[#BloombergLP-bslstl-MapComparator]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::MapComparator
:relfileprefix: ../../
:mrdocs:

This class compares map keys with `TreeNode` objects using `COMPARATOR`.

== Synopsis

Declared in `<bslstl_mapcomparator.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class KEY,
    class VALUE,
    class COMPARATOR>
class MapComparator;
----

== Description

This class overloads the function‐call operator to compare a referenced `bslalg::RbTreeNode` object with a object of the parameterized `KEY` type, assuming the reference to `bslalg::RbTreeNode` is a base of a `bslstl::TreeNode` holding a `pair<KEY, VALUE>`, using a functor of the parameterized `COMPARATOR` type.

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/MapComparator/NodeType.adoc[`NodeType`] 
| This alias represents the type of node holding a `ValueType` object.
| xref:BloombergLP/bslstl/MapComparator/ValueType.adoc[`ValueType`] 
| This alias represents the type of the values held by nodes in an `bslalg::RbTree` object.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/MapComparator/2constructor-08.adoc[`MapComparator`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/bslstl/MapComparator/keyComparator-05.adoc[`keyComparator`] 
| `keyComparator` overloads
| xref:BloombergLP/bslstl/MapComparator/operator_call-00f.adoc[`operator()`] 
| Function call operators
| xref:BloombergLP/bslstl/MapComparator/swap.adoc[`swap`] 
| Efficiently exchange the value of this object with the value of the specified `other` object. This method provides the no‐throw exception‐safety guarantee.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/swap-015.adoc[`swap`]
| Efficiently exchange the values of the specified `a` and `b` objects. This function provides the no‐throw exception‐safety guarantee.
|===


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