feat: Support graymatter headers to asciidoc files when enabled

Author: halkeye

packages/gatsby-transformer-asciidoc/README.md

@@ -85,6 +85,22 @@ In the asciidoc file you can insert your image just by using:
 - In case a `pathPrefix` is set it will altered the images location.
 - In case you want to be able to override the defined imagesdir inside of your asciidoc file you have to end the path with a `@` (e.g. `/images@`).
 
+## Support front/graymatter
+
+```javascript
+// In your gatsby-config.js
+plugins: [
+  {
+    resolve: `gatsby-transformer-asciidoc`,
+    options: {
+      attributes: {
+        "skip-front-matter": true,
+      },
+    },
+  },
+]
+```
+
 ## How to query
 
 A sample GraphQL query to get AsciiDoc nodes:

packages/gatsby-transformer-asciidoc/package.json

@@ -8,7 +8,8 @@
   },
   "dependencies": {
     "@babel/runtime": "^7.15.4",
-    "asciidoctor": "^2.2.5"
+    "asciidoctor": "^2.2.5",
+    "gray-matter": "^4.0.2"
   },
   "devDependencies": {
     "@babel/cli": "^7.15.4",

packages/gatsby-transformer-asciidoc/src/gatsby-node.js

@@ -1,4 +1,5 @@
 const asciidoc = require(`asciidoctor`)()
+const grayMatter = require(`gray-matter`)
 const _ = require(`lodash`)
 
 function unstable_shouldOnCreateNode({ node }, pluginOptions = {}) {
@@ -97,6 +98,10 @@ async function onCreateNode(
       pageAttributes,
     }
 
+    if (doc.getAttribute(`front-matter`)) {
+      asciiNode.frontmatter = grayMatter(doc.getAttribute(`front-matter`))
+    }
+
     asciiNode.internal.contentDigest = createContentDigest(asciiNode)
 
     createNode(asciiNode)