libbase/GnashAlgorithm.h

   1 // GnashAlgorithm.h: useful templates and functors for generic algorithms
   2 //
   3 //   Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012
   4 //   Free Software Foundation, Inc.
   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, write to the Free Software
  18 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19 //
  20
  21 #ifndef GNASH_ALGORITHM_H
  22 #define GNASH_ALGORITHM_H
  23
  24 #include <algorithm>
  25 #include <functional>
  26
  27 namespace gnash {
  28
  29 /// Return a pointer to a type
  30 template<typename T>
  31 struct CreatePointer
  32 {
  33     typedef T* result_type;
  34     result_type operator()(T& t) {
  35         return &t;
  36     }
  37 };
  38
  39 /// Erase elements from an associative container based on a predicate
  40 //
  41 /// This removes elements from a container such as a map if they fulfil a
  42 /// particular condition. Because keys of associative container are const,
  43 /// we can't do this using iterators, because we can't write to them.
  44 template<typename Container, typename Predicate>
  45 void EraseIf(Container& c, Predicate p)
  46 {
  47     typedef typename Container::iterator iterator;
  48
  49     for (iterator i = c.begin(), e = c.end(); i != e; ) {
  50         iterator stored = i++;
  51         if (p(*stored)) c.erase(stored);
  52     }
  53 }
  54
  55 /// Get the size of an array without passing a pointer by mistake
  56 template<typename T, size_t N>
  57 size_t
  58 arraySize(T(&)[N])
  59 {
  60     return N;
  61 }
  62
  63 /// Call a functor on the second element of each element in a range.
  64 //
  65 /// @tparam T           An iterator type satisfying the requirements of a
  66 ///                     forward iterator
  67 /// @tparam U           The type of the functor op.
  68 /// @param begin        The start of the range to call op on.
  69 /// @param end          The end of the range to call op on.
  70 /// @param op           The function to call on each second element.
  71 template<typename T, typename U>
  72 void
  73 foreachSecond(T begin, T end, U op)
  74 {
  75     typedef typename std::iterator_traits<T>::value_type value_type;
  76
  77     std::for_each(begin, end, std::bind(op,
  78                 std::bind(&value_type::second, std::placeholders::_1)));
  79 }
  80
  81 } // namespace gnash
  82
  83 #endif
  84