[−][src]Trait frame_support::storage::StorageDecodeLength

pub trait StorageDecodeLength: Sealed + DecodeLength {
    fn decode_len(key: &[u8]) -> Option<usize> { ... }
}

Marker trait that will be implemented for types that support to decode their length in an effificent way. It is expected that the length is at the beginning of the encoded object and that the length is a Compact<u32>.

This trait is sealed.

Provided methods

`fn decode_len(key: &[u8]) -> Option<usize>`

Decode the length of the storage value at key.

This function assumes that the length is at the beginning of the encoded object and is a Compact<u32>.

Returns None if the storage value does not exist or the decoding failed.

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Implementors

`impl<T: Encode> StorageDecodeLength for Vec<T>`[src]