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LSST Data Management Base Package
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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
29namespace lsst {
30namespace afw {
31namespace typehandling {
32
33PolymorphicValue::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
37PolymorphicValue::~PolymorphicValue() noexcept = default;
38
40 : _value(other._value ? other._value->cloneStorable() : nullptr) {}
41PolymorphicValue::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
62bool PolymorphicValue::empty() const noexcept { return !_value; }
63
64PolymorphicValue::operator Storable&() { return get(); }
65PolymorphicValue::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
78bool PolymorphicValue::operator==(PolymorphicValue const& other) const noexcept {
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
#define LSST_EXCEPT(type,...)
Create an exception with a given type.
Definition Exception.h:48
Container that passes Storable objects by value while preserving type.
void swap(PolymorphicValue &other) noexcept
Exchange the contents of this container and another.
bool operator==(PolymorphicValue const &other) const noexcept
Test whether the contained Storables are equal.
Storable & get()
Return a reference to the internal Storable, if one exists.
PolymorphicValue & operator=(PolymorphicValue const &other)
Try to assign a PolymorphicValue.
bool empty() const noexcept
Check whether this object contains a Storable.
PolymorphicValue(Storable const &value)
Create a new object containing a copy of a Storable.
std::size_t hash_value() const
Return a hash of this object (optional operation).
Interface supporting iteration over heterogenous containers.
Definition Storable.h:58
Reports errors in the logical structure of the program.
Definition Runtime.h:46
void swap(PolymorphicValue &lhs, PolymorphicValue &rhs) noexcept
Swap specialization for PolymorphicValue.
T swap(T... args)