[commands] Add RepeatCommand (#4009)

Co-authored-by: Starlight220 <53231611+Starlight220@users.noreply.github.com>

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/Command.java

@@ -257,6 +257,22 @@ public interface Command {
     return new PerpetualCommand(this);
   }
 
+  /**
+   * Decorates this command to run repeatedly, restarting it when it ends, until this command is
+   * interrupted. The decorated command can still be canceled.
+   *
+   * <p>Note: This decorator works by composing this command within a CommandGroup. The command
+   * cannot be used independently after being decorated, or be re-decorated with a different
+   * decorator, unless it is manually cleared from the list of grouped commands with {@link
+   * CommandGroupBase#clearGroupedCommand(Command)}. The decorated command can, however, be further
+   * decorated without issue.
+   *
+   * @return the decorated command
+   */
+  default RepeatCommand repeat() {
+    return new RepeatCommand(this);
+  }
+
   /**
    * Decorates this command to run "by proxy" by wrapping it in a {@link ProxyScheduleCommand}. This
    * is useful for "forking off" from command groups when the user does not wish to extend the

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/RepeatCommand.java

@@ -0,0 +1,70 @@
+// 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.
+
+package edu.wpi.first.wpilibj2.command;
+
+import static edu.wpi.first.wpilibj2.command.CommandGroupBase.registerGroupedCommands;
+import static edu.wpi.first.wpilibj2.command.CommandGroupBase.requireUngrouped;
+
+/**
+ * A command that runs another command repeatedly, restarting it when it ends, until this command is
+ * interrupted. While this class does not extend {@link CommandGroupBase}, it is still considered a
+ * CommandGroup, as it allows one to compose another command within it; the command instances that
+ * are passed to it cannot be added to any other groups, or scheduled individually.
+ *
+ * <p>As a rule, CommandGroups require the union of the requirements of their component commands.
+ *
+ * <p>This class is provided by the NewCommands VendorDep
+ */
+public class RepeatCommand extends CommandBase {
+  protected final Command m_command;
+
+  /**
+   * Creates a new RepeatCommand. Will run another command repeatedly, restarting it whenever it
+   * ends, until this command is interrupted.
+   *
+   * @param command the command to run repeatedly
+   */
+  public RepeatCommand(Command command) {
+    requireUngrouped(command);
+    registerGroupedCommands(command);
+    m_command = command;
+    m_requirements.addAll(command.getRequirements());
+  }
+
+  @Override
+  public void initialize() {
+    m_command.initialize();
+  }
+
+  @Override
+  public void execute() {
+    m_command.execute();
+    if (m_command.isFinished()) {
+      // restart command
+      m_command.end(false);
+      m_command.initialize();
+    }
+  }
+
+  @Override
+  public boolean isFinished() {
+    return false;
+  }
+
+  @Override
+  public void end(boolean interrupted) {
+    m_command.end(interrupted);
+  }
+
+  @Override
+  public boolean runsWhenDisabled() {
+    return m_command.runsWhenDisabled();
+  }
+
+  @Override
+  public RepeatCommand repeat() {
+    return this;
+  }
+}

wpilibNewCommands/src/main/native/cpp/frc2/command/Command.cpp

@@ -11,6 +11,7 @@
 #include "frc2/command/ParallelRaceGroup.h"
 #include "frc2/command/PerpetualCommand.h"
 #include "frc2/command/ProxyScheduleCommand.h"
+#include "frc2/command/RepeatCommand.h"
 #include "frc2/command/SequentialCommandGroup.h"
 #include "frc2/command/WaitCommand.h"
 #include "frc2/command/WaitUntilCommand.h"
@@ -87,6 +88,10 @@ PerpetualCommand Command::Perpetually() && {
   return PerpetualCommand(std::move(*this).TransferOwnership());
 }
 
