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LSST Data Management Base Package
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Key.h
Go to the documentation of this file.
1// -*- lsst-c++ -*-
2#ifndef AFW_TABLE_Key_h_INCLUDED
3#define AFW_TABLE_Key_h_INCLUDED
4
6
10
11namespace lsst {
12namespace afw {
13namespace table {
14
15namespace detail {
16
17class Access;
18
19} // namespace detail
20
52template <typename T>
53class Key : public KeyBase<T>, public FieldBase<T> {
54public:
56
65 template <typename OtherT>
66 bool operator==(Key<OtherT> const& other) const noexcept {
67 return false;
68 }
69 template <typename OtherT>
70 bool operator!=(Key<OtherT> const& other) const noexcept {
71 return true;
72 }
73
74 bool operator==(Key const& other) const noexcept {
75 return _offset == other._offset && this->getElementCount() == other.getElementCount();
76 }
77 bool operator!=(Key const& other) const noexcept { return !this->operator==(other); }
79
81 std::size_t hash_value() const noexcept {
82 // Completely arbitrary seed
83 return cpputils::hashCombine(17, _offset, this->getElementCount());
84 }
85
87 std::size_t getOffset() const noexcept { return _offset; }
88
97 bool isValid() const noexcept { return _valid; }
98
104 Key() noexcept : FieldBase<T>(FieldBase<T>::makeDefault()), _offset(0), _valid(false) {}
105
106 Key(Key const&) noexcept = default;
107 Key(Key&&) noexcept = default;
108 Key& operator=(Key const&) noexcept = default;
109 Key& operator=(Key&&) noexcept = default;
110 ~Key() noexcept = default;
111
113 inline friend std::ostream& operator<<(std::ostream& os, Key<T> const& key) {
114 return os << "Key<" << Key<T>::getTypeString() << ">(offset=" << key.getOffset()
115 << ", nElements=" << key.getElementCount() << ")";
116 }
117
118private:
119 friend class detail::Access;
120 friend class BaseRecord;
121
122 explicit Key(std::size_t offset, FieldBase<T> const& fb = FieldBase<T>()) noexcept
123 : FieldBase<T>(fb), _offset(offset), _valid(true) {}
124
125 std::size_t _offset;
126 bool _valid;
127};
128} // namespace table
129} // namespace afw
130} // namespace lsst
131
132namespace std {
133template <typename T>
134struct hash<lsst::afw::table::Key<T>> {
137 size_t operator()(argument_type const& obj) const noexcept { return obj.hash_value(); }
138};
139} // namespace std
140
141#endif // !AFW_TABLE_Key_h_INCLUDED
A base class for Key that allows subfield keys to be extracted for some field types.
Definition KeyBase.h:20
A class used as a handle to a particular field in a table.
Definition Key.h:53
bool operator==(Key< OtherT > const &other) const noexcept
Equality comparison.
Definition Key.h:66
std::size_t getOffset() const noexcept
Return the offset (in bytes) of this field within a record.
Definition Key.h:87
bool operator!=(Key const &other) const noexcept
Definition Key.h:77
Key() noexcept
Default construct a field.
Definition Key.h:104
Key(Key &&) noexcept=default
bool isValid() const noexcept
Return true if the key was initialized to valid offset.
Definition Key.h:97
std::size_t hash_value() const noexcept
Return a hash of this object.
Definition Key.h:81
bool operator==(Key const &other) const noexcept
Definition Key.h:74
bool operator!=(Key< OtherT > const &other) const noexcept
Definition Key.h:70
Key(Key const &) noexcept=default
std::size_t hashCombine(std::size_t seed) noexcept
Combine hashes.
Definition hashCombine.h:35
STL namespace.
static std::string getTypeString()
Return a string description of the field type.
Definition FieldBase.cc:56
std::size_t getElementCount() const noexcept
Return the number of subfield elements (always one for scalars).
Definition FieldBase.h:48
static FieldBase makeDefault() noexcept
Definition FieldBase.h:69
lsst::afw::table::Key< T > argument_type
Definition Key.h:135
size_t operator()(argument_type const &obj) const noexcept
Definition Key.h:137