src/Generic.h

   1 /*
   2  * Copyright (C) 1996-2018 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #ifndef SQUID_GENERIC_H
  10 #define SQUID_GENERIC_H
  11
  12 #include "dlink.h"
  13
  14 #include <ostream>
  15
  16 template <class _Arg, class _Result>
  17 struct unary_function {
  18     typedef _Arg argument_type;
  19     typedef _Result result_type;
  20 };
  21
  22 template <class L, class T>
  23 T& for_each(L const &head, T& visitor)
  24 {
  25     for (L const *node = &head; node; node=node->next)
  26         visitor(*node);
  27
  28     return visitor;
  29 }
  30
  31 template <class T>
  32 T& for_each(dlink_list const &collection, T& visitor)
  33 {
  34     for (dlink_node const *node = collection.head; node; node=node->next)
  35         visitor(*(typename T::argument_type const *)node->data);
  36
  37     return visitor;
  38 }
  39
  40 /* RBC 20030718 - use this to provide instance expecting classes a pointer to a
  41  * singleton
  42  */
  43
  44 template <class C>
  45 class InstanceToSingletonAdapter : public C
  46 {
  47
  48 public:
  49     void *operator new (size_t byteCount) { return ::operator new (byteCount);}
  50
  51     void operator delete (void *address) { ::operator delete (address);}
  52
  53     InstanceToSingletonAdapter(C const *instance) : theInstance (instance) {}
  54
  55     C const * operator-> () const {return theInstance; }
  56
  57     C * operator-> () {return const_cast<C *>(theInstance); }
  58
  59     C const & operator * () const {return *theInstance; }
  60
  61     C & operator * () {return *const_cast<C *>(theInstance); }
  62
  63     operator C const * () const {return theInstance;}
  64
  65     operator C *() {return const_cast<C *>(theInstance);}
  66
  67 private:
  68     C const *theInstance;
  69 };
  70
  71 template <class InputIterator, class Visitor>
  72 Visitor& for_each(InputIterator from, InputIterator to, Visitor& visitor)
  73 {
  74     while (!(from == to)) {
  75         typename InputIterator::value_type &value = *from;
  76         ++from;
  77         visitor(value);
  78     }
  79
  80     return visitor;
  81 }
  82
  83 /* generic ostream printer */
  84 template <class Pointer>
  85 struct PointerPrinter {
  86     PointerPrinter(std::ostream &astream, std::string aDelimiter) : os(astream), delimiter (aDelimiter) {}
  87
  88     void operator () (Pointer aNode) {
  89         os << *aNode << delimiter;
  90     }
  91
  92     std::ostream &os;
  93     std::string delimiter;
  94 };
  95
  96 #endif /* SQUID_GENERIC_H */
  97