From ac9839efefaab7d529af46739b6e48612ccd8521 Mon Sep 17 00:00:00 2001
From: han0110 <tinghan0110@gmail.com>
Date: Fri, 10 Jun 2022 16:32:09 +0800
Subject: [PATCH] feat: expose necessary structure of ConstraintSystem

---
 halo2_proofs/src/plonk.rs             | 15 +++++
 halo2_proofs/src/plonk/circuit.rs     | 92 +++++++++++++++++++++++++--
 halo2_proofs/src/plonk/lookup.rs      | 18 ++++--
 halo2_proofs/src/plonk/permutation.rs | 13 +++-
 4 files changed, 127 insertions(+), 11 deletions(-)

diff --git a/halo2_proofs/src/plonk.rs b/halo2_proofs/src/plonk.rs
index 9be2fdbc79..f9a6587af6 100644
--- a/halo2_proofs/src/plonk.rs
+++ b/halo2_proofs/src/plonk.rs
@@ -110,6 +110,21 @@ impl<C: CurveAffine> VerifyingKey<C> {
             cs: self.cs.pinned(),
         }
     }
+
+    /// Returns commitments of fixed polynomials
+    pub fn fixed_commitments(&self) -> &Vec<C> {
+        &self.fixed_commitments
+    }
+
+    /// Returns `VerifyingKey` of permutation
+    pub fn permutation(&self) -> &permutation::VerifyingKey<C> {
+        &self.permutation
+    }
+
+    /// Returns `ConstraintSystem`
+    pub fn cs(&self) -> &ConstraintSystem<C::Scalar> {
+        &self.cs
+    }
 }
 
 /// Minimal representation of a verification key that can be used to identify
diff --git a/halo2_proofs/src/plonk/circuit.rs b/halo2_proofs/src/plonk/circuit.rs
index a0dce53110..460bdb5db6 100644
--- a/halo2_proofs/src/plonk/circuit.rs
+++ b/halo2_proofs/src/plonk/circuit.rs
@@ -33,7 +33,8 @@ impl<C: ColumnType> Column<C> {
         Column { index, column_type }
     }
 
-    pub(crate) fn index(&self) -> usize {
+    /// Index of this column.
+    pub fn index(&self) -> usize {
         self.index
     }
 
@@ -280,6 +281,18 @@ pub struct FixedQuery {
     pub(crate) rotation: Rotation,
 }
 
+impl FixedQuery {
+    /// Column index
+    pub fn column_index(&self) -> usize {
+        self.column_index
+    }
+
+    /// Rotation of this query
+    pub fn rotation(&self) -> Rotation {
+        self.rotation
+    }
+}
+
 /// Query of advice column at a certain relative location
 #[derive(Copy, Clone, Debug)]
 pub struct AdviceQuery {
@@ -291,6 +304,18 @@ pub struct AdviceQuery {
     pub(crate) rotation: Rotation,
 }
 
+impl AdviceQuery {
+    /// Column index
+    pub fn column_index(&self) -> usize {
+        self.column_index
+    }
+
+    /// Rotation of this query
+    pub fn rotation(&self) -> Rotation {
+        self.rotation
+    }
+}
+
 /// Query of instance column at a certain relative location
 #[derive(Copy, Clone, Debug)]
 pub struct InstanceQuery {
@@ -302,6 +327,18 @@ pub struct InstanceQuery {
     pub(crate) rotation: Rotation,
 }
 
+impl InstanceQuery {
+    /// Column index
+    pub fn column_index(&self) -> usize {
+        self.column_index
+    }
+
+    /// Rotation of this query
+    pub fn rotation(&self) -> Rotation {
+        self.rotation
+    }
+}
+
 /// A fixed column of a lookup table.
 ///
 /// A lookup table can be loaded into this column via [`Layouter::assign_table`]. Columns
@@ -930,7 +967,7 @@ pub(crate) struct PointIndex(pub usize);
 /// A "virtual cell" is a PLONK cell that has been queried at a particular relative offset
 /// within a custom gate.
 #[derive(Clone, Debug)]
-pub(crate) struct VirtualCell {
+pub struct VirtualCell {
     pub(crate) column: Column<Any>,
     pub(crate) rotation: Rotation,
 }
@@ -1054,8 +1091,9 @@ impl<F: Field, C: Into<Constraint<F>>, Iter: IntoIterator<Item = C>> IntoIterato
     }
 }
 
+/// Gate
 #[derive(Clone, Debug)]
-pub(crate) struct Gate<F: Field> {
+pub struct Gate<F: Field> {
     name: &'static str,
     constraint_names: Vec<&'static str>,
     polys: Vec<Expression<F>>,
@@ -1074,7 +1112,8 @@ impl<F: Field> Gate<F> {
         self.constraint_names[constraint_index]
     }
 
