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use ark_ff::PrimeField;
use ark_relations::gr1cs::SynthesisError;
use ark_std::ops::{BitOr, BitOrAssign};
use crate::{
eq::EqGadget,
fields::{fp::FpVar, FieldVar},
};
use super::Boolean;
impl<F: PrimeField> Boolean<F> {
fn _or(&self, other: &Self) -> Result<Self, SynthesisError> {
use Boolean::*;
match (self, other) {
(&Constant(false), x) | (x, &Constant(false)) => Ok(x.clone()),
(&Constant(true), _) | (_, &Constant(true)) => Ok(Constant(true)),
(Var(ref x), Var(ref y)) => Ok(Var(x.or(y)?)),
}
}
/// Outputs `bits[0] | bits[1] | ... | bits.last().unwrap()`.
///
/// ```
/// # fn main() -> Result<(), ark_relations::gr1cs::SynthesisError> {
/// // We'll use the BLS12-381 scalar field for our constraints.
/// use ark_test_curves::bls12_381::Fr;
/// use ark_relations::gr1cs::*;
/// use ark_r1cs_std::prelude::*;
///
/// let cs = ConstraintSystem::<Fr>::new_ref();
///
/// let a = Boolean::new_witness(cs.clone(), || Ok(true))?;
/// let b = Boolean::new_witness(cs.clone(), || Ok(false))?;
/// let c = Boolean::new_witness(cs.clone(), || Ok(false))?;
///
/// Boolean::kary_or(&[a.clone(), b.clone(), c.clone()])?.enforce_equal(&Boolean::TRUE)?;
/// Boolean::kary_or(&[a.clone(), c.clone()])?.enforce_equal(&Boolean::TRUE)?;
/// Boolean::kary_or(&[b.clone(), c.clone()])?.enforce_equal(&Boolean::FALSE)?;
///
/// assert!(cs.is_satisfied().unwrap());
/// # Ok(())
/// # }
/// ```
#[tracing::instrument(target = "gr1cs")]
pub fn kary_or(bits: &[Self]) -> Result<Self, SynthesisError> {
assert!(!bits.is_empty());
if bits.len() <= 3 {
let mut cur: Option<Self> = None;
for next in bits {
cur = if let Some(b) = cur {
Some(b | next)
} else {
Some(next.clone())
};
}
Ok(cur.expect("should not be 0"))
} else {
// b0 | b1 | ... | bN == 1 if and only if not all of b0, b1, ..., bN are 0.
// We can enforce this by requiring that the sum of b0, b1, ..., bN is not 0.
let sum_bits: FpVar<_> = bits.iter().map(|b| FpVar::from(b.clone())).sum();
sum_bits.is_neq(&FpVar::zero())
}
}
}
impl<'a, F: PrimeField> BitOr<Self> for &'a Boolean<F> {
type Output = Boolean<F>;
/// Outputs `self | other`.
///
/// If at least one of `self` and `other` are constants, then this method
/// *does not* create any constraints or variables.
///
/// ```
/// # fn main() -> Result<(), ark_relations::gr1cs::SynthesisError> {
/// // We'll use the BLS12-381 scalar field for our constraints.
/// use ark_test_curves::bls12_381::Fr;
/// use ark_relations::gr1cs::*;
/// use ark_r1cs_std::prelude::*;
///
/// let cs = ConstraintSystem::<Fr>::new_ref();
///
/// let a = Boolean::new_witness(cs.clone(), || Ok(true))?;
/// let b = Boolean::new_witness(cs.clone(), || Ok(false))?;
///
/// (&a | &b).enforce_equal(&Boolean::TRUE)?;
/// (&b | &a).enforce_equal(&Boolean::TRUE)?;
///
/// (&a | &a).enforce_equal(&Boolean::TRUE)?;
/// (&b | &b).enforce_equal(&Boolean::FALSE)?;
///
/// assert!(cs.is_satisfied().unwrap());
/// # Ok(())
/// # }
/// ```
#[tracing::instrument(target = "gr1cs", skip(self, other))]
fn bitor(self, other: Self) -> Self::Output {
self._or(other).unwrap()
}
}
impl<'a, F: PrimeField> BitOr<&'a Self> for Boolean<F> {
type Output = Boolean<F>;
#[tracing::instrument(target = "gr1cs", skip(self, other))]
fn bitor(self, other: &Self) -> Self::Output {
self._or(&other).unwrap()
}
}
impl<'a, F: PrimeField> BitOr<Boolean<F>> for &'a Boolean<F> {
type Output = Boolean<F>;
#[tracing::instrument(target = "gr1cs", skip(self, other))]
fn bitor(self, other: Boolean<F>) -> Self::Output {
self._or(&other).unwrap()
}
}
impl<F: PrimeField> BitOr<Self> for Boolean<F> {
type Output = Self;
#[tracing::instrument(target = "gr1cs", skip(self, other))]
fn bitor(self, other: Self) -> Self::Output {
self._or(&other).unwrap()
}
}
impl<F: PrimeField> BitOrAssign<Self> for Boolean<F> {
/// Sets `self = self | other`.
#[tracing::instrument(target = "gr1cs", skip(self, other))]
fn bitor_assign(&mut self, other: Self) {
let result = self._or(&other).unwrap();
*self = result;
}
}
impl<'a, F: PrimeField> BitOrAssign<&'a Self> for Boolean<F> {
/// Sets `self = self | other`.
#[tracing::instrument(target = "gr1cs", skip(self, other))]
fn bitor_assign(&mut self, other: &'a Self) {
let result = self._or(other).unwrap();
*self = result;
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{
alloc::{AllocVar, AllocationMode},
boolean::test_utils::run_binary_exhaustive,
prelude::EqGadget,
GR1CSVar,
};
use ark_test_curves::bls12_381::Fr;
#[test]
fn or() {
run_binary_exhaustive::<Fr>(|a, b| {
let cs = a.cs().or(b.cs());
let both_constant = a.is_constant() && b.is_constant();
let computed = &a | &b;
let expected_mode = if both_constant {
AllocationMode::Constant
} else {
AllocationMode::Witness
};
let expected =
Boolean::new_variable(cs.clone(), || Ok(a.value()? | b.value()?), expected_mode)?;
assert_eq!(expected.value(), computed.value());
expected.enforce_equal(&computed)?;
if !both_constant {
assert!(cs.is_satisfied().unwrap());
}
Ok(())
})
.unwrap()
}
}