1use crate::prelude::*;
 2use algebra::Field;
 3use r1cs_core::{ConstraintSystem, SynthesisError};
 4
 5/// If condition is `true`, return `first`; else, select `second`.
 6pub trait CondSelectGadget<ConstraintF: Field>
 7where
 8    Self: Sized,
 9{
10    fn conditionally_select<CS: ConstraintSystem<ConstraintF>>(
11        cs: CS,
12        cond: &Boolean,
13        first: &Self,
14        second: &Self,
15    ) -> Result<Self, SynthesisError>;
16
17    fn cost() -> usize;
18}
19
20/// Uses two bits to perform a lookup into a table
21pub trait TwoBitLookupGadget<ConstraintF: Field>
22where
23    Self: Sized,
24{
25    type TableConstant;
26    fn two_bit_lookup<CS: ConstraintSystem<ConstraintF>>(
27        cs: CS,
28        bits: &[Boolean],
29        constants: &[Self::TableConstant],
30    ) -> Result<Self, SynthesisError>;
31
32    fn cost() -> usize;
33}
34
35/// Uses three bits to perform a lookup into a table, where the last bit
36/// performs negation
37pub trait ThreeBitCondNegLookupGadget<ConstraintF: Field>
38where
39    Self: Sized,
40{
41    type TableConstant;
42    fn three_bit_cond_neg_lookup<CS: ConstraintSystem<ConstraintF>>(
43        cs: CS,
44        bits: &[Boolean],
45        b0b1: &Boolean,
46        constants: &[Self::TableConstant],
47    ) -> Result<Self, SynthesisError>;
48
49    fn cost() -> usize;
50}