LSSTApplications  18.1.0
LSSTDataManagementBasePackage
PolymorphicValue.cc
Go to the documentation of this file.
1 // -*- LSST-C++ -*-
2 /*
3  * This file is part of afw.
4  *
5  * Developed for the LSST Data Management System.
6  * This product includes software developed by the LSST Project
7  * (https://www.lsst.org).
8  * See the COPYRIGHT file at the top-level directory of this distribution
9  * for details of code ownership.
10  *
11  * This program is free software: you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation, either version 3 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program. If not, see <https://www.gnu.org/licenses/>.
23  */
24 
25 #include "lsst/pex/exceptions.h"
26 
28 
29 namespace lsst {
30 namespace afw {
31 namespace typehandling {
32 
33 PolymorphicValue::PolymorphicValue(Storable const& value) : _value(value.cloneStorable()) {}
34 // No move-constructor, because putting a pointer to Storable&& into a
35 // shared_ptr is safe only if the object was dynamically allocated
36 
37 PolymorphicValue::~PolymorphicValue() noexcept = default;
38 
40  : _value(other._value ? other._value->cloneStorable() : nullptr) {}
41 PolymorphicValue::PolymorphicValue(PolymorphicValue&&) noexcept = default; // other._value emptied
42 
44  if (other._value) {
45  _value = other._value->cloneStorable();
46  } else {
47  _value.reset();
48  }
49  return *this;
50 }
52  using std::swap;
53  swap(_value, other._value);
54  return *this;
55 }
56 
58  using std::swap;
59  swap(_value, other._value);
60 }
61 
62 bool PolymorphicValue::empty() const noexcept { return !_value; }
63 
64 PolymorphicValue::operator Storable&() { return get(); }
65 PolymorphicValue::operator Storable const&() const { return get(); }
67  // Both casts are safe; see Effective C++, Item 3
68  return const_cast<Storable&>(static_cast<PolymorphicValue const&>(*this).get());
69 }
71  if (_value) {
72  return *_value;
73  } else {
74  throw LSST_EXCEPT(pex::exceptions::LogicError, "Dereferenced empty PolymorphicValue.");
75  }
76 }
77 
79  if (!empty() && !other.empty()) {
80  return get().equals(other.get());
81  } else {
82  // At least one pointer is null; pointer comparison has desired behavior
83  return _value == other._value;
84  }
85 }
86 
88 
89 } // namespace typehandling
90 } // namespace afw
91 } // namespace lsst
PolymorphicValue & operator=(PolymorphicValue const &other)
Try to assign a PolymorphicValue.
Container that passes Storable objects by value while preserving type.
T swap(T... args)
PolymorphicValue(Storable const &value)
Create a new object containing a copy of a Storable.
Interface supporting iteration over heterogenous containers.
Definition: Storable.h:56
A base class for image defects.
Reports errors in the logical structure of the program.
Definition: Runtime.h:46
std::size_t hash_value() const
Return a hash of this object (optional operation).
#define LSST_EXCEPT(type,...)
Create an exception with a given type.
Definition: Exception.h:48
bool empty() const noexcept
Check whether this object contains a Storable.
void swap(PolymorphicValue &other) noexcept
Exchange the contents of this container and another.
ItemVariant const * other
Definition: Schema.cc:56
Storable & get()
Return a reference to the internal Storable, if one exists.
bool operator==(PolymorphicValue const &other) const noexcept
Test whether the contained Storables are equal.