1#![cfg_attr(not(feature = "std"), no_std)]
  2//! This crate implements common "gadgets" that make
  3//! programming rank-1 constraint systems easier.
  4#![deny(
  5    warnings,
  6    unused,
  7    future_incompatible,
  8    nonstandard_style,
  9    rust_2018_idioms
 10)]
 11
 12#[macro_use]
 13extern crate ark_std;
 14
 15#[macro_use]
 16extern crate ark_relations;
 17
 18#[doc(hidden)]
 19#[macro_use]
 20extern crate derivative;
 21
 22/// Some utility macros for making downstream impls easier.
 23#[macro_use]
 24pub mod macros;
 25
 26pub(crate) use ark_std::vec::Vec;
 27
 28use ark_ff::Field;
 29
 30/// This module implements gadgets related to bit manipulation, such as
 31/// `Boolean` and `UInt`s.
 32pub mod bits;
 33pub use self::bits::*;
 34
 35/// This module implements gadgets related to field arithmetic.
 36pub mod fields;
 37
 38/// This module implements gadgets related to group arithmetic, and specifically
 39/// elliptic curve arithmetic.
 40pub mod groups;
 41
 42/// This module implements gadgets related to computing pairings in bilinear
 43/// groups.
 44pub mod pairing;
 45
 46/// This module describes a trait for allocating new variables in a constraint
 47/// system.
 48pub mod alloc;
 49/// This module describes a trait for checking equality of variables.
 50pub mod eq;
 51/// This module describes traits for conditionally selecting a variable from a
 52/// list of variables.
 53pub mod select;
 54
 55#[allow(missing_docs)]
 56pub mod prelude {
 57    pub use crate::{
 58        alloc::*,
 59        bits::{boolean::Boolean, uint32::UInt32, uint8::UInt8, ToBitsGadget, ToBytesGadget},
 60        eq::*,
 61        fields::{FieldOpsBounds, FieldVar},
 62        groups::{CurveVar, GroupOpsBounds},
 63        pairing::PairingVar,
 64        select::*,
 65        R1CSVar,
 66    };
 67}
 68
 69/// This trait describes some core functionality that is common to high-level
 70/// variables, such as `Boolean`s, `FieldVar`s, `GroupVar`s, etc.
 71pub trait R1CSVar<F: Field> {
 72    /// The type of the "native" value that `Self` represents in the constraint
 73    /// system.
 74    type Value: core::fmt::Debug + Eq + Clone;
 75
 76    /// Returns the underlying `ConstraintSystemRef`.
 77    ///
 78    /// If `self` is a constant value, then this *must* return
 79    /// `ark_relations::r1cs::ConstraintSystemRef::None`.
 80    fn cs(&self) -> ark_relations::r1cs::ConstraintSystemRef<F>;
 81
 82    /// Returns `true` if `self` is a circuit-generation-time constant.
 83    fn is_constant(&self) -> bool {
 84        self.cs().is_none()
 85    }
 86
 87    /// Returns the value that is assigned to `self` in the underlying
 88    /// `ConstraintSystem`.
 89    fn value(&self) -> Result<Self::Value, ark_relations::r1cs::SynthesisError>;
 90}
 91
 92impl<F: Field, T: R1CSVar<F>> R1CSVar<F> for [T] {
 93    type Value = Vec<T::Value>;
 94
 95    fn cs(&self) -> ark_relations::r1cs::ConstraintSystemRef<F> {
 96        let mut result = ark_relations::r1cs::ConstraintSystemRef::None;
 97        for var in self {
 98            result = var.cs().or(result);
 99        }
100        result
101    }
102
103    fn value(&self) -> Result<Self::Value, ark_relations::r1cs::SynthesisError> {
104        let mut result = Vec::new();
105        for var in self {
106            result.push(var.value()?);
107        }
108        Ok(result)
109    }
110}
111
112impl<'a, F: Field, T: 'a + R1CSVar<F>> R1CSVar<F> for &'a T {
113    type Value = T::Value;
114
115    fn cs(&self) -> ark_relations::r1cs::ConstraintSystemRef<F> {
116        (*self).cs()
117    }
118
119    fn value(&self) -> Result<Self::Value, ark_relations::r1cs::SynthesisError> {
120        (*self).value()
121    }
122}
123
124/// A utility trait to convert `Self` to `Result<T, SynthesisErrorA`.>
125pub trait Assignment<T> {
126    /// Converts `self` to `Result`.
127    fn get(self) -> Result<T, ark_relations::r1cs::SynthesisError>;
128}
129
130impl<T> Assignment<T> for Option<T> {
131    fn get(self) -> Result<T, ark_relations::r1cs::SynthesisError> {
132        self.ok_or(ark_relations::r1cs::SynthesisError::AssignmentMissing)
133    }
134}
135
136/// Specifies how to convert a variable of type `Self` to variables of
137/// type `FpVar<ConstraintF>`
138pub trait ToConstraintFieldGadget<ConstraintF: ark_ff::PrimeField> {
139    /// Converts `self` to `FpVar<ConstraintF>` variables.
140    fn to_constraint_field(
141        &self,
142    ) -> Result<Vec<crate::fields::fp::FpVar<ConstraintF>>, ark_relations::r1cs::SynthesisError>;
143}