From df3829c7efd3327059cd5ab606a038c845936506 Mon Sep 17 00:00:00 2001
From: IWANABETHATGUY <17974631+IWANABETHATGUY@users.noreply.github.com>
Date: Thu, 14 Aug 2025 14:51:24 +0000
Subject: [PATCH] feat(oxc_codegen): support configure initial indent when
 using `oxc_codegen` (#13091)

Here is an example in rolldown https://github.com/rolldown/rolldown/pull/5724/files#diff-8a1733ecebbc28acb7d0c6ccd52499d7d2c9611f046b0b4a30ee3e1f939cbf13R57-R74, when concate multiple module, rolldown uses the output of  `oxc_codegen` for AST and  adding head and tail of the concatenatedModules with string replace to make sure generates the correct sourcemap with minimum effort.
In this scenario, rolldown needs `oxc_codegen` to start generating string with initial ident `1`
---
 crates/oxc_codegen/src/lib.rs              | 1 +
 crates/oxc_codegen/src/options.rs          | 7 +++++++
 crates/oxc_codegen/tests/integration/js.rs | 7 +++++++
 3 files changed, 15 insertions(+)

diff --git a/crates/oxc_codegen/src/lib.rs b/crates/oxc_codegen/src/lib.rs
index 86830aa35137b..c1ec1bc36f019 100644
--- a/crates/oxc_codegen/src/lib.rs
+++ b/crates/oxc_codegen/src/lib.rs
@@ -197,6 +197,7 @@ impl<'a> Codegen<'a> {
     pub fn build(mut self, program: &Program<'a>) -> CodegenReturn {
         self.quote = if self.options.single_quote { Quote::Single } else { Quote::Double };
         self.source_text = Some(program.source_text);
+        self.indent = self.options.initial_indent;
         self.code.reserve(program.source_text.len());
         self.build_comments(&program.comments);
         if let Some(path) = &self.options.source_map_path {
diff --git a/crates/oxc_codegen/src/options.rs b/crates/oxc_codegen/src/options.rs
index 5fc98f49bf388..d4f7674c55038 100644
--- a/crates/oxc_codegen/src/options.rs
+++ b/crates/oxc_codegen/src/options.rs
@@ -38,6 +38,11 @@ pub struct CodegenOptions {
     ///
     /// Default is `1`.
     pub indent_width: usize,
+
+    /// Initial indentation level for generated code.
+    ///
+    /// Default is `0`.
+    pub initial_indent: u32,
 }
 
 impl Default for CodegenOptions {
@@ -49,6 +54,7 @@ impl Default for CodegenOptions {
             source_map_path: None,
             indent_char: IndentChar::default(),
             indent_width: DEFAULT_INDENT_WIDTH,
+            initial_indent: 0,
         }
     }
 }
@@ -63,6 +69,7 @@ impl CodegenOptions {
             source_map_path: None,
             indent_char: IndentChar::default(),
             indent_width: DEFAULT_INDENT_WIDTH,
+            initial_indent: 0,
         }
     }
 
diff --git a/crates/oxc_codegen/tests/integration/js.rs b/crates/oxc_codegen/tests/integration/js.rs
index 302e057b4dfb5..cc55b3cc90119 100644
--- a/crates/oxc_codegen/tests/integration/js.rs
+++ b/crates/oxc_codegen/tests/integration/js.rs
@@ -647,4 +647,11 @@ fn indentation() {
             ..CodegenOptions::default()
         },
     );
+
+    // Test initial indent with 1
+    test_options(
+        "let foo = 1;",
+        "\tlet foo = 1;\n",
+        CodegenOptions { initial_indent: 1, ..CodegenOptions::default() },
+    );
 }