From 7875d6ed2c16ded8419e9e1bb237d5a6f759234b Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Thu, 20 May 2021 11:22:19 +0100
Subject: [PATCH] utils: Break out [Index]Vec::ensure_element_with ext traits

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 src/bundles.rs |  5 +----
 src/utils.rs   | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/bundles.rs b/src/bundles.rs
index 6c8af351..7232ac29 100644
--- a/src/bundles.rs
+++ b/src/bundles.rs
@@ -886,10 +886,7 @@ impl InstanceBundles {
         },
       };
 
-      let iu: usize = parsed.index().into();
-      if ib.bundles.get(iu).is_none() {
-        ib.bundles.resize_with(iu+1, default);
-      }
+      ib.bundles.ensure_element_with(parsed.index().into(), default);
 
       if_let!{ BundleSavefile::Bundle(id) = parsed;
                else continue; }
diff --git a/src/utils.rs b/src/utils.rs
index fd2e530b..335de872 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -623,3 +623,19 @@ impl<T: io::Seek> T {
   #[throws(io::Error)]
   fn rewind(&mut self) { self.seek(io::SeekFrom::Start(0))? }
 }
+
+#[ext(pub)]
+impl<T> Vec<T> {
+  fn ensure_element_with<F>(&mut self, i: usize, f: F) where F: FnMut() -> T {
+    if self.get(i).is_none() {
+      self.resize_with(i+1, f);
+    }
+  }
+}
+
+#[ext(pub)]
+impl<I,T> IndexVec<I,T> where I: index_vec::Idx {
+  fn ensure_element_with<F>(&mut self, i: I, f: F) where F: FnMut() -> T {
+    self.raw.ensure_element_with(i.index(), f)
+  }
+}
-- 
2.30.2