As string_view operations on std::map<std::string> won't be integrated
until C++26, placeholder implementations are used which are less efficient
in a couple of situations (e.g. insert with hint).
Currently in the entire C API of WPILib we have ~8 different ways of handling strings. The C API actually isn't built for pure C callers (We don't actually have any of those). Instead, they're built for interop between languages like LabVIEW and C# which can talk to C API's directly.
For output parameters, the choice was fairly obvious. An output struct containing a const string pointer and a length makes the most sense. Its easy to use these from most other languages, and doesn't require special null termination handling. Freeing these is also easy, as if you ever receive one of these string structures, theres just a single function call to free it.
Input parameters are a bit more complex. To be used from pure C, and from LabVIEW, a null terminated string is the best in most cases. However, null terminated strings in general have a lot of downsides. Additionally, from LabVIEW there are other considerations around encoding that having a wrapper struct helps make a bit easier. From a language like C#, a wrapper struct is by far the easiest, as custom marshalling can make it trivial to marshal both UTF8 and UTF16 strings down.
The final consideration is its nice to have an identical concept for both input and output. It makes the rules fairly easy to understand.
WPILib will not have any APIs that manipulate a string allocated externally. This means WPI_String can be const, as across the boundary it is always const.
If a WPILib API takes a const WPI_String*, WPILib will not manipulate or attempt to free that string, and that string is treated as an input. It is up to the caller to handle that memory, WPILib will never hold onto that memory longer than the call.
If a WPILib API takes a WPI_String*, that string is an output. WPILib will allocate that API with WPI_AllocateString(), fill in the string, and return to the caller. When the caller is done with the string, they must free it with WPI_FreeString().
If an output struct contains a WPI_String member, that member is considered read only, and should not be explicitly freed. The caller should call the free function for that struct.
If an array of WPI_Strings are returned, each individual string is considered read only, and should not be explicitly freed. The free function for that array should be called by the caller.
If an input struct containing a WPI_String, or an input array of WPI_Strings is passed to WPILib, the individual strings will not be manipulated or freed by WPILib, and the caller owns and should free that memory.
Callbacks also follow these rules. The most common is a callback either getting passed a const WPI_String* or a struct containing a WPI_String. In both of these cases, the callback target should consider these strings read only, and not attempt to free them or manipulate them.
Putting an early exit if statement at the top instead of wrapping the
whole file contents unbreaks unit test configs, as was discovered for
SysId. It reduces nesting as well.
Unused plugins were removed from the beginnings of files as well.
Provides an implementation of a XRP-specific plugin that sends binary messages over UDP (to account for the less performant hardware on the XRP).
This plugin leverages the work already done for the WebSocket protocol and does a translation to/from JSON/binary.
Many teams have issues trying to read the DS too early. By switching to an optional, we cause teams to check 2 things. Either 1) they explicitly check, and their code is correct, or 2) they just read .value() and their code reboots in a loop. However, because the DS will eventually connect, this 2nd case is ok, and should theoretically be undetectable on the field.
- Twine, StringRef, Format, and NativeFormatting have been removed
- Logging now uses fmtlib style formatting
- Nearly all uses of wpi::outs/errs have been replaced with fmt::print() or
std::puts()/std::fputs() (for unformatted strings).
- A wpi/fmt/raw_ostream.h header has been added to enable
fmt::print() with wpi::raw_ostream
* Add .clang-tidy configuration.
* A separate .clang-tidy is used for hal includes to suppress modernize-use-using
(as these are C headers).
* Add NOLINT where necessary for a clean run.
* Add clang-tidy job to lint-format workflow. This workflow is now only run on PRs.
To reduce runtime, clang-tidy is only run on files changed in the PR.
Two wpilibc changes; both are unlikely to break user code:
* BuiltInAccelerometer: Make SetRange() final
* Counter: Make SetMaxPeriod() final
After these cleanups, the only file that does not run cleanly is
cscore_raw_cv.h due to it not being standalone.
This makes code easier to read and more consistent between C++ and Java.
Also update clang-format settings to always add a line break (even if no braces are used).
This is a breaking change to the WebSockets layer to align it with
recent specification documentation work.
To support this, HAL SimValue changed readonly to a direction enum.
This allows specifying bidirectional in addition to input and output.
The SimValue change is specifically designed to avoid API and ABI breakage.
This is completely transparent in C++; in Java a new callback class was added,
and the old readonly functions have been marked deprecated.
A new SimValue creation function for enums allows specifying double values
for each enum value, not just strings. This allows mapping enum values to
doubles in the WebSockets layer.
A ":" in the SimDevice name now maps it to different WebSocket types (e.g.
"Accel:Name" becomes type "Accel", device "Name"). The type is hidden
in the GUI.
Other WebSockets changes:
* Implemented match_time and game_data
* Added joystick rumble data
* Added builtin accelerometer support
* SimValue enums are mapped to string and double value on WS interface
* Added WebSockets protocol specification
* Added READMEs
Currently, Encoder.reset() must make a round trip to the sensor and back
in order for the count to be updated for the user program. As the sim layer
also resets the internal encoder count, this creates a race condition (a WS
message with a new count can be "in flight" during a reset and update the
count).
This changes the WS layer to not put reset on the wire, but instead keep an
offset count internal to the robot program. The value on the wire is not
reset, but rather all sends and receives are adjusted as necessary to the
internal robot count.
This approach is straightforward, but does result in the value on the wire
not matching the value in the user program. A future improvement will fix
this, but this change fixes the immediate race condition problem.
This allows access to HAL-level simulation data via a WebSocket connection.
The server additionally serves local files.
The following environment variables can be used for configuration:
HALSIMWS_USERROOT (server) - local directory to use for file serving for /user/ URIs, defaults to ./sim/user
HALSIMWS_SYSROOT (server) - local directory to use for file serving for all other URIs, defaults to ./sim
HALSIMWS_URI (client or server) - WebSocket URI, defaults to /wpilibws
HALSIMWS_PORT (client or server) - port number, defaults to 8080
HALSIMWS_HOST (client) - host to connect to, defaults to localhost
Co-authored-by: Zhiquan Yeo <zyeo8@bloomberg.net>
Co-authored-by: Peter Johnson <johnson.peter@gmail.com>
Co-authored-by: jpokornyiii <jpokornyiii@gmail.com>
