From 9dfc6ac3798fc56fa090f81b9fbee0bec9be74e0 Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Sat, 22 Aug 2020 15:09:47 -0600
Subject: [PATCH] Add first pieces of the API.

---
 src/plonk.rs         | 13 ++++++-
 src/plonk/circuit.rs | 82 ++++++++++++++++++++++++++++++++++++++++++--
 src/plonk/prover.rs  |  8 +++--
 src/plonk/srs.rs     |  8 +++--
 4 files changed, 103 insertions(+), 8 deletions(-)

diff --git a/src/plonk.rs b/src/plonk.rs
index 66f3e32..97eba66 100644
--- a/src/plonk.rs
+++ b/src/plonk.rs
@@ -103,12 +103,23 @@ fn test_proving() {
     // Initialize the polynomial commitment parameters
     let params: Params<EqAffine> = Params::new::<DummyHash<Fq>>(K);
 
+    struct MyConfig {}
     struct MyCircuit<F: Field> {
         a: Option<F>,
     }
 
     impl<F: Field> Circuit<F> for MyCircuit<F> {
-        fn synthesize(&self, cs: &mut impl ConstraintSystem<F>) -> Result<(), Error> {
+        type Config = MyConfig;
+
+        fn configure(meta: &mut MetaCircuit) -> MyConfig {
+            MyConfig {}
+        }
+
+        fn synthesize(
+            &self,
+            cs: &mut impl ConstraintSystem<F>,
+            config: MyConfig,
+        ) -> Result<(), Error> {
             for _ in 0..10 {
                 let (_, _, _, _) = cs.multiply(|| {
                     let a = self.a.ok_or(Error::SynthesisError)?;
diff --git a/src/plonk/circuit.rs b/src/plonk/circuit.rs
index c0168d2..48da226 100644
--- a/src/plonk/circuit.rs
+++ b/src/plonk/circuit.rs
@@ -1,10 +1,12 @@
-use super::Error;
+use core::cmp::max;
+use core::ops::{Add, Mul};
 
+use super::Error;
 use crate::arithmetic::Field;
 
 /// This represents a PLONK wire, which could be a fixed (selector) wire or an
 /// advice wire.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub enum Wire {
     /// A wires
     A(usize),
@@ -59,8 +61,82 @@ pub trait ConstraintSystem<F: Field> {
 /// backend prover can ask the circuit to synthesize using some given
 /// [`ConstraintSystem`] implementation.
 pub trait Circuit<F: Field> {
+    /// This is a configuration object that stores things like wires.
+    type Config;
+
+    /// The circuit is given an opportunity to describe the exact gate
+    /// arrangement, wire arrangement, etc.
+    fn configure(meta: &mut MetaCircuit) -> Self::Config;
+
     /// Given the provided `cs`, synthesize the circuit. The concrete type of
     /// the caller will be different depending on the context, and they may or
     /// may not expect to have a witness present.
-    fn synthesize(&self, cs: &mut impl ConstraintSystem<F>) -> Result<(), Error>;
+    fn synthesize(
+        &self,
+        cs: &mut impl ConstraintSystem<F>,
+        config: Self::Config,
+    ) -> Result<(), Error>;
+}
+
+/// Low-degree polynomial representing an identity that must hold over the committed wires.
+#[derive(Clone, Debug)]
+pub enum Polynomial<F> {
+    /// This is a wire queried at a certain relative location
+    Wire(Wire, isize),
+    /// This is the sum of two polynomials
+    Sum(Box<Polynomial<F>>, Box<Polynomial<F>>),
+    /// This is the product of two polynomials
+    Product(Box<Polynomial<F>>, Box<Polynomial<F>>),
+    /// This is a scaled polynomial
+    Scaled(Box<Polynomial<F>>, F),
+}
+
+impl<F: Field> Polynomial<F> {
+    fn degree(&self) -> usize {
+        match self {
+            Polynomial::Wire(_, _) => 1,
+            Polynomial::Sum(ref a, ref b) => max(a.degree(), b.degree()),
+            Polynomial::Product(ref a, ref b) => a.degree() + b.degree(),
+            Polynomial::Scaled(ref poly, _) => poly.degree(),
+        }
+    }
+}
+
+impl<F> Add for Polynomial<F> {
+    type Output = Polynomial<F>;
+    fn add(self, rhs: Polynomial<F>) -> Polynomial<F> {
+        Polynomial::Sum(Box::new(self), Box::new(rhs))
+    }
+}
+
+impl<F> Mul for Polynomial<F> {
+    type Output = Polynomial<F>;
+    fn mul(self, rhs: Polynomial<F>) -> Polynomial<F> {
+        Polynomial::Product(Box::new(self), Box::new(rhs))
+    }
+}
+
+impl<F> Mul<F> for Polynomial<F> {
+    type Output = Polynomial<F>;
+    fn mul(self, rhs: F) -> Polynomial<F> {
+        Polynomial::Scaled(Box::new(self), rhs)
+    }
+}
+
+/// This is a description of the circuit environment, such as the gate, wire and
+/// permutation arrangements.
+#[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,
+}
+
+impl Default for MetaCircuit {
+    fn default() -> MetaCircuit {
+        MetaCircuit {}
+    }
 }
diff --git a/src/plonk/prover.rs b/src/plonk/prover.rs
index d06119d..b0b66bf 100644
--- a/src/plonk/prover.rs
+++ b/src/plonk/prover.rs
@@ -1,5 +1,5 @@
 use super::{
-    circuit::{Circuit, ConstraintSystem, Wire},
+    circuit::{Circuit, ConstraintSystem, MetaCircuit, Wire},
     hash_point, Error, Proof, SRS,
 };
 use crate::arithmetic::{
@@ -78,8 +78,12 @@ impl<C: CurveAffine> Proof<C> {
             sm: vec![],
         };
 
+        let mut meta = MetaCircuit::default();
+
+        let config = ConcreteCircuit::configure(&mut meta);
+
         // Synthesize the circuit to obtain the witness and other information.
-        circuit.synthesize(&mut witness)?;
+        circuit.synthesize(&mut witness, config)?;
 
         // Create a transcript for obtaining Fiat-Shamir challenges.
         let mut transcript = HBase::init(C::Base::one());
diff --git a/src/plonk/srs.rs b/src/plonk/srs.rs
index 0a9acdb..7d0487d 100644
--- a/src/plonk/srs.rs
+++ b/src/plonk/srs.rs
@@ -1,5 +1,5 @@
 use super::{
-    circuit::{Circuit, ConstraintSystem, Wire},
+    circuit::{Circuit, ConstraintSystem, MetaCircuit, Wire},
     domain::EvaluationDomain,
     Error, GATE_DEGREE, SRS,
 };
@@ -54,8 +54,12 @@ impl<C: CurveAffine> SRS<C> {
             sm: vec![],
         };
 
+        let mut meta = MetaCircuit::default();
+
+        let config = ConcreteCircuit::configure(&mut meta);
+
         // Synthesize the circuit to obtain SRS
-        circuit.synthesize(&mut assembly)?;
+        circuit.synthesize(&mut assembly, config)?;
 
         assembly.sa.resize(params.n as usize, C::Scalar::zero());
         assembly.sb.resize(params.n as usize, C::Scalar::zero());