From 7b6b94c5ca2d34c4885d627aeaf52bd3039409f6 Mon Sep 17 00:00:00 2001
From: Florian Klink <flokli@flokli.de>
Date: Tue, 3 Jun 2025 22:28:26 +0300
Subject: [PATCH] refactor(nix-compat/nixhash): use a bit more map and
 ok_or_else

This looks more readable like this.

Change-Id: Iaa750fae66c7263612f169405eb7d38fb9541b04
Reviewed-on: https://cl.snix.dev/c/snix/+/30552
Autosubmit: Florian Klink <flokli@flokli.de>
Reviewed-by: Ilan Joselevich <personal@ilanjoselevich.com>
Tested-by: besadii
---
 snix/nix-compat/src/nixhash/mod.rs | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/snix/nix-compat/src/nixhash/mod.rs b/snix/nix-compat/src/nixhash/mod.rs
index 507242690..edb34e57b 100644
--- a/snix/nix-compat/src/nixhash/mod.rs
+++ b/snix/nix-compat/src/nixhash/mod.rs
@@ -210,11 +210,7 @@ pub enum Error {
 /// one communicated out-of-band.
 pub fn from_str(s: &str, algo_str: Option<&str>) -> NixHashResult<NixHash> {
     // if algo_str is some, parse or bail out
-    let algo: Option<HashAlgo> = if let Some(algo_str) = algo_str {
-        Some(algo_str.try_into()?)
-    } else {
-        None
-    };
+    let algo: Option<HashAlgo> = algo_str.map(HashAlgo::try_from).transpose()?;
 
     // Peek at the beginning of the string to detect SRI hashes.
     if s.starts_with("sha1-")
@@ -240,6 +236,7 @@ pub fn from_str(s: &str, algo_str: Option<&str>) -> NixHashResult<NixHash> {
         || s.starts_with("md5:")
     {
         let parsed_nixhash = from_nix_str(s)?;
+
         // ensure the algo matches with what has been passed externally, if so.
         if let Some(algo) = algo {
             if algo != parsed_nixhash.algo() {
@@ -250,11 +247,8 @@ pub fn from_str(s: &str, algo_str: Option<&str>) -> NixHashResult<NixHash> {
     }
 
     // Neither of these, assume a bare digest, so there MUST be an externally-passed algo.
-    match algo {
-        // Fail if there isn't.
-        None => Err(Error::MissingInlineHashAlgo(s.to_string())),
-        Some(algo) => decode_digest(s.as_bytes(), algo),
-    }
+    let algo = algo.ok_or_else(|| Error::MissingInlineHashAlgo(s.to_string()))?;
+    decode_digest(s.as_bytes(), algo)
 }
 
 /// Parses a Nix hash string ($algo:$digest) to a NixHash.