aboutsummaryrefslogtreecommitdiff
path: root/odb/simple-object-result.hxx
blob: 925896ea08834f03abc71bc3afd11e5c64508c3a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
// file      : odb/simple-object-result.hxx
// copyright : Copyright (c) 2009-2015 Code Synthesis Tools CC
// license   : GNU GPL v2; see accompanying LICENSE file

#ifndef ODB_SIMPLE_OBJECT_RESULT_HXX
#define ODB_SIMPLE_OBJECT_RESULT_HXX

#include <odb/pre.hxx>

#include <cstddef>  // std::size_t
#include <utility>  // std::move

#include <odb/forward.hxx>
#include <odb/traits.hxx>
#include <odb/result.hxx>
#include <odb/object-result.hxx>
#include <odb/pointer-traits.hxx>

#include <odb/details/config.hxx>     // ODB_CXX11

namespace odb
{
  // Implementation for non-polymorphic objects with object id.
  //
  template <typename T>
  class object_result_impl: public result_impl
  {
  protected:
    // In result_impl, T is always non-const and the same as object_type.
    //
    typedef T object_type;
    typedef odb::object_traits<object_type> object_traits;
    typedef typename object_traits::id_type id_type;

    typedef typename object_traits::pointer_type pointer_type;
    typedef odb::pointer_traits<pointer_type> pointer_traits;

    friend class result<T>;
    friend class result<const T>;
    friend class result_iterator<T, class_object>;
    friend class result_iterator<const T, class_object>;
    friend class object_result_iterator<T, id_type, false>;
    friend class object_result_iterator<const T, id_type, false>;

  protected:
    object_result_impl (odb::connection& conn)
        : result_impl (conn), begin_ (true), end_ (false), current_ ()
    {
    }

    // To make this work with all kinds of pointers (raw, std::auto_ptr,
    // shared), we need to make sure we don't make any copies of the
    // pointer on the return path.
    //
    pointer_type&
    current ()
    {
      if (pointer_traits::null_ptr (current_) && !end_)
        load ();

      return current_;
    }

    void
    release ()
    {
      current_ = pointer_type ();
      guard_.release ();
    }

    void
    begin ()
    {
      if (begin_)
      {
        next ();
        begin_ = false;
      }
    }

    bool
    end () const
    {
      return end_;
    }

  protected:
    // The fetch argument is a hint to the implementation. If it is
    // false then it means load_id() was already called (and presumably
    // fetched the data into the object image) and the object image
    // is still valid (so the implementation doesn't need to fetch
    // the data again).
    //
    virtual void
    load (object_type&, bool fetch = true) = 0;

    virtual id_type
    load_id () = 0;

    virtual void
    next () = 0;

    virtual void
    cache () = 0;

    virtual std::size_t
    size () = 0;

  protected:
#ifdef ODB_CXX11
    void
    current (pointer_type& p, bool guard = true)
    {
      current_ = std::move (p);

      if (guard)
        guard_.reset (current_);
      else
        guard_.reset ();
    }

    void
    current (pointer_type&& p, bool guard = true)
    {
      current (p, guard);
    }
#else
    void
    current (pointer_type p, bool guard = true)
    {
      current_ = p;

      if (guard)
        guard_.reset (current_);
      else
        guard_.reset ();
    }
#endif

    bool begin_;
    bool end_;

  private:
    void
    load ();

  private:
    pointer_type current_;
    typename pointer_traits::guard guard_;
  };

  template <typename T, typename ID>
  class object_result_iterator<T, ID, false>
  {
  public:
    // T can be const T while object_type is always non-const.
    //
    typedef typename object_traits<T>::object_type object_type;
    typedef typename object_traits<T>::id_type id_type;

    typedef object_result_impl<object_type> result_impl_type;

  public:
    object_result_iterator (result_impl_type* res)
        : res_ (res)
    {
    }

  public:
    typename object_traits<T>::pointer_type
    load ()
    {
      typename object_traits<T>::pointer_type r (res_->current ());
      res_->release ();
      return r;
    }

    void
    load (object_type&);

    id_type
    id ()
    {
      return res_->load_id ();
    }

  protected:
    result_impl_type* res_;
  };
}

#include <odb/simple-object-result.txx>

#include <odb/post.hxx>

#endif // ODB_SIMPLE_OBJECT_RESULT_HXX