-    pub(crate) fn polynomials(&self) -> &[Expression<F>] {
+    /// Returns constraints of this gate
+    pub fn polynomials(&self) -> &[Expression<F>] {
         &self.polys
     }
 
@@ -1648,6 +1687,51 @@ impl<F: Field> ConstraintSystem<F> {
                 // and the interstitial values.)
             + 1 // for at least one row
     }
+
+    /// Returns number of fixed columns
+    pub fn num_fixed_columns(&self) -> usize {
+        self.num_fixed_columns
+    }
+
+    /// Returns number of advice columns
+    pub fn num_advice_columns(&self) -> usize {
+        self.num_advice_columns
+    }
+
+    /// Returns number of instance columns
+    pub fn num_instance_columns(&self) -> usize {
+        self.num_instance_columns
+    }
+
+    /// Returns gates
+    pub fn gates(&self) -> &Vec<Gate<F>> {
+        &self.gates
+    }
+
+    /// Returns advice queries
+    pub fn advice_queries(&self) -> &Vec<(Column<Advice>, Rotation)> {
+        &self.advice_queries
+    }
+
+    /// Returns instance queries
+    pub fn instance_queries(&self) -> &Vec<(Column<Instance>, Rotation)> {
+        &self.instance_queries
+    }
+
+    /// Returns fixed queries
+    pub fn fixed_queries(&self) -> &Vec<(Column<Fixed>, Rotation)> {
+        &self.fixed_queries
+    }
+
+    /// Returns permutation argument
+    pub fn permutation(&self) -> &permutation::Argument {
+        &self.permutation
+    }
+
+    /// Returns lookup arguments
+    pub fn lookups(&self) -> &Vec<lookup::Argument<F>> {
+        &self.lookups
+    }
 }
 
 /// Exposes the "virtual cells" that can be queried while creating a custom gate or lookup
diff --git a/halo2_proofs/src/plonk/lookup.rs b/halo2_proofs/src/plonk/lookup.rs
index 8b4e8258d3..68cda75d37 100644
--- a/halo2_proofs/src/plonk/lookup.rs
+++ b/halo2_proofs/src/plonk/lookup.rs
@@ -6,10 +6,10 @@ pub(crate) mod prover;
 pub(crate) mod verifier;
 
 #[derive(Clone)]
-pub(crate) struct Argument<F: Field> {
-    pub name: &'static str,
-    pub input_expressions: Vec<Expression<F>>,
-    pub table_expressions: Vec<Expression<F>>,
+pub struct Argument<F: Field> {
+    pub(crate) name: &'static str,
+    pub(crate) input_expressions: Vec<Expression<F>>,
+    pub(crate) table_expressions: Vec<Expression<F>>,
 }
 
 impl<F: Field> Debug for Argument<F> {
@@ -81,4 +81,14 @@ impl<F: Field> Argument<F> {
             2 + input_degree + table_degree,
         )
     }
+
+    /// Returns input of this argument
+    pub fn input_expressions(&self) -> &Vec<Expression<F>> {
+        &self.input_expressions
+    }
+
+    /// Returns table of this argument
+    pub fn table_expressions(&self) -> &Vec<Expression<F>> {
+        &self.table_expressions
+    }
 }
diff --git a/halo2_proofs/src/plonk/permutation.rs b/halo2_proofs/src/plonk/permutation.rs
index 23ade0d3aa..26a4d805d6 100644
--- a/halo2_proofs/src/plonk/permutation.rs
+++ b/halo2_proofs/src/plonk/permutation.rs
@@ -13,7 +13,7 @@ use std::io;
 
 /// A permutation argument.
 #[derive(Debug, Clone)]
-pub(crate) struct Argument {
+pub struct Argument {
     /// A sequence of columns involved in the argument.
     pub(super) columns: Vec<Column<Any>>,
 }
@@ -67,17 +67,24 @@ impl Argument {
         }
     }
 
-    pub(crate) fn get_columns(&self) -> Vec<Column<Any>> {
+    pub fn get_columns(&self) -> Vec<Column<Any>> {
         self.columns.clone()
     }
 }
 
 /// The verifying key for a single permutation argument.
 #[derive(Clone, Debug)]
-pub(crate) struct VerifyingKey<C: CurveAffine> {
+pub struct VerifyingKey<C: CurveAffine> {
     commitments: Vec<C>,
 }
 
+impl<C: CurveAffine> VerifyingKey<C> {
+    /// Returns commitments of sigma polynomials
+    pub fn commitments(&self) -> &Vec<C> {
+        &self.commitments
+    }
+}
+
 /// The proving key for a single permutation argument.
 #[derive(Clone, Debug)]
 pub(crate) struct ProvingKey<C: CurveAffine> {