use crate::pairing::{Engine};
use crate::pairing::ff::Field;
use std::ops::{Add, Sub};
use std::fmt;
use std::error::Error;
use std::io;
use std::marker::PhantomData;
pub trait Circuit<E: Engine> {
fn synthesize<CS: ConstraintSystem<E>>(
self,
cs: &mut CS
) -> Result<(), SynthesisError>;
}
#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
pub struct Variable(pub(crate) Index);
impl Variable {
pub fn new_unchecked(idx: Index) -> Variable {
Variable(idx)
}
pub fn get_unchecked(&self) -> Index {
self.0
}
}
#[derive(Copy, Clone, PartialEq, Debug, Hash, Eq)]
pub enum Index {
Input(usize),
Aux(usize)
}
#[derive(Clone)]
pub struct LinearCombination<E: Engine>(pub(crate) Vec<(Variable, E::Fr)>);
impl<E: Engine> AsRef<[(Variable, E::Fr)]> for LinearCombination<E> {
fn as_ref(&self) -> &[(Variable, E::Fr)] {
&self.0
}
}
impl<E: Engine> LinearCombination<E> {
pub fn zero() -> LinearCombination<E> {
LinearCombination(vec![])
}
}
impl<E: Engine> Add<(E::Fr, Variable)> for LinearCombination<E> {
type Output = LinearCombination<E>;
fn add(mut self, (coeff, var): (E::Fr, Variable)) -> LinearCombination<E> {
self.0.push((var, coeff));
self
}
}
impl<E: Engine> Sub<(E::Fr, Variable)> for LinearCombination<E> {
type Output = LinearCombination<E>;
fn sub(self, (mut coeff, var): (E::Fr, Variable)) -> LinearCombination<E> {
coeff.negate();
self + (coeff, var)
}
}
impl<E: Engine> Add<Variable> for LinearCombination<E> {
type Output = LinearCombination<E>;
fn add(self, other: Variable) -> LinearCombination<E> {
self + (E::Fr::one(), other)
}
}
impl<E: Engine> Sub<Variable> for LinearCombination<E> {
type Output = LinearCombination<E>;
fn sub(self, other: Variable) -> LinearCombination<E> {
self - (E::Fr::one(), other)
}
}
impl<'a, E: Engine> Add<&'a LinearCombination<E>> for LinearCombination<E> {
type Output = LinearCombination<E>;
fn add(mut self, other: &'a LinearCombination<E>) -> LinearCombination<E> {
for s in &other.0 {
self = self + (s.1, s.0);
}
self
}
}
impl<'a, E: Engine> Sub<&'a LinearCombination<E>> for LinearCombination<E> {
type Output = LinearCombination<E>;
fn sub(mut self, other: &'a LinearCombination<E>) -> LinearCombination<E> {
for s in &other.0 {
self = self - (s.1, s.0);
}
self
}
}
impl<'a, E: Engine> Add<(E::Fr, &'a LinearCombination<E>)> for LinearCombination<E> {
type Output = LinearCombination<E>;
fn add(mut self, (coeff, other): (E::Fr, &'a LinearCombination<E>)) -> LinearCombination<E> {
for s in &other.0 {
let mut tmp = s.1;
tmp.mul_assign(&coeff);
self = self + (tmp, s.0);
}
self
}
}
impl<'a, E: Engine> Sub<(E::Fr, &'a LinearCombination<E>)> for LinearCombination<E> {
type Output = LinearCombination<E>;
fn sub(mut self, (coeff, other): (E::Fr, &'a LinearCombination<E>)) -> LinearCombination<E> {
for s in &other.0 {
let mut tmp = s.1;
tmp.mul_assign(&coeff);
self = self - (tmp, s.0);
}
self
}
}
#[derive(Debug)]
pub enum SynthesisError {
AssignmentMissing,
DivisionByZero,
Unsatisfiable,
PolynomialDegreeTooLarge,
UnexpectedIdentity,
IoError(io::Error),
MalformedVerifyingKey,
UnconstrainedVariable
}
impl From<io::Error> for SynthesisError {
fn from(e: io::Error) -> SynthesisError {
SynthesisError::IoError(e)
}
}
impl SynthesisError {
pub fn self_description(&self) -> &str {
match *self {
SynthesisError::AssignmentMissing => "an assignment for a variable could not be computed",
SynthesisError::DivisionByZero => "division by zero",
SynthesisError::Unsatisfiable => "unsatisfiable constraint system",
SynthesisError::PolynomialDegreeTooLarge => "polynomial degree is too large",
SynthesisError::UnexpectedIdentity => "encountered an identity element in the CRS",
SynthesisError::IoError(_) => "encountered an I/O error",
SynthesisError::MalformedVerifyingKey => "malformed verifying key",
SynthesisError::UnconstrainedVariable => "auxillary variable was unconstrained"
}
}
}
impl Error for SynthesisError {
