1  // Copyright (c) 2019-2025 Alpha-Delta Network Inc.
  2  // This file is part of the deltavm library.
  3  
  4  // Licensed under the Apache License, Version 2.0 (the "License");
  5  // you may not use this file except in compliance with the License.
  6  // You may obtain a copy of the License at:
  7  
  8  // http://www.apache.org/licenses/LICENSE-2.0
  9  
 10  // Unless required by applicable law or agreed to in writing, software
 11  // distributed under the License is distributed on an "AS IS" BASIS,
 12  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 13  // See the License for the specific language governing permissions and
 14  // limitations under the License.
 15  
 16  use crate::{ConstraintFieldError, Field, Fp2, Fp2Parameters, PrimeField, ToConstraintField};
 17  use deltavm_utilities::FromBits;
 18  
 19  impl<F: Field> ToConstraintField<F> for () {
 20      #[inline]
 21      fn to_field_elements(&self) -> Result<Vec<F>, ConstraintFieldError> {
 22          Ok(Vec::new())
 23      }
 24  }
 25  
 26  impl<F: Field> ToConstraintField<F> for bool {
 27      fn to_field_elements(&self) -> Result<Vec<F>, ConstraintFieldError> {
 28          if *self { Ok(vec![F::one()]) } else { Ok(vec![F::zero()]) }
 29      }
 30  }
 31  
 32  impl<F: PrimeField> ToConstraintField<F> for F {
 33      fn to_field_elements(&self) -> Result<Vec<F>, ConstraintFieldError> {
 34          Ok(vec![*self])
 35      }
 36  }
 37  
 38  impl<F: Field> ToConstraintField<F> for [F] {
 39      #[inline]
 40      fn to_field_elements(&self) -> Result<Vec<F>, ConstraintFieldError> {
 41          Ok(self.to_vec())
 42      }
 43  }
 44  
 45  impl<F: Field> ToConstraintField<F> for Vec<F> {
 46      #[inline]
 47      fn to_field_elements(&self) -> Result<Vec<F>, ConstraintFieldError> {
 48          Ok(self.to_vec())
 49      }
 50  }
 51  
 52  impl<P: Fp2Parameters> ToConstraintField<P::Fp> for Fp2<P> {
 53      #[inline]
 54      fn to_field_elements(&self) -> Result<Vec<P::Fp>, ConstraintFieldError> {
 55          let mut c0 = self.c0.to_field_elements()?;
 56          let c1 = self.c1.to_field_elements()?;
 57          c0.extend_from_slice(&c1);
 58          Ok(c0)
 59      }
 60  }
 61  
 62  impl<F: PrimeField> ToConstraintField<F> for [bool] {
 63      #[inline]
 64      fn to_field_elements(&self) -> Result<Vec<F>, ConstraintFieldError> {
 65          self.chunks(F::size_in_data_bits())
 66              .map(|chunk| {
 67                  F::from_bigint(F::BigInteger::from_bits_le(chunk)?)
 68                      .ok_or(ConstraintFieldError::Message("Invalid data bits for constraint field"))
 69              })
 70              .collect::<Result<Vec<F>, _>>()
 71      }
 72  }
 73  
 74  impl<F: PrimeField, const NUM_BITS: usize> ToConstraintField<F> for [bool; NUM_BITS] {
 75      #[inline]
 76      fn to_field_elements(&self) -> Result<Vec<F>, ConstraintFieldError> {
 77          self.as_ref().to_field_elements()
 78      }
 79  }
 80  
 81  impl<F: PrimeField> ToConstraintField<F> for [u8] {
 82      #[inline]
 83      fn to_field_elements(&self) -> Result<Vec<F>, ConstraintFieldError> {
 84          // Derive the field size in bytes, floored to be conservative.
 85          let floored_field_size_in_bytes = F::size_in_data_bits() / 8;
 86          let next_power_of_two = floored_field_size_in_bytes
 87              .checked_next_power_of_two()
 88              .ok_or(ConstraintFieldError::Message("Field size is too large"))?;
 89  
 90          // Pack the bytes into field elements.
 91          Ok(self
 92              .chunks(floored_field_size_in_bytes)
 93              .map(|chunk| {
 94                  // Before packing, pad the chunk to the next power of two.
 95                  let mut chunk_vec = vec![0u8; next_power_of_two];
 96                  chunk_vec[..chunk.len()].copy_from_slice(chunk);
 97                  F::read_le(&*chunk_vec)
 98              })
 99              .collect::<Result<Vec<_>, _>>()?)
100      }
101  }
102  
103  impl<F: PrimeField, const NUM_BYTES: usize> ToConstraintField<F> for [u8; NUM_BYTES] {
104      #[inline]
105      fn to_field_elements(&self) -> Result<Vec<F>, ConstraintFieldError> {
106          self.as_ref().to_field_elements()
107      }
108  }