[#BloombergLP-bdlcc-Cache-2constructor-01]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlcc.adoc[bdlcc]::xref:BloombergLP/bdlcc/Cache.adoc[Cache]::Cache
:relfileprefix: ../../../
:mrdocs:

Create an empty cache with custom hash and equality functors.

== Synopsis

Declared in `<bdlcc_cache.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
Cache(
    xref:BloombergLP/bdlcc/CacheEvictionPolicy/Enum.adoc[CacheEvictionPolicy::Enum] evictionPolicy,
    std::size_t lowWatermark,
    std::size_t highWatermark,
    HASH const& hashFunction,
    EQUAL const& equalFunction,
    xref:BloombergLP/bslma/Allocator.adoc[bslma::Allocator]* basicAllocator = 0);
----

== Description

Create an empty cache using the specified `evictionPolicy`, `lowWatermark`, and `highWatermark`. The specified `hashFunction` is used to generate the hash values for a given key, and the specified `equalFunction` is used to determine whether two keys have the same value. Optionally specify the `basicAllocator` used to supply memory. If `basicAllocator` is 0, the currently installed default allocator is used. The behavior is undefined unless `lowWatermark <= highWatermark`, `1 <= lowWatermark`, and `1 <= highWatermark`.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *evictionPolicy*
| policy used to select items for eviction
| *lowWatermark*
| size at which eviction stops
| *highWatermark*
| size at which eviction starts after an insert
| *hashFunction*
| hash functor applied to keys
| *equalFunction*
| equality functor applied to keys
| *basicAllocator*
| allocator used to supply memory
|===


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