Struct Encoder

pub struct Encoder { /* private fields */ }

Efficient encoding of circuit selectors

This encoder represents selectors as points in a k-dimensional space where each coordinate is between 0 and max_degree, and their sum doesn’t exceed max_degree. This approach allows encoding many selectors with significantly fewer columns than the traditional approach of using one boolean column per selector.

Implementations

impl Encoder

pub fn new(cnt: usize, max_degree: u32, reserve_invalid: bool) -> Self

Create a new encoder for a given number of flags and maximum degree. The flags will correspond to points in F^k, where k is the number of variables. The zero point is reserved for the dummy row. max_degree is the upper bound for the flag expressions, but the eval function of the encoder itself will use some constraints of degree max_degree + 1. reserve_invalid indicates if the encoder should reserve the (0, …, 0) point as an invalid/dummy flag.

pub fn get_flag_expr<AB: InteractionBuilder>( &self, flag_idx: usize, vars: &[AB::Var], ) -> AB::Expr

Get the polynomial expression that equals 1 when the variables encode the flag at index flag_idx

pub fn get_flag_pt(&self, flag_idx: usize) -> Vec<u32>

Get the point coordinates that correspond to the flag at index flag_idx

pub fn is_valid<AB: InteractionBuilder>(&self, vars: &[AB::Var]) -> AB::Expr

Returns an expression that is 1 if the variables encode a valid flag and 0 if they encode the invalid point

pub fn flags<AB: InteractionBuilder>(&self, vars: &[AB::Var]) -> Vec<AB::Expr>

Returns all flag expressions for the given variables

pub fn sum_of_unused<AB: InteractionBuilder>( &self, vars: &[AB::Var], ) -> AB::Expr

Returns the sum of expressions for all unused points This is used to ensure that variables encode only valid flags

pub fn width(&self) -> usize

Returns the number of variables used for encoding

pub fn contains_flag<AB: InteractionBuilder>( &self, vars: &[AB::Var], flag_idxs: &[usize], ) -> AB::Expr

Returns an expression that is 1 if flag_idxs contains the encoded flag and 0 otherwise

pub fn contains_flag_range<AB: InteractionBuilder>( &self, vars: &[AB::Var], range: RangeInclusive<usize>, ) -> AB::Expr

Returns an expression that is 1 if (l..=r) contains the encoded flag and 0 otherwise

pub fn flag_with_val<AB: InteractionBuilder>( &self, vars: &[AB::Var], flag_idx_vals: &[(usize, usize)], ) -> AB::Expr

Returns an expression that is 0 if flag_idxs_vals doesn’t contain the encoded flag and the corresponding val if it does flag_idxs_vals is a list of tuples (flag_idx, val)

Trait Implementations

impl Clone for Encoder

fn clone(&self) -> Encoder

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Encoder

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

Formats the value using the given formatter.

impl<AB: InteractionBuilder> SubAir<AB> for Encoder

type AirContext<'a> = &'a [<AB as AirBuilder>::Var] where AB: 'a, AB::Var: 'a, AB::Expr: 'a

Type to define the context, typically in terms of AB::Expr that are needed to define the SubAir’s constraints.

fn eval<'a>(&'a self, builder: &'a mut AB, local: &'a [AB::Var])

where AB: 'a, AB::Expr: 'a,