  72                 _after = to
  73         end
  74 end
  75
  76 class IteratorRange[E: Discrete]
  77         # Iterator on ranges.
  78 special Iterator[E]
  79         var _range: Range[E]
  80         redef readable var _item: E
  81
  82         redef fun is_ok do return _item < _range.after
  83
  84         redef fun next do _item = _item.succ
  85
  86         init(r: Range[E])
  87         do
  88                 _range = r
  89                 _item = r.first
  90         end
  91 end