From a2947a4edcd3b1aaf14b2a8e8b956d083d092b6b Mon Sep 17 00:00:00 2001
From: Alexey Pyltsyn <lex61rus@gmail.com>
Date: Tue, 22 Oct 2019 15:20:41 +0300
Subject: [PATCH] Add line highlighting for live code blocks

---
 .../package.json                              |  1 +
 .../src/theme/CodeBlock/index.js              | 39 +++++++++++++++----
 2 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/packages/docusaurus-theme-live-codeblock/package.json b/packages/docusaurus-theme-live-codeblock/package.json
index d70228fb0b30..1efc6ed94d7a 100644
--- a/packages/docusaurus-theme-live-codeblock/package.json
+++ b/packages/docusaurus-theme-live-codeblock/package.json
@@ -11,6 +11,7 @@
     "@philpl/buble": "^0.19.7",
     "classnames": "^2.2.6",
     "clipboard": "^2.0.4",
+    "parse-numeric-range": "^0.0.2",
     "prism-react-renderer": "^1.0.1",
     "react-live": "^2.1.2"
   },
diff --git a/packages/docusaurus-theme-live-codeblock/src/theme/CodeBlock/index.js b/packages/docusaurus-theme-live-codeblock/src/theme/CodeBlock/index.js
index 9e14e2fbc08e..93b2c083bfc9 100644
--- a/packages/docusaurus-theme-live-codeblock/src/theme/CodeBlock/index.js
+++ b/packages/docusaurus-theme-live-codeblock/src/theme/CodeBlock/index.js
@@ -10,11 +10,20 @@ import classnames from 'classnames';
 import Highlight, {defaultProps} from 'prism-react-renderer';
 import defaultTheme from 'prism-react-renderer/themes/palenight';
 import Clipboard from 'clipboard';
+import rangeParser from 'parse-numeric-range';
 import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
 import Playground from '@theme/Playground';
 import styles from './styles.module.css';
 
-export default ({children, className: languageClassName, live, ...props}) => {
+const highlightLinesRangeRegex = /{([\d,-]+)}/;
+
+export default ({
+  children,
+  className: languageClassName,
+  live,
+  metastring,
+  ...props
+}) => {
   const {
     siteConfig: {
       themeConfig: {prismTheme},
@@ -23,6 +32,12 @@ export default ({children, className: languageClassName, live, ...props}) => {
   const [showCopied, setShowCopied] = useState(false);
   const target = useRef(null);
   const button = useRef(null);
+  let highlightLines = [];
+
+  if (metastring && highlightLinesRangeRegex.test(metastring)) {
+    const highlightLinesRange = metastring.match(highlightLinesRangeRegex)[1];
+    highlightLines = rangeParser.parse(highlightLinesRange).filter(n => n > 0);
+  }
 
   useEffect(() => {
     let clipboard;
@@ -73,13 +88,21 @@ export default ({children, className: languageClassName, live, ...props}) => {
             ref={target}
             className={classnames(className, styles.codeBlock)}
             style={style}>
-            {tokens.map((line, i) => (
-              <div key={i} {...getLineProps({line, key: i})}>
-                {line.map((token, key) => (
-                  <span key={key} {...getTokenProps({token, key})} />
-                ))}
-              </div>
-            ))}
+            {tokens.map((line, i) => {
+              const lineProps = getLineProps({line, key: i});
+
+              if (highlightLines.includes(i + 1)) {
+                lineProps.className = `${lineProps.className} highlight-line`;
+              }
+
+              return (
+                <div key={i} {...lineProps}>
+                  {line.map((token, key) => (
+                    <span key={key} {...getTokenProps({token, key})} />
+                  ))}
+                </div>
+              );
+            })}
           </pre>
           <button
             ref={button}