LvaluePropertyMap
The LvaluePropertyMap provides operator[]
and function get()
for accessing a
reference to a value object. The return type refines that of function get()
in ReadablePropertyMap; it can only be a reference (for a mutable LvaluePropertyMap) or a const reference (for a non-mutable LvaluePropertyMap).
Refinement of
ReadablePropertyMap
for non-mutable or ReadWritePropertyMap for mutable property map.
Notation
PMap |
A type that is a model of LvaluePropertyMap. |
pmap |
An object of type PMap. |
key |
An object of type boost::property_traits<PMap>::key_type. |
Associated Types
Reference Type |
boost::property_traits<PMap>::reference |
The reference type, which must be a reference or const reference to
the value type of the property map.
|
Property Map Category
| boost::property_traits<PMap>::category |
The category of the property: a type convertible to
boost::lvalue_property_map_tag.
|
Valid Expressions
Name | Expression | Return Type | Description |
Access Property Value |
pmap[key] |
value_type& for mutable, const value_type&
otherwise.
|
Obtain a reference to the value associated with key. |
Concept Checking Class
template <class PMap, class Key>
struct LvaluePropertyMapConcept
{
typedef typename property_traits<PMap>::category Category;
typedef boost::lvalue_property_map_tag LvalueTag;
typedef const typename property_traits<PMap>::value_type& const_reference;
void constraints() {
function_requires< ReadWritePropertyMapConcept<PMap, Key> >();
function_requires< ConvertibleConcept<Category, LvalueTag> >();
const_reference ref = pmap[k];
}
PMap pmap;
Key k;
};
template <class PMap, class Key>
struct Mutable_LvaluePropertyMapConcept
{
typedef typename property_traits<PMap>::category Category;
typedef boost::lvalue_property_map_tag LvalueTag;
typedef typename property_traits<PMap>::value_type& reference;
void constraints() {
function_requires< ReadWritePropertyMapConcept<PMap, Key> >();
function_requires<ConvertibleConcept<Category, LvalueTag> >();
reference ref = pmap[k];
}
PMap pmap;
Key k;
};
See Also
Property map concepts