Struct PrecompileTranscript 

pub struct PrecompileTranscript { /* private fields */ }

Precompile transcript implemented with a Poseidon2 sponge.

Structure

Standard Poseidon2 sponge: 12 elements = rate (8 elements) + capacity (4 elements)

Operation

• Record: Each precompile commitment is recorded by absorbing it into the rate, updating the capacity
• State: The evolving capacity tracks all absorbed commitments in order
• Finalization: Squeeze with zero rate to extract a transcript digest (the sequential commitment)

Implementation Note

We store only the 4-element capacity portion between absorptions since since the rate is always overwritten when absorbing blocks that are a multiple of the rate width.

Implementations

impl PrecompileTranscript

pub fn new() -> PrecompileTranscript

Creates a new sponge with zero capacity.

pub fn from_state(state: Word) -> PrecompileTranscript

Creates a transcript from an existing state (for VM operations like log_precompile).

pub fn state(&self) -> Word

Returns the current transcript state (capacity word).

pub fn record(&mut self, commitment: PrecompileCommitment)

Records a precompile commitment into the transcript, updating the state.

pub fn finalize(self) -> Word

Finalizes the transcript to a digest (sequential commitment to all recorded requests).

Details

The output is equivalent to the sequential hash of all PrecompileCommitments, followed by two empty words. This is because

• Each commitment is represented as two words, a multiple of the rate.
• The initial capacity is set to the zero word since we absorb full double words when calling record or finalize.

Trait Implementations

impl Clone for PrecompileTranscript

fn clone(&self) -> PrecompileTranscript

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PrecompileTranscript

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

Formats the value using the given formatter.

impl Default for PrecompileTranscript

fn default() -> PrecompileTranscript

Returns the “default value” for a type.

impl PartialEq for PrecompileTranscript

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for PrecompileTranscript

impl Eq for PrecompileTranscript

impl StructuralPartialEq for PrecompileTranscript