Struct DataStackRegisterAccess 

pub struct DataStackRegisterAccess<'a> { /* private fields */ }

Handle to one register slot, taken with DataStack::access_register.

A register has a fixed type chosen when it was pushed, and is either empty or full. Reads and takes check the requested type against the register type and return None on a mismatch.

Implementations

impl<'a> DataStackRegisterAccess<'a>

pub fn type_hash(&self) -> TypeHash

Returns the type this register slot was declared with.

pub fn layout(&self) -> Layout

Returns the memory layout of the register slot.

pub fn type_hash_layout(&self) -> (TypeHash, Layout)

Returns type and layout together, reading the header only once.

pub fn has_value(&self) -> bool

Returns true when the register currently holds a value.

pub fn read<T: 'static>(&'a self) -> Option<&'a T>

Borrows the stored value, or returns None when the register is empty or holds another type.

pub fn write<T: 'static>(&'a mut self) -> Option<&'a mut T>

Borrows the stored value mutably, or returns None when the register is empty or holds another type.

pub fn take<T: 'static>(&mut self) -> Option<T>

Moves the value out and leaves the register empty.

Returns None when the register is empty or holds another type.

pub fn free(&mut self) -> bool

Drops the stored value in place and leaves the register empty.

Returns false when there was nothing to drop.

pub fn set<T: Finalize + 'static>(&mut self, value: T)

Moves a value into the register, dropping whatever was there.

Does nothing when T is not the type the register was declared with.

pub fn move_to(&mut self, other: &mut Self)

Moves this register value into other, leaving this one empty.

Does nothing when the two registers differ in type or layout, or when they are the same slot.