feat: improve markdown parser

Author: antfu

packages/slidev/node/parser.ts

@@ -69,7 +69,7 @@ function stringifySlide(data: SlideInfo, idx = 1) {
 
   return (data.raw.startsWith('---') || idx === 0)
     ? data.raw
-    : `------\n${data.raw}`
+    : `---\n${data.raw.startsWith('\n') ? data.raw : `\n${data.raw}`}`
 }
 
 function prettifySlide(data: SlideInfo) {
@@ -96,8 +96,6 @@ export function parse(
 ): SlidevMarkdown {
   const lines = markdown.split(/\n/g)
   const slides: SlideInfo[] = []
-  let start = 0
-  let dividers = 0
 
   function parseContent(raw: string) {
     const result = matter(raw)
@@ -116,37 +114,40 @@ export function parse(
     }
   }
 
-  lines.forEach((line, i) => {
-    line = line.trimRight()
-
-    if (line === '---')
-      dividers += 1
-
-    // more than than 4 dashes
-    const isHardDivider = !!line.match(/^----+$/)
-
-    if (dividers >= 3 || isHardDivider) {
-      const end = i
-      const raw = lines.slice(start, end).join('\n')
-      slides.push({
-        start,
-        end,
-        ...parseContent(raw),
-      })
-      dividers = isHardDivider ? 2 : 1
-      start = isHardDivider ? i + 1 : i
-    }
-  })
+  let start = 0
 
-  if (start !== lines.length - 1) {
-    const raw = lines.slice(start).join('\n')
+  function slice(end: number) {
+    if (start === end)
+      return
+    const raw = lines.slice(start, end).join('\n')
     slides.push({
       start,
-      end: lines.length,
+      end,
       ...parseContent(raw),
     })
+    start = end + 1
   }
 
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i].trimRight()
+    if (line.match(/^---+$/)) {
+      slice(i)
+
+      const next = lines[i + 1]
+      // found frontmatter, skip next dash
+      if (line.length === 3 && !next?.match(/^\s*$/)) {
+        start = i
+        for (i += 1; i < lines.length; i++) {
+          if (lines[i].trimRight().match(/^---$/))
+            break
+        }
+      }
+    }
+  }
+
+  if (start !== lines.length - 1)
+    slice(lines.length - 1)
+
   const headmatter = slides?.[0].frontmatter || {}
   const config: SlidevConfig = Object.assign({}, headmatter.config || {})
 

test/__snapshots__/parser.test.ts.snap

@@ -21,7 +21,7 @@ layout: center
 This is notes
 -->
 
-------
+---
 
 # Morning
 
@@ -47,7 +47,7 @@ console.log('Hello World')
 \`\`\`
 
 
-------
+---
 
 # Hello
 
@@ -57,7 +57,7 @@ console.log('Hello World')
 - Yo
 
 
-------
+---
 
 Nice to meet you
 "

test/fixtures/markdown/frontmatter.md

@@ -10,7 +10,8 @@ layout: center
 ---
 # Hello
 <!-- This is notes -->
-------
+---
+
 # Morning
 ---
 layout: text

test/fixtures/markdown/minimal.md

@@ -8,13 +8,14 @@ Sample Text
 console.log('Hello World')
 ```
 
-------
+---
 
 # Hello
 
 - Hello
 - Hi
 - Hey
 - Yo
-------
+---
+
 Nice to meet you

test/parser.test.ts

@@ -1,6 +1,6 @@
 import { resolve, basename } from 'path'
 import fg from 'fast-glob'
-import { prettify, load, stringify } from '../packages/slidev/node'
+import { prettify, load, stringify, parse } from '../packages/slidev/node'
 
 describe('md parser', () => {
   const files = fg.sync('*.md', {
@@ -19,4 +19,33 @@ describe('md parser', () => {
       expect(stringify(data)).toMatchSnapshot('formatted')
     })
   }
+
+  it('parse', () => {
+    const data = parse(`
+a
+
+---
+
+b
+
+---
+layout: z
+---
+c
+----
+d
+----
+e
+
+---
+
+f
+
+---
+`)
+    expect(data.slides.map(i => i.content.trim()))
+      .toEqual(Array.from('abcdef'))
+    expect(data.slides[2].frontmatter)
+      .toEqual({ layout: 'z' })
+  })
 })