From c16141be9a150934e2a35604459cb6373553b702 Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Sat, 22 Aug 2020 15:15:39 -0600
Subject: [PATCH] Introduce `Variable` type

---
 src/plonk/circuit.rs | 28 ++++++++++++++++------------
 src/plonk/prover.rs  | 12 ++++++------
 src/plonk/srs.rs     | 12 ++++++------
 3 files changed, 28 insertions(+), 24 deletions(-)

diff --git a/src/plonk/circuit.rs b/src/plonk/circuit.rs
index 48da226..f016b6b 100644
--- a/src/plonk/circuit.rs
+++ b/src/plonk/circuit.rs
@@ -9,15 +9,19 @@ use crate::arithmetic::Field;
 #[derive(Clone, Debug)]
 pub enum Wire {
     /// A wires
-    A(usize),
+    A,
     /// B wires
-    B(usize),
+    B,
     /// C wires
-    C(usize),
+    C,
     /// D wires
-    D(usize),
+    D,
 }
 
+/// Represents a pointer to a value in the constraint system.
+#[derive(Clone, Debug)]
+pub struct Variable(pub(crate) Wire, pub(crate) usize);
+
 /// This trait allows a [`Circuit`] to direct some backend to assign a witness
 /// for a constraint system.
 pub trait ConstraintSystem<F: Field> {
@@ -30,13 +34,13 @@ pub trait ConstraintSystem<F: Field> {
         sd: F,
         sm: F,
         f: impl Fn() -> Result<(F, F, F, F), Error>,
-    ) -> Result<(Wire, Wire, Wire, Wire), Error>;
+    ) -> Result<(Variable, Variable, Variable, Variable), Error>;
 
     /// a * b - c = 0
     fn multiply(
         &mut self,
         f: impl Fn() -> Result<(F, F, F), Error>,
-    ) -> Result<(Wire, Wire, Wire, Wire), Error> {
+    ) -> Result<(Variable, Variable, Variable, Variable), Error> {
         self.create_gate(F::zero(), F::zero(), F::one(), F::zero(), F::one(), || {
             let (a, b, c) = f()?;
             Ok((a, b, c, F::zero()))
@@ -47,7 +51,7 @@ pub trait ConstraintSystem<F: Field> {
     fn add(
         &mut self,
         f: impl Fn() -> Result<(F, F, F), Error>,
-    ) -> Result<(Wire, Wire, Wire, Wire), Error> {
+    ) -> Result<(Variable, Variable, Variable, Variable), Error> {
         self.create_gate(F::one(), F::one(), F::one(), F::zero(), F::zero(), || {
             let (a, b, c) = f()?;
             Ok((a, b, c, F::zero()))
@@ -128,11 +132,11 @@ impl<F> Mul<F> for Polynomial<F> {
 #[derive(Debug, Clone)]
 pub struct MetaCircuit {
     // num_fixed_wires: usize,
-// num_advice_wires: usize,
-// permutations: Vec<Vec<Wire>>,
-// gates: Vec<Polynomial>,
-// queries: HashSet<(Wire, usize)>,
-// num_queries: usize,
+    // num_advice_wires: usize,
+    // permutations: Vec<Vec<Wire>>,
+    // gates: Vec<Polynomial>,
+    // queries: HashSet<(Wire, usize)>,
+    // num_queries: usize,
 }
 
 impl Default for MetaCircuit {
diff --git a/src/plonk/prover.rs b/src/plonk/prover.rs
index b0b66bf..f6016cf 100644
--- a/src/plonk/prover.rs
+++ b/src/plonk/prover.rs
@@ -1,5 +1,5 @@
 use super::{
-    circuit::{Circuit, ConstraintSystem, MetaCircuit, Wire},
+    circuit::{Circuit, ConstraintSystem, MetaCircuit, Wire, Variable},
     hash_point, Error, Proof, SRS,
 };
 use crate::arithmetic::{
@@ -42,13 +42,13 @@ impl<C: CurveAffine> Proof<C> {
                 sd: F,
                 sm: F,
                 f: impl Fn() -> Result<(F, F, F, F), Error>,
-            ) -> Result<(Wire, Wire, Wire, Wire), Error> {
+            ) -> Result<(Variable, Variable, Variable, Variable), Error> {
                 let (a, b, c, d) = f()?;
                 let tmp = Ok((
-                    Wire::A(self.a.len()),
-                    Wire::B(self.a.len()),
-                    Wire::C(self.a.len()),
-                    Wire::D(self.a.len()),
+                    Variable(Wire::A, self.a.len()),
+                    Variable(Wire::B, self.a.len()),
+                    Variable(Wire::C, self.a.len()),
+                    Variable(Wire::D, self.a.len()),
                 ));
                 self.a.push(a);
                 self.b.push(b);
diff --git a/src/plonk/srs.rs b/src/plonk/srs.rs
index 7d0487d..c61f8cb 100644
--- a/src/plonk/srs.rs
+++ b/src/plonk/srs.rs
@@ -1,5 +1,5 @@
 use super::{
-    circuit::{Circuit, ConstraintSystem, MetaCircuit, Wire},
+    circuit::{Circuit, ConstraintSystem, MetaCircuit, Wire, Variable},
     domain::EvaluationDomain,
     Error, GATE_DEGREE, SRS,
 };
@@ -30,12 +30,12 @@ impl<C: CurveAffine> SRS<C> {
                 sd: F,
                 sm: F,
                 _: impl Fn() -> Result<(F, F, F, F), Error>,
-            ) -> Result<(Wire, Wire, Wire, Wire), Error> {
+            ) -> Result<(Variable, Variable, Variable, Variable), Error> {
                 let tmp = Ok((
-                    Wire::A(self.sa.len()),
-                    Wire::B(self.sa.len()),
-                    Wire::C(self.sa.len()),
-                    Wire::D(self.sa.len()),
+                    Variable(Wire::A, self.sa.len()),
+                    Variable(Wire::B, self.sa.len()),
+                    Variable(Wire::C, self.sa.len()),
+                    Variable(Wire::D, self.sa.len()),
                 ));
                 self.sa.push(sa);
                 self.sb.push(sb);