ceph/src/boost/libs/contract/example/features/private_protected_virtual.cpp

   1
   2 // Copyright (C) 2008-2018 Lorenzo Caminiti
   3 // Distributed under the Boost Software License, Version 1.0 (see accompanying
   4 // file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
   5 // See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
   6
   7 #include <boost/contract.hpp>
   8 #include <limits>
   9 #include <cassert>
  10
  11 //[private_protected_virtual_counter
  12 class counter {
  13     // Virtual private and protected functions still declare extra
  14     // `virtual_* = 0` parameter (otherwise they cannot be overridden), but...
  15 protected:
  16     virtual void set(int n, boost::contract::virtual_* = 0) {
  17         boost::contract::check c = boost::contract::function() // ...no `v`.
  18             .precondition([&] {
  19                 BOOST_CONTRACT_ASSERT(n <= 0);
  20             })
  21             .postcondition([&] {
  22                 BOOST_CONTRACT_ASSERT(get() == n);
  23             })
  24         ;
  25
  26         n_ = n;
  27     }
  28
  29 private:
  30     virtual void dec(boost::contract::virtual_* = 0) {
  31         boost::contract::old_ptr<int> old_get = BOOST_CONTRACT_OLDOF(get()); // ...no `v`.
  32         boost::contract::check c = boost::contract::function() // ...no `v`.
  33             .precondition([&] {
  34                 BOOST_CONTRACT_ASSERT(
  35                         get() + 1 >= std::numeric_limits<int>::min());
  36             })
  37             .postcondition([&] {
  38                 BOOST_CONTRACT_ASSERT(get() == *old_get - 1);
  39             })
  40         ;
  41
  42         set(get() - 1);
  43     }
  44
  45     int n_;
  46
  47     /* ... */
  48 //]
  49
  50 public:
  51     virtual int get(boost::contract::virtual_* v = 0) const {
  52         int result;
  53         boost::contract::check c = boost::contract::public_function(
  54                 v, result, this)
  55             .postcondition([&] (int const result) {
  56                 BOOST_CONTRACT_ASSERT(result <= 0);
  57                 BOOST_CONTRACT_ASSERT(result == n_);
  58             })
  59         ;
  60
  61         return result = n_;
  62     }
  63
  64     counter() : n_(0) {} // Should contract constructor and destructor too.
  65
  66     void invariant() const {
  67         BOOST_CONTRACT_ASSERT(get() <= 0);
  68     }
  69
  70     friend int main();
  71 };
  72
  73 //[private_protected_virtual_counter10
  74 class counter10
  75     #define BASES public counter
  76     : BASES
  77 {
  78 public:
  79     typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types;
  80     #undef BASES
  81
  82     // Overriding from non-public members so no subcontracting, no override_...
  83
  84     virtual void set(int n, boost::contract::virtual_* v = 0) /* override */ {
  85         boost::contract::check c = boost::contract::public_function(v, this)
  86             .precondition([&] {
  87                 BOOST_CONTRACT_ASSERT(n % 10 == 0);
  88             })
  89             .postcondition([&] {
  90                 BOOST_CONTRACT_ASSERT(get() == n);
  91             })
  92         ;
  93
  94         counter::set(n);
  95     }
  96
  97     virtual void dec(boost::contract::virtual_* v = 0) /* override */ {
  98         boost::contract::old_ptr<int> old_get = BOOST_CONTRACT_OLDOF(v, get());
  99         boost::contract::check c = boost::contract::public_function(v, this)
 100             .precondition([&] {
 101                 BOOST_CONTRACT_ASSERT(
 102                         get() + 10 >= std::numeric_limits<int>::min());
 103             })
 104             .postcondition([&] {
 105                 BOOST_CONTRACT_ASSERT(get() == *old_get - 10);
 106             })
 107         ;
 108
 109         set(get() - 10);
 110     }
 111
 112     /* ... */
 113 //]
 114
 115     virtual int get(boost::contract::virtual_* v = 0) const {
 116         int result;
 117         boost::contract::check c = boost::contract::public_function<
 118                 override_get>(v, result, &counter10::get, this);
 119
 120         return result = counter::get();
 121     }
 122     BOOST_CONTRACT_OVERRIDE(get)
 123
 124     // Should contract default constructor and destructor too.
 125
 126     void invariant() const {
 127         BOOST_CONTRACT_ASSERT(get() % 10 == 0);
 128     }
 129 };
 130
 131 int main() {
 132     counter cnt;
 133     assert(cnt.get() == 0);
 134     cnt.dec();
 135     assert(cnt.get() == -1);
 136
 137     counter10 cnt10;
 138     counter& b = cnt10; // Polymorphic calls.
 139     assert(b.get() == 0);
 140     b.dec();
 141     assert(b.get() == -10);
 142
 143     return 0;
 144 }
 145