Fix email labels with final digits

Related to micromark/micromark-extension-gfm-autolink-literal#7.
Related to remarkjs/remark#862.
Closes GH-5.

Co-authored-by: Rich Trott <rtrott@gmail.com>

index.js

@@ -153,8 +153,12 @@ function findUrl(_, protocol, domain, path, match) {
  * @param {RegExpMatchObject} match
  */
 function findEmail(_, atext, label, match) {
-  // Not an expected previous character.
-  if (!previous(match, true) || /[_-]$/.test(label)) {
+  if (
+    // Not an expected previous character.
+    !previous(match, true) ||
+    // Label ends in not allowed character.
+    /[_-\d]$/.test(label)
+  ) {
     return false
   }
 

test/email-tld-digits.html

@@ -0,0 +1,39 @@
+<p>a@0.0</p>
+<p><a href="mailto:a@0.b">a@0.b</a></p>
+<p>a@a.29</p>
+<p><a href="mailto:a@a.b">a@a.b</a></p>
+<p><a href="mailto:a@0.0.c">a@0.0.c</a></p>
+<p>react@0.11.1</p>
+<p>react@0.12.0-rc1</p>
+<p>react@0.14.0-alpha1</p>
+<p>react@16.7.0-alpha.2</p>
+<p>react@0.0.0-experimental-aae83a4b9</p>
+<p>[ react@0.11.1</p>
+<p>[ react@0.12.0-rc1</p>
+<p>[ react@0.14.0-alpha1</p>
+<p>[ react@16.7.0-alpha.2</p>
+<p>[ react@0.0.0-experimental-aae83a4b9</p>
+<hr>
+<p>react@a</p>
+<p>react@1</p>
+<p><a href="mailto:react@1.a">react@1.a</a></p>
+<p>react@1.1</p>
+<p><a href="mailto:react@1.a-b">react@1.a-b</a></p>
+<p><a href="mailto:react@1.a1b">react@1.a1b</a></p>
+<p><a href="mailto:react@1.1-b">react@1.1-b</a></p>
+<p><a href="mailto:react@1.1-alpha">react@1.1-alpha</a></p>
+<p>react@1.1-alpha1</p>
+<p><a href="mailto:react@1.1-a">react@1.1-a</a></p>
+<p>react@1.a-1</p>
+<hr>
+<p>[ react@a</p>
+<p>[ react@1</p>
+<p>[ <a href="mailto:react@1.a">react@1.a</a></p>
+<p>[ react@1.1</p>
+<p>[ <a href="mailto:react@1.a-b">react@1.a-b</a></p>
+<p>[ <a href="mailto:react@1.a1b">react@1.a1b</a></p>
+<p>[ <a href="mailto:react@1.1-b">react@1.1-b</a></p>
+<p>[ <a href="mailto:react@1.1-alpha">react@1.1-alpha</a></p>
+<p>[ react@1.1-alpha1</p>
+<p>[ <a href="mailto:react@1.1-a">react@1.1-a</a></p>
+<p>[ react@1.a-1</p>

test/email-tld-digits.md

@@ -0,0 +1,77 @@
+a@0.0
+
+a@0.b
+
+a@a.29
+
+a@a.b
+
+a@0.0.c
+
+react@0.11.1
+
+react@0.12.0-rc1
+
+react@0.14.0-alpha1
+
+react@16.7.0-alpha.2
+
+react@0.0.0-experimental-aae83a4b9
+
+[ react@0.11.1
+
+[ react@0.12.0-rc1
+
+[ react@0.14.0-alpha1
+
+[ react@16.7.0-alpha.2
+
+[ react@0.0.0-experimental-aae83a4b9
+
+---
+
+react@a
+
+react@1
+
+react@1.a
+
+react@1.1
+
+react@1.a-b
+
+react@1.a1b
+
+react@1.1-b
+
+react@1.1-alpha
+
+react@1.1-alpha1
+
+react@1.1-a
+
+react@1.a-1
+
+---
+
+[ react@a
+
+[ react@1
+
+[ react@1.a
+
+[ react@1.1
+
+[ react@1.a-b
+
+[ react@1.a1b
+
+[ react@1.1-b
+
+[ react@1.1-alpha
+
+[ react@1.1-alpha1
+
+[ react@1.1-a
+
+[ react@1.a-1