ark_relations/r1cs/
mod.rs

1//! Core interface for working with Rank-1 Constraint Systems (R1CS).
2
3use ark_std::vec::Vec;
4
5/// A result type specialized to `SynthesisError`.
6pub type Result<T> = core::result::Result<T, SynthesisError>;
7
8#[macro_use]
9mod impl_lc;
10mod constraint_system;
11mod error;
12#[cfg(feature = "std")]
13mod trace;
14
15#[cfg(feature = "std")]
16pub use crate::r1cs::trace::{ConstraintLayer, ConstraintTrace, TraceStep, TracingMode};
17
18pub use tracing::info_span;
19
20pub use ark_ff::{Field, ToConstraintField};
21pub use constraint_system::{
22    ConstraintMatrices, ConstraintSynthesizer, ConstraintSystem, ConstraintSystemRef, Namespace,
23    OptimizationGoal, SynthesisMode,
24};
25pub use error::SynthesisError;
26
27use core::cmp::Ordering;
28
29/// A sparse representation of constraint matrices.
30pub type Matrix<F> = Vec<Vec<(F, usize)>>;
31
32#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
33/// An opaque counter for symbolic linear combinations.
34pub struct LcIndex(usize);
35
36/// Represents the different kinds of variables present in a constraint system.
37#[derive(Copy, Clone, PartialEq, Debug, Eq)]
38pub enum Variable {
39    /// Represents the "zero" constant.
40    Zero,
41    /// Represents of the "one" constant.
42    One,
43    /// Represents a public instance variable.
44    Instance(usize),
45    /// Represents a private witness variable.
46    Witness(usize),
47    /// Represents of a linear combination.
48    SymbolicLc(LcIndex),
49}
50
51/// A linear combination of variables according to associated coefficients.
52#[derive(Debug, Clone, PartialEq, Eq, Default)]
53pub struct LinearCombination<F: Field>(pub Vec<(F, Variable)>);
54
55/// Generate a `Namespace` with name `name` from `ConstraintSystem` `cs`.
56/// `name` must be a `&'static str`.
57#[macro_export]
58macro_rules! ns {
59    ($cs:expr, $name:expr) => {{
60        let span = $crate::r1cs::info_span!(target: "r1cs", $name);
61        let id = span.id();
62        let _enter_guard = span.enter();
63        core::mem::forget(_enter_guard);
64        core::mem::forget(span);
65        $crate::r1cs::Namespace::new($cs.clone(), id)
66    }};
67}
68
69impl Variable {
70    /// Is `self` the zero variable?
71    #[inline]
72    pub fn is_zero(&self) -> bool {
73        matches!(self, Variable::Zero)
74    }
75
76    /// Is `self` the one variable?
77    #[inline]
78    pub fn is_one(&self) -> bool {
79        matches!(self, Variable::One)
80    }
81
82    /// Is `self` an instance variable?
83    #[inline]
84    pub fn is_instance(&self) -> bool {
85        matches!(self, Variable::Instance(_))
86    }
87
88    /// Is `self` a witness variable?
89    #[inline]
90    pub fn is_witness(&self) -> bool {
91        matches!(self, Variable::Witness(_))
92    }
93
94    /// Is `self` a linear combination?
95    #[inline]
96    pub fn is_lc(&self) -> bool {
97        matches!(self, Variable::SymbolicLc(_))
98    }
99
100    /// Get the `LcIndex` in `self` if `self.is_lc()`.
101    #[inline]
102    pub fn get_lc_index(&self) -> Option<LcIndex> {
103        match self {
104            Variable::SymbolicLc(index) => Some(*index),
105            _ => None,
106        }
107    }
108
109    /// Returns `Some(usize)` if `!self.is_lc()`, and `None` otherwise.
110    #[inline]
111    pub fn get_index_unchecked(&self, witness_offset: usize) -> Option<usize> {
112        match self {
113            // The one variable always has index 0
114            Variable::One => Some(0),
115            Variable::Instance(i) => Some(*i),
116            Variable::Witness(i) => Some(witness_offset + *i),
117            _ => None,
118        }
119    }
120}
121
122impl PartialOrd for Variable {
123    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
124        use Variable::*;
125        match (self, other) {
126            (Zero, Zero) => Some(Ordering::Equal),
127            (One, One) => Some(Ordering::Equal),
128            (Zero, _) => Some(Ordering::Less),
129            (One, _) => Some(Ordering::Less),
130            (_, Zero) => Some(Ordering::Greater),
131            (_, One) => Some(Ordering::Greater),
132
133            (Instance(i), Instance(j)) | (Witness(i), Witness(j)) => i.partial_cmp(j),
134            (Instance(_), Witness(_)) => Some(Ordering::Less),
135            (Witness(_), Instance(_)) => Some(Ordering::Greater),
136
137            (SymbolicLc(i), SymbolicLc(j)) => i.partial_cmp(j),
138            (_, SymbolicLc(_)) => Some(Ordering::Less),
139            (SymbolicLc(_), _) => Some(Ordering::Greater),
140        }
141    }
142}
143
144impl Ord for Variable {
145    fn cmp(&self, other: &Self) -> Ordering {
146        self.partial_cmp(other).unwrap()
147    }
148}
ark_relations/r1cs/mod.rs

ark_relations/r1cs/
mod.rs
