Struct ink_storage::Box

pub struct Box<T> where
    T: SpreadLayout,  { /* fields omitted */ }

A dynamically allocated storage entity.

Users can use this in order to make certain SpreadLayout storage entities used in contexts that require a PackedLayout storage entity by simply packing the storage entity within a storage::Box.

Dynamic allocations caused by the creation of storage::Box instances do have some limited overhead:

• The dynamic allocation itself has to be provided by some dynamic storage allocator that needs to be invoked.
• Each dynamic storage allocation implies roughly 1.12 bits of overhead.
• Upon ever first dereferencing of a storage::Box instance a cryptographic hash routine is run in order to compute the underlying storage key.

Use this abstraction with caution due to the aforementioned performance implications.

Implementations

impl<T> Box<T> where
    T: SpreadLayout, 

pub fn new(value: T) -> Self

Creates a new boxed entity.

impl<T> Box<T> where
    T: SpreadLayout, 

pub fn get(boxed: &Self) -> &T

Returns a shared reference to the boxed value.

Note

This loads the value from the pointed to contract storage if this did not happen before.

Panics

If loading from contract storage failed.

pub fn get_mut(boxed: &mut Self) -> &mut T

Returns an exclusive reference to the boxed value.

Note

This loads the value from the pointed to contract storage if this did not happen before.

Panics

If loading from contract storage failed.

Trait Implementations

impl<T> AsMut<T> for StorageBox<T> where
    T: SpreadLayout, 

fn as_mut(&mut self) -> &mut T

Performs the conversion.

impl<T> AsRef<T> for StorageBox<T> where
    T: SpreadLayout, 

fn as_ref(&self) -> &T

Performs the conversion.

impl<T> Borrow<T> for StorageBox<T> where
    T: SpreadLayout, 

fn borrow(&self) -> &T

Immutably borrows from an owned value.

impl<T> BorrowMut<T> for StorageBox<T> where
    T: SpreadLayout, 

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value.

impl<T: Debug> Debug for Box<T> where
    T: SpreadLayout, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Decode for StorageBox<T> where
    T: SpreadLayout, 

fn decode<I: Input>(value: &mut I) -> Result<Self, Error>

Attempt to deserialise the value from input.

fn skip<I>(input: &mut I) -> Result<(), Error> where
    I: Input, 

Attempt to skip the encoded value from input.

fn encoded_fixed_size() -> Option<usize>

Returns the fixed encoded size of the type.

impl<T> Deref for StorageBox<T> where
    T: SpreadLayout, 

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T> DerefMut for StorageBox<T> where
    T: SpreadLayout, 

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T> Display for StorageBox<T> where
    T: Display + SpreadLayout, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Drop for StorageBox<T> where
    T: SpreadLayout, 

fn drop(&mut self)

Executes the destructor for this type.

impl<T> Encode for StorageBox<T> where
    T: SpreadLayout, 

fn size_hint(&self) -> usize

If possible give a hint of expected size of the encoding.

fn encode_to<O: Output + ?Sized>(&self, dest: &mut O)

Convert self to a slice and append it to the destination.

fn encode(&self) -> Vec<u8>

Convert self to an owned vector.

fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R

Convert self to a slice and then invoke the given closure with it.

fn encoded_size(&self) -> usize

Calculates the encoded size.

impl<T> Hash for StorageBox<T> where
    T: Hash + SpreadLayout, 

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl<T> Ord for StorageBox<T> where
    T: Ord + SpreadLayout, 

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl<T> PackedLayout for StorageBox<T> where
    T: SpreadLayout, 

fn pull_packed(&mut self, _at: &Key)

Indicates to self that is has just been pulled from the storage.

fn push_packed(&self, _at: &Key)

Indicates to self that it is about to be pushed to contract storage.

fn clear_packed(&self, _at: &Key)

Indicates to self that it is about to be cleared from contract storage.

impl<T> PartialEq<Box<T>> for StorageBox<T> where
    T: PartialEq + SpreadLayout, 

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<T> PartialOrd<Box<T>> for StorageBox<T> where
    T: PartialOrd + SpreadLayout, 

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Self) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Self) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn ge(&self, other: &Self) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

fn gt(&self, other: &Self) -> bool

This method tests greater than (for self and other) and is used by the > operator.

impl<T> SpreadLayout for StorageBox<T> where
    T: SpreadLayout, 

const FOOTPRINT: u64

The footprint of the type.

fn pull_spread(ptr: &mut KeyPtr) -> Self

Pulls an instance of Self from the contract storage.

fn push_spread(&self, ptr: &mut KeyPtr)

Pushes an instance of Self to the contract storage.

fn clear_spread(&self, ptr: &mut KeyPtr)

Clears an instance of Self from the contract storage.

const REQUIRES_DEEP_CLEAN_UP: bool

Indicates whether a type requires deep clean-up of its state meaning that a clean-up routine has to decode an entity into an instance in order to eventually recurse upon its tear-down. This is not required for the majority of primitive data types such as i32, however types such as storage::Box that might want to forward the clean-up procedure to their inner T require a deep clean-up.

impl<T> StorageLayout for StorageBox<T> where
    T: SpreadLayout, 

fn layout(key_ptr: &mut KeyPtr) -> Layout

Returns the static storage layout of Self.

impl<T> TypeInfo for StorageBox<T> where
    T: SpreadLayout + 'static, 

type Identity = Self

The type identifying for which type info is provided.

fn type_info() -> Type

Returns the static type identifier for Self.

impl<T> Eq for StorageBox<T> where
    T: Eq + SpreadLayout,