Struct TransactionPayloadDecoder 

pub struct TransactionPayloadDecoder<'payload, 'outputs> { /* private fields */ }

Decoder that checks a payload created using TransactionPayloadBuilder and describes its methods without calling them, for example to show a transaction to the user before it is signed.

It runs the same decoding code as TransactionPayloadCaller, so it applies every rule that depends only on the payload. A payload that it accepts can still be rejected by the caller in two cases, which depend on execution:

• the declared outputs don’t fit into the output buffer of the caller, which allocates each of them at a multiple of 16 bytes ([Alignment::MAX]) after the previous one: they fit if the capacities of Self::declared_outputs(), each except the last rounded up to a multiple of 16, add up to at most the size of the output buffer (32 KiB in SimpleWalletBase::execute(), see OUTPUT_BUFFER_SIZE); the caller checks this when it is created, before it calls any method
• an #[output] that a later method uses as a slot doesn’t hold an address after its method was called; the caller checks this when it reaches that slot, so when the caller rejects a payload for it, the decoder either accepts the payload or rejects it with an error from later in the payload

A payload can declare outputs that no method writes. The decoder and the caller accept it, the memory of such an output is allocated but never used, while TransactionPayloadBuilder never creates such a payload.

Descriptions contain no pointers into memory other than the payload, so any payload can be decoded safely.

Implementations

impl<'payload, 'outputs> TransactionPayloadDecoder<'payload, 'outputs>

pub fn new( payload: &'payload [u128], declared_outputs: &'outputs mut [MaybeUninit<DeclaredOutput>; 16], ) -> Result<Self, TransactionPayloadDecoderError>

Create a new instance and read the outputs that the payload declares, at most MAX_OUTPUTS, into declared_outputs.

Returns an error if the outputs that the payload declares can’t be read. Every payload starts with them, so an empty payload is too small.

pub fn declared_outputs(&self) -> &[DeclaredOutput]

Outputs that the payload declares, by output index

pub fn next_method( &mut self, ) -> Result<Option<DecodedMethod<'_, 'payload>>, TransactionPayloadDecoderError>

Decode and check the next method, None if there are no more methods in the payload.

The method is returned only after all of it was checked. Its arguments are stored in the decoder and replaced by the next call. After an error, every call returns TransactionPayloadDecoderError::FailedEarlier.

Trait Implementations

impl<'payload, 'outputs> Debug for TransactionPayloadDecoder<'payload, 'outputs>

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

Formats the value using the given formatter.