object: update to_string callback to use b_stream instead of b_stringstream

object/include/blue/object/string.h

@@ -5,6 +5,8 @@
 #include <blue/object/object.h>
 #include <blue/object/type.h>
 
+struct b_stream;
+
 #define B_STRING(p)  ((b_string *)(p))
 
 #define B_CSTR(s)    (b_string_create_from_cstr(s))
@@ -33,6 +35,7 @@ static inline void b_string_release(b_string *str)
 BLUE_API char *b_string_steal(b_string *str);
 BLUE_API b_status b_string_reserve(b_string *str, size_t capacity);
 BLUE_API b_status b_string_replace_all(b_string *str, const char *new_data);
+BLUE_API b_status b_string_open_stream(b_string *str, struct b_stream **out);
 
 BLUE_API void b_string_append_s(b_string *dest, const b_string *src);
 BLUE_API void b_string_append_cstr(b_string *dest, const char *src);