From fe6a1254ebbc124c3a5a4942a62f75e82ab486c5 Mon Sep 17 00:00:00 2001
From: mrBrutus <[omitted]>
Date: Sun, 16 Feb 2020 13:02:37 +0100
Subject: [PATCH] enable Highlight.js line numbers and -highlights

---
 exampleSite/config.toml                  | 6 ++++++
 layouts/partials/reveal-hugo/slides.html | 6 +++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/exampleSite/config.toml b/exampleSite/config.toml
index d835452..50dd6a7 100644
--- a/exampleSite/config.toml
+++ b/exampleSite/config.toml
@@ -20,8 +20,12 @@ name = "Josh Dzielak"
 [markup.goldmark.renderer]
 unsafe = true
 [markup.highlight]
+# setting the theme for highlighting by Hugo 
 # we need a style that looks good in both light and dark background!
 style = "tango"
+# to allow the use of Highlight.js line numbers and highlights
+# (see https://github.com/hakimel/reveal.js#line-numbers--highlights)
+codeFences = false
 
 [outputFormats.Reveal]
 baseName = "index"
@@ -30,6 +34,8 @@ isHTML = true
 
 [params.reveal_hugo]
 history = true
+# setting the theme for highlighting by Highlight.js
+highlight_theme = "github"
 
 # used in content/template-example
 [params.reveal_hugo.templates.grey]
diff --git a/layouts/partials/reveal-hugo/slides.html b/layouts/partials/reveal-hugo/slides.html
index d1157b2..0bed8a9 100644
--- a/layouts/partials/reveal-hugo/slides.html
+++ b/layouts/partials/reveal-hugo/slides.html
@@ -6,7 +6,11 @@
     {{- $content := replace .Content "<div class=\"footnotes\">\n\n<hr />" "<div class=\"footnotes\">" -}}
     <!-- <code> blocks processed by Hugo's highlighter have a data-lang attribute. For those, we disable -->
     <!-- highlight.js by changing the language class to "nohighlight", and adding "data-noescape".       -->
-    {{- $content := replaceRE `<code class="language-\w+"\s+data-lang="\w+"` `<code class="nohighlight" data-noescape` $content -}}
+    {{- $content := replaceRE `<code class="language-\w+"\s+data-lang="\w+"` `<code class="nohighlight" data-noescape` $content -}}    
+    <!-- enable Highlight.js line numbers when the markdown code block language selection is followed by "{}" e.g. ```js{} -->
+    {{- $content := replaceRE `(<code class="language-\w+){}(">)` `$1" data-line-numbers>` $content -}}
+    <!-- enable Highlight.js line highlights when the language selection is followed by "{<line numbers>}" e.g. ```js{1,5-7} -->          
+    {{- $content := replaceRE `(<code class="language-\w+){(\S+)}(">)` `$1" data-line-numbers="$2">` $content -}}            
     <!-- Support both <hr /> (blackfriday) and <hr> (mmark) -->
     {{- $content := replace $content "<hr>" "<hr />" -}}
     <!-- Split the processed content by <hr /> tag -->