---
name: "std::__detail::_Map_base"
section: "3cxx"
platform: "linux"
package: "libstdc++-10-doc"
version: "10.2.1-6"
release: "Debian 11 (Bullseye)"
platforms: ["linux"]
url: "https://new.carta.tech/std::__detail::_Map_base"
---

# std::\_\_detail::\_Map\_base(3cxx)

## NAME

std::\_\_detail::\_Map\_base\< \_Key, \_Value, \_Alloc, \_ExtractKey, \_Equal, \_H1, \_H2, \_Hash, \_RehashPolicy, \_Traits, \_Unique\_keys \>

## SYNOPSIS

Inherited by **std::\_Hashtable\< \_Key, \_Value, \_Alloc, \_ExtractKey, \_Equal, \_H1, \_H2, \_Hash, \_RehashPolicy, \_Traits \>**.

## Detailed Description

### template\<typename \_Key, typename \_Value, typename \_Alloc, typename \_ExtractKey, typename \_Equal, typename \_H1, typename \_H2, typename \_Hash, typename \_RehashPolicy, typename \_Traits, bool \_Unique\_keys = \_Traits::\_\_unique\_keys::value\>

struct std::\_\_detail::\_Map\_base\< \_Key, \_Value, \_Alloc, \_ExtractKey, \_Equal, \_H1, \_H2, \_Hash, \_RehashPolicy, \_Traits, \_Unique\_keys \>" Primary class template \_Map\_base.

If the hashtable has a value type of the form pair\<T1, T2\> and a key extraction policy (\_ExtractKey) that returns the first part of the pair, the hashtable gets a mapped\_type typedef. If it satisfies those criteria and also has unique keys, then it also gets an operator\[\].

Definition at line 645 of file hashtable\_policy.h.

## Author

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