Struct VecMapper

pub struct VecMapper<SA, T, A = CurrentStorage>
where
    SA: StorageMapperApi,
    T: TopEncode + TopDecode + 'static,
{ /* private fields */ }

Manages a list of items of the same type. Saves each of the items under a separate key in storage. To produce each individual key, it concatenates the main key with a serialized 4-byte index. Indexes start from 1, instead of 0. (We avoid 0-value indexes to prevent confusion between an uninitialized variable and zero.) It also stores the count separately, at what would be index 0. The count is always kept in sync automatically.

Implementations

impl<SA, T, A> VecMapper<SA, T, A>

where SA: StorageMapperApi, A: StorageAddress<SA>, T: TopEncode + TopDecode,

pub fn len(&self) -> usize

Number of items managed by the mapper.

pub fn is_empty(&self) -> bool

True if no items present in the mapper.

pub fn get(&self, index: usize) -> T

Get item at index from storage. Index must be valid (1 <= index <= count).

pub fn get_unchecked(&self, index: usize) -> T

Get item at index from storage. There are no restrictions on the index, calling for an invalid index will simply return the zero-value.

pub fn get_or_else<F: FnOnce() -> T>(self, index: usize, or_else: F) -> T

Get item at index from storage. If index is valid (1 <= index <= count), returns value at index, else calls lambda given as argument. The lambda only gets called lazily if the index is not valid.

pub fn item_is_empty(&self, index: usize) -> bool

Checks whether or not there is anything ins storage at index. Index must be valid (1 <= index <= count).

pub fn item_is_empty_unchecked(&self, index: usize) -> bool

Checks whether or not there is anything in storage at index. There are no restrictions on the index, calling for an invalid index will simply return true.

pub fn load_as_vec(&self) -> Vec<T>

Loads all items from storage and places them in a Vec. Can easily consume a lot of gas.

pub fn iter(&self) -> Iter<'_, SA, T, A>

Provides a forward iterator.

impl<SA, T> VecMapper<SA, T, CurrentStorage>

where SA: StorageMapperApi, T: TopEncode + TopDecode,

pub fn push(&mut self, item: &T) -> usize

Add one item at the end of the list. Returns the index of the newly inserted item, which is also equal to the new number of elements.

pub fn extend_from_slice(&mut self, items: &[T]) -> usize

Adds multiple items at the end of the list. Cheaper than multiple push-es because the count only gets updated once at the end. Returns the index of the last inserted item, which is also equal to the new number of elements.

pub fn set(&mut self, index: usize, item: &T)

Set item at index in storage. Index must be valid (1 <= index <= count).

pub fn update<R, F: FnOnce(&mut T) -> R>(&mut self, index: usize, f: F) -> R

Syntactic sugar, to more compactly express a get, update and set in one line. Takes whatever lies in storage, apples the given closure and saves the final value back to storage. Propagates the return value of the given function.

pub fn clear_entry(&self, index: usize)

Clears item at index from storage. Index must be valid (1 <= index <= count).

pub fn clear_entry_unchecked(&self, index: usize)

Clears item at index from storage. There are no restrictions on the index, calling for an invalid index will simply do nothing.

pub fn swap_remove(&mut self, index: usize)

Clears item at index from storage by swap remove last item takes the index of the item to remove and we remove the last index.

pub fn clear(&mut self)

Deletes all contents form storage and sets count to 0. Can easily consume a lot of gas.

Trait Implementations

impl<'a, SA, T, A> IntoIterator for &'a VecMapper<SA, T, A>

where SA: StorageMapperApi, A: StorageAddress<SA>, T: TopEncode + TopDecode + 'static,

type Item = T

The type of the elements being iterated over.

type IntoIter = Iter<'a, SA, T, A>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<SA, T> StorageClearable for VecMapper<SA, T, CurrentStorage>

where SA: StorageMapperApi, T: TopEncode + TopDecode,

fn clear(&mut self)

Clears all the entries owned by the storage.

impl<SA, T> StorageMapper<SA> for VecMapper<SA, T, CurrentStorage>

where SA: StorageMapperApi, T: TopEncode + TopDecode,

fn new(base_key: StorageKey<SA>) -> Self

Will be called automatically by the #[storage_mapper] annotation generated code.

impl<SA, T> StorageMapperFromAddress<SA> for VecMapper<SA, T, ManagedAddress<SA>>

where SA: StorageMapperApi, T: TopEncode + TopDecode,

fn new_from_address( address: ManagedAddress<SA>, base_key: StorageKey<SA>, ) -> Self

Will be called automatically by the #[storage_mapper_from_address] annotation generated code.

impl<SA, T> TopEncodeMulti for VecMapper<SA, T, CurrentStorage>

where SA: StorageMapperApi, T: TopEncode + TopDecode,

Behaves like a MultiResultVec when an endpoint result.

fn multi_encode_or_handle_err<O, H>( &self, output: &mut O, h: H, ) -> Result<(), H::HandledErr>

where O: TopEncodeMultiOutput, H: EncodeErrorHandler,

Version of top_encode that can handle errors as soon as they occur. For instance in can exit immediately and make sure that if it returns, it is a success. By not deferring error handling, this can lead to somewhat smaller bytecode.

fn multi_encode<O>(&self, output: &mut O) -> Result<(), EncodeError>

where O: TopEncodeMultiOutput,

Attempt to serialize the value to ouput.

impl<SA, T> TypeAbi for VecMapper<SA, T, CurrentStorage>

where SA: StorageMapperApi, T: TopEncode + TopDecode + TypeAbi,

Behaves like a MultiResultVec when an endpoint result.

type Unmanaged = VecMapper<SA, T>

fn type_name() -> TypeName

fn type_name_rust() -> TypeName

fn provide_type_descriptions<TDC: TypeDescriptionContainer>( accumulator: &mut TDC, )

A type can provide more than its own name. For instance, a struct can also provide the descriptions of the type of its fields. TypeAbi doesn’t care for the exact accumulator type, which is abstracted by the TypeDescriptionContainer trait.

fn type_names() -> TypeNames

impl<SA, T> TypeAbiFrom<VecMapper<SA, T>> for MultiValueEncoded<SA, T>

where SA: StorageMapperApi, T: TopEncode + TopDecode,

impl<SA, T> TypeAbiFrom<VecMapper<SA, T>> for VecMapper<SA, T, CurrentStorage>

where SA: StorageMapperApi, T: TopEncode + TopDecode,