View Template Library

match_element<Container_a, Container_b, Const_tag_a, Base_a, FindType_a, KeyDataPair_a, KeyDataPair_b>


Category: functors	Component type: type

Description

match_element<> is a function object. Specifically, it is an Adaptable Predicate, which means it is a function object that tests the truth or falsehood of some condition. If f is an object of class match_element<> and x is an member of container_b, then f(x) returns true if x is in container_a and false otherwise.

Example

Finds the first element in list L that is also in list M.

list<int> L,M;
...
list<int>::iterator first_match = 
       find_if(L.begin(), L.end(),match_element<list<int>,list<int> >(M));
assert(first_match == L.end());

Definition

Defined in functors.hpp.

Template parameters

Parameter	Description	Default
`container_a`	The view's container A type: the type of container referenced by this view
`container_b`	The view's container B type: the type of container referenced by this view
`const_tag_a`	The view's const tag: either `const_view_tag` or `mutable_view_tag`	`const_view_tag`
`base_a`	The view's ownership type: the base class that determines if the view references or owns the container	`referenced_ownership`
`FindType_a`	A tag to indicate whether the container's has a member function find, or whether the std::find will be used. InternalFindElement, NoInternalFindElement or PairInternalEqualRange.	`ContainerTrait<container_a>::FindType`
`KeyDataPair_a`	A tag to indicate whether the container's value type is a pair. KeyDataPair or NoKeyDataPair	`ContainerTrait<container_a>::ValuePairType`
`KeyDataPair_b`	A tag to indicate whether the container's value type is a pair. KeyDataPair or NoKeyDataPair	`ContainerTrait<container_b>::ValuePairType`

Model of

Adaptable Predicate, DefaultConstructible

Type requirements

Public base classes

Unary_function<container_b::value_type,bool>.

Members

Member	Where defined	Description
`argument_type`	Adaptable Predicate	The type of the first argument: `container_b::value_type`
`result_type`	Adaptable Predicate	The type of the result: `bool`
`match_element()`	DefaultConstructible	The default constructor.
`match_element(const container_a &)`	match_element	The constructor.
`bool operator()(const T& x)`	Unary Function	Function call operator. The return value is `x != 0`.

New members

All of match_element's members are defined in the Adaptable Predicate and DefaultConstructible requirements. match_element does not introduce any new members.