Add new C++ Command framework (#1785)

This is the C++ version of #1682.

The old command framework is still available, but will be deprecated.

Due to name conflicts, the new framework is in the frc2 namespace.
Eventually (after the old command framework is removed in a future year)
it will be moved into the main frc namespace.

wpilibcExamples/src/main/cpp/examples/Frisbeebot/include/Constants.h

@@ -0,0 +1,73 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+/**
+ * The Constants header provides a convenient place for teams to hold robot-wide
+ * numerical or bool constants.  This should not be used for any other purpose.
+ *
+ * It is generally a good idea to place constants into subsystem- or
+ * command-specific namespaces within this header, which can then be used where
+ * they are needed.
+ */
+
+namespace DriveConstants {
+const int kLeftMotor1Port = 0;
+const int kLeftMotor2Port = 1;
+const int kRightMotor1Port = 2;
+const int kRightMotor2Port = 3;
+
+const int kLeftEncoderPorts[]{0, 1};
+const int kRightEncoderPorts[]{2, 3};
+const bool kLeftEncoderReversed = false;
+const bool kRightEncoderReversed = true;
+
+const int kEncoderCPR = 1024;
+const double kWheelDiameterInches = 6;
+const double kEncoderDistancePerPulse =
+    // Assumes the encoders are directly mounted on the wheel shafts
+    (kWheelDiameterInches * 3.142) / static_cast<double>(kEncoderCPR);
+}  // namespace DriveConstants
+
+namespace ShooterConstants {
+const int kEncoderPorts[]{4, 5};
+const bool kEncoderReversed = false;
+const int kEncoderCPR = 1024;
+const double kEncoderDistancePerPulse =
+    // Distance units will be rotations
+    1. / static_cast<double>(kEncoderCPR);
+
+const int kShooterMotorPort = 4;
+const int kFeederMotorPort = 5;
+
+const double kShooterFreeRPS = 5300;
+const double kShooterTargetRPS = 4000;
+const double kShooterToleranceRPS = 50;
+
+const double kP = 1;
+const double kI = 0;
+const double kD = 0;
+
+// On a real robot the feedforward constants should be empirically determined;
+// these are reasonable guesses.
+const double kSFractional = .05;
+const double kVFractional =
+    // Should have value 1 at free speed...
+    1. / kShooterFreeRPS;
+
+const double kFeederSpeed = .5;
+}  // namespace ShooterConstants
+
+namespace AutoConstants {
+const double kAutoTimeoutSeconds = 12;
+const double kAutoShootTimeSeconds = 7;
+}  // namespace AutoConstants
+
+namespace OIConstants {
+const int kDriverControllerPort = 1;
+}  // namespace OIConstants

wpilibcExamples/src/main/cpp/examples/Frisbeebot/include/Robot.h

@@ -0,0 +1,34 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2019 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc2/command/Command.h>
+
+#include <frc/TimedRobot.h>
+
+#include "RobotContainer.h"
+
+class Robot : public frc::TimedRobot {
+ public:
+  void RobotInit() override;
+  void RobotPeriodic() override;
+  void DisabledInit() override;
+  void DisabledPeriodic() override;
+  void AutonomousInit() override;
+  void AutonomousPeriodic() override;
+  void TeleopInit() override;
+  void TeleopPeriodic() override;
+  void TestPeriodic() override;
+
+ private:
+  // Have it null by default so that if testing teleop it
+  // doesn't have undefined behavior and potentially crash.
+  frc2::Command* m_autonomousCommand = nullptr;
+
+  RobotContainer m_container;
+};

