add experiment demos

demos/src/Experiments/Linter/Vue/extension/plugins/HeadingLevel.ts

@@ -0,0 +1,30 @@
+import { EditorView } from 'prosemirror-view'
+import LinterPlugin, { Result as Issue } from '../LinterPlugin'
+
+export class HeadingLevel extends LinterPlugin {
+  fixHeader(level: number) {
+    return function ({ state, dispatch }: EditorView, issue: Issue) {
+      dispatch(state.tr.setNodeMarkup(issue.from - 1, undefined, { level }))
+    }
+  }
+
+  scan() {
+    let lastHeadLevel: number | null = null
+
+    this.doc.descendants((node, position) => {
+      if (node.type.name === 'heading') {
+        // Check whether heading levels fit under the current level
+        const { level } = node.attrs
+
+        if (lastHeadLevel != null && level > lastHeadLevel + 1) {
+          this.record(`Heading too small (${level} under ${lastHeadLevel})`,
+            position + 1, position + 1 + node.content.size,
+            this.fixHeader(lastHeadLevel + 1))
+        }
+        lastHeadLevel = level
+      }
+    })
+
+    return this
+  }
+}