From 8a837b8973960abeb7ecc72ca3096e43196c71d7 Mon Sep 17 00:00:00 2001
From: Sandeep Nambiar <sandeep.turing@gmail.com>
Date: Tue, 25 Jul 2023 04:52:42 +0200
Subject: [PATCH] feat: add extra namespaces to the exported file

---
 csbindgen/src/builder.rs | 15 ++++++++++++++-
 csbindgen/src/emitter.rs |  8 +++++++-
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/csbindgen/src/builder.rs b/csbindgen/src/builder.rs
index 4ff3427..77f8403 100644
--- a/csbindgen/src/builder.rs
+++ b/csbindgen/src/builder.rs
@@ -29,6 +29,7 @@ pub struct BindgenOptions {
     pub csharp_if_symbol: String,
     pub csharp_if_dll_name: String,
     pub csharp_use_function_pointer: bool,
+    pub csharp_imported_namespaces: Vec<String>,
 }
 
 impl Default for Builder {
@@ -51,6 +52,7 @@ impl Default for Builder {
                 csharp_if_symbol: "".to_string(),
                 csharp_if_dll_name: "".to_string(),
                 csharp_use_function_pointer: true,
+                csharp_imported_namespaces: vec![],
             },
         }
     }
@@ -63,7 +65,9 @@ impl Builder {
 
     /// Add an input .rs file(such as generated from bindgen) to generate binding.
     pub fn input_bindgen_file<T: AsRef<Path>>(mut self, input_bindgen_file: T) -> Builder {
-        self.options.input_bindgen_files.push(input_bindgen_file.as_ref().to_path_buf());
+        self.options
+            .input_bindgen_files
+            .push(input_bindgen_file.as_ref().to_path_buf());
         self
     }
 
@@ -109,6 +113,15 @@ impl Builder {
         self
     }
 
+    /// configure C# extra import namespace,
+    /// "using {csharp_namespace};"
+    pub fn csharp_import_namespace<T: Into<String>>(mut self, csharp_namespace: T) -> Builder {
+        self.options
+            .csharp_imported_namespaces
+            .push(csharp_namespace.into());
+        self
+    }
+
     /// configure C# class name(default is `NativeMethods`),
     /// `public static unsafe partial class {csharp_class_name}`
     pub fn csharp_class_name<T: Into<String>>(mut self, csharp_class_name: T) -> Builder {
diff --git a/csbindgen/src/emitter.rs b/csbindgen/src/emitter.rs
index 9c5d7f9..dc7c6e1 100644
--- a/csbindgen/src/emitter.rs
+++ b/csbindgen/src/emitter.rs
@@ -46,7 +46,7 @@ pub fn emit_rust_method(list: &Vec<ExternMethod>, options: &BindgenOptions) -> S
             "
 #[no_mangle]
 pub unsafe extern \"C\" fn {method_prefix}{method_name}(
-{parameters}    
+{parameters}
 ){return_line}
 {{
     {method_type_path2}{method_name}(
@@ -290,6 +290,11 @@ pub fn emit_csharp(
         enum_string.push('\n');
     }
 
+    let mut imported_namespaces = String::new();
+    for name in &options.csharp_imported_namespaces {
+        imported_namespaces.push_str_ln(format!("using {name};").as_str());
+    }
+
     let result = format!(
         "// <auto-generated>
 // This code is generated by csbindgen.
@@ -299,6 +304,7 @@ pub fn emit_csharp(
 #pragma warning disable CS8981
 using System;
 using System.Runtime.InteropServices;
+{imported_namespaces}
 
 namespace {namespace}
 {{