[#BloombergLP-bslstl-HashTable-tryEmplace-0b]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::xref:BloombergLP/bslstl/HashTable.adoc[HashTable]::tryEmplace
:relfileprefix: ../../../
:mrdocs:

Emplace a value for a transparent `key` if missing; otherwise return existing.

== Synopsis

Declared in `<bslstl_hashtable.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class LOOKUP_KEY,
    class... ARGS>
xref:BloombergLP/bslalg/BidirectionalLink.adoc[bslalg::BidirectionalLink]*
tryEmplace(
    bool* isInsertedFlag,
    xref:BloombergLP/bslalg/BidirectionalLink.adoc[bslalg::BidirectionalLink]* hint,
    LOOKUP_KEY&& key,
    ARGS&&... args)
requires BloombergLP::bslmf::IsTransparentPredicate<HASHER,    LOOKUP_KEY>::value
   && BloombergLP::bslmf::IsTransparentPredicate<COMPARATOR,LOOKUP_KEY>::value;
----

== Description

If a key equivalent to the specified `key` already exists in this hash‐table, load `false` into the specified `isInsertedFlag` and return a pointer to the existing entry. Otherwise, insert into this hash‐table a newly‐created `value_type` object, constructed from `key` and the specified `args`, load `true` into `isInsertedFlag` and return a pointer to the newly created entry. Use the optionally specified `hint` as a starting place for the search for the existing key.

== Return Value

pointer to the existing or newly created entry

== Parameters

[cols="1,4"]
|===
| Name| Description
| *isInsertedFlag*
| set to `true` if a new entry was inserted
| *hint*
| optional starting node for the key search
| *key*
| transparent key used to find or insert an entry
| *args*
| arguments used to construct the mapped value
|===


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