feat(transformers): add transformerRemoveEmptyLines

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 +1,37 @@
+import type { ShikiTransformer } from '@shikijs/types'
+
+export interface TransformerRemoveEmptyLinesOptions {
+  /**
+   * Remove lines that contain only whitespace in addition to truly empty lines.
+   * @default true
+   */
+  removeWhitespaceOnlyLines?: boolean
+}
+
+/**
+ * Remove empty lines from the highlighted code output.
+ *
+ * Useful when you want to strip blank lines from code snippets
+ * before rendering (e.g. removing leading/trailing blank lines
+ * that come from template literals).
+ *
+ * @see {@link https://github.com/shikijs/shiki/issues/1206}
+ */
+export function transformerRemoveEmptyLines(
+  options: TransformerRemoveEmptyLinesOptions = {},
+): ShikiTransformer {
+  const { removeWhitespaceOnlyLines = true } = options
+
+  return {
+    name: '@shikijs/transformers:remove-empty-lines',
+    tokens(lines) {
+      return lines.filter((line) => {
+        if (line.length === 0)
+          return false
+        if (removeWhitespaceOnlyLines)
+          return line.some(token => token.content.trim().length > 0)
+        return true
+      })
+    },
+  }
+}