[#llvm-ValueMapCallbackVH]
= xref:llvm.adoc[llvm]::ValueMapCallbackVH
:relfileprefix: ../
:mrdocs:

CallbackVH that updates its ValueMap when the contained Value changes.

== Synopsis

Declared in `<llvm/IR/ValueMap.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    typename KeyT,
    typename ValueT,
    typename Config>
class ValueMapCallbackVH final
    : public xref:llvm/CallbackVH.adoc[CallbackVH]
----

== Description

Behavior follows the user's preferences expressed through the Config object.

== Base Classes

[cols="1,4"]
|===
| Name| Description
| `xref:llvm/CallbackVH.adoc[CallbackVH]`
| Value handle with callbacks on RAUW and destruction.
|===

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:llvm/ValueHandleBase/operator_assign-0b.adoc[`operator=`] 
| Assignment operators
| xref:llvm/ValueMapCallbackVH/Unwrap.adoc[`Unwrap`] 
| Return the key as type `KeyT.`
| xref:llvm/ValueMapCallbackVH/allUsesReplacedWith.adoc[`allUsesReplacedWith`]  [.small]#[virtual]#
| Notify the Config and optionally remap this key when RAUWd.
| xref:llvm/ValueMapCallbackVH/deleted.adoc[`deleted`]  [.small]#[virtual]#
| Notify the Config and erase this key when the Value is deleted.
| xref:llvm/ValueHandleBase/operator_star.adoc[`operator*`] 
| Return a reference to the tracked Value.
| xref:llvm/ValueHandleBase/operator_ptr.adoc[`operator‐>`] 
| Return a pointer to the tracked Value.
| xref:llvm/CallbackVH/2conversion.adoc[`operator Value*`] 
| Implicit conversion to the tracked Value pointer.
|===


== Static Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:llvm/ValueHandleBase/ValueIsDeleted.adoc[`ValueIsDeleted`] 
| Notify all handles that `V` is being destroyed.
| xref:llvm/ValueHandleBase/ValueIsRAUWd.adoc[`ValueIsRAUWd`] 
| Notify all handles that `Old` is being RAUW'd to `New.`
|===


== Protected Enums

[cols="1,4"]
|===
| Name| Description
| xref:llvm/ValueHandleBase/HandleBaseKind.adoc[`HandleBaseKind`] 
| This indicates what sub class the handle actually is.
|===


== Protected Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:llvm/CallbackVH/operator_assign.adoc[`operator=`] 
| Copy‐assign from another callback handle.
| xref:llvm/ValueHandleBase/RemoveFromUseList.adoc[`RemoveFromUseList`] 
| Remove this ValueHandle from its current use list.
| xref:llvm/ValueHandleBase/clearValPtr.adoc[`clearValPtr`] 
| Clear the underlying pointer without clearing the use list.
| xref:llvm/ValueHandleBase/getValPtr.adoc[`getValPtr`] 
| Return the raw Value pointer held by this handle.
| xref:llvm/CallbackVH/setValPtr.adoc[`setValPtr`] 
| Point this handle at `P.`
|===


== Protected Static Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:llvm/ValueHandleBase/isValid.adoc[`isValid`] 
| Return true if `V` is a non‐null Value pointer.
|===


== Friends

[cols="1,4"]
|===
| Name| Description
| `xref:llvm/DenseMapInfo-034d.adoc[llvm::DenseMapInfo]`
| Traits type that supplies DenseMap hashing and equality for value type `T.`
| `xref:llvm/ValueMap.adoc[llvm::ValueMap]`
| See the file comment.
|===


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