Interface for a heterogeneous map. More...

#include <GenericMap.h>

Inheritance diagram for lsst::afw::typehandling::GenericMap< K >:

Public Types
using	key_type = K

using	size_type = std::size_t

using	difference_type = std::ptrdiff_t

Public Member Functions
virtual	~GenericMap () noexcept=default

virtual size_type	size () const noexcept=0
	Return the number of key-value pairs in the map.

virtual bool	empty () const noexcept=0
	Return `true` if this map contains no key-value pairs.

virtual size_type	max_size () const noexcept=0
	Return the maximum number of elements the container is able to hold due to system or library implementation limitations.

template<typename T >
size_type	count (Key< K, T > const &key) const
	Return the number of elements mapped to the specified key.

virtual bool	contains (K const &key) const =0
	Return `true` if this map contains a mapping whose key has the specified label.

template<typename T >
bool	contains (Key< K, T > const &key) const
	Return `true` if this map contains a mapping for the specified key.

virtual std::vector< K > const &	keys () const noexcept=0
	Return the set of all keys, without type information.

template<class Visitor >
auto	apply (Visitor &&visitor) const
	Apply an operation to each key-value pair in the map.

template<class Visitor >
auto	apply (Visitor &&visitor)
	Apply a modifying operation to each key-value pair in the map.


template<typename T , typename std::enable_if_t<!detail::IS_SMART_PTR< T >, int > = 0>
T &	at (Key< K, T > const &key)
	Return a reference to the mapped value of the element with key equal to `key`.

template<typename T , typename std::enable_if_t<!detail::IS_SMART_PTR< T >, int > = 0>
T const &	at (Key< K, T > const &key) const
	Return a reference to the mapped value of the element with key equal to `key`.

template<typename T , typename std::enable_if_t< std::is_base_of< Storable, T >::value, int > = 0>
std::shared_ptr< T >	at (Key< K, std::shared_ptr< T > > const &key) const
	Return a reference to the mapped value of the element with key equal to `key`.


virtual bool	operator== (GenericMap const &other) const noexcept
	Test for map equality.

bool	operator!= (GenericMap const &other) const
	Test for map equality.

Protected Types
using	StorableType
	The types that can be stored in a map.


using	ConstValueReference = decltype(_typeToConstRef(std::declval<StorableType>()))
	A type-agnostic reference to the value stored inside the map.

using	ValueReference = decltype(_typeToRef(std::declval<StorableType>()))
	A type-agnostic reference to the value stored inside the map.

Protected Member Functions

virtual ConstValueReference	unsafeLookup (K key) const =0
	Return a reference to the mapped value of the element with key equal to `key`.

ValueReference	unsafeLookup (K key)
	Return a reference to the mapped value of the element with key equal to `key`.

Detailed Description

template<typename K>
class lsst::afw::typehandling::GenericMap< K >

Interface for a heterogeneous map.

Objects of type GenericMap cannot necessarily have keys added or removed, although mutable values can be modified as usual. In Python, a GenericMap behaves like a collections.abc.Mapping. See MutableGenericMap for a GenericMap that must allow insertions and deletions.

Template Parameters

K	the key type of the map.

A Key for the map is parameterized by both the key type K and a corresponding value type V. The map is indexed uniquely by a value of type K; no two entries in the map may have identical values of Key::getId().

All operations are sensitive to the value type of the key: a contains call requesting an integer labeled "value", for example, will report no such integer if instead there is a string labeled "value". For Python compatibility, a GenericMap does not store type information internally, instead relying on RTTI for type checking.

All subclasses must guarantee, as a class invariant, that every value in the map is implicitly nothrow-convertible to the type indicated by its key. For example, MutableGenericMap ensures this by appropriately templating all operations that create new key-value pairs.

