Make sure we can write to a file

Author: liuzicheng1987

include/rfl/bson/load.hpp

@@ -2,7 +2,7 @@
 #define RFL_BSON_LOAD_HPP_
 
 #include "../Result.hpp"
-#include "../io/load_string.hpp"
+#include "../io/load_bytes.hpp"
 #include "read.hpp"
 
 namespace rfl {

include/rfl/bson/save.hpp

@@ -6,7 +6,7 @@
 #include <string>
 
 #include "../Result.hpp"
-#include "../io/save_string.hpp"
+#include "../io/save_bytes.hpp"
 #include "write.hpp"
 
 namespace rfl {

include/rfl/bson/write.hpp

@@ -6,48 +6,50 @@
 #include <ostream>
 #include <sstream>
 #include <string>
+#include <utility>
 
 #include "../parsing/Parent.hpp"
 #include "Parser.hpp"
 
 namespace rfl {
 namespace bson {
 
-/// Returns BSON bytes.
+/// Returns BSON bytes. Careful: It is the responsibility of the caller to call
+/// bson_free on the returned pointer.
 template <class T>
-std::vector<char> write(const T& _obj) {
+std::pair<uint8_t*, size_t> to_buffer(const T& _obj) noexcept {
   using ParentType = parsing::Parent<Writer>;
-  bson_t* doc;
+  bson_t* doc = nullptr;
   uint8_t* buf = nullptr;
   size_t buflen = 0;
-
   bson_writer_t* bson_writer =
       bson_writer_new(&buf, &buflen, 0, bson_realloc_ctx, NULL);
-
   bson_writer_begin(bson_writer, &doc);
-
   const auto rfl_writer = Writer(doc);
-
   Parser<T>::write(rfl_writer, _obj, typename ParentType::Root{});
-
   bson_writer_end(bson_writer);
-
   const auto len = bson_writer_get_length(bson_writer);
-
   bson_writer_destroy(bson_writer);
+  return std::make_pair(buf, len);
+}
 
+/// Returns BSON bytes.
+template <class T>
+std::vector<char> write(const T& _obj) noexcept {
+  auto [buf, len] = to_buffer(_obj);
   const auto result = std::vector<char>(reinterpret_cast<char*>(buf),
                                         reinterpret_cast<char*>(buf) + len);
-
   bson_free(buf);
-
   return result;
 }
 
 /// Writes a BSON into an ostream.
 template <class T>
-std::ostream& write(const T& _obj, std::ostream& _stream) {
-  // TODO
+std::ostream& write(const T& _obj, std::ostream& _stream) noexcept {
+  auto [buf, len] = to_buffer(_obj);
+  _stream.write(reinterpret_cast<const char*>(buf), len);
+  bson_free(buf);
+  return _stream;
 }
 
 }  // namespace bson