wpilibcExamples/src/main/cpp/examples/Frisbeebot/include/RobotContainer.h

@@ -0,0 +1,102 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc2/command/Command.h>
+#include <frc2/command/ConditionalCommand.h>
+#include <frc2/command/InstantCommand.h>
+#include <frc2/command/ParallelRaceGroup.h>
+#include <frc2/command/RunCommand.h>
+#include <frc2/command/SequentialCommandGroup.h>
+#include <frc2/command/WaitCommand.h>
+#include <frc2/command/WaitUntilCommand.h>
+
+#include <frc/XboxController.h>
+#include <frc/smartdashboard/SendableChooser.h>
+
+#include "Constants.h"
+#include "subsystems/DriveSubsystem.h"
+#include "subsystems/ShooterSubsystem.h"
+
+namespace ac = AutoConstants;
+
+/**
+ * This class is where the bulk of the robot should be declared.  Since
+ * Command-based is a "declarative" paradigm, very little robot logic should
+ * actually be handled in the {@link Robot} periodic methods (other than the
+ * scheduler calls).  Instead, the structure of the robot (including subsystems,
+ * commands, and button mappings) should be declared here.
+ */
+class RobotContainer {
+ public:
+  RobotContainer();
+
+  frc2::Command* GetAutonomousCommand();
+
+ private:
+  // The driver's controller
+  frc::XboxController m_driverController{OIConstants::kDriverControllerPort};
+
+  // The robot's subsystems and commands are defined here...
+
+  // The robot's subsystems
+  DriveSubsystem m_drive;
+  ShooterSubsystem m_shooter;
+
+  // A simple autonomous routine that shoots the loaded frisbees
+  frc2::SequentialCommandGroup m_autonomousCommand =
+      frc2::SequentialCommandGroup{
+          // Start the command by spinning up the shooter...
+          frc2::InstantCommand([this] { m_shooter.Enable(); }, {&m_shooter}),
+          // Wait until the shooter is at speed before feeding the frisbees
+          frc2::WaitUntilCommand([this] { return m_shooter.AtSetpoint(); }),
+          // Start running the feeder
+          frc2::InstantCommand([this] { m_shooter.RunFeeder(); }, {&m_shooter}),
+          // Shoot for the specified time
+          frc2::WaitCommand(ac::kAutoShootTimeSeconds)}
+          // Add a timeout (will end the command if, for instance, the shooter
+          // never gets up to
+          // speed)
+          .WithTimeout(ac::kAutoTimeoutSeconds)
+          // When the command ends, turn off the shooter and the feeder
+          .WhenFinished([this] {
+            m_shooter.Disable();
+            m_shooter.StopFeeder();
+          });
+
+  // Assorted commands to be bound to buttons
+
+  frc2::InstantCommand m_spinUpShooter{[this] { m_shooter.Enable(); },
+                                       {&m_shooter}};
+
+  frc2::InstantCommand m_stopShooter{[this] { m_shooter.Disable(); },
+                                     {&m_shooter}};
+
+  // Shoots if the shooter wheen has reached the target speed
+  frc2::ConditionalCommand m_shoot{
+      // Run the feeder
+      frc2::InstantCommand{[this] { m_shooter.RunFeeder(); }, {&m_shooter}},
+      // Do nothing
+      frc2::InstantCommand(),
+      // Determine which of the above to do based on whether the shooter has
+      // reached the
+      // desired speed
+      [this] { return m_shooter.AtSetpoint(); }};
+
+  frc2::InstantCommand m_stopFeeder{[this] { m_shooter.StopFeeder(); },
+                                    {&m_shooter}};
+
+  frc2::InstantCommand m_driveHalfSpeed{[this] { m_drive.SetMaxOutput(.5); },
+                                        {}};
+  frc2::InstantCommand m_driveFullSpeed{[this] { m_drive.SetMaxOutput(1); },
+                                        {}};
+
+  // The chooser for the autonomous routines
+
+  void ConfigureButtonBindings();
+};

wpilibcExamples/src/main/cpp/examples/Frisbeebot/include/subsystems/DriveSubsystem.h

@@ -0,0 +1,96 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc2/command/SubsystemBase.h>
+
+#include <frc/Encoder.h>
+#include <frc/PWMVictorSPX.h>
+#include <frc/SpeedControllerGroup.h>
+#include <frc/drive/DifferentialDrive.h>
+
+#include "Constants.h"
+
+class DriveSubsystem : public frc2::SubsystemBase {
+ public:
+  DriveSubsystem();
+
+  /**
+   * Will be called periodically whenever the CommandScheduler runs.
+   */
+  void Periodic() override;
+
+  // Subsystem methods go here.
+
+  /**
+   * Drives the robot using arcade controls.
+   *
+   * @param fwd the commanded forward movement
+   * @param rot the commanded rotation
+   */
+  void ArcadeDrive(double fwd, double rot);
+
+  /**
+   * Resets the drive encoders to currently read a position of 0.
+   */
+  void ResetEncoders();
+
+  /**
+   * Gets the average distance of the TWO encoders.
+   *
+   * @return the average of the TWO encoder readings
+   */
+  double GetAverageEncoderDistance();
+
+  /**
+   * Gets the left drive encoder.
+   *
+   * @return the left drive encoder
+   */
+  frc::Encoder& GetLeftEncoder();
+
+  /**
+   * Gets the right drive encoder.
+   *
+   * @return the right drive encoder
+   */
+  frc::Encoder& GetRightEncoder();
+
+  /**
+   * Sets the max output of the drive.  Useful for scaling the drive to drive
+   * more slowly.
+   *
+   * @param maxOutput the maximum output to which the drive will be constrained
+   */
+  void SetMaxOutput(double maxOutput);
+
+ private:
+  // Components (e.g. motor controllers and sensors) should generally be
+  // declared private and exposed only through public methods.
+
+  // The motor controllers
+  frc::PWMVictorSPX m_left1;
+  frc::PWMVictorSPX m_left2;
+  frc::PWMVictorSPX m_right1;
+  frc::PWMVictorSPX m_right2;
+
+  // The motors on the left side of the drive
+  frc::SpeedControllerGroup m_leftMotors{m_left1, m_left2};
+
+  // The motors on the right side of the drive
+  frc::SpeedControllerGroup m_rightMotors{m_right1, m_right2};
+
+  // The robot's drive
+  frc::DifferentialDrive m_drive{m_leftMotors, m_rightMotors};
+
+  // The left-side drive encoder
+  frc::Encoder m_leftEncoder;
+
+  // The right-side drive encoder
+  frc::Encoder m_rightEncoder;
+};

wpilibcExamples/src/main/cpp/examples/Frisbeebot/include/subsystems/ShooterSubsystem.h

@@ -0,0 +1,37 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc2/command/PIDSubsystem.h>
+
+#include <frc/Encoder.h>
+#include <frc/PWMVictorSPX.h>
+
+class ShooterSubsystem : public frc2::PIDSubsystem {
+ public:
+  ShooterSubsystem();
+
+  void UseOutput(double output) override;
+
+  double GetSetpoint() override;
+
+  double GetMeasurement() override;
+
+  void Disable() override;
+
+  bool AtSetpoint();
+
+  void RunFeeder();
+
+  void StopFeeder();
+
+ private:
+  frc::PWMVictorSPX m_shooterMotor;
+  frc::PWMVictorSPX m_feederMotor;
+  frc::Encoder m_shooterEncoder;
+};