[#BloombergLP-bslstl-SetComparator-operator_call-04f]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::xref:BloombergLP/bslstl/SetComparator.adoc[SetComparator]::operator()
:relfileprefix: ../../../
:mrdocs:

Return whether `lhs` is ordered before the key stored in `rhs`.

== Synopsis

Declared in `<bslstl_setcomparator.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class LOOKUP_KEY>
bool
operator()(
    LOOKUP_KEY const& lhs,
    xref:BloombergLP/bslalg/RbTreeNode.adoc[bslalg::RbTreeNode] const& rhs);
----

== Description

Return `true` if the specified `lhs` is less than (ordered before, according to the comparator held by this object) `value()` of the specified `rhs` after being cast to `NodeType`, and `false` otherwise. The behavior is undefined unless `rhs` can be safely cast to `NodeType`.

== Return Value

`true` if `lhs` is ordered before the key in `rhs`, and `false` otherwise

== Parameters

[cols="1,4"]
|===
| Name| Description
| *lhs*
| lookup key to compare
| *rhs*
| tree node whose key is compared
|===


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