Implemented class StreamBuffer, which I'm quite satisfied with.

luprex/core/cpp/luasnap.cpp

@@ -26,7 +26,7 @@ LuaSnap::~LuaSnap() {
     std::cerr << "LuaSnap destructor not implemented yet" << std::endl;
 }
 
-void LuaSnap::serialize(Packer *pk) {
+void LuaSnap::serialize(StreamBuffer *sb) {
     // Lua stack should be empty.
     assert(lua_gettop(state_) == 0);
 
@@ -63,25 +63,26 @@ void LuaSnap::serialize(Packer *pk) {
     assert(lua_gettop(state_) == 2);
 
     // Write dummy length, use eris to write data, then overwrite length.
-    pk->write_int64(0);
-    size_t tell = pk->tellp();
-    eris_dump(state_, pk->lua_writer, pk->lua_writer_ud());
-    pk->overwrite_int64(tell, pk->tellp() - tell);
+    sb->write_int64(0);
+    int64_t pos1 = sb->write_count();
+    eris_dump(state_, sb->lua_writer, sb->lua_writer_ud());
+    int64_t pos2 = sb->write_count();
+    sb->overwrite_int64(pos1, pos2 - pos1);
     lua_settop(state_, 0);
-    std::cerr << "Eris dump is " << (pk->tellp() - tell) << " bytes." << std::endl;
+    std::cerr << "Eris dump is " << pos2-pos1 << " bytes." << std::endl;
 }
 
-void LuaSnap::deserialize(Unpacker *unpk) {
+void LuaSnap::deserialize(StreamBuffer *sb) {
     // Lua stack should be empty.
     assert(lua_gettop(state_) == 0);
 
-    // Get a reader subsection containing the eris data.
-    size_t len = unpk->read_int64();
-    Unpacker subsec = unpk->read_section(len);
+    // Get the length of the eris dump.
+    int64_t len = sb->read_int64();
+    void *ud = sb->lua_reader_ud(len);
 
     // Call eris with the permanents table and passing the snapshot as a lua_Reader.
     lua_getfield(state_, LUA_REGISTRYINDEX, "unpersist");
-    eris_undump(state_, subsec.lua_reader, subsec.lua_reader_ud());
+    eris_undump(state_, sb->lua_reader, ud);
     assert(lua_gettop(state_) == 2);
 
     // Set up a stack frame.
@@ -122,21 +123,17 @@ void LuaSnap::deserialize(Unpacker *unpk) {
 // require us to maintain any additional code.
 
 bool LuaSnap::have_snapshot() const {
-    return !snapshot_.empty();
+    return snapshot_.write_count() != 0;
 }
 
 void LuaSnap::snapshot() {
-    assert(snapshot_.empty());
-    std::ostringstream oss;
-    Packer pk(&oss);
-    serialize(&pk);
-    snapshot_ = oss.str();
+    assert(snapshot_.write_count() == 0);
+    serialize(&snapshot_);
 }
 
 void LuaSnap::rollback() {
-    assert(!snapshot_.empty());
-    Unpacker unpk(snapshot_.c_str(), snapshot_.size());
-    deserialize(&unpk);
+    assert(snapshot_.write_count() != 0);
+    deserialize(&snapshot_);
     snapshot_.clear();
 }