[#BloombergLP-bslstl-HashTable_ComparatorWrapper-0e]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::HashTable_ComparatorWrapper
:relfileprefix: ../../
:mrdocs:

Wrapper ensuring a comparator's call operator is const‐qualified.

== Synopsis

Declared in `<bslstl_hashtable.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class FUNCTOR>
class HashTable_ComparatorWrapper;
----

== Description

This class provides a wrapper around a functor that can compare two values and return a `bool`, so that the function call operator is always declared as `const` qualified.

TBD Provide an optimization for the case of an empty base functor, where we can safely const_cast want calling the base class operator.

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/HashTable_ComparatorWrapper-0e/2constructor-04.adoc[`HashTable_ComparatorWrapper`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/bslstl/HashTable_ComparatorWrapper-0e/functor.adoc[`functor`] 
| Return a reference providing non‐modifiable access to the hash functor wrapped by this object.
| xref:BloombergLP/bslstl/HashTable_ComparatorWrapper-0e/operator_call.adoc[`operator()`] 
| Call the wrapped comparator with `arg1` and `arg2`.
| xref:BloombergLP/bslstl/HashTable_ComparatorWrapper-0e/swap.adoc[`swap`] 
| Exchange the wrapped comparator with that of `other`.
|===


== Specializations

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/HashTable_ComparatorWrapper-0d.adoc[`HashTable_ComparatorWrapper<FUNCTOR const>`] 
| Partial specialization wrapping a const‐qualified comparator.
| xref:BloombergLP/bslstl/HashTable_ComparatorWrapper-07.adoc[`HashTable_ComparatorWrapper<FUNCTOR&>`] 
| Partial specialization wrapping a comparator reference.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/swap-044.adoc[`swap`]
| Swap the functors wrapped by `lhs` and `rhs`.
|===


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