A GenericMap may contain primitive types, strings, Storable, and shared pointers to Storable as values. It does not support unique pointers to Storable because such pointers are read destructively. For safety reasons, it may not contain references, C-style pointers, or arrays to any type. Due to implementation restrictions, const types (except pointers to const Storable) are not currently supported.

Definition at line 79 of file GenericMap.h.

Member Typedef Documentation

◆ ConstValueReference

template<typename K >

using lsst::afw::typehandling::GenericMap< K >::ConstValueReference = decltype(_typeToConstRef(std::declval<StorableType>()))

protected

A type-agnostic reference to the value stored inside the map.

These are the reference equivalents (T const& or T&) of StorableType.

Definition at line 369 of file GenericMap.h.

◆ difference_type

template<typename K >

using lsst::afw::typehandling::GenericMap< K >::difference_type = std::ptrdiff_t

Definition at line 83 of file GenericMap.h.

◆ key_type

template<typename K >

using lsst::afw::typehandling::GenericMap< K >::key_type = K

Definition at line 81 of file GenericMap.h.

◆ size_type

template<typename K >

using lsst::afw::typehandling::GenericMap< K >::size_type = std::size_t

Definition at line 82 of file GenericMap.h.

◆ StorableType

template<typename K >

using lsst::afw::typehandling::GenericMap< K >::StorableType

protected

Initial value:

std::variant<bool, int, long, long long, float, double, std::string,

PolymorphicValue, std::shared_ptr<Storable const>>

std::string

std::shared_ptr

The types that can be stored in a map.

Keys of any subclass of Storable are implemented using PolymorphicValue to preserve type.

Definition at line 359 of file GenericMap.h.

◆ ValueReference

template<typename K >

using lsst::afw::typehandling::GenericMap< K >::ValueReference = decltype(_typeToRef(std::declval<StorableType>()))

protected

A type-agnostic reference to the value stored inside the map.

These are the reference equivalents (T const& or T&) of StorableType.

Definition at line 370 of file GenericMap.h.

Constructor & Destructor Documentation

◆ ~GenericMap()

template<typename K >

virtual lsst::afw::typehandling::GenericMap< K >::~GenericMap ( )

virtualdefaultnoexcept

Member Function Documentation

◆ apply() [1/2]

template<typename K >

template<class Visitor >

auto lsst::afw::typehandling::GenericMap< K >::apply ( Visitor && visitor )

inline

Apply a modifying operation to each key-value pair in the map.

Template Parameters

Visitor a callable that takes a key and a value. Requirements as for apply(Visitor&&) const, except that it may take non-const references to values.

Parameters

visitor the visitor to apply

Returns: if Visitor has a return value, a std::vector of values returned from applying visitor to each key in keys, in that order. Otherwise, void.

Exception Safety: Provides basic exception safety if Visitor is exception-safe.

Note: This implementation calls keys, then calls unsafeLookup for each key before passing the result to visitor.

Definition at line 331 of file GenericMap.h.

                                  {
        // Delegate to private methods to hide special-casing of Visitor
        return _apply(visitor);
    }

◆ apply() [2/2]

template<typename K >

template<class Visitor >

auto lsst::afw::typehandling::GenericMap< K >::apply ( Visitor && visitor ) const

inline

Apply an operation to each key-value pair in the map.

Template Parameters

Visitor a callable that takes a key and a value. See below for exact requirements.

Parameters

visitor the visitor to apply

Returns: if Visitor has a return value, a std::vector of values returned from applying visitor to each key in keys, in that order. Otherwise, void.

Exception Safety: Provides the same level of exception safety as Visitor, or strong exception safety if Visitor cannot throw.

A Visitor must define one or more operator() that take a weakly-typed key and a value. Each operator() must return the same type (which may be void). Through any combination of overloading or templates, the visitor must accept values of the following types:

either bool or bool const&
either int or int const&
either long or long const&
either long long or long long const&
either float or float const&
either double or double const&
std::string const&
Storable const&
std::shared_ptr<Storable const>

Note: This implementation calls keys, then calls unsafeLookup for each key before passing the result to visitor.

