[#bsl-Vector_DeduceIteratorCategory-0d]
= xref:bsl.adoc[bsl]::Vector_DeduceIteratorCategory
:relfileprefix: ../
:mrdocs:

This `struct` provides a primitive means to distinguish between iterator types and fundamental types, in order to dispatch to the correct implementation of a function template (or constructor template) passed two arguments of identical type. By default, it is assumed that any type that is not a fundamental type, as determined by the type trait `bsl::is_fundamental`, must be an iterator type. `std::iterator_traits` is updated in C++17 to provide a SFINAE‐friendly instantiation of the primary‐template for types that do not provide all of the nested typedef names, but we cannot portably rely on such a scheme yet.

== Synopsis

Declared in `<bslstl_vector.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class BSLSTL_ITERATOR,
    bool BSLSTL_NOTSPECIALIZED = is_fundamental<BSLSTL_ITERATOR>::value>
struct Vector_DeduceIteratorCategory;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:bsl/Vector_DeduceIteratorCategory-0d/type.adoc[`type`] 
| The deduced iterator category of `BSLSTL_ITERATOR`, or `Nil` for fundamental types.
|===


== Specializations

[cols="1,4"]
|===
| Name| Description
| xref:bsl/Vector_DeduceIteratorCategory-0f.adoc[`Vector_DeduceIteratorCategory<BSLSTL_ITERATOR, true>`] 
| This partial specialization of the `struct` template for fundamental types provides a nested `type` that is not an iterator category, so can be used to control the internal dispatch of function template overloads taking two arguments of the same type.
|===



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