A class used as a handle to a particular field in a table. More...

#include <fwd.h>

Inheritance diagram for lsst::afw::table::Key< T >:

Public Types
typedef T	Value
	the type returned by BaseRecord::get More...

typedef T &	Reference
	the type returned by BaseRecord::operator[] (non-const) More...

typedef T const &	ConstReference
	the type returned by BaseRecord::operator[] (const) More...

typedef T	Element
	the type of subfields (the same as the type itself for scalars) More...

Public Member Functions
std::size_t	hash_value () const noexcept
	Return a hash of this object. More...

int	getOffset () const noexcept
	Return the offset (in bytes) of this field within a record. More...

bool	isValid () const noexcept
	Return true if the key was initialized to valid offset. More...

	Key () noexcept
	Default construct a field. More...

	Key (Key const &) noexcept=default

	Key (Key &&) noexcept=default

Key &	operator= (Key const &) noexcept=default

Key &	operator= (Key &&) noexcept=default

	~Key () noexcept=default

int	getElementCount () const noexcept
	Return the number of subfield elements (always one for scalars). More...


template<typename OtherT >
bool	operator== (Key< OtherT > const &other) const noexcept
	Equality comparison. More...

template<typename OtherT >
bool	operator!= (Key< OtherT > const &other) const noexcept
	Equality comparison. More...

bool	operator== (Key const &other) const noexcept
	Equality comparison. More...

bool	operator!= (Key const &other) const noexcept
	Equality comparison. More...

Static Public Member Functions
static std::string	getTypeString ()
	Return a string description of the field type. More...

Static Public Attributes
static bool const	HAS_NAMED_SUBFIELDS = false

Protected Member Functions
void	stream (std::ostream &os) const
	Defines how Fields are printed. More...

Reference	getReference (Element *p, ndarray::Manager::Ptr const &) const
	Used to implement BaseRecord::operator[] (non-const). More...

ConstReference	getConstReference (Element const *p, ndarray::Manager::Ptr const &) const
	Used to implement BaseRecord::operator[] (const). More...

Value	getValue (Element const *p, ndarray::Manager::Ptr const &) const
	Used to implement BaseRecord::get. More...

void	setValue (Element *p, ndarray::Manager::Ptr const &, Value v) const
	Used to implement BaseRecord::set. More...

Static Protected Member Functions
static FieldBase	makeDefault () noexcept
	Needed to allow Keys to be default-constructed. More...

Friends
class	detail::Access

class	BaseRecord

std::ostream &	operator<< (std::ostream &os, Key< T > const &key)
	Stringification. More...

Detailed Description

template<typename T>
class lsst::afw::table::Key< T >

A class used as a handle to a particular field in a table.

All access to table data ultimately goes through Key objects, which know (via an internal offset) how to address and cast the internal data buffer of a record or table.

Keys can be obtained from a Schema by name:

schema.find("myfield").key

and are also returned when a new field is added. Compound and array keys also provide accessors to retrieve scalar keys to their elements (see the documentation for the KeyBase specializations), even though these element keys do not correspond to a field that exists in any Schema. For example:

Schema schema;
Key< Array<float> > arrayKey = schema.addField< Array<float> >("array", "docs for array", 5);
Key< Point<int> > pointKey = schema.addField< Point<int> >("point", "docs for point");
Key<float> elementKey = arrayKey[3];
Key<int> xKey = pointKey.getX();
std::shared_ptr<BaseTable> table = BaseTable::make(schema);
std::shared_ptr<BaseRecord> record = table.makeRecord();
assert(&record[arrayKey][3] == &record[elementKey3]);
assert(record.get(pointKey).getX() == record[xKey]);

Key inherits from FieldBase to allow a key for a dynamically-sized field to know its size without needing to specialize Key itself or hold a full Field object.

Definition at line 45 of file fwd.h.

Member Typedef Documentation

◆ ConstReference

template<typename T>

typedef T const& lsst::afw::table::FieldBase< T >::ConstReference

inherited

the type returned by BaseRecord::operator[] (const)

Definition at line 46 of file FieldBase.h.

◆ Element

template<typename T>

typedef T lsst::afw::table::FieldBase< T >::Element

inherited

the type of subfields (the same as the type itself for scalars)

Definition at line 47 of file FieldBase.h.

◆ Reference

template<typename T>

typedef T& lsst::afw::table::FieldBase< T >::Reference

inherited

the type returned by BaseRecord::operator[] (non-const)

Definition at line 45 of file FieldBase.h.

◆ Value

template<typename T>

typedef T lsst::afw::table::FieldBase< T >::Value

inherited

the type returned by BaseRecord::get

Definition at line 44 of file FieldBase.h.

