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//! Module containing the definition of the Polynomial.
use tfhe_versionable::Versionize;
use crate::core_crypto::backward_compatibility::entities::polynomial::PolynomialVersions;
use crate::core_crypto::commons::parameters::*;
use crate::core_crypto::commons::traits::*;
use std::ops::{Index, IndexMut};
/// A [`polynomial`](`Polynomial`).
#[derive(Clone, Copy, Debug, PartialEq, Eq, serde::Serialize, serde::Deserialize, Versionize)]
#[versionize(PolynomialVersions)]
pub struct Polynomial<C: Container> {
data: C,
}
impl<T, C: Container<Element = T>> AsRef<[T]> for Polynomial<C> {
fn as_ref(&self) -> &[T] {
self.data.as_ref()
}
}
impl<T, C: ContainerMut<Element = T>> AsMut<[T]> for Polynomial<C> {
fn as_mut(&mut self) -> &mut [T] {
self.data.as_mut()
}
}
impl<C: Container, I: std::slice::SliceIndex<[C::Element]>> Index<I> for Polynomial<C> {
type Output = <[C::Element] as Index<I>>::Output;
fn index(&self, index: I) -> &Self::Output {
self.as_ref().index(index)
}
}
impl<C: ContainerMut, I: std::slice::SliceIndex<[C::Element]>> IndexMut<I> for Polynomial<C> {
fn index_mut(&mut self, index: I) -> &mut Self::Output {
self.as_mut().index_mut(index)
}
}
impl<Scalar, C: Container<Element = Scalar>> Polynomial<C> {
/// Create a [`Polynomial`] from an existing container.
///
/// # Note
///
/// This function only wraps a container in the appropriate type.
///
/// This docstring exhibits [`Polynomial`] primitives usage.
///
/// ```rust
/// use tfhe::core_crypto::prelude::*;
///
/// // DISCLAIMER: these toy example parameters are not guaranteed to be secure or yield correct
/// // computations
/// // Define parameters for Polynomial creation
/// let polynomial_size = PolynomialSize(1024);
///
/// // Create a new Polynomial
/// let polynomial = Polynomial::new(0u64, polynomial_size);
///
/// assert_eq!(polynomial.polynomial_size(), polynomial_size);
/// assert_eq!(polynomial.degree(), polynomial_size.0 - 1);
///
/// // Demonstrate how to recover the allocated container
/// let underlying_container: Vec<u64> = polynomial.into_container();
///
/// // Recreate a polynomial using from_container
/// let polynomial = Polynomial::from_container(underlying_container);
///
/// assert_eq!(polynomial.polynomial_size(), polynomial_size);
/// assert_eq!(polynomial.degree(), polynomial_size.0 - 1);
/// ```
pub fn from_container(container: C) -> Self {
assert!(
container.container_len() > 0,
"Got an empty container to create a Polynomial"
);
Self { data: container }
}
/// Return the [`PolynomialSize`] of the [`Polynomial`].
///
/// See [`Polynomial::from_container`] for usage.
pub fn polynomial_size(&self) -> PolynomialSize {
PolynomialSize(self.data.container_len())
}
/// Return the degree of the [`Polynomial`] as a usize.
///
/// degree == [`PolynomialSize`] - 1
///
/// See [`Polynomial::from_container`] for usage.
pub fn degree(&self) -> usize {
self.polynomial_size().0 - 1
}
/// Consume the entity and return its underlying container.
///
/// See [`Polynomial::from_container`] for usage.
pub fn into_container(self) -> C {
self.data
}
/// Return a view of the [`Polynomial`]. This is useful if an algorithm takes a view by value.
pub fn as_view(&self) -> PolynomialView<'_, Scalar> {
PolynomialView::from_container(self.as_ref())
}
}
impl<'a, Scalar: 'a, C: Container<Element = Scalar>> Polynomial<C> {
/// Iterate on the elements of the [`Polynomial`].
pub fn iter(&'a self) -> impl Iterator<Item = &'a Scalar> {
self.as_ref().iter()
}
}
impl<'a, Scalar: 'a, C: ContainerMut<Element = Scalar>> Polynomial<C> {
/// Mutable variant of [`Polynomial::as_view`].
pub fn as_mut_view(&mut self) -> PolynomialMutView<'_, Scalar> {
PolynomialMutView::from_container(self.as_mut())
}
/// Iterate on the elements of the [`Polynomial`] allowing to modify them.
pub fn iter_mut(&'a mut self) -> impl Iterator<Item = &'a mut Scalar> {
self.as_mut().iter_mut()
}
}
/// A [`Polynomial`] owning the memory for its own storage.
pub type PolynomialOwned<Scalar> = Polynomial<Vec<Scalar>>;
/// A [`Polynomial`] immutably borrowing memory for its own storage.
pub type PolynomialView<'data, Scalar> = Polynomial<&'data [Scalar]>;
/// A [`Polynomial`] mutably borrowing memory for its own storage.
pub type PolynomialMutView<'data, Scalar> = Polynomial<&'data mut [Scalar]>;
impl<Scalar> PolynomialOwned<Vec<Scalar>>
where
Scalar: Copy,
{
/// Allocate memory and create a new owned [`Polynomial`].
///
/// # Note
///
/// This function allocates a vector of the appropriate size and wraps it in the appropriate
/// type.
///
/// See [`Polynomial::from_container`] for usage.
pub fn new(fill_with: Scalar, polynomial_size: PolynomialSize) -> PolynomialOwned<Scalar> {
PolynomialOwned::from_container(vec![fill_with; polynomial_size.0])
}
}
/// Metadata used in the [`CreateFrom`] implementation to create [`Polynomial`] entities.
#[derive(Clone, Copy)]
pub struct PolynomialCreationMetadata {}
impl<C: Container> CreateFrom<C> for Polynomial<C> {
type Metadata = PolynomialCreationMetadata;
#[inline]
fn create_from(from: C, _: Self::Metadata) -> Self {
Self::from_container(from)
}
}