Add 'packages/turndown-plugin-gfm/' from commit '0f43299c17108e9508e7e6237369e86f504ea60a'

git-subtree-dir: packages/turndown-plugin-gfm
git-subtree-mainline: ebebdd0b07
git-subtree-split: 0f43299c17

packages/turndown-plugin-gfm/src/highlighted-code-block.js

@@ -0,0 +1,25 @@
+var highlightRegExp = /highlight-(?:text|source)-([a-z0-9]+)/
+
+export default function highlightedCodeBlock (turndownService) {
+  turndownService.addRule('highlightedCodeBlock', {
+    filter: function (node) {
+      var firstChild = node.firstChild
+      return (
+        node.nodeName === 'DIV' &&
+        highlightRegExp.test(node.className) &&
+        firstChild &&
+        firstChild.nodeName === 'PRE'
+      )
+    },
+    replacement: function (content, node, options) {
+      var className = node.className || ''
+      var language = (className.match(highlightRegExp) || [null, ''])[1]
+
+      return (
+        '\n\n' + options.fence + language + '\n' +
+        node.firstChild.textContent +
+        '\n' + options.fence + '\n\n'
+      )
+    }
+  })
+}