From: Simon Tatham <anakin@pobox.com>
Date: Sun, 13 Apr 2025 07:02:53 +0000 (+0100)
Subject: Bug in conversion from slice
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?a=commitdiff_plain;h=8500dfae515ec4c90ece03b695d6c81ed90893f5;p=nimber.git

Bug in conversion from slice

I forgot the analogue of truncating the Vec. But here we can truncate
while it's still in cheap slice form, before making a Vec at all.
---

diff --git a/src/finitenimber.rs b/src/finitenimber.rs
index cb76756..782ff21 100644
--- a/src/finitenimber.rs
+++ b/src/finitenimber.rs
@@ -284,15 +284,17 @@ impl From<Vec<Word>> for FiniteNimber {
 
 impl From<&[Word]> for FiniteNimber {
     fn from(slice: &[Word]) -> FiniteNimber {
-        match slice
+        match dbg!(slice
             .iter()
             .enumerate()
             .rev()
-            .find(|(_index, word)| **word != 0)
+            .find(|(_index, word)| **word != 0))
         {
             None => Self(FiniteNimberEnum::Single(0)),
             Some((0, w)) => Self(FiniteNimberEnum::Single(*w)),
-            Some(_) => Self(FiniteNimberEnum::Vector(slice.into()))
+            Some((pos, _)) => {
+                Self(FiniteNimberEnum::Vector(slice[..=pos].into()))
+            }
         }
     }
 }