Constructor & Destructor Documentation

◆ Key() [1/3]

template<typename T>

lsst::afw::table::Key< T >::Key ( )

inlinenoexcept

Default construct a field.

The new field will be invalid until a valid Key is assigned to it.

Definition at line 104 of file Key.h.

104 : FieldBase<T>(FieldBase<T>::makeDefault()), _offset(-1) {}

lsst::afw::table::FieldBase::makeDefault

static FieldBase makeDefault() noexcept

Needed to allow Keys to be default-constructed.

Definition: FieldBase.h:71

◆ Key() [2/3]

template<typename T>

lsst::afw::table::Key< T >::Key ( Key< T > const & )

defaultnoexcept

◆ Key() [3/3]

template<typename T>

lsst::afw::table::Key< T >::Key ( Key< T > && )

defaultnoexcept

◆ ~Key()

template<typename T>

lsst::afw::table::Key< T >::~Key ( )

defaultnoexcept

Member Function Documentation

◆ getConstReference()

template<typename T>

ConstReference lsst::afw::table::FieldBase< T >::getConstReference	(	Element const *	p,
		ndarray::Manager::Ptr const &
	)		const

inlineprotectedinherited

Used to implement BaseRecord::operator[] (const).

Definition at line 80 of file FieldBase.h.

80 { return *p; }

◆ getElementCount()

template<typename T>

int lsst::afw::table::FieldBase< T >::getElementCount ( ) const

inlinenoexceptinherited

Return the number of subfield elements (always one for scalars).

Definition at line 50 of file FieldBase.h.

50 { return 1; }

◆ getOffset()

template<typename T>

int lsst::afw::table::Key< T >::getOffset ( ) const

inlinenoexcept

Return the offset (in bytes) of this field within a record.

Definition at line 87 of file Key.h.

87 { return _offset; }

◆ getReference()

template<typename T>

Reference lsst::afw::table::FieldBase< T >::getReference	(	Element *	p,
		ndarray::Manager::Ptr const &
	)		const

inlineprotectedinherited

Used to implement BaseRecord::operator[] (non-const).

Definition at line 77 of file FieldBase.h.

77 { return *p; }

◆ getTypeString()

template<typename T >

std::string lsst::afw::table::FieldBase< T >::getTypeString ( )

staticinherited

Return a string description of the field type.

Definition at line 56 of file FieldBase.cc.

                                       {
     return TypeTraits<T>::getName();
 }

◆ getValue()

template<typename T>

Value lsst::afw::table::FieldBase< T >::getValue	(	Element const *	p,
		ndarray::Manager::Ptr const &
	)		const

inlineprotectedinherited

Used to implement BaseRecord::get.

Definition at line 83 of file FieldBase.h.

83 { return *p; }

◆ hash_value()

template<typename T>

std::size_t lsst::afw::table::Key< T >::hash_value ( ) const

inlinenoexcept

Return a hash of this object.

Definition at line 81 of file Key.h.

                                           {
         // Completely arbitrary seed
         return utils::hashCombine(17, _offset, this->getElementCount());
     }

◆ isValid()

template<typename T>

bool lsst::afw::table::Key< T >::isValid ( ) const

inlinenoexcept

Return true if the key was initialized to valid offset.

This does not guarantee that a key is valid with any particular schema, or even that any schemas still exist in which this key is valid.

A key that is default constructed will always be invalid.

Definition at line 97 of file Key.h.

97 { return _offset >= 0; }

◆ makeDefault()

template<typename T>

static FieldBase lsst::afw::table::FieldBase< T >::makeDefault ( )

inlinestaticprotectednoexceptinherited

Needed to allow Keys to be default-constructed.

Definition at line 71 of file FieldBase.h.

71 { return FieldBase(); }

lsst::afw::table::FieldBase::FieldBase

FieldBase()=default

◆ operator!=() [1/2]

template<typename T>

template<typename OtherT >

bool lsst::afw::table::Key< T >::operator!= ( Key< OtherT > const & other ) const

inlinenoexcept

Equality comparison.

Two keys with different types are never equal. Keys with the same type are equal if they point to the same location in a table, regardless of what Schema they were constructed from (for instance, if a field has a different name in one Schema than another, but is otherwise the same, the two keys will be equal).

Definition at line 70 of file Key.h.

                                                              {
         return true;
     }

◆ operator!=() [2/2]

template<typename T>

bool lsst::afw::table::Key< T >::operator!= ( Key< T > const & other ) const

inlinenoexcept

Equality comparison.

