LeechCraft  0.6.70-13729-g7046a9d2a7
Modular cross-platform feature rich live environment.
lazyinitializer.h
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29 
30 #pragma once
31 
32 #include <functional>
33 #include <boost/optional.hpp>
34 
35 namespace LC
36 {
37 namespace Util
38 {
49  template<typename Source, typename Object>
51  {
52  Source Source_;
53 
54  boost::optional<Object> Object_;
55 
56  std::function<Object (Source)> Initializer_;
57  std::function<void (Source&)> ClearSource_;
58  public:
70  template<typename Init>
71  LazyInitializer (const Source& source,
72  const Init& initializer,
73  const std::function<void (Source&)>& clear = [] (Source& src) { src = Source {}; })
74  : Source_ { source }
75  , Initializer_ { initializer }
76  , ClearSource_ { clear }
77  {
78  }
79 
84  LazyInitializer (const Object& object)
85  : Object_ { object }
86  {
87  }
88 
94  LazyInitializer& operator= (const Object& object)
95  {
96  Object_ = object;
97  ClearSource_ (Source_);
98  return *this;
99  }
100 
104  operator Object ()
105  {
106  CheckInit ();
107  return *Object_;
108  }
109 
112  Object& operator-> ()
113  {
114  CheckInit ();
115  return *Object_;
116  }
117 
118  void Force ()
119  {
120  CheckInit ();
121  }
122  private:
123  void CheckInit ()
124  {
125  if (!Object_)
126  {
127  Object_ = Initializer_ (Source_);
128  ClearSource_ (Source_);
129  }
130  }
131  };
132 }
133 }
Provides lazy initialization on first access to an object.
LazyInitializer(const Object &object)
Constructs an evaluated initializer from the object.
LazyInitializer(const Source &source, const Init &initializer, const std::function< void(Source &)> &clear=[](Source &src) { src=Source {};})
Constructs an unevaluated lazy initializer.
LazyInitializer & operator=(const Object &object)
Assigns an object to this lazy (making it evaluated) initializer and clears the source.
Definition: constants.h:35
Object & operator->()
Indirection operator, forcing object construction.