From 6d06c25fac2bb7c3adf40af17b6e908413a2e24f Mon Sep 17 00:00:00 2001
From: Simon Gardling <titaniumtown@gmail.com>
Date: Mon, 16 May 2022 17:20:08 -0400
Subject: [PATCH] further refactoring

---
 src/lib.rs      |  1 +
 src/main.rs     |  1 +
 src/math_app.rs |  4 ++--
 src/misc.rs     | 28 +++++-----------------------
 tests/misc.rs   |  3 +--
 5 files changed, 10 insertions(+), 27 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 2c003ed..bf5c700 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,6 +9,7 @@
 #![feature(const_assume)]
 #![feature(const_option_ext)]
 #![feature(const_slice_index)]
+#![feature(split_array)]
 
 #[macro_use]
 extern crate static_assertions;
diff --git a/src/main.rs b/src/main.rs
index e28b930..9e13e88 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -9,6 +9,7 @@
 #![feature(const_assume)]
 #![feature(const_option_ext)]
 #![feature(const_slice_index)]
+#![feature(split_array)]
 
 #[macro_use]
 extern crate static_assertions;
diff --git a/src/math_app.rs b/src/math_app.rs
index 797433f..d92b3ed 100644
--- a/src/math_app.rs
+++ b/src/math_app.rs
@@ -150,7 +150,7 @@ impl MathApp {
 						return None;
 					}
 
-					let (commit, cached_data) = crate::misc::hashed_storage_read(data);
+					let (commit, cached_data) = crate::misc::hashed_storage_read(data)?;
 
 					debug_assert!(!commit.is_empty());
 					debug_assert!(!cached_data.is_empty());
@@ -188,7 +188,7 @@ impl MathApp {
 						return None;
 					}
 
-					let (commit, func_data) = crate::misc::hashed_storage_read(data);
+					let (commit, func_data) = crate::misc::hashed_storage_read(data)?;
 
 					debug_assert!(!commit.is_empty());
 					debug_assert!(!func_data.is_empty());
diff --git a/src/misc.rs b/src/misc.rs
index 9003d29..3d2695a 100644
--- a/src/misc.rs
+++ b/src/misc.rs
@@ -312,12 +312,6 @@ pub const HASH_LENGTH: usize = 8;
 
 #[allow(dead_code)]
 pub fn hashed_storage_create(hash: [u8; HASH_LENGTH], data: &[u8]) -> String {
-	debug_assert!(!data.is_empty());
-
-	unsafe {
-		assume(!data.is_empty());
-	}
-
 	// cannot use `from_utf8` seems to break on wasm. no clue why
 	[&hash, data]
 		.concat()
@@ -327,28 +321,16 @@ pub fn hashed_storage_create(hash: [u8; HASH_LENGTH], data: &[u8]) -> String {
 }
 
 #[allow(dead_code)]
-pub fn hashed_storage_read(data: String) -> ([u8; HASH_LENGTH], Vec<u8>) {
-	debug_assert!(data.len() > HASH_LENGTH);
-	unsafe {
-		assume(!data.is_empty());
-		assume(data.len() > HASH_LENGTH);
+pub fn hashed_storage_read(data: String) -> Option<([u8; HASH_LENGTH], Vec<u8>)> {
+	if HASH_LENGTH >= data.len() {
+		return None;
 	}
 
 	// can't use data.as_bytes() here for some reason, seems to break on wasm?
 	let decoded_1 = data.chars().map(|c| c as u8).collect::<Vec<u8>>();
 
-	let (hash, cached_data) = decoded_1.split_at(8);
-	debug_assert_eq!(hash.len(), HASH_LENGTH);
+	let (hash, cached_data) = decoded_1.split_array_ref::<HASH_LENGTH>();
 	debug_assert!(!cached_data.is_empty());
 
-	unsafe {
-		assume(!cached_data.is_empty());
-		assume(!hash.is_empty());
-		assume(hash.len() == HASH_LENGTH);
-	}
-
-	(
-		unsafe { hash.try_into().unwrap_unchecked() },
-		cached_data.to_vec(),
-	)
+	Some((*hash, cached_data.to_vec()))
 }
diff --git a/tests/misc.rs b/tests/misc.rs
index 255c96e..be9452d 100644
--- a/tests/misc.rs
+++ b/tests/misc.rs
@@ -106,6 +106,5 @@ fn hashed_storage() {
 	);
 
 	let read = hashed_storage_read(storage);
-	assert_eq!(read.0.to_vec(), commit);
-	assert_eq!(read.1, data);
+	assert_eq!(read.map(|(a, b)| (a.to_vec(), b)), Some((commit, data)));
 }