gcc/hash-map-traits.h

   1 /* A hash map traits.
   2    Copyright (C) 2015 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef HASH_MAP_TRAITS_H
  21 #define HASH_MAP_TRAITS_H
  22
  23 /* Bacause mem-stats.h uses default hashmap traits, we have to
  24    put the class to this separate header file.  */
  25
  26 /* implement default behavior for traits when types allow it.  */
  27
  28 struct default_hashmap_traits
  29 {
  30   /* Hashes the passed in key.  */
  31
  32   template<typename T>
  33   static hashval_t
  34   hash (T *p)
  35     {
  36       return uintptr_t (p) >> 3;
  37     }
  38
  39   /* If the value converts to hashval_t just use it.  */
  40
  41   template<typename T> static hashval_t hash (T v) { return v; }
  42
  43   /* Return true if the two keys passed as arguments are equal.  */
  44
  45   template<typename T>
  46   static bool
  47   equal_keys (const T &a, const T &b)
  48     {
  49       return a == b;
  50     }
  51
  52   /* Called to dispose of the key and value before marking the entry as
  53      deleted.  */
  54
  55   template<typename T> static void remove (T &v) { v.~T (); }
  56
  57   /* Mark the passed in entry as being deleted.  */
  58
  59   template<typename T>
  60   static void
  61   mark_deleted (T &e)
  62     {
  63       mark_key_deleted (e.m_key);
  64     }
  65
  66   /* Mark the passed in entry as being empty.  */
  67
  68   template<typename T>
  69   static void
  70   mark_empty (T &e)
  71     {
  72       mark_key_empty (e.m_key);
  73     }
  74
  75   /* Return true if the passed in entry is marked as deleted.  */
  76
  77   template<typename T>
  78   static bool
  79   is_deleted (T &e)
  80     {
  81       return e.m_key == (void *)1;
  82     }
  83
  84   /* Return true if the passed in entry is marked as empty.  */
  85
  86   template<typename T> static bool is_empty (T &e) { return e.m_key == NULL; }
  87
  88 private:
  89   template<typename T>
  90   static void
  91   mark_key_deleted (T *&k)
  92     {
  93       k = reinterpret_cast<T *> (1);
  94     }
  95
  96   template<typename T>
  97   static void
  98   mark_key_empty (T *&k)
  99     {
 100       k = static_cast<T *> (0);
 101     }
 102 };
 103
 104 #endif // HASH_MAP_TRAITS_H