Struct StorageVec 

pub struct StorageVec<V: Codec32> { /* private fields */ }

A persistent dynamic array stored in contract storage.

StorageVec provides a Vec-like interface over contract storage slots. It stores a length counter and individual elements at derived slot addresses.

Type Parameters

• V - Element type, must implement Codec32 for 32-byte encoding

Storage Layout

• derive_slot(namespace, ["vec:len"]) - Length as u64
• derive_slot(namespace, ["vec:elem", index]) - Element at index

Example

const NS_HISTORY: Namespace = Namespace([1u8; 32]);
let history = StorageVec::<u64>::new(NS_HISTORY);

// Push elements
history.push(&100)?;
history.push(&200)?;

// Get length
let len = history.len()?; // 2

// Get element
let first = history.get(0)?.unwrap(); // 100

// Pop element
let last = history.pop()?.unwrap(); // 200

Implementations

impl<V: Codec32> StorageVec<V>

pub const fn new(namespace: Namespace) -> Self

Creates a new vector with the specified namespace.

pub fn len_slot(&self) -> [u8; 32]

Returns the storage slot for the length counter.

pub fn slot_for_index(&self, index: u64) -> [u8; 32]

Returns the storage slot for an element at the given index.

pub fn len_in<B: StorageBackend>(&self, backend: &B) -> Result<u64>

Returns the number of elements (with explicit backend).

pub fn is_empty_in<B: StorageBackend>(&self, backend: &B) -> Result<bool>

Checks if the vector is empty (with explicit backend).

pub fn get_in<B: StorageBackend>( &self, backend: &B, index: u64, ) -> Result<Option<V>>

Gets the element at index (with explicit backend).

Returns None if index is out of bounds.

pub fn set_in<B: StorageBackend>( &self, backend: &mut B, index: u64, value: &V, ) -> Result<bool>

Sets the element at index (with explicit backend).

Returns false if index is out of bounds.

pub fn push_in<B: StorageBackend>( &self, backend: &mut B, value: &V, ) -> Result<u64>

Appends an element to the end (with explicit backend).

Returns the index where the element was inserted.

pub fn pop_in<B: StorageBackend>(&self, backend: &mut B) -> Result<Option<V>>

Removes and returns the last element (with explicit backend).

Returns None if the vector is empty.

pub fn clear_in<B: StorageBackend>(&self, backend: &mut B) -> Result<()>

Clears the vector by setting length to 0 (with explicit backend).

Note: This doesn’t zero out element slots, just resets the length.

pub fn len(&self) -> Result<u64>

Returns the number of elements (production, uses HostStorage).

pub fn get(&self, index: u64) -> Result<Option<V>>

Gets the element at index (production, uses HostStorage).

pub fn set(&self, index: u64, value: &V) -> Result<bool>

Sets the element at index (production, uses HostStorage).

pub fn push(&self, value: &V) -> Result<u64>

Appends an element to the end (production, uses HostStorage).

pub fn pop(&self) -> Result<Option<V>>

Removes and returns the last element (production, uses HostStorage).

pub fn clear(&self) -> Result<()>

Clears the vector (production, uses HostStorage).