feat(build): allow using `@` prefix with `@include:` (#2292)

__tests__/e2e/markdown-extensions/bar.md

@@ -0,0 +1 @@
+# Bar

__tests__/e2e/markdown-extensions/index.md

@@ -175,4 +175,8 @@ export default config
 
 ## Markdown File Inclusion
 
-<!--@include: ./foo.md-->
+<!--@include: ./foo.md-->
+
+## Markdown At File Inclusion
+
+<!--@include: @/markdown-extensions/bar.md-->

__tests__/e2e/markdown-extensions/markdown-extensions.test.ts

@@ -63,7 +63,7 @@ describe('Table of Contents', () => {
   test('render toc', async () => {
     const items = page.locator('#table-of-contents + nav ul li')
     const count = await items.count()
-    expect(count).toBe(23)
+    expect(count).toBe(24)
   })
 })
 
@@ -229,4 +229,8 @@ describe('Markdown File Inclusion', () => {
     const h1 = page.locator('#markdown-file-inclusion + h1')
     expect(await h1.getAttribute('id')).toBe('foo')
   })
+  test('render markdown using @', async () => {
+    const h1 = page.locator('#markdown-at-file-inclusion + h1')
+    expect(await h1.getAttribute('id')).toBe('bar')
+  })
 })

docs/guide/markdown.md

@@ -691,7 +691,13 @@ You can also [import snippets](#import-code-snippets) in code groups:
 
 ## Markdown File Inclusion
 
-You can include a markdown file in another markdown file like this:
+You can include a markdown file in another markdown file.
+
+::: tip
+You can also prefix the markdown path with `@`, it will act as the source root. By default it's the VitePress project root, unless `srcDir` is configured.
+:::
+
+For example, you can include a relative markdown file using this:
 
 **Input**
 

src/node/markdownToVue.ts

@@ -87,9 +87,15 @@ export async function createMarkdownToVueRenderFn(
     // resolve includes
     let includes: string[] = []
     src = src.replace(includesRE, (m, m1) => {
+      if (!m1.length) return m
+
+      const atPresent = m1[0] === '@'
       try {
-        const dir = path.dirname(fileOrig) // include paths are strict relative file paths w/o aliases
-        const includePath = path.join(dir, m1)
+        const dir = atPresent ? srcDir : path.dirname(fileOrig)
+        const includePath = path.join(
+          dir,
+          atPresent ? m1.slice(m1.length > 1 && m1[1] === '/' ? 2 : 1) : m1
+        )
         const content = fs.readFileSync(includePath, 'utf-8')
         includes.push(slash(includePath))
         return content