[#btck-Iterator]
= xref:btck.adoc[btck]::Iterator
:relfileprefix: ../
:mrdocs:

Random‐access iterator that lazily materializes views of a collection by index.

== Synopsis

Declared in `<kernel/bitcoinkernel_wrapper.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    typename Collection,
    typename ValueType,
    auto GetFunc>
class Iterator;
----

== Description

Dereferencing invokes `GetFunc` on the collection with the current index, returning a copy (a lightweight view), so the iterator does not hold elements.

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:btck/Iterator/difference_type.adoc[`difference_type`] 
| Signed distance between iterators.
| xref:btck/Iterator/iterator_category.adoc[`iterator_category`] 
| Iterator category tag.
| xref:btck/Iterator/iterator_concept.adoc[`iterator_concept`] 
| Iterator concept tag.
| xref:btck/Iterator/value_type.adoc[`value_type`] 
| The element type produced on dereference.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:btck/Iterator/2constructor-0dc.adoc[`Iterator`]         [.small]#[constructor]#
| Constructors
| xref:btck/Iterator/operator_star.adoc[`operator*`] 
| Returns the element at the current index.
| xref:btck/Iterator/operator_plus.adoc[`operator+`] 
| Returns an iterator advanced by `n` positions.
| xref:btck/Iterator/operator_inc-01c.adoc[`operator++`] 
| Increment operators
| xref:btck/Iterator/operator_plus_eq.adoc[`operator+=`] 
| Advances the iterator by `n` positions.
| xref:btck/Iterator/operator_minus-03.adoc[`operator‐`] 
| Subtraction operators
| xref:btck/Iterator/operator_dec-02.adoc[`operator‐‐`] 
| Decrement operators
| xref:btck/Iterator/operator_minus_eq.adoc[`operator‐=`] 
| Rewinds the iterator by `n` positions.
| xref:btck/Iterator/operator_subs.adoc[`operator[]`] 
| Returns the element `n` positions from the current one.
| xref:btck/Iterator/operator_eq.adoc[`operator==`] 
| Tests two iterators for equality.
| xref:btck/Iterator/operator_3way.adoc[`operator<=>`] 
| Orders two iterators by index.
|===


== Friends

[cols="1,4"]
|===
| Name| Description
| `xref:btck/operator_plus.adoc[btck::operator+]`
| Returns an iterator advanced by `n` positions (offset on the left).
|===


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