An example visitor that prints each key-value pair to standard output:

template <typename K>
class Printer {
public:
    template <typename V>
    void operator()(K const& key, V const& value) {
        std::cout << key << ": " << value << "," << std::endl;
    }

    void operator()(K const& key, Storable const& value) {
        std::cout << key << ": ";
        try {
            std::cout << value;
        } catch (UnsupportedOperationException const&) {
            std::cout << "[unprintable]";
        }
        std::cout << "," << std::endl;
    }

    void operator()(K const& key, std::shared_ptr<Storable const> value) {
        if (value != nullptr) {
            operator()(key, *value);
        } else {
            operator()(key, "null");
        }
    }
};

Definition at line 309 of file GenericMap.h.

                                        {
        // Delegate to private methods to hide special-casing of Visitor
        return _apply(visitor);
    }

◆ at() [1/3]

template<typename K >

template<typename T , typename std::enable_if_t< std::is_base_of< Storable, T >::value, int > = 0>

std::shared_ptr< T > lsst::afw::typehandling::GenericMap< K >::at ( Key< K, std::shared_ptr< T > > const & key ) const

inline

Return a reference to the mapped value of the element with key equal to key.

Template Parameters

T	the type of the element mapped to `key`. It may be the exact type of the element, if known, or any type to which its references or pointers can be implicitly converted (e.g., a superclass). For example, references to built-in types are not convertible, so you can't retrieve an `int` with `T=long`.

Parameters

key	the key of the element to find

Returns: a reference to the T mapped to key, if one exists

Exceptions

pex::exceptions::OutOfRangeError Thrown if the map does not have a T with the specified key

Exception Safety: Provides strong exception safety.

Note: This implementation calls unsafeLookup once, then uses templates and RTTI to determine if the value is of the expected type.

Definition at line 121 of file GenericMap.h.

                                                                   {
        // Delegate to private methods to hide further special-casing of T
        return _at(key);
    }

◆ at() [2/3]

template<typename K >

template<typename T , typename std::enable_if_t<!detail::IS_SMART_PTR< T >, int > = 0>

T & lsst::afw::typehandling::GenericMap< K >::at ( Key< K, T > const & key )

inline

Return a reference to the mapped value of the element with key equal to key.

Template Parameters

T	the type of the element mapped to `key`. It may be the exact type of the element, if known, or any type to which its references or pointers can be implicitly converted (e.g., a superclass). For example, references to built-in types are not convertible, so you can't retrieve an `int` with `T=long`.

Parameters

key	the key of the element to find

Returns: a reference to the T mapped to key, if one exists

Exceptions

pex::exceptions::OutOfRangeError Thrown if the map does not have a T with the specified key

Exception Safety: Provides strong exception safety.

Note: This implementation calls unsafeLookup once, then uses templates and RTTI to determine if the value is of the expected type.

Definition at line 109 of file GenericMap.h.

                                {
        // Both casts are safe; see Effective C++, Item 3
        return const_cast<T&>(static_cast<const GenericMap&>(*this).at(key));
    }

◆ at() [3/3]

template<typename K >

template<typename T , typename std::enable_if_t<!detail::IS_SMART_PTR< T >, int > = 0>

T const & lsst::afw::typehandling::GenericMap< K >::at ( Key< K, T > const & key ) const

inline

Return a reference to the mapped value of the element with key equal to key.

Template Parameters

T	the type of the element mapped to `key`. It may be the exact type of the element, if known, or any type to which its references or pointers can be implicitly converted (e.g., a superclass). For example, references to built-in types are not convertible, so you can't retrieve an `int` with `T=long`.

Parameters

key	the key of the element to find

Returns: a reference to the T mapped to key, if one exists

Exceptions

pex::exceptions::OutOfRangeError Thrown if the map does not have a T with the specified key

Exception Safety: Provides strong exception safety.