fn description(&self) -> &str {
self.self_description()
}
}
impl fmt::Display for SynthesisError {
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
if let &SynthesisError::IoError(ref e) = self {
write!(f, "I/O error: ")?;
e.fmt(f)
} else {
write!(f, "{}", self.self_description())
}
}
}
pub trait ConstraintSystem<E: Engine>: Sized {
type Root: ConstraintSystem<E>;
fn one() -> Variable {
Variable::new_unchecked(Index::Input(0))
}
fn alloc<F, A, AR>(
&mut self,
annotation: A,
f: F
) -> Result<Variable, SynthesisError>
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>;
fn alloc_input<F, A, AR>(
&mut self,
annotation: A,
f: F
) -> Result<Variable, SynthesisError>
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>;
fn enforce<A, AR, LA, LB, LC>(
&mut self,
annotation: A,
a: LA,
b: LB,
c: LC
)
where A: FnOnce() -> AR, AR: Into<String>,
LA: FnOnce(LinearCombination<E>) -> LinearCombination<E>,
LB: FnOnce(LinearCombination<E>) -> LinearCombination<E>,
LC: FnOnce(LinearCombination<E>) -> LinearCombination<E>;
fn push_namespace<NR, N>(&mut self, name_fn: N)
where NR: Into<String>, N: FnOnce() -> NR;
fn pop_namespace(&mut self);
fn get_root(&mut self) -> &mut Self::Root;
fn namespace<'a, NR, N>(
&'a mut self,
name_fn: N
) -> Namespace<'a, E, Self::Root>
where NR: Into<String>, N: FnOnce() -> NR
{
self.get_root().push_namespace(name_fn);
Namespace(self.get_root(), PhantomData)
}
}
pub struct Namespace<'a, E: Engine, CS: ConstraintSystem<E> + 'a>(&'a mut CS, PhantomData<E>);
impl<'cs, E: Engine, CS: ConstraintSystem<E>> ConstraintSystem<E> for Namespace<'cs, E, CS> {
type Root = CS::Root;
fn one() -> Variable {
CS::one()
}
fn alloc<F, A, AR>(
&mut self,
annotation: A,
f: F
) -> Result<Variable, SynthesisError>
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>
{
self.0.alloc(annotation, f)
}
fn alloc_input<F, A, AR>(
&mut self,
annotation: A,
f: F
) -> Result<Variable, SynthesisError>
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>
{
self.0.alloc_input(annotation, f)
}
fn enforce<A, AR, LA, LB, LC>(
&mut self,
annotation: A,
a: LA,
b: LB,
c: LC
)
where A: FnOnce() -> AR, AR: Into<String>,
LA: FnOnce(LinearCombination<E>) -> LinearCombination<E>,
LB: FnOnce(LinearCombination<E>) -> LinearCombination<E>,
LC: FnOnce(LinearCombination<E>) -> LinearCombination<E>
{
self.0.enforce(annotation, a, b, c)
}
fn push_namespace<NR, N>(&mut self, _: N)
where NR: Into<String>, N: FnOnce() -> NR
{
panic!("only the root's push_namespace should be called");
}
fn pop_namespace(&mut self)
{
panic!("only the root's pop_namespace should be called");
}
fn get_root(&mut self) -> &mut Self::Root
{
self.0.get_root()
}
}
impl<'a, E: Engine, CS: ConstraintSystem<E>> Drop for Namespace<'a, E, CS> {
fn drop(&mut self) {
self.get_root().pop_namespace()
}
}
impl<'cs, E: Engine, CS: ConstraintSystem<E>> ConstraintSystem<E> for &'cs mut CS {
type Root = CS::Root;
fn one() -> Variable {
CS::one()
}
fn alloc<F, A, AR>(
&mut self,
annotation: A,
f: F
) -> Result<Variable, SynthesisError>
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>
{
(**self).alloc(annotation, f)
}
fn alloc_input<F, A, AR>(
&mut self,
annotation: A,
f: F
) -> Result<Variable, SynthesisError>
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>
{
(**self).alloc_input(annotation, f)
}
fn enforce<A, AR, LA, LB, LC>(
&mut self,
annotation: A,
a: LA,
b: LB,
c: LC
)
where A: FnOnce() -> AR, AR: Into<String>,
LA: FnOnce(LinearCombination<E>) -> LinearCombination<E>,
LB: FnOnce(LinearCombination<E>) -> LinearCombination<E>,
LC: FnOnce(LinearCombination<E>) -> LinearCombination<E>
{
(**self).enforce(annotation, a, b, c)
}
fn push_namespace<NR, N>(&mut self, name_fn: N)
where NR: Into<String>, N: FnOnce() -> NR
{
(**self).push_namespace(name_fn)
}
fn pop_namespace(&mut self)
{
(**self).pop_namespace()
}
fn get_root(&mut self) -> &mut Self::Root
{
(**self).get_root()
}
}