[#bsl-hash-0b]
= xref:bsl.adoc[bsl]::xref:bsl/hash-06.adoc[hash]<BSLSTL_KEY const>
:relfileprefix: ../
:mrdocs:

This class provides hashing functionality for constant key types, by delegating to the same function for non‐constant key types.

== Synopsis

Declared in `<bslstl_hash.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class BSLSTL_KEY>
struct xref:bsl/hash-06.adoc[hash]<BSLSTL_KEY const>
    : xref:bsl/hash-06.adoc[hash<BSLSTL_KEY>]
----

== Base Classes

[cols="1,4"]
|===
| Name| Description
| `xref:bsl/hash-06.adoc[hash<BSLSTL_KEY>]`
| Empty base class for hashing. This class, and all explicit and partial specializations of this class, shall conform to the C++11 Hash Requirements (C++11 17.6.3.4, [hash.requirements]). Unless this template is explicitly specialized, it will use the default hash algorithm provided by `bslh::Hash<>` to supply hash values. In order to hash a user‐defined type using `bsl::hash`, `bsl::hash` must be explicitly specialized for the type, or, preferably, `hashAppend` must be implemented for the type. For more details on `hashAppend` and `bslh::Hash` see the component `bslh_hash`.
|===

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslh/Hash-02/HashAlgorithm.adoc[`HashAlgorithm`] 
| Make the `HASH_ALGORITHM` template parameter available to clients.
| xref:BloombergLP/bslh/Hash-02/result_type.adoc[`result_type`] 
| The type of the hash value that will be returned by the function‐call operator.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/hash-06/operator_call-0a.adoc[`operator()`] 
| Function call operators
|===



[.small]#Created with https://www.mrdocs.com[MrDocs]#