[wpilib] Add functional interface equivalents to MotorController (#6053)

This does not deprecate any current functionality, but prepares the way for future deprecation.

The drive classes now accept void(double) functions, which makes them more flexible.

The C++ API ended up a bit more verbose, but the Java API is really concise with method references, which is >80% of our userbase. For example:

`DifferentialDrive drive = new DifferentialDrive(m_leftMotor::set, m_rightMotor::set);`

Lambdas can be passed to interoperate with vendor motor controller APIs that don't have e.g., set(double), so CTRE doesn't have to maintain their WPI_ classes anymore.

MotorControllerGroup was replaced with PWMMotorController.addFollower() for PWM motor controllers. Users of CAN motor controllers should use their vendor's follower functionality.

wpilibc/src/test/native/cpp/drive/DifferentialDriveTest.cpp

@@ -5,7 +5,7 @@
 #include <gtest/gtest.h>
 
 #include "frc/drive/DifferentialDrive.h"
-#include "motorcontrol/MockMotorController.h"
+#include "motorcontrol/MockPWMMotorController.h"
 
 TEST(DifferentialDriveTest, ArcadeDriveIK) {
   // Forward
@@ -240,9 +240,10 @@ TEST(DifferentialDriveTest, TankDriveIKSquared) {
 }
 
 TEST(DifferentialDriveTest, ArcadeDrive) {
-  frc::MockMotorController left;
-  frc::MockMotorController right;
-  frc::DifferentialDrive drive{left, right};
+  frc::MockPWMMotorController left;
+  frc::MockPWMMotorController right;
+  frc::DifferentialDrive drive{[&](double output) { left.Set(output); },
+                               [&](double output) { right.Set(output); }};
   drive.SetDeadband(0.0);
 
   // Forward
@@ -277,9 +278,10 @@ TEST(DifferentialDriveTest, ArcadeDrive) {
 }
 
 TEST(DifferentialDriveTest, ArcadeDriveSquared) {
-  frc::MockMotorController left;
-  frc::MockMotorController right;
-  frc::DifferentialDrive drive{left, right};
+  frc::MockPWMMotorController left;
+  frc::MockPWMMotorController right;
+  frc::DifferentialDrive drive{[&](double output) { left.Set(output); },
+                               [&](double output) { right.Set(output); }};
   drive.SetDeadband(0.0);
 
   // Forward
@@ -314,9 +316,10 @@ TEST(DifferentialDriveTest, ArcadeDriveSquared) {
 }
 
 TEST(DifferentialDriveTest, CurvatureDrive) {
-  frc::MockMotorController left;
-  frc::MockMotorController right;
-  frc::DifferentialDrive drive{left, right};
+  frc::MockPWMMotorController left;
+  frc::MockPWMMotorController right;
+  frc::DifferentialDrive drive{[&](double output) { left.Set(output); },
+                               [&](double output) { right.Set(output); }};
   drive.SetDeadband(0.0);
 
   // Forward
@@ -351,9 +354,10 @@ TEST(DifferentialDriveTest, CurvatureDrive) {
 }
 
 TEST(DifferentialDriveTest, CurvatureDriveTurnInPlace) {
-  frc::MockMotorController left;
-  frc::MockMotorController right;
-  frc::DifferentialDrive drive{left, right};
+  frc::MockPWMMotorController left;
+  frc::MockPWMMotorController right;
+  frc::DifferentialDrive drive{[&](double output) { left.Set(output); },
+                               [&](double output) { right.Set(output); }};
   drive.SetDeadband(0.0);
 
   // Forward
@@ -388,9 +392,10 @@ TEST(DifferentialDriveTest, CurvatureDriveTurnInPlace) {
 }
 
 TEST(DifferentialDriveTest, TankDrive) {
-  frc::MockMotorController left;
-  frc::MockMotorController right;
-  frc::DifferentialDrive drive{left, right};
+  frc::MockPWMMotorController left;
+  frc::MockPWMMotorController right;
+  frc::DifferentialDrive drive{[&](double output) { left.Set(output); },
+                               [&](double output) { right.Set(output); }};
   drive.SetDeadband(0.0);
 
   // Forward
@@ -425,9 +430,10 @@ TEST(DifferentialDriveTest, TankDrive) {
 }
 
 TEST(DifferentialDriveTest, TankDriveSquared) {
-  frc::MockMotorController left;
-  frc::MockMotorController right;
-  frc::DifferentialDrive drive{left, right};
+  frc::MockPWMMotorController left;
+  frc::MockPWMMotorController right;
+  frc::DifferentialDrive drive{[&](double output) { left.Set(output); },
+                               [&](double output) { right.Set(output); }};
   drive.SetDeadband(0.0);
 
