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`

Author: IWANABETHATGUY

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 {

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,
         }
     }
 

crates/oxc_codegen/tests/integration/js.rs

@@ -647,4 +647,11 @@ fn indentation() {
             ..CodegenOptions::default()
         },
     );
+
+    // Test spaces with width 4
+    test_options(
+        "let foo = 1;",
+        "\tlet foo = 1;\n",
+        CodegenOptions { initial_indent: 1, ..CodegenOptions::default() },
+    );
 }