Note: This implementation calls unsafeLookup once, then uses templates and RTTI to determine if the value is of the expected type.

Definition at line 115 of file GenericMap.h.

                                            {
        // Delegate to private methods to hide further special-casing of T
        return _at(key);
    }

◆ contains() [1/2]

template<typename K >

virtual bool lsst::afw::typehandling::GenericMap< K >::contains ( K const & key ) const

pure virtual

Return true if this map contains a mapping whose key has the specified label.

More formally, this method returns true if and only if this map contains a mapping with a key k such that k.getId() == key. There can be at most one such mapping.

Parameters

key	the weakly-typed key to search for

Returns: true if this map contains a mapping for key, regardless of value type.

Exception Safety: Provides strong exception safety.

Implemented in lsst::afw::typehandling::SimpleGenericMap< K >.

◆ contains() [2/2]

template<typename K >

template<typename T >

bool lsst::afw::typehandling::GenericMap< K >::contains ( Key< K, T > const & key ) const

inline

Return true if this map contains a mapping for the specified key.

This is equivalent to testing whether at(key) would succeed.

Template Parameters

T	the value corresponding to `key`

Parameters

key	the key to search for

Returns: true if this map contains a mapping from the specified key to a T

Exception Safety: Provides strong exception safety.

Note: This implementation calls contains(K const&) const. If the call returns true, it calls unsafeLookup, then uses templates and RTTI to determine if the value is of the expected type. The performance of this method depends strongly on the performance of contains(K const&).

Definition at line 194 of file GenericMap.h.

                                              {
        // Delegate to private methods to hide special-casing of T
        return _contains(key);
    }

◆ count()

template<typename K >

template<typename T >

size_type lsst::afw::typehandling::GenericMap< K >::count ( Key< K, T > const & key ) const

inline

Return the number of elements mapped to the specified key.

Template Parameters

T	the value corresponding to `key`

Parameters

key	key value of the elements to count

Returns: number of T with key key, that is, either 1 or 0.

Exception Safety: Provides strong exception safety.

Note: This implementation calls contains.

Definition at line 157 of file GenericMap.h.

                                                {
        return contains(key) ? 1 : 0;
    }

◆ empty()

template<typename K >

virtual bool lsst::afw::typehandling::GenericMap< K >::empty ( ) const

pure virtualnoexcept

Return true if this map contains no key-value pairs.

Implemented in lsst::afw::typehandling::SimpleGenericMap< K >.

◆ keys()

template<typename K >

virtual std::vector< K > const & lsst::afw::typehandling::GenericMap< K >::keys ( ) const

pure virtualnoexcept

Return the set of all keys, without type information.

Returns: a read-only view of all keys currently in the map, in the same iteration order as this object. The view will be updated by changes to the underlying map.

Warning: Do not modify this map while iterating over its keys.; Do not store the returned reference in variables that outlive the map; destroying the map will invalidate the reference.

Note: The keys are returned as a list, rather than a set, so that subclasses can give them a well-defined iteration order.

Implemented in lsst::afw::typehandling::SimpleGenericMap< K >.

◆ max_size()

template<typename K >

virtual size_type lsst::afw::typehandling::GenericMap< K >::max_size ( ) const

pure virtualnoexcept

Return the maximum number of elements the container is able to hold due to system or library implementation limitations.

Note: This value typically reflects the theoretical limit on the size of the container. At runtime, the size of the container may be limited to a value smaller than max_size() by the amount of RAM available.

Implemented in lsst::afw::typehandling::SimpleGenericMap< K >.

◆ operator!=()

template<typename K >

bool lsst::afw::typehandling::GenericMap< K >::operator!= ( GenericMap< K > const & other ) const

inline

Test for map equality.

Two GenericMap objects are considered equal if they map the same keys to the same values. The two objects do not need to have the same implementation class. If either class orders its keys, the order is ignored.

