Update struct to split declaration and definition

codegen/datatypes.py

@@ -92,16 +92,23 @@ class CEnum:
 class CStruct:
     name: str
     cargs: list["CArg"]
+    typedef_name: str | None = None
 
     def __str__(self) -> str:
-        typedef = f"typedef struct {self.name} {self.name};\n"
-        header = f"struct {self.name} {{\n"
+        return self.declare() + self.define()
+
+    def declare(self) -> str:
+        declaration = f"typedef struct {self.name} {self.typedef_name if self.typedef_name is not None else self.name};\n"
+        return declaration
+
+    def define(self):
+        definition = f"struct {self.name} {{\n"
         args = ""
         for arg in self.cargs:
             args += f"  {str(arg)};\n"
         footer = "};\n"
 
-        return typedef + header + args + footer;
+        return definition + args + footer;
 
 
 CUserType = Union[CStruct, CEnum]