Encode HTML more efficiently

packages/html/html.ml

@@ -1,42 +1,16 @@
 (* Based on https://github.com/facebook/react/blob/97d75c9c8bcddb0daed1ed062101c7f5e9b825f4/packages/react-dom-bindings/src/server/escapeTextForBrowser.js#L51-L98 *)
 (* https://discuss.ocaml.org/t/html-encoding-of-string/4289/4 *)
 let encode s =
-  let add = Buffer.add_string in
-  let len = String.length s in
-  let buff = Buffer.create len in
-  let max_idx = len - 1 in
-  let flush buff start i =
-    if start < len then Buffer.add_substring buff s start (i - start)
-  in
-  let rec escape_inner start i =
-    if i > max_idx then flush buff start i
-    else
-      let next = i + 1 in
-      match String.get s i with
-      | '&' ->
-          flush buff start i;
-          add buff "&amp;";
-          escape_inner next next
-      | '<' ->
-          flush buff start i;
-          add buff "&lt;";
-          escape_inner next next
-      | '>' ->
-          flush buff start i;
-          add buff "&gt;";
-          escape_inner next next
-      | '\'' ->
-          flush buff start i;
-          add buff "&#x27;";
-          escape_inner next next
-      | '\"' ->
-          flush buff start i;
-          add buff "&quot;";
-          escape_inner next next
-      | _ -> escape_inner start next
-  in
-  escape_inner 0 0 |> ignore;
-  Buffer.contents buff
+  let buffer = Buffer.create (String.length s * 2) in
+  s
+  |> String.iter (function
+       | '&' -> Buffer.add_string buffer "&amp;"
+       | '<' -> Buffer.add_string buffer "&lt;"
+       | '>' -> Buffer.add_string buffer "&gt;"
+       | '"' -> Buffer.add_string buffer "&quot;"
+       | '\'' -> Buffer.add_string buffer "&#x27;"
+       | c -> Buffer.add_char buffer c);
+  Buffer.contents buffer
 
 let is_self_closing_tag = function
   (* https://github.com/facebook/react/blob/97d75c9c8bcddb0daed1ed062101c7f5e9b825f4/packages/react-dom-bindings/src/shared/omittedCloseTags.js *)