ark_r1cs_std/
cmp.rs

1use ark_ff::{Field, PrimeField};
2use ark_relations::r1cs::SynthesisError;
3
4use crate::{boolean::Boolean, eq::EqGadget, R1CSVar};
5
6/// Specifies how to generate constraints for comparing two variables.
7pub trait CmpGadget<F: Field>: R1CSVar<F> + EqGadget<F> {
8    fn is_gt(&self, other: &Self) -> Result<Boolean<F>, SynthesisError> {
9        other.is_lt(self)
10    }
11
12    fn is_ge(&self, other: &Self) -> Result<Boolean<F>, SynthesisError>;
13
14    fn is_lt(&self, other: &Self) -> Result<Boolean<F>, SynthesisError> {
15        Ok(!self.is_ge(other)?)
16    }
17
18    fn is_le(&self, other: &Self) -> Result<Boolean<F>, SynthesisError> {
19        other.is_ge(self)
20    }
21}
22
23/// Mimics the behavior of `std::cmp::PartialOrd` for `()`.
24impl<F: Field> CmpGadget<F> for () {
25    fn is_gt(&self, _other: &Self) -> Result<Boolean<F>, SynthesisError> {
26        Ok(Boolean::FALSE)
27    }
28
29    fn is_ge(&self, _other: &Self) -> Result<Boolean<F>, SynthesisError> {
30        Ok(Boolean::TRUE)
31    }
32
33    fn is_lt(&self, _other: &Self) -> Result<Boolean<F>, SynthesisError> {
34        Ok(Boolean::FALSE)
35    }
36
37    fn is_le(&self, _other: &Self) -> Result<Boolean<F>, SynthesisError> {
38        Ok(Boolean::TRUE)
39    }
40}
41
42/// Mimics the lexicographic comparison behavior of `std::cmp::PartialOrd` for `[T]`.
43impl<T: CmpGadget<F>, F: PrimeField> CmpGadget<F> for [T] {
44    fn is_ge(&self, other: &Self) -> Result<Boolean<F>, SynthesisError> {
45        let mut result = Boolean::TRUE;
46        let mut all_equal_so_far = Boolean::TRUE;
47        for (a, b) in self.iter().zip(other) {
48            all_equal_so_far &= a.is_eq(b)?;
49            result &= a.is_gt(b)? | &all_equal_so_far;
50        }
51        Ok(result)
52    }
53}
ark_r1cs_std/cmp.rs

ark_r1cs_std/
cmp.rs