Note: This implementation calls keys on both objects and compares the results. If the two objects have the same keys, it calls unsafeLookup for each key and compares the values.

Definition at line 245 of file GenericMap.h.

245{ return !(*this == other); }

◆ operator==()

template<typename K >

virtual bool lsst::afw::typehandling::GenericMap< K >::operator== ( GenericMap< K > const & other ) const

inlinevirtualnoexcept

Test for map equality.

Two GenericMap objects are considered equal if they map the same keys to the same values. The two objects do not need to have the same implementation class. If either class orders its keys, the order is ignored.

Note: This implementation calls keys on both objects and compares the results. If the two objects have the same keys, it calls unsafeLookup for each key and compares the values.

Definition at line 229 of file GenericMap.h.

                                                                    {
        auto keys1 = this->keys();
        auto keys2 = other.keys();
        if (!std::is_permutation(keys1.begin(), keys1.end(), keys2.begin(), keys2.end())) {
            return false;
        }
        for (K const& key : keys1) {
            // Can't use std::variant::operator== here because
            // std::reference_wrapper isn't equality-comparable.
            if (!detail::refwrap_equals()(this->unsafeLookup(key), other.unsafeLookup(key))) {
                return false;
            }
        }
        return true;
    }

◆ size()

template<typename K >

virtual size_type lsst::afw::typehandling::GenericMap< K >::size ( ) const

pure virtualnoexcept

Return the number of key-value pairs in the map.

Implemented in lsst::afw::typehandling::SimpleGenericMap< K >.

◆ unsafeLookup() [1/2]

template<typename K >

ValueReference lsst::afw::typehandling::GenericMap< K >::unsafeLookup ( K key )

inlineprotected

Return a reference to the mapped value of the element with key equal to key.

This method is the primary way to implement the GenericMap interface.

Parameters

key	the key of the element to find

Returns: the value mapped to key, if one exists

Exceptions

pex::exceptions::OutOfRangeError Thrown if the map does not have a value with the specified key

Exception Safety: Must provide strong exception safety.

Definition at line 391 of file GenericMap.h.

                                       {
        ConstValueReference constRef = static_cast<const GenericMap&>(*this).unsafeLookup(key);
        return std::visit(
            [](auto const & v) { return ValueReference(detail::refwrap_const_cast(v)); },
            constRef
        );
    }

◆ unsafeLookup() [2/2]

template<typename K >

virtual ConstValueReference lsst::afw::typehandling::GenericMap< K >::unsafeLookup ( K key ) const

protectedpure virtual

Return a reference to the mapped value of the element with key equal to key.

This method is the primary way to implement the GenericMap interface.

Parameters

key	the key of the element to find

Returns: the value mapped to key, if one exists

Exceptions

pex::exceptions::OutOfRangeError Thrown if the map does not have a value with the specified key

Exception Safety: Must provide strong exception safety.

Implemented in lsst::afw::typehandling::SimpleGenericMap< K >.

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

/j/snowflake/release/lsstsw/stack/lsst-scipipe-8.0.0/Linux64/afw/g5a732f18d5+53520f316c/include/lsst/afw/typehandling/GenericMap.h

Public Types

Public Member Functions

Protected Types

Protected Member Functions

Detailed Description

Member Typedef Documentation

◆ ConstValueReference

◆ difference_type

◆ key_type

◆ size_type

◆ StorableType

◆ ValueReference

Constructor & Destructor Documentation

◆ ~GenericMap()

Member Function Documentation

◆ apply() [1/2]

◆ apply() [2/2]

◆ at() [1/3]

◆ at() [2/3]

◆ at() [3/3]

◆ contains() [1/2]

◆ contains() [2/2]

◆ count()

◆ empty()

◆ keys()

◆ max_size()

◆ operator!=()

◆ operator==()

◆ size()

◆ unsafeLookup() [1/2]

◆ unsafeLookup() [2/2]