[#BloombergLP-bslstl-IteratorUtil_LegacyInsertDistance-03]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::IteratorUtil_LegacyInsertDistance
:relfileprefix: ../../
:mrdocs:

Utility for type‐based dispatch of insert‐distance calculation.

== Synopsis

Declared in `<bslstl_iteratorutil.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class t_INPUT_ITERATOR,
    class t_SENTINEL,
    bool t_MATCHING_SENTINEL = bsl::is_convertible<t_SENTINEL, t_INPUT_ITERATOR>::value>
struct IteratorUtil_LegacyInsertDistance;
----

== Description

This supporting utility type is used for type‐based dispatch as part of the implementation of the similarly structured functions `insertDistance` and `canCalculateInsertDistance` from `IteratorUtil`. Selection between the primary template and secondary (much simpler) one is performed based on the defaulted third parameter that checks if the (template parameter) type `t_SENTINEL` is convertible to the (template parameter) type `t_INPUT_ITERATOR`. When the primary template is selected, the decision to delegate distance calculation to `bsl::distance` is performed using tag dispatch.

== Static Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/IteratorUtil_LegacyInsertDistance-03/canCalculate.adoc[`canCalculate`] 
| Return whether insert‐distance can be calculated for these types.
| xref:BloombergLP/bslstl/IteratorUtil_LegacyInsertDistance-03/insertDistance.adoc[`insertDistance`] 
| Return the insertable element count for the specified iterator range.
|===


== Specializations

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/IteratorUtil_LegacyInsertDistance-0c.adoc[`IteratorUtil_LegacyInsertDistance<t_INPUT_ITERATOR, t_SENTINEL, false>`] 
| Partial specialization that does not support insert‐distance calculation.
|===



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