This means that during loading we can validate that what is saved
is also that what is expected. Additionally, this makes all list
types similar to how they are stored on disk:
First a gamma to indicate length, followed by the data.
The size still depends on the type.
In the end, the code was already doing the right thing, but a few
functions deep, and not really obvious. When validating what objects
can handle SLE_VAR_NULL, it is nicer to just have this obvious.
Using SL_ARR for this gives us a bit of trouble later on, where we
add a length-field to SL_ARR. This of course is not the intention
of SLE_CONDNULL. So better seperate it.
The current SaveLoad is a bit inconsistent how long a length field
is. Sometimes it is a 32bit, sometimes a gamma. Make it consistent
across the board by making them all gammas.
This helps external tooling to understand if a SL_STRUCT should
be skipped when reading. Basically, this transforms an SL_STRUCT
into a SL_STRUCTLIST with either 0 or 1 length.
This wasn't consistently done, and often variables were used that
were read by an earlier blob. By moving it next to the struct
itself, the code becomes a bit more self-contained and easier to
read.
Additionally, this allows for external tooling to know how many
structs to expect, instead of having to know where to find the
length-field or a hard-coded value that can change at any moment.
There was a lot of code duplication for no real reason. Now with
SLEG_STRUCT support, we can just re-use the code, hopefully making
it easier for future-us to make changes to this, without breaking
everything for old games.
With the new SLEG_STRUCT it is much easier to embed a struct
in a struct, where the sub-struct has limitations on when it is
being used.
This makes both the code easier to read (less magic) and avoids
the SaveLoad needing to know all these things about Stations
and Vehicles.
The commits following this will use this new functionality.
Currently, a few places do this manually. This has as drawback that
the Save() and Load() code need to be in sync, and that any change
can result in (old) savegames no longer loading. In general, it is
annoying code to maintain.
By putting everything in a description table, and use that for
both Save() and Load(), it becomes easier to see what is going on,
and hopefully less likely for people to make mistakes.
You can easily mistake SlList / SL_LST to be a list of SL_VAR, but
it is a list of SL_REF. With this rename, it hopefully saves a few
people from "wtf?" moments.
Prepare the full description and send it to SlObject. This does
require some code to be able to read to a SLE_VAR_NULL, like strings
etc, as there is no way to know their length beforehand.
It was rather confusing which one was for what, especially as some
SaveLoad flags were settings-only. Clean up this mess a bit by
having only Setting flags.
Basically, this changes "SaveLoad *" to either:
1) "SaveLoadTable" if a list of SaveLoads was meant
2) "SaveLoad &" if a single entry was meant
As added bonus, this removes SL_END / SLE_END / SLEG_END. This
also adds core/span.hpp, a "std::span"-lite.
It now follows very simple rules:
0 - Fatal, user should know about this
1 - Error, but we are recovering
2 - Warning, wrong but okay if you don't know
3 - Info, information you might care about
4 -
5 - Debug #1 - High level debug messages
6 - Debug #2 - Low level debug messages
7 - Trace information
