mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.DataStructures/SequenceExtensions.cs

   1 //
   2 // SequenceExtensions.cs
   3 //
   4 // Authors:
   5 //      Alexander Chebaturkin (chebaturkin@gmail.com)
   6 //
   7 // Copyright (C) 2011 Alexander Chebaturkin
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System;
  30 using System.Collections.Generic;
  31
  32 namespace Mono.CodeContracts.Static.DataStructures {
  33         public static class SequenceExtensions {
  34                 public static Sequence<T> Cons<T> (this Sequence<T> rest, T elem)
  35                 {
  36                         return Sequence<T>.Cons (elem, rest);
  37                 }
  38
  39                 public static Sequence<T> Append<T> (this Sequence<T> list, Sequence<T> append)
  40                 {
  41                         if (list == null)
  42                                 return append;
  43                         if (append == null)
  44                                 return list;
  45
  46                         return Cons (list.Tail.Append (append), list.Head);
  47                 }
  48
  49                 public static Sequence<T> Where<T> (this Sequence<T> list, Predicate<T> keep)
  50                 {
  51                         if (list == null)
  52                                 return null;
  53                         Sequence<T> rest = list.Tail.Where (keep);
  54                         if (!keep (list.Head))
  55                                 return rest;
  56
  57                         if (rest == list.Tail)
  58                                 return list;
  59
  60                         return Cons (rest, list.Head);
  61                 }
  62
  63                 public static void Apply<T> (this Sequence<T> list, Action<T> action)
  64                 {
  65                         Sequence<T>.Apply (list, action);
  66                 }
  67
  68                 public static IEnumerable<T> AsEnumerable<T> (this Sequence<T> list)
  69                 {
  70                         return Sequence<T>.PrivateGetEnumerable (list);
  71                 }
  72
  73                 public static bool Any<T> (this Sequence<T> list, Predicate<T> predicate)
  74                 {
  75                         if (list == null)
  76                                 return false;
  77
  78                         if (predicate (list.Head))
  79                                 return true;
  80
  81                         return list.Tail.Any (predicate);
  82                 }
  83
  84                 public static bool All<T> (this Sequence<T> list, Predicate<T> predicate)
  85                 {
  86                         if (list == null)
  87                                 return true;
  88
  89                         if (!predicate (list.Head))
  90                                 return false;
  91
  92                         return list.Tail.All (predicate);
  93                 }
  94
  95                 public static int Length<T> (this Sequence<T> list)
  96                 {
  97                         return Sequence<T>.LengthOf (list);
  98                 }
  99
 100                 public static bool IsEmpty<T> (this Sequence<T> list)
 101                 {
 102                         return list == null;
 103                 }
 104
 105                 public static Sequence<S> Select<T, S> (this Sequence<T> list, Func<T, S> selector)
 106                 {
 107                         return Sequence<T>.Select (list, selector);
 108                 }
 109
 110                 public static T Last<T> (this Sequence<T> list)
 111                 {
 112                         if (list == null)
 113                                 return default(T);
 114
 115                         while (Sequence<T>.LengthOf (list) > 1)
 116                                 list = list.Tail;
 117
 118                         return list.Head;
 119                 }
 120
 121                 public static Sequence<T> Coerce<S, T> (this Sequence<S> list)
 122                         where S : T
 123                 {
 124                         return list.Select (l => (T) l);
 125                 }
 126
 127                 public static Sequence<T> Reverse<T> (this Sequence<T> list)
 128                 {
 129                         Sequence<T> rest = null;
 130
 131                         for (Sequence<T> cur = list; cur != null; cur = cur.Tail)
 132                                 rest = rest.Cons (cur.Head);
 133
 134                         return rest;
 135                 }
 136
 137                 public static void ForEach<T> (this Sequence<T> seq, Action<T> action)
 138                 {
 139                         if (seq == null)
 140                                 return;
 141
 142                         action (seq.Head);
 143                         seq.Tail.ForEach (action);
 144                 }
 145         }
 146 }