From b344065debe0bf9dee7c054a01c2925ee99f830e Mon Sep 17 00:00:00 2001
From: Leandro Balmaceda <leandro@spideroak-inc.com>
Date: Thu, 1 Dec 2016 14:41:22 -0300
Subject: [PATCH] Add option to overwrite the default prefilter for links

---
 lib/configs/commonmark.js |  7 +++++++
 lib/configs/default.js    |  7 +++++++
 lib/configs/full.js       |  7 +++++++
 lib/rules_core/linkify.js |  9 ++++++++-
 test/misc.js              | 14 ++++++++++++++
 5 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/lib/configs/commonmark.js b/lib/configs/commonmark.js
index 40d8c1d0..a13a7272 100644
--- a/lib/configs/commonmark.js
+++ b/lib/configs/commonmark.js
@@ -12,6 +12,13 @@ module.exports = {
     linkify:      false,        // autoconvert URL-like texts to links
     linkTarget:   '',           // set target to open link in
 
+    // linkifyPrefilter. Function that overwrite the default link prefilter,
+    // specified by this regex: /www|@|\:\/\//
+    //
+    // @param { string } link that will be tested.
+    // @returns { Boolean } whether or not the link passes the prefilter.
+    linkifyPrefilter: null,
+
     // Enable some language-neutral replacements + quotes beautification
     typographer:  false,
 
diff --git a/lib/configs/default.js b/lib/configs/default.js
index ae01184b..7dee16bb 100644
--- a/lib/configs/default.js
+++ b/lib/configs/default.js
@@ -12,6 +12,13 @@ module.exports = {
     linkify:      false,        // autoconvert URL-like texts to links
     linkTarget:   '',           // set target to open link in
 
+    // linkifyPrefilter. Function that overwrite the default link prefilter,
+    // specified by this regex: /www|@|\:\/\//
+    //
+    // @param { string } link that will be tested.
+    // @returns { Boolean } whether or not the link passes the prefilter.
+    linkifyPrefilter: null,
+
     // Enable some language-neutral replacements + quotes beautification
     typographer:  false,
 
diff --git a/lib/configs/full.js b/lib/configs/full.js
index f1ac24d6..d39c2835 100644
--- a/lib/configs/full.js
+++ b/lib/configs/full.js
@@ -12,6 +12,13 @@ module.exports = {
     linkify:      false,        // autoconvert URL-like texts to links
     linkTarget:   '',           // set target to open link in
 
+    // linkifyPrefilter. Function that overwrite the default link prefilter,
+    // specified by this regex: /www|@|\:\/\//
+    //
+    // @param { string } link that will be tested.
+    // @returns { Boolean } whether or not the link passes the prefilter.
+    linkifyPrefilter: null,
+
     // Enable some language-neutral replacements + quotes beautification
     typographer:  false,
 
diff --git a/lib/rules_core/linkify.js b/lib/rules_core/linkify.js
index e9bc88c5..245e2b69 100644
--- a/lib/rules_core/linkify.js
+++ b/lib/rules_core/linkify.js
@@ -95,7 +95,14 @@ module.exports = function linkify(state) {
       }
       if (htmlLinkLevel > 0) { continue; }
 
-      if (token.type === 'text' && LINK_SCAN_RE.test(token.content)) {
+      var linkifyPrefilter = state.options.linkifyPrefilter;
+      var passPrefilter = LINK_SCAN_RE.test(token.content);
+      if (linkifyPrefilter && typeof linkifyPrefilter === 'function') {
+        // Use the custom prefilter for links.
+        passPrefilter = linkifyPrefilter(token.content);
+      }
+
+      if (token.type === 'text' && passPrefilter) {
 
         // Init linkifier in lazy manner, only if required.
         if (!linkifier) {
diff --git a/test/misc.js b/test/misc.js
index 6e7e30ec..541e50b3 100644
--- a/test/misc.js
+++ b/test/misc.js
@@ -105,6 +105,20 @@ describe('API', function () {
     assert.strictEqual(md.render('```\n&\n```'), '<pre><code>&amp;\n</code></pre>\n');
   });
 
+  it('Linkify prefilter', function () {
+    var md = new Remarkable({
+      linkify: true,
+      linkifyPrefilter: function (str) {
+        // Only linkify if link starts with https://
+        return /^https?:\/\//.test(str);
+      }
+    });
+
+    assert.strictEqual(md.render('https://www.google.com'),
+      '<p><a href="https://www.google.com">https://www.google.com</a></p>\n');
+    assert.strictEqual(md.render('www.google.com'), '<p>www.google.com</p>\n');
+  });
+
   it('force hardbreaks', function () {
     var md = new Remarkable({ breaks: true });