lib/gl_set.hh

   1 /* Abstract set data type as a C++ class.
   2    Copyright (C) 2006-2024 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2018.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation, either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _GL_SET_HH
  19 #define _GL_SET_HH
  20
  21 #include "gl_set.h"
  22 #include "gl_xset.h"
  23
  24 #include <stdlib.h>     /* because Gnulib's <stdlib.h> may '#define free ...' */
  25
  26 /* gl_Set is a C++ wrapper around the gl_set data type.
  27    Its element type is 'ELTYPE *'.
  28
  29    It is merely a pointer, not a smart pointer. In other words:
  30    it does NOT do reference-counting, and the destructor does nothing.  */
  31
  32 template <class T> class gl_Set;
  33
  34 template <class ELTYPE>
  35 class gl_Set<ELTYPE *>
  36 {
  37 public:
  38   // ------------------------------ Constructors ------------------------------
  39
  40   gl_Set ()
  41     : _ptr (NULL)
  42     {}
  43
  44   /* Creates an empty set.
  45      IMPLEMENTATION is one of GL_ARRAY_SET, GL_LINKEDHASH_SET, GL_HASH_SET.
  46      EQUALS_FN is an element comparison function or NULL.
  47      HASHCODE_FN is an element hash code function or NULL.
  48      DISPOSE_FN is an element disposal function or NULL.  */
  49   gl_Set (gl_set_implementation_t implementation,
  50           bool (*equals_fn) (ELTYPE * /*elt1*/, ELTYPE * /*elt2*/),
  51           size_t (*hashcode_fn) (ELTYPE *),
  52           void (*dispose_fn) (ELTYPE *))
  53     : _ptr (gl_set_create_empty (implementation,
  54                                  reinterpret_cast<gl_setelement_equals_fn>(equals_fn),
  55                                  reinterpret_cast<gl_setelement_hashcode_fn>(hashcode_fn),
  56                                  reinterpret_cast<gl_setelement_dispose_fn>(dispose_fn)))
  57     {}
  58
  59   /* Copy constructor.  */
  60   gl_Set (const gl_Set& x)
  61     { _ptr = x._ptr; }
  62
  63   /* Assignment operator.  */
  64   gl_Set& operator= (const gl_Set& x)
  65     { _ptr = x._ptr; return *this; }
  66
  67   // ------------------------------- Destructor -------------------------------
  68
  69   ~gl_Set ()
  70     { _ptr = NULL; }
  71
  72   // ----------------------- Read-only member functions -----------------------
  73
  74   /* Returns the current number of elements in the set.  */
  75   size_t size () const
  76     { return gl_set_size (_ptr); }
  77
  78   /* Searches whether an element is already in the set.
  79      Returns true if found, or false if not present in the set.  */
  80   bool search (ELTYPE * elt) const
  81     { return gl_set_search (_ptr, elt); }
  82
  83   // ----------------------- Modifying member functions -----------------------
  84
  85   /* Adds an element to the set.
  86      Returns true if it was not already in the set and added, false otherwise.  */
  87   bool add (ELTYPE * elt)
  88     { return gl_set_add (_ptr, elt); }
  89
  90   /* Removes an element from the set.
  91      Returns true if it was found and removed.  */
  92   bool remove (ELTYPE * elt)
  93     { return gl_set_remove (_ptr, elt); }
  94
  95   /* Frees the entire set.
  96      (But this call does not free the elements of the set.  It only invokes
  97      the DISPOSE_FN on each of the elements of the set.)  */
  98   void free ()
  99     { gl_set_free (_ptr); _ptr = NULL; }
 100
 101   // ------------------------------ Private stuff ------------------------------
 102
 103 private:
 104   gl_set_t _ptr;
 105
 106 public:
 107   // -------------------------------- Iterators --------------------------------
 108   // Only a forward iterator.
 109   // Does not implement the STL operations (++, *, and != .end()), but a simpler
 110   // interface that needs only one virtual function call per iteration instead
 111   // of three.
 112
 113   class iterator {
 114   public:
 115
 116     /* If there is a next element, stores the next element in ELT, advances the
 117        iterator and returns true.  Otherwise, returns false.  */
 118     bool next (ELTYPE *& elt)
 119       {
 120         const void *next_elt;
 121         bool has_next = gl_set_iterator_next (&_state, &next_elt);
 122         if (has_next)
 123           elt = static_cast<ELTYPE *>(next_elt);
 124         return has_next;
 125       }
 126
 127     ~iterator ()
 128       { gl_set_iterator_free (&_state); }
 129
 130   #if defined __xlC__ || defined __HP_aCC || defined __SUNPRO_CC
 131   public:
 132   #else
 133   private:
 134     friend iterator gl_Set::begin ();
 135   #endif
 136
 137     iterator (gl_set_t ptr)
 138       : _state (gl_set_iterator (ptr))
 139       {}
 140
 141   private:
 142
 143     gl_set_iterator_t _state;
 144   };
 145
 146   /* Creates an iterator traversing the set.
 147      The set's contents must not be modified while the iterator is in use,
 148      except for removing the last returned element.  */
 149   iterator begin ()
 150     { return iterator (_ptr); }
 151 };
 152
 153 #endif /* _GL_SET_HH */