From e4ef148e26c700891ebe31e62a55ebaf8a8c4009 Mon Sep 17 00:00:00 2001
From: lucasxia01 <lucasxia01@gmail.com>
Date: Fri, 12 Jan 2024 21:10:57 +0000
Subject: [PATCH] updated to use span instead of vector

---
 .../cpp/src/barretenberg/crypto/poseidon2/poseidon2.cpp      | 5 ++---
 .../cpp/src/barretenberg/crypto/poseidon2/poseidon2.hpp      | 2 +-
 .../cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.cpp | 5 ++---
 .../cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.hpp | 2 +-
 .../barretenberg/stdlib/hash/poseidon2/poseidon2.test.cpp    | 3 ++-
 5 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/barretenberg/cpp/src/barretenberg/crypto/poseidon2/poseidon2.cpp b/barretenberg/cpp/src/barretenberg/crypto/poseidon2/poseidon2.cpp
index ad96dc312713..65c6dc0f1684 100644
--- a/barretenberg/cpp/src/barretenberg/crypto/poseidon2/poseidon2.cpp
+++ b/barretenberg/cpp/src/barretenberg/crypto/poseidon2/poseidon2.cpp
@@ -5,10 +5,9 @@ namespace crypto {
  * @brief Hashes a vector of field elements
  */
 template <typename Params>
-typename Poseidon2<Params>::FF Poseidon2<Params>::hash(const std::vector<typename Poseidon2<Params>::FF>& input)
+typename Poseidon2<Params>::FF Poseidon2<Params>::hash(const std::span<typename Poseidon2<Params>::FF>& input)
 {
-    auto input_span = input;
-    return Sponge::hash_fixed_length(input_span);
+    return Sponge::hash_fixed_length(input);
 }
 
 /**
diff --git a/barretenberg/cpp/src/barretenberg/crypto/poseidon2/poseidon2.hpp b/barretenberg/cpp/src/barretenberg/crypto/poseidon2/poseidon2.hpp
index 6969c680e177..6f86bb35e3fa 100644
--- a/barretenberg/cpp/src/barretenberg/crypto/poseidon2/poseidon2.hpp
+++ b/barretenberg/cpp/src/barretenberg/crypto/poseidon2/poseidon2.hpp
@@ -16,7 +16,7 @@ template <typename Params> class Poseidon2 {
     /**
      * @brief Hashes a vector of field elements
      */
-    static FF hash(const std::vector<FF>& input);
+    static FF hash(const std::span<FF>& input);
     /**
      * @brief Hashes vector of bytes by chunking it into 31 byte field elements and calling hash()
      * @details Slice function cuts out the required number of bytes from the byte vector
diff --git a/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.cpp b/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.cpp
index ff8e31dd56eb..167c6779c773 100644
--- a/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.cpp
+++ b/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.cpp
@@ -8,15 +8,14 @@ using namespace proof_system;
 /**
  * @brief Hash a vector of field_ct.
  */
-template <typename C> field_t<C> poseidon2<C>::hash(C& builder, const std::vector<field_ct>& inputs)
+template <typename C> field_t<C> poseidon2<C>::hash(C& builder, const std::span<field_ct>& inputs)
 {
 
     /* Run the sponge by absorbing all the input and squeezing one output.
      * This should just call the sponge variable length hash function
      *
      */
-    auto input{ inputs };
-    return Sponge::hash_fixed_length(builder, input);
+    return Sponge::hash_fixed_length(builder, inputs);
 }
 
 /**
diff --git a/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.hpp b/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.hpp
index fcfb93f91d26..521a33413bcb 100644
--- a/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.hpp
+++ b/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.hpp
@@ -26,7 +26,7 @@ template <typename Builder> class poseidon2 {
     using Sponge = FieldSponge<Params::t - 1, 1, Params::t, Permutation, Builder>;
 
   public:
-    static field_ct hash(Builder& builder, const std::vector<field_ct>& in);
+    static field_ct hash(Builder& builder, const std::span<field_ct>& in);
     static field_ct hash_buffer(Builder& builder, const stdlib::byte_array<Builder>& input);
 };
 
diff --git a/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.test.cpp b/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.test.cpp
index 797cec6669c1..f4dae1642e40 100644
--- a/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.test.cpp
+++ b/barretenberg/cpp/src/barretenberg/stdlib/hash/poseidon2/poseidon2.test.cpp
@@ -68,7 +68,8 @@ template <typename Builder> class StdlibPoseidon2 : public testing::Test {
 
         // num_inputs - 1 iterations since the first hash hashes two elements
         for (size_t i = 0; i < num_inputs - 1; ++i) {
-            left = poseidon2::hash(builder, { left, right });
+            std::vector<fr_ct> inputs = { left, right };
+            left = poseidon2::hash(builder, inputs);
         }
 
         builder.set_public_input(left.witness_index);