1use ark_ff::Field;
 2use ark_relations::r1cs::SynthesisError;
 3use ark_std::vec::Vec;
 4
 5use crate::{boolean::Boolean, uint8::UInt8};
 6
 7/// Specifies constraints for conversion to a little-endian bit representation
 8/// of `self`.
 9pub trait ToBitsGadget<F: Field> {
10    /// Outputs the canonical little-endian bit-wise representation of `self`.
11    ///
12    /// This is the correct default for 99% of use cases.
13    fn to_bits_le(&self) -> Result<Vec<Boolean<F>>, SynthesisError>;
14
15    /// Outputs a possibly non-unique little-endian bit-wise representation of
16    /// `self`.
17    ///
18    /// If you're not absolutely certain that your usecase can get away with a
19    /// non-canonical representation, please use `self.to_bits()` instead.
20    fn to_non_unique_bits_le(&self) -> Result<Vec<Boolean<F>>, SynthesisError> {
21        self.to_bits_le()
22    }
23
24    /// Outputs the canonical big-endian bit-wise representation of `self`.
25    fn to_bits_be(&self) -> Result<Vec<Boolean<F>>, SynthesisError> {
26        let mut res = self.to_bits_le()?;
27        res.reverse();
28        Ok(res)
29    }
30
31    /// Outputs a possibly non-unique big-endian bit-wise representation of
32    /// `self`.
33    fn to_non_unique_bits_be(&self) -> Result<Vec<Boolean<F>>, SynthesisError> {
34        let mut res = self.to_non_unique_bits_le()?;
35        res.reverse();
36        Ok(res)
37    }
38}
39
40impl<F: Field> ToBitsGadget<F> for Boolean<F> {
41    fn to_bits_le(&self) -> Result<Vec<Boolean<F>>, SynthesisError> {
42        Ok(vec![self.clone()])
43    }
44}
45
46impl<F: Field> ToBitsGadget<F> for [Boolean<F>] {
47    /// Outputs `self`.
48    fn to_bits_le(&self) -> Result<Vec<Boolean<F>>, SynthesisError> {
49        Ok(self.to_vec())
50    }
51}
52
53impl<F: Field, T> ToBitsGadget<F> for Vec<T>
54where
55    [T]: ToBitsGadget<F>,
56{
57    fn to_bits_le(&self) -> Result<Vec<Boolean<F>>, SynthesisError> {
58        self.as_slice().to_bits_le().map(|v| v.to_vec())
59    }
60
61    fn to_non_unique_bits_le(&self) -> Result<Vec<Boolean<F>>, SynthesisError> {
62        self.as_slice().to_non_unique_bits_le().map(|v| v.to_vec())
63    }
64}
65
66/// Specifies constraints for conversion to a little-endian byte representation
67/// of `self`.
68pub trait ToBytesGadget<F: Field> {
69    /// Outputs a canonical, little-endian, byte decomposition of `self`.
70    ///
71    /// This is the correct default for 99% of use cases.
72    fn to_bytes(&self) -> Result<Vec<UInt8<F>>, SynthesisError>;
73
74    /// Outputs a possibly non-unique byte decomposition of `self`.
75    ///
76    /// If you're not absolutely certain that your usecase can get away with a
77    /// non-canonical representation, please use `self.to_bytes(cs)` instead.
78    fn to_non_unique_bytes(&self) -> Result<Vec<UInt8<F>>, SynthesisError> {
79        self.to_bytes()
80    }
81}
82
83impl<'a, F: Field, T: 'a + ToBytesGadget<F>> ToBytesGadget<F> for &'a T {
84    fn to_bytes(&self) -> Result<Vec<UInt8<F>>, SynthesisError> {
85        (*self).to_bytes()
86    }
87}
88
89/// Specifies how to convert a variable of type `Self` to variables of
90/// type `FpVar<ConstraintF>`
91pub trait ToConstraintFieldGadget<ConstraintF: ark_ff::PrimeField> {
92    /// Converts `self` to `FpVar<ConstraintF>` variables.
93    fn to_constraint_field(
94        &self,
95    ) -> Result<Vec<crate::fields::fp::FpVar<ConstraintF>>, ark_relations::r1cs::SynthesisError>;
96}