feat: add transformer-remove-empty-lines

packages/transformers/src/index.ts

@@ -10,6 +10,7 @@ export * from './transformers/notation-highlight'
 export * from './transformers/notation-highlight-word'
 export * from './transformers/notation-map'
 export * from './transformers/remove-comments'
+export * from './transformers/remove-empty-lines'
 export * from './transformers/remove-line-breaks'
 export * from './transformers/remove-notation-escape'
 export * from './transformers/render-indent-guides'

packages/transformers/src/transformers/remove-empty-lines.ts

@@ -0,0 +1,22 @@
+import type { ShikiTransformer } from '@shikijs/types'
+
+/**
+ * Remove empty lines from the code.
+ */
+export function transformerRemoveEmptyLines(): ShikiTransformer {
+  return {
+    name: '@shikijs/transformers:remove-empty-lines',
+    code(code) {
+      code.children = code.children.filter((line) => {
+        if (line.type !== 'element')
+          return true
+        const isAllWhitespace = line.children.every((token) => {
+          if (token.type !== 'text')
+            return false
+          return !token.value.trim()
+        })
+        return !isAllWhitespace
+      })
+    },
+  }
+}

packages/transformers/test/remove-empty-lines.test.ts

@@ -0,0 +1,24 @@
+import { codeToHtml } from 'shiki'
+import { describe, expect, it } from 'vitest'
+import { transformerRemoveEmptyLines } from '../src'
+
+describe('transformer-remove-empty-lines', () => {
+  it('removes empty lines', async () => {
+    const code = `
+line 1
+
+line 2
+
+line 3
+`
+    const html = await codeToHtml(code, {
+      lang: 'js',
+      theme: 'github-dark',
+      transformers: [
+        transformerRemoveEmptyLines(),
+      ],
+    })
+
+    expect(html).toMatchSnapshot()
+  })
+})