gdbsupport/next-iterator.h

   1 /* A "next" iterator for GDB, the GNU debugger.
   2    Copyright (C) 2019-2020 Free Software Foundation, Inc.
   3
   4    This file is part of GDB.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef COMMON_NEXT_ITERATOR_H
  20 #define COMMON_NEXT_ITERATOR_H
  21
  22 /* An iterator that uses the 'next' field of a type to iterate.  This
  23    can be used with various GDB types that are stored as linked
  24    lists.  */
  25
  26 template<typename T>
  27 struct next_iterator
  28 {
  29   typedef next_iterator self_type;
  30   typedef T *value_type;
  31   typedef T *&reference;
  32   typedef T **pointer;
  33   typedef std::forward_iterator_tag iterator_category;
  34   typedef int difference_type;
  35
  36   explicit next_iterator (T *item)
  37     : m_item (item)
  38   {
  39   }
  40
  41   /* Create a one-past-the-end iterator.  */
  42   next_iterator ()
  43     : m_item (nullptr)
  44   {
  45   }
  46
  47   value_type operator* () const
  48   {
  49     return m_item;
  50   }
  51
  52   bool operator== (const self_type &other) const
  53   {
  54     return m_item == other.m_item;
  55   }
  56
  57   bool operator!= (const self_type &other) const
  58   {
  59     return m_item != other.m_item;
  60   }
  61
  62   self_type &operator++ ()
  63   {
  64     m_item = m_item->next;
  65     return *this;
  66   }
  67
  68 private:
  69
  70   T *m_item;
  71 };
  72
  73 /* A range adapter that allows iterating over a linked list.  */
  74
  75 template<typename T, typename Iterator = next_iterator<T>>
  76 class next_adapter
  77 {
  78 public:
  79
  80   explicit next_adapter (T *item)
  81     : m_item (item)
  82   {
  83   }
  84
  85   using iterator = Iterator;
  86
  87   iterator begin () const
  88   {
  89     return iterator (m_item);
  90   }
  91
  92   iterator end () const
  93   {
  94     return iterator ();
  95   }
  96
  97 private:
  98
  99   T *m_item;
 100 };
 101
 102 #endif /* COMMON_NEXT_ITERATOR_H */