From 68da2a7803db9a97b8eab3cd893f5371ba947f98 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gustavo=20Gir=C3=A1ldez?= <ggiraldez@manas.tech>
Date: Mon, 23 Oct 2023 12:52:24 -0400
Subject: [PATCH] chore: use an enum instead of Either to model the result of
 opcode stepping

---
 Cargo.lock                    |  2 --
 acvm-repo/acvm/Cargo.toml     |  1 -
 acvm-repo/acvm/src/pwg/mod.rs | 18 +++++++++++-------
 tooling/debugger/Cargo.toml   |  1 -
 tooling/debugger/src/lib.rs   |  7 +++----
 5 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index f7e1ecae19c..5601dbae53d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -42,7 +42,6 @@ dependencies = [
  "acvm_blackbox_solver",
  "acvm_stdlib",
  "brillig_vm",
- "either",
  "indexmap 1.9.3",
  "num-bigint",
  "num-traits",
@@ -2544,7 +2543,6 @@ version = "0.16.0"
 dependencies = [
  "acvm",
  "easy-repl",
- "either",
  "nargo",
  "noirc_printable_type",
  "owo-colors",
diff --git a/acvm-repo/acvm/Cargo.toml b/acvm-repo/acvm/Cargo.toml
index 0d0dadd77f8..f51bb627fd9 100644
--- a/acvm-repo/acvm/Cargo.toml
+++ b/acvm-repo/acvm/Cargo.toml
@@ -16,7 +16,6 @@ repository.workspace = true
 num-bigint.workspace = true
 num-traits.workspace = true
 thiserror.workspace = true
-either = "1.8.1"
 
 acir.workspace = true
 stdlib.workspace = true
diff --git a/acvm-repo/acvm/src/pwg/mod.rs b/acvm-repo/acvm/src/pwg/mod.rs
index ee974574e72..de78e46174f 100644
--- a/acvm-repo/acvm/src/pwg/mod.rs
+++ b/acvm-repo/acvm/src/pwg/mod.rs
@@ -18,7 +18,6 @@ use self::{
 use crate::{BlackBoxFunctionSolver, Language};
 
 use thiserror::Error;
-use either::Either;
 
 // arithmetic
 pub(crate) mod arithmetic;
@@ -64,6 +63,11 @@ impl std::fmt::Display for ACVMStatus {
     }
 }
 
+pub enum StepResult<'a, B: BlackBoxFunctionSolver> {
+    Status(ACVMStatus),
+    IntoBrillig(BrilligSolver<'a, B>),
+}
+
 // This enum represents the different cases in which an
 // opcode can be unsolvable.
 // The most common being that one of its input has not been
@@ -337,27 +341,27 @@ impl<'a, B: BlackBoxFunctionSolver> ACVM<'a, B> {
         }
     }
 
-    pub fn step_into_brillig_opcode(&mut self) -> Either<BrilligSolver<'a, B>, ACVMStatus> {
+    pub fn step_into_brillig_opcode(&mut self) -> StepResult<'a, B> {
         if let Opcode::Brillig(brillig) = &self.opcodes[self.instruction_pointer] {
             let witness = &mut self.witness_map;
             match BrilligSolver::<B>::should_skip(witness, brillig) {
                 Ok(true) => {
                     let resolution = BrilligSolver::<B>::zero_out_brillig_outputs(witness, brillig);
-                    Either::Right(self.handle_opcode_resolution(resolution))
+                    StepResult::Status(self.handle_opcode_resolution(resolution))
                 }
                 Ok(false) => {
                     let solver = BrilligSolver::new(witness, brillig, self.backend, self.instruction_pointer);
                     match solver {
-                        Ok(solver) => Either::Left(solver),
-                        Err(..) => Either::Right(self.handle_opcode_resolution(solver.map(|_| ()))),
+                        Ok(solver) => StepResult::IntoBrillig(solver),
+                        Err(..) => StepResult::Status(self.handle_opcode_resolution(solver.map(|_| ()))),
                     }
                 }
                 Err(err) => {
-                    Either::Right(self.handle_opcode_resolution(Err(err)))
+                    StepResult::Status(self.handle_opcode_resolution(Err(err)))
                 }
             }
         } else {
-            Either::Right(self.solve_opcode())
+            StepResult::Status(self.solve_opcode())
         }
     }
 
diff --git a/tooling/debugger/Cargo.toml b/tooling/debugger/Cargo.toml
index 5413ef25103..7e06c549d2d 100644
--- a/tooling/debugger/Cargo.toml
+++ b/tooling/debugger/Cargo.toml
@@ -15,4 +15,3 @@ noirc_printable_type.workspace = true
 thiserror.workspace = true
 easy-repl = "0.2.1"
 owo-colors = "3"
-either = "1.8.1"
diff --git a/tooling/debugger/src/lib.rs b/tooling/debugger/src/lib.rs
index b98cef611ec..b63b97cf2cc 100644
--- a/tooling/debugger/src/lib.rs
+++ b/tooling/debugger/src/lib.rs
@@ -1,5 +1,5 @@
 use acvm::acir::circuit::OpcodeLocation;
-use acvm::pwg::{ACVMStatus, BrilligSolver, ErrorLocation, OpcodeResolutionError, ACVM, BrilligSolverStatus};
+use acvm::pwg::{ACVMStatus, BrilligSolver, ErrorLocation, OpcodeResolutionError, ACVM, BrilligSolverStatus, StepResult};
 use acvm::BlackBoxFunctionSolver;
 use acvm::{acir::circuit::Circuit, acir::native_types::WitnessMap};
 
@@ -13,7 +13,6 @@ use easy_repl::{command, CommandStatus, Critical, Repl};
 use std::cell::{Cell, RefCell};
 
 use owo_colors::OwoColorize;
-use either::Either;
 
 enum SolveResult {
     Done,
@@ -67,11 +66,11 @@ impl<'backend, B: BlackBoxFunctionSolver> DebugContext<'backend, B> {
             self.step_brillig_opcode()
         } else {
             match self.acvm.step_into_brillig_opcode() {
-                Either::Left(solver) => {
+                StepResult::IntoBrillig(solver) => {
                     self.brillig_solver = Some(solver);
                     self.step_brillig_opcode()
                 }
-                Either::Right(status) => {
+                StepResult::Status(status) => {
                     self.handle_acvm_status(status)
                 }
             }