From 951a6226c94521a754f9c5dc9b3c9129f5b736c0 Mon Sep 17 00:00:00 2001
From: Georgios Konstantopoulos <me@gakonst.com>
Date: Mon, 23 Mar 2020 09:32:05 +0200
Subject: [PATCH] feat: TestConstraintCounter

---
 r1cs-std/src/lib.rs                     |  1 +
 r1cs-std/src/test_constraint_counter.rs | 74 +++++++++++++++++++++++++
 2 files changed, 75 insertions(+)
 create mode 100644 r1cs-std/src/test_constraint_counter.rs

diff --git a/r1cs-std/src/lib.rs b/r1cs-std/src/lib.rs
index 74b0607..b0180c2 100644
--- a/r1cs-std/src/lib.rs
+++ b/r1cs-std/src/lib.rs
@@ -34,6 +34,7 @@ use ralloc::{collections::BTreeMap, string::String, vec::Vec};
 use std::{collections::BTreeMap, string::String, vec::Vec};
 
 pub mod test_constraint_system;
+pub mod test_constraint_counter;
 
 pub mod bits;
 pub use self::bits::*;
diff --git a/r1cs-std/src/test_constraint_counter.rs b/r1cs-std/src/test_constraint_counter.rs
new file mode 100644
index 0000000..6fc4c72
--- /dev/null
+++ b/r1cs-std/src/test_constraint_counter.rs
@@ -0,0 +1,74 @@
+use crate::String;
+use algebra::Field;
+use r1cs_core::{ConstraintSystem, Index, LinearCombination, SynthesisError, Variable};
+
+/// Constraint counter for testing purposes.
+pub struct TestConstraintCounter {
+    pub num_inputs:      usize,
+    pub num_aux:         usize,
+    pub num_constraints: usize,
+}
+
+impl TestConstraintCounter {
+    pub fn new() -> TestConstraintCounter {
+        TestConstraintCounter {
+            num_aux: 0,
+            num_inputs: 0,
+            num_constraints: 0,
+        }
+    }
+}
+
+impl<ConstraintF: Field> ConstraintSystem<ConstraintF> for TestConstraintCounter {
+    type Root = Self;
+
+    fn alloc<F, A, AR>(&mut self, _: A, _: F) -> Result<Variable, SynthesisError>
+    where
+        F: FnOnce() -> Result<ConstraintF, SynthesisError>,
+        A: FnOnce() -> AR,
+        AR: Into<String>,
+    {
+        let var = Variable::new_unchecked(Index::Aux(self.num_aux));
+        self.num_aux += 1;
+        Ok(var)
+    }
+
+    fn alloc_input<F, A, AR>(&mut self, _: A, _: F) -> Result<Variable, SynthesisError>
+    where
+        F: FnOnce() -> Result<ConstraintF, SynthesisError>,
+        A: FnOnce() -> AR,
+        AR: Into<String>,
+    {
+        let var = Variable::new_unchecked(Index::Input(self.num_inputs));
+        self.num_inputs += 1;
+
+        Ok(var)
+    }
+
+    fn enforce<A, AR, LA, LB, LC>(&mut self, _: A, _: LA, _: LB, _: LC)
+    where
+        A: FnOnce() -> AR,
+        AR: Into<String>,
+        LA: FnOnce(LinearCombination<ConstraintF>) -> LinearCombination<ConstraintF>,
+        LB: FnOnce(LinearCombination<ConstraintF>) -> LinearCombination<ConstraintF>,
+        LC: FnOnce(LinearCombination<ConstraintF>) -> LinearCombination<ConstraintF>,
+    {
+        self.num_constraints += 1;
+    }
+
+    fn push_namespace<NR, N>(&mut self, _: N)
+    where
+        NR: Into<String>,
+        N: FnOnce() -> NR,
+    {}
+
+    fn pop_namespace(&mut self) { }
+
+    fn get_root(&mut self) -> &mut Self::Root {
+        self
+    }
+
+    fn num_constraints(&self) -> usize {
+        self.num_constraints
+    }
+}
\ No newline at end of file