Introduce max_suggestion_distance function to avoid duplicating the heuristic

1 files changed, 8 insertions, 0 deletions

diff --git a/src/libsyntax/util/lev_distance.rs b/src/libsyntax/util/lev_distance.rs
index 28f8510ce3f..9bf96311122 100644
--- a/src/libsyntax/util/lev_distance.rs
+++ b/src/libsyntax/util/lev_distance.rs
@@ -41,6 +41,14 @@ pub fn lev_distance(me: &str, t: &str) -> usize {
     dcol[t_last + 1]
 }
 
+pub fn max_suggestion_distance(name: &str) -> usize {
+    use std::cmp::max;
+    // As a loose rule to avoid obviously incorrect suggestions, clamp the
+    // maximum edit distance we will accept for a suggestion to one third of
+    // the typo'd name's length.
+    max(name.len(), 3) / 3
+}
+
 #[test]
 fn test_lev_distance() {
     use std::char::{ from_u32, MAX };