Struct BasicDynLookupConfig

pub struct BasicDynLookupConfig<const KEY_COL: usize> {
    pub to_lookup: Vec<([Column<Advice>; KEY_COL], Column<Fixed>)>,
    pub table: [Column<Advice>; KEY_COL],
    pub table_is_enabled: Column<Fixed>,
}

A simple dynamic lookup table for when you want to verify some length KEY_COL key is in a provided (dynamic) table of the same format.

Note that you can also use this to look up (key, out) pairs, where you consider the whole pair as the new key.

We can have multiple sets of dedicated columns to be looked up: these can be specified when calling new, but typically we just need 1 set.

The table consists of advice columns. Since this table may have poisoned rows (blinding factors), we use a fixed column table_selector which is default 0 and only 1 on enabled rows of the table. The dynamic lookup will check that for (key, key_is_enabled) in to_lookup we have key matches one of the rows in table where table_selector == key_is_enabled. Reminder: the Halo2 lookup argument will ignore the poisoned rows in to_lookup (see [https://zcash.github.io/halo2/design/proving-system/lookup.html#zero-knowledge-adjustment]), but it will not ignore the poisoned rows in table.

Part of this design consideration is to allow a key of [F::ZERO; KEY_COL] to still be used as a valid key in the lookup argument. By default, unfilled rows in to_lookup will be all zeros; we require at least one row in table where table_is_enabled = 0 and the rest of the row in table are also 0s.

Fields

to_lookup: Vec<([Column<Advice>; KEY_COL], Column<Fixed>)>

Columns for cells to be looked up. Consists of (key, key_is_enabled).

table: [Column<Advice>; KEY_COL]

Table to look up against.

table_is_enabled: Column<Fixed>

Selector to enable a row in table to actually be part of the lookup table. This is to prevent blinding factors in table advice columns from being used in the lookup.

Implementations

impl<const KEY_COL: usize> BasicDynLookupConfig<KEY_COL>

pub fn new<P: Phase, F: Field>( meta: &mut ConstraintSystem<F>, phase: impl Fn() -> P, num_lu_sets: usize, ) -> Self

Assumes all columns are in the same phase P to make life easier. We enable equality on all columns because we envision both the columns to lookup and the table will need to talk to halo2-lib.

pub fn assign_virtual_to_lookup_to_raw<F: ScalarField>( &self, layouter: impl Layouter<F>, keys: impl IntoIterator<Item = [AssignedValue<F>; KEY_COL]>, copy_manager: Option<&SharedCopyConstraintManager<F>>, )

Assign managed lookups. The keys must have already been raw assigned beforehand.

copy_manager must be provided unless you are only doing witness generation without constraints.

pub fn assign_virtual_to_lookup_to_raw_from_offset<F: ScalarField>( &self, region: &mut Region<'_, F>, keys: impl IntoIterator<Item = [AssignedValue<F>; KEY_COL]>, offset: usize, copy_manager: Option<&SharedCopyConstraintManager<F>>, )

Assign managed lookups. The keys must have already been raw assigned beforehand.

copy_manager must be provided unless you are only doing witness generation without constraints.

pub fn assign_virtual_table_to_raw<F: ScalarField>( &self, layouter: impl Layouter<F>, rows: impl IntoIterator<Item = [AssignedValue<F>; KEY_COL]>, copy_manager: Option<&SharedCopyConstraintManager<F>>, )

Assign virtual table to raw. The rows must have already been raw assigned beforehand.

copy_manager must be provided unless you are only doing witness generation without constraints.

pub fn assign_virtual_table_to_raw_from_offset<F: ScalarField>( &self, region: &mut Region<'_, F>, rows: impl IntoIterator<Item = [AssignedValue<F>; KEY_COL]>, offset: usize, copy_manager: Option<&SharedCopyConstraintManager<F>>, )

Assign virtual table to raw. The rows must have already been raw assigned beforehand.

copy_manager must be provided unless you are only doing witness generation without constraints.

Trait Implementations

impl<const KEY_COL: usize> Clone for BasicDynLookupConfig<KEY_COL>

fn clone(&self) -> BasicDynLookupConfig<KEY_COL>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<const KEY_COL: usize> Debug for BasicDynLookupConfig<KEY_COL>

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

Formats the value using the given formatter.