   // Forward

wpilibc/src/test/native/cpp/drive/MecanumDriveTest.cpp

@@ -5,7 +5,7 @@
 #include <gtest/gtest.h>
 
 #include "frc/drive/MecanumDrive.h"
-#include "motorcontrol/MockMotorController.h"
+#include "motorcontrol/MockPWMMotorController.h"
 
 TEST(MecanumDriveTest, CartesianIK) {
   // Forward
@@ -82,11 +82,14 @@ TEST(MecanumDriveTest, CartesianIKGyro90CW) {
 }
 
 TEST(MecanumDriveTest, Cartesian) {
-  frc::MockMotorController fl;
-  frc::MockMotorController rl;
-  frc::MockMotorController fr;
-  frc::MockMotorController rr;
-  frc::MecanumDrive drive{fl, rl, fr, rr};
+  frc::MockPWMMotorController fl;
+  frc::MockPWMMotorController rl;
+  frc::MockPWMMotorController fr;
+  frc::MockPWMMotorController rr;
+  frc::MecanumDrive drive{[&](double output) { fl.Set(output); },
+                          [&](double output) { rl.Set(output); },
+                          [&](double output) { fr.Set(output); },
+                          [&](double output) { rr.Set(output); }};
   drive.SetDeadband(0.0);
 
   // Forward
@@ -126,11 +129,14 @@ TEST(MecanumDriveTest, Cartesian) {
 }
 
 TEST(MecanumDriveTest, CartesianGyro90CW) {
-  frc::MockMotorController fl;
-  frc::MockMotorController fr;
-  frc::MockMotorController rl;
-  frc::MockMotorController rr;
-  frc::MecanumDrive drive{fl, rl, fr, rr};
+  frc::MockPWMMotorController fl;
+  frc::MockPWMMotorController rl;
+  frc::MockPWMMotorController fr;
+  frc::MockPWMMotorController rr;
+  frc::MecanumDrive drive{[&](double output) { fl.Set(output); },
+                          [&](double output) { rl.Set(output); },
+                          [&](double output) { fr.Set(output); },
+                          [&](double output) { rr.Set(output); }};
   drive.SetDeadband(0.0);
 
   // Forward in global frame; left in robot frame
@@ -170,11 +176,14 @@ TEST(MecanumDriveTest, CartesianGyro90CW) {
 }
 
 TEST(MecanumDriveTest, Polar) {
-  frc::MockMotorController fl;
-  frc::MockMotorController fr;
-  frc::MockMotorController rl;
-  frc::MockMotorController rr;
-  frc::MecanumDrive drive{fl, rl, fr, rr};
+  frc::MockPWMMotorController fl;
+  frc::MockPWMMotorController rl;
+  frc::MockPWMMotorController fr;
+  frc::MockPWMMotorController rr;
+  frc::MecanumDrive drive{[&](double output) { fl.Set(output); },
+                          [&](double output) { rl.Set(output); },
+                          [&](double output) { fr.Set(output); },
+                          [&](double output) { rr.Set(output); }};
   drive.SetDeadband(0.0);
 
   // Forward

wpilibc/src/test/native/cpp/motorcontrol/MockPWMMotorController.cpp

@@ -0,0 +1,31 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "motorcontrol/MockPWMMotorController.h"
+
+using namespace frc;
+
+void MockPWMMotorController::Set(double speed) {
+  m_speed = m_isInverted ? -speed : speed;
+}
+
+double MockPWMMotorController::Get() const {
+  return m_speed;
+}
+
+void MockPWMMotorController::SetInverted(bool isInverted) {
+  m_isInverted = isInverted;
+}
+
+bool MockPWMMotorController::GetInverted() const {
+  return m_isInverted;
+}
+
+void MockPWMMotorController::Disable() {
+  m_speed = 0;
+}
+
+void MockPWMMotorController::StopMotor() {
+  Disable();
+}

wpilibc/src/test/native/cpp/motorcontrol/MotorControllerGroupTest.cpp

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include <gtest/gtest.h>
+#include <wpi/deprecated.h>
 
 #include "motorcontrol/MockMotorController.h"
 
@@ -32,6 +33,8 @@ std::ostream& operator<<(std::ostream& os,
   return os;
 }
 
+WPI_IGNORE_DEPRECATED
+
 /**
  * A fixture used for MotorControllerGroup testing.
  */
@@ -124,3 +127,5 @@ TEST_P(MotorControllerGroupTest, StopMotor) {
 
 INSTANTIATE_TEST_SUITE_P(Tests, MotorControllerGroupTest,
                          testing::Values(TEST_ONE, TEST_TWO, TEST_THREE));
+
+WPI_UNIGNORE_DEPRECATED