Use lookup table

1 files changed, 13 insertions, 5 deletions

diff --git a/askama_escape/src/lib.rs b/askama_escape/src/lib.rs
index ef6c1f9..e09a32d 100644
--- a/askama_escape/src/lib.rs
+++ b/askama_escape/src/lib.rs
@@ -113,12 +113,20 @@ impl Escaper for Html {
     {
         let mut last = 0;
         for (index, byte) in string.bytes().enumerate() {
+            const MIN_CHAR: u8 = b'"';
+            const MAX_CHAR: u8 = b'>';
+            const TABLE: [Option<&&str>; (MAX_CHAR - MIN_CHAR + 1) as usize] = {
+                let mut table = [None; (MAX_CHAR - MIN_CHAR + 1) as usize];
+                table[(b'<' - MIN_CHAR) as usize] = Some(&"&lt;");
+                table[(b'>' - MIN_CHAR) as usize] = Some(&"&gt;");
+                table[(b'&' - MIN_CHAR) as usize] = Some(&"&amp;");
+                table[(b'"' - MIN_CHAR) as usize] = Some(&"&quot;");
+                table[(b'\'' - MIN_CHAR) as usize] = Some(&"&#x27;");
+                table
+            };
+
             let escaped = match byte {
-                b'<' => Some(&"&lt;"),
-                b'>' => Some(&"&gt;"),
-                b'&' => Some(&"&amp;"),
-                b'"' => Some(&"&quot;"),
-                b'\'' => Some(&"&#x27;"),
+                MIN_CHAR..=MAX_CHAR => TABLE[(byte - MIN_CHAR) as usize],
                 _ => None,
             };
             if let Some(escaped) = escaped {