feat: allow usage of nested file buffers

Author: thetutlage

src/file_buffer.ts

@@ -28,7 +28,7 @@ export class FileBuffer {
   /**
    * Collected lines
    */
-  #buffer: string[] = []
+  #buffer: (string | FileBuffer)[] = []
 
   /**
    * Current indentation size. Each call to indent will increment
@@ -66,8 +66,13 @@ export class FileBuffer {
    * @param text - The text to write as a new line
    * @returns This FileBuffer instance for method chaining
    */
-  writeLine(text: string): this {
-    this.#buffer.push(`${' '.repeat(this.#identationSize)}${text}\n`)
+  writeLine(text: string | FileBuffer): this {
+    if (typeof text === 'string') {
+      this.#buffer.push(`${' '.repeat(this.#identationSize)}${text}\n`)
+    } else {
+      this.#buffer.push(text)
+      this.#buffer.push('')
+    }
     return this
   }
 
@@ -77,8 +82,12 @@ export class FileBuffer {
    * @param text - The text to write without a newline
    * @returns This FileBuffer instance for method chaining
    */
-  write(text: string): this {
-    this.#buffer.push(`${' '.repeat(this.#identationSize)}${text}`)
+  write(text: string | FileBuffer): this {
+    if (typeof text === 'string') {
+      this.#buffer.push(`${' '.repeat(this.#identationSize)}${text}`)
+    } else {
+      this.#buffer.push(text)
+    }
     return this
   }
 
@@ -106,6 +115,10 @@ export class FileBuffer {
     return this
   }
 
+  toString() {
+    return this.flush()
+  }
+
   /**
    * Return template as a string, joining all buffer lines
    *

tests/file_buffer.spec.ts

@@ -0,0 +1,52 @@
+/*
+ * @adonisjs/assembler
+ *
+ * (c) AdonisJS
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+import { test } from '@japa/runner'
+import { FileBuffer } from '../src/file_buffer.ts'
+
+test.group('File buffer', () => {
+  test('use nested file buffers', ({ assert }) => {
+    const buffer = new FileBuffer()
+    const importsBuffer = buffer.create()
+
+    buffer.write(importsBuffer)
+    buffer.write('export namespace {').indent()
+    buffer.dedent().write('}')
+
+    importsBuffer.write(`import foo from './foo.ts'`)
+    importsBuffer.write(`import bar from './bar.ts'`)
+
+    assert.snapshot(buffer.flush()).matchInline(`
+      "import foo from './foo.ts'
+      import bar from './bar.ts'
+      export namespace {
+      }"
+    `)
+  })
+
+  test('use nested file buffers with a line break', ({ assert }) => {
+    const buffer = new FileBuffer()
+    const importsBuffer = buffer.create()
+
+    buffer.writeLine(importsBuffer)
+    buffer.write('export namespace {').indent()
+    buffer.dedent().write('}')
+
+    importsBuffer.write(`import foo from './foo.ts'`)
+    importsBuffer.write(`import bar from './bar.ts'`)
+
+    assert.snapshot(buffer.flush()).matchInline(`
+      "import foo from './foo.ts'
+      import bar from './bar.ts'
+
+      export namespace {
+      }"
+    `)
+  })
+})