[#BloombergLP-bslstl-UnorderedMapKeyConfiguration-0b]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::xref:BloombergLP/bslstl/UnorderedMapKeyConfiguration-0f.adoc[UnorderedMapKeyConfiguration]<xref:bsl/basic_string-0faf.adoc[basic_string<char>] const, xref:bsl/pair-0b.adoc[pair<basic_string<char> const, Json>]>
:relfileprefix: ../../
:mrdocs:

This `struct` provides a namespace for key‐configuration utilities used by `bsl::unordered_map` to extract keys from stored value objects.

== Synopsis

Declared in `<bslstl_unorderedmapkeyconfiguration.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<>
struct xref:BloombergLP/bslstl/UnorderedMapKeyConfiguration-0f.adoc[UnorderedMapKeyConfiguration]<xref:bsl/basic_string-0faf.adoc[basic_string<char>] const, xref:bsl/pair-0b.adoc[pair<basic_string<char> const, Json>]>;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/UnorderedMapKeyConfiguration-0b/KeyType.adoc[`KeyType`] 
| This `typedef` is an alias to the (template parameter) `KEY`.
| xref:BloombergLP/bslstl/UnorderedMapKeyConfiguration-0b/ValueType.adoc[`ValueType`] 
| This `typedef` is an alias to the (template parameter) `VALUE_TYPE`.
|===


== Static Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/UnorderedMapKeyConfiguration-0b/extractKey.adoc[`extractKey`] 
| Return the member `first` of the specified object `obj`. `obj.first` must be of type `VALUE_TYPE::first_type`, which is the `key` portion of `obj`.
|===



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