Two keys with different types are never equal. Keys with the same type are equal if they point to the same location in a table, regardless of what Schema they were constructed from (for instance, if a field has a different name in one Schema than another, but is otherwise the same, the two keys will be equal).

Definition at line 77 of file Key.h.

77 { return !this->operator==(other); }

lsst::afw::table::Key::operator==

bool operator==(Key< OtherT > const &other) const noexcept

Equality comparison.

Definition: Key.h:66

other

ItemVariant const * other

Definition: Schema.cc:56

◆ operator=() [1/2]

template<typename T>

Key& lsst::afw::table::Key< T >::operator= ( Key< T > const & )

defaultnoexcept

◆ operator=() [2/2]

template<typename T>

Key& lsst::afw::table::Key< T >::operator= ( Key< T > && )

defaultnoexcept

◆ operator==() [1/2]

template<typename T>

template<typename OtherT >

bool lsst::afw::table::Key< T >::operator== ( Key< OtherT > const & other ) const

inlinenoexcept

Equality comparison.

Two keys with different types are never equal. Keys with the same type are equal if they point to the same location in a table, regardless of what Schema they were constructed from (for instance, if a field has a different name in one Schema than another, but is otherwise the same, the two keys will be equal).

Definition at line 66 of file Key.h.

                                                              {
         return false;
     }

◆ operator==() [2/2]

template<typename T>

bool lsst::afw::table::Key< T >::operator== ( Key< T > const & other ) const

inlinenoexcept

Equality comparison.

Two keys with different types are never equal. Keys with the same type are equal if they point to the same location in a table, regardless of what Schema they were constructed from (for instance, if a field has a different name in one Schema than another, but is otherwise the same, the two keys will be equal).

Definition at line 74 of file Key.h.

                                                      {
         return _offset == other._offset && this->getElementCount() == other.getElementCount();
     }

◆ setValue()

template<typename T>

void lsst::afw::table::FieldBase< T >::setValue	(	Element *	p,
		ndarray::Manager::Ptr const &	,
		Value	v
	)		const

inlineprotectedinherited

Used to implement BaseRecord::set.

Definition at line 86 of file FieldBase.h.

86 { *p = v; }

◆ stream()

template<typename T>

void lsst::afw::table::FieldBase< T >::stream ( std::ostream & os ) const

inlineprotectedinherited

Defines how Fields are printed.

Definition at line 74 of file FieldBase.h.

74 {}

Friends And Related Function Documentation

◆ BaseRecord

template<typename T>

friend class BaseRecord

friend

Definition at line 120 of file Key.h.

◆ detail::Access

template<typename T>

friend class detail::Access

friend

Definition at line 119 of file Key.h.

◆ operator<<

template<typename T>

std::ostream& operator<<	(	std::ostream &	os,
		Key< T > const &	key
	)

friend

Stringification.

Definition at line 113 of file Key.h.

                                                                             {
         return os << "Key<" << Key<T>::getTypeString() << ">(offset=" << key.getOffset()
                   << ", nElements=" << key.getElementCount() << ")";
     }

Member Data Documentation

◆ HAS_NAMED_SUBFIELDS

template<typename T>

bool const lsst::afw::table::KeyBase< T >::HAS_NAMED_SUBFIELDS = false

staticinherited

Definition at line 22 of file KeyBase.h.

The documentation for this class was generated from the following files:

/j/snowflake/release/lsstsw/stack/Linux64/afw/19.0.0-4-ga671dab3b+1/include/lsst/afw/table/fwd.h
/j/snowflake/release/lsstsw/stack/Linux64/afw/19.0.0-4-ga671dab3b+1/include/lsst/afw/table/Key.h

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Member Functions

Static Protected Member Functions

Friends

Detailed Description

template<typename T> class lsst::afw::table::Key< T >

Member Typedef Documentation

◆ ConstReference

◆ Element

◆ Reference

◆ Value

Constructor & Destructor Documentation

◆ Key() [1/3]

◆ Key() [2/3]

◆ Key() [3/3]

◆ ~Key()

Member Function Documentation

◆ getConstReference()

◆ getElementCount()

◆ getOffset()

◆ getReference()

◆ getTypeString()

◆ getValue()

◆ hash_value()

◆ isValid()

◆ makeDefault()

◆ operator!=() [1/2]

◆ operator!=() [2/2]

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ operator==() [1/2]

◆ operator==() [2/2]

◆ setValue()

◆ stream()

Friends And Related Function Documentation

◆ BaseRecord

◆ detail::Access

◆ operator<<

Member Data Documentation

◆ HAS_NAMED_SUBFIELDS

template<typename T>
class lsst::afw::table::Key< T >