Markdown: horizontal rule support (#258)

Author: platypii

src/components/Markdown/Markdown.test.tsx

@@ -103,6 +103,19 @@ describe('Markdown', () => {
     const { getByText } = render(<Markdown text={text} />)
     expect(getByText('This is a blockquote.')).toBeDefined()
   })
+
+  it('renders a horizontal rule', () => {
+    const text = 'First paragraph\n---\nSecond paragraph'
+    const { container } = render(<Markdown text={text} />)
+
+    const paragraphs = container.querySelectorAll('p')
+    expect(paragraphs.length).toBe(2)
+    expect(paragraphs[0]?.textContent).toBe('First paragraph')
+    expect(paragraphs[1]?.textContent).toBe('Second paragraph')
+
+    const hr = container.querySelector('hr')
+    expect(hr).toBeDefined()
+  })
 })
 
 describe('Markdown code blocks', () => {

src/components/Markdown/Markdown.tsx

@@ -17,6 +17,7 @@ type Token =
   | { type: 'list', ordered: boolean, items: Token[][] }
   | { type: 'blockquote', children: Token[] }
   | { type: 'codeblock', language?: string, content: string }
+  | { type: 'hr' }
 
 function parseMarkdown(text: string): Token[] {
   const tokens: Token[] = []
@@ -50,6 +51,13 @@ function parseMarkdown(text: string): Token[] {
       continue
     }
 
+    // Horizontal rule
+    if (/^---+$/.test(line.trim())) {
+      tokens.push({ type: 'hr' })
+      i++
+      continue
+    }
+
     // Heading
     const headingMatch = /^(#{1,6})\s+(.*)/.exec(line)
     if (headingMatch !== null) {
@@ -110,6 +118,7 @@ function parseMarkdown(text: string): Token[] {
       if (ln.startsWith('>')) break // blockquote
       if (/^(#{1,6})\s+/.test(ln)) break // heading
       if (/^(\s*)([-*+–•‣◦○⚬]|\d+\.)\s+/.test(ln)) break // list item
+      if (/^---+$/.test(ln.trim())) break // horizontal rule
 
       paraLines.push(ln)
       i++
@@ -499,6 +508,8 @@ function renderTokens(tokens: Token[], keyPrefix = ''): ReactNode[] {
           { key },
           createElement('code', null, token.content)
         )
+      case 'hr':
+        return createElement('hr', { key })
       default:
         return null
     }