Struct MutateContext 

pub struct MutateContext<'a, State = ()> { /* private fields */ }

State and recursive operations shared by mutation callbacks and context policies.

A matched callback owns mutation of its value. Recursive operations reborrow the mutator, so mutable state cannot remain borrowed across them. The context does not store a node: inspect the callback argument and pass it explicitly to default recursion.

Implementations

impl<State> MutateContext<'_, State>

pub fn state(&self) -> &State

User state shared by every callback in this mutation.

pub fn state_mut(&mut self) -> &mut State

Mutably borrow the user state.

pub fn inplace_mode(&self) -> InplaceMode

Engine-established permission for this callback’s current value.

This is not authority to modify a borrow: default in-place descent also requires consuming a MutateValue.

pub fn def_region_kind(&self) -> DefRegionKind

Definition-region state active at the callback’s current value.

pub fn with_def_region_kind<T>( &mut self, kind: DefRegionKind, callback: impl FnOnce(&mut MutateContext<'_, State>) -> Result<T>, ) -> Result<T>

Run recursive operations in a definition region, preserving an outer Pattern. The previous context is restored on return, error, or unwinding.

pub fn mutate<T>(&mut self, value: &T) -> Result<Any>

where for<'x> AnyView<'x>: From<&'x T>,

Mutate a borrowed value through the same callback chain. The value and its descendants begin on the non-in-place path.

pub fn mutate_with<T>( &mut self, value: &T, def_region_kind: DefRegionKind, ) -> Result<Any>

where for<'x> AnyView<'x>: From<&'x T>,

Mutate a borrowed value under an explicit definition-region state.

pub fn maybe_inplace_mutate<T: Into<Any>>(&mut self, value: T) -> Result<Any>

Mutate an owned value, allowing an in-place attempt when it remains uniquely owned and no matched callback borrows it.

pub fn maybe_inplace_mutate_with<T: Into<Any>>( &mut self, value: T, def_region_kind: DefRegionKind, ) -> Result<Any>

Mutate an owned value under an explicit definition-region state.

pub fn maybe_inplace_mutate_with_mode<T: Into<Any>>( &mut self, value: T, def_region_kind: DefRegionKind, mode: InplaceMode, ) -> Result<Any>

Mutate an owned value under an explicit region and in-place permission.

Disallow keeps this input on the copy path even when uniquely owned.

pub fn default_mutate<T>(&mut self, value: &T) -> Result<Any>

where for<'x> AnyView<'x>: From<&'x T>,

Apply default copy-only mutation to an explicitly borrowed value.

This may be called repeatedly while holding node borrows. The value’s children re-enter callback dispatch, but the value itself does not.

pub fn mutate_result<T>(&mut self, value: &T) -> Result<UnchangedOr<Any>>

where for<'x> AnyView<'x>: From<&'x T>,

Mutate a borrowed child while preserving an unchanged result.

pub fn mutate_with_result<T>( &mut self, value: &T, kind: DefRegionKind, ) -> Result<UnchangedOr<Any>>

where for<'x> AnyView<'x>: From<&'x T>,

Mutate a borrowed child under an explicit region, preserving unchanged.

pub fn default_mutate_result<T>( &mut self, value: &T, ) -> Result<UnchangedOr<Any>>

where for<'x> AnyView<'x>: From<&'x T>,

Apply default mutation without materializing an unchanged original.

pub fn default_maybe_inplace_mutate<T>( &mut self, value: MutateValue<'_, T>, ) -> Result<Any>

Consume the handle for default descent with its existing permission.

pub fn default_maybe_inplace_mutate_result<T>( &mut self, value: MutateValue<'_, T>, ) -> Result<UnchangedOr<Any>>

Consume the handle for default descent, preserving permission and Unchanged.

pub fn default_mutate_with_mode<T>( &mut self, value: MutateValue<'_, T>, mode: InplaceMode, ) -> Result<Any>

Continue default mutation after relinquishing the callback value’s borrows.

The mode can restrict, but cannot upgrade, the handle’s permission. Retained owning aliases force copying; temporary handles can be dropped before this call to preserve reuse of the current value.

pub fn default_mutate_with_mode_result<T>( &mut self, value: MutateValue<'_, T>, mode: InplaceMode, ) -> Result<UnchangedOr<Any>>

Consume the callback value for default descent, preserving Unchanged.

pub fn var_remap_get(&mut self, var: &StructuralView) -> Result<Option<Any>>

Look up an invocation-local identity substitution.

pub fn var_remap_set( &mut self, var: &StructuralView, mutated_value: &Any, ) -> Result<()>

Store an invocation-local identity substitution.