ark_r1cs_std/
cmp.rs

1use ark_ff::{Field, PrimeField};
2use ark_relations::gr1cs::SynthesisError;
3
4use crate::{boolean::Boolean, eq::EqGadget, GR1CSVar};
5
6/// Specifies how to generate constraints for comparing two variables.
7pub trait CmpGadget<F: Field>: GR1CSVar<F> + EqGadget<F> {
8    /// Checks if `self` is greater than `other`.
9    fn is_gt(&self, other: &Self) -> Result<Boolean<F>, SynthesisError> {
10        other.is_lt(self)
11    }
12
13    /// Checks if `self` is greater than or equal to `other`.
14    fn is_ge(&self, other: &Self) -> Result<Boolean<F>, SynthesisError>;
15
16    /// Checks if `self` is less than `other`.
17    fn is_lt(&self, other: &Self) -> Result<Boolean<F>, SynthesisError> {
18        Ok(!self.is_ge(other)?)
19    }
20
21    /// Checks if `self` is less than or equal to `other`.
22    fn is_le(&self, other: &Self) -> Result<Boolean<F>, SynthesisError> {
23        other.is_ge(self)
24    }
25}
26
27/// Mimics the behavior of `std::cmp::PartialOrd` for `()`.
28impl<F: Field> CmpGadget<F> for () {
29    fn is_gt(&self, _other: &Self) -> Result<Boolean<F>, SynthesisError> {
30        Ok(Boolean::FALSE)
31    }
32
33    fn is_ge(&self, _other: &Self) -> Result<Boolean<F>, SynthesisError> {
34        Ok(Boolean::TRUE)
35    }
36
37    fn is_lt(&self, _other: &Self) -> Result<Boolean<F>, SynthesisError> {
38        Ok(Boolean::FALSE)
39    }
40
41    fn is_le(&self, _other: &Self) -> Result<Boolean<F>, SynthesisError> {
42        Ok(Boolean::TRUE)
43    }
44}
45
46/// Mimics the lexicographic comparison behavior of `std::cmp::PartialOrd` for
47/// `[T]`.
48impl<T: CmpGadget<F>, F: PrimeField> CmpGadget<F> for [T] {
49    fn is_ge(&self, other: &Self) -> Result<Boolean<F>, SynthesisError> {
50        let mut result = Boolean::TRUE;
51        let mut all_equal_so_far = Boolean::TRUE;
52        for (a, b) in self.iter().zip(other) {
53            all_equal_so_far &= a.is_eq(b)?;
54            result &= a.is_gt(b)? | &all_equal_so_far;
55        }
56        Ok(result)
57    }
58}
ark_r1cs_std/cmp.rs

ark_r1cs_std/
cmp.rs
