From 8abe4684291880507204085f0e560574d171d31b Mon Sep 17 00:00:00 2001
From: Michael Chirico <michaelchirico4@gmail.com>
Date: Sat, 10 Apr 2021 05:01:49 -0700
Subject: [PATCH] [r mode] Tweak regex for dots

See https://stat.ethz.ch/R-manual/R-devel/library/base/html/dots.html and https://stat.ethz.ch/R-manual/R-devel/library/base/html/Reserved.html

Currently CodeMirror treats things like `..1.` and `...1` identically to `...`, `..1`, `..2`, etc.

The former two parse, but they parse as regular R objects per the naming rules seen e.g. here https://stat.ethz.ch/R-manual/R-devel/library/base/html/make.names.html

> A syntactically valid name consists of letters, numbers and the dot or underline characters and starts with a letter or the dot not followed by a number. Names such as ".2way" are not valid, and neither are the reserved words.

Please LMK if this should be tested, with the caveat that this is my first ever contribution to JS code so some hand-holding would be nice
---
 mode/r/r.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mode/r/r.js b/mode/r/r.js
index 6feeb11f83..de34c201bd 100644
--- a/mode/r/r.js
+++ b/mode/r/r.js
@@ -54,7 +54,7 @@ CodeMirror.defineMode("r", function(config) {
     } else if (ch == "`") {
       stream.match(/[^`]+`/);
       return "variable-3";
-    } else if (ch == "." && stream.match(/.[.\d]+/)) {
+    } else if (ch == "." && stream.match(/.(?:[.]|\d+)/)) {
       return "keyword";
     } else if (/[a-zA-Z\.]/.test(ch)) {
       stream.eatWhile(/[\w\.]/);