[#BloombergLP-bdlb-TopologicalSortUtil-sort-04]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlb.adoc[bdlb]::xref:BloombergLP/bdlb/TopologicalSortUtil.adoc[TopologicalSortUtil]::sort
:relfileprefix: ../../../
:mrdocs:

Sort nodes into topological order given edge relations.

== Synopsis

Declared in `<bdlb_topologicalsortutil.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class NODE_TYPE>
static
bool
sort(
    xref:bsl/vector-00d.adoc[bsl::vector<NODE_TYPE>]* result,
    xref:bsl/vector-00d.adoc[bsl::vector<NODE_TYPE>]* unsorted,
    xref:bsl/vector-00d.adoc[bsl::vector<bsl::pair<NODE_TYPE, NODE_TYPE>>] const& relations);
----

== Description

Sort the elements of `NODE_TYPE` in topological order determined by the specified `relations` and load the resulting linear ordered set to the specified `result`. If the sort is unsuccessful, load the elements that have not been ordered to the specified `unsorted` list. The input relations are provided as pairs of the form (U, V) where U precedes V in the output. Return `false` if sort fails due to a cycle in the input else return `true` if sort successful. Note that even if the method returns `false`, `result` may contain a subset of elements in the right topological order, essentially elements that the routine was able to sort before the cycle was discovered and `unsorted` will contain the elements that the routine was unable to sort.

== Return Value

`true` if the sort succeeds, and `false` if a cycle is found

== Parameters

[cols="1,4"]
|===
| Name| Description
| *result*
| destination for the ordered nodes
| *unsorted*
| destination for nodes left unsorted on failure
| *relations*
| directed edges (U, V) where U precedes V
|===


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