+RepeatCommand Command::Repeat() && {
+  return RepeatCommand(std::move(*this).TransferOwnership());
+}
+
 ProxyScheduleCommand Command::AsProxy() {
   return ProxyScheduleCommand(this);
 }

wpilibNewCommands/src/main/native/cpp/frc2/command/RepeatCommand.cpp

@@ -0,0 +1,45 @@
+// 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 "frc2/command/RepeatCommand.h"
+
+using namespace frc2;
+
+RepeatCommand::RepeatCommand(std::unique_ptr<Command>&& command) {
+  if (!CommandGroupBase::RequireUngrouped(*command)) {
+    return;
+  }
+  m_command = std::move(command);
+  m_command->SetGrouped(true);
+  AddRequirements(m_command->GetRequirements());
+}
+
+void RepeatCommand::Initialize() {
+  m_command->Initialize();
+}
+
+void RepeatCommand::Execute() {
+  m_command->Execute();
+  if (m_command->IsFinished()) {
+    // restart command
+    m_command->End(false);
+    m_command->Initialize();
+  }
+}
+
+bool RepeatCommand::IsFinished() {
+  return false;
+}
+
+void RepeatCommand::End(bool interrupted) {
+  m_command->End(interrupted);
+}
+
+bool RepeatCommand::RunsWhenDisabled() const {
+  return m_command->RunsWhenDisabled();
+}
+
+RepeatCommand RepeatCommand::Repeat() && {
+  return std::move(*this);
+}

wpilibNewCommands/src/main/native/include/frc2/command/Command.h

@@ -29,6 +29,7 @@ class ParallelDeadlineGroup;
 class SequentialCommandGroup;
 class PerpetualCommand;
 class ProxyScheduleCommand;
+class RepeatCommand;
 
 /**
  * A state machine representing a complete action to be performed by the robot.
@@ -185,6 +186,14 @@ class Command {
    */
   virtual PerpetualCommand Perpetually() &&;
 
+  /**
+   * Decorates this command to run repeatedly, restarting it when it ends, until
+   * this command is interrupted. The decorated command can still be canceled.
+   *
+   * @return the decorated command
+   */
+  virtual RepeatCommand Repeat() &&;
+
   /**
    * Decorates this command to run "by proxy" by wrapping it in a
    * ProxyScheduleCommand. This is useful for "forking off" from command groups

wpilibNewCommands/src/main/native/include/frc2/command/RepeatCommand.h

@@ -0,0 +1,81 @@
+// 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.
+
+#pragma once
+
+#ifdef _WIN32
+#pragma warning(push)
+#pragma warning(disable : 4521)
+#endif
+
+#include <memory>
+#include <utility>
+
+#include "frc2/command/CommandBase.h"
+#include "frc2/command/CommandGroupBase.h"
+#include "frc2/command/CommandHelper.h"
+
+namespace frc2 {
+/**
+ * A command that runs another command repeatedly, restarting it when it ends,
+ * until this command is interrupted. While this class does not extend {@link
+ * CommandGroupBase}, it is still considered a CommandGroup, as it allows one to
+ * compose another command within it; the command instances that are passed to
+ * it cannot be added to any other groups, or scheduled individually.
+ *
+ * <p>As a rule, CommandGroups require the union of the requirements of their
+ * component commands.
+ *
+ * <p>This class is provided by the NewCommands VendorDep
+ */
+class RepeatCommand : public CommandHelper<CommandBase, RepeatCommand> {
+ public:
+  /**
+   * Creates a new RepeatCommand. Will run another command repeatedly,
+   * restarting it whenever it ends, until this command is interrupted.
+   *
+   * @param command the command to run repeatedly
+   */
+  explicit RepeatCommand(std::unique_ptr<Command>&& command);
+
+  /**
+   * Creates a new RepeatCommand. Will run another command repeatedly,
+   * restarting it whenever it ends, until this command is interrupted.
+   *
+   * @param command the command to run repeatedly
+   */
+  template <class T, typename = std::enable_if_t<std::is_base_of_v<
+                         Command, std::remove_reference_t<T>>>>
+  explicit RepeatCommand(T&& command)
+      : RepeatCommand(std::make_unique<std::remove_reference_t<T>>(
+            std::forward<T>(command))) {}
+
+  RepeatCommand(RepeatCommand&& other) = default;
+
+  // No copy constructors for command groups
+  RepeatCommand(const RepeatCommand& other) = delete;
+
+  // Prevent template expansion from emulating copy ctor
+  RepeatCommand(RepeatCommand&) = delete;
+
+  void Initialize() override;
+
+  void Execute() override;
+
+  bool IsFinished() override;
+
+  void End(bool interrupted) override;
+
+  bool RunsWhenDisabled() const override;
+
+  RepeatCommand Repeat() && override;
+
+ private:
+  std::unique_ptr<Command> m_command;
+};
+}  // namespace frc2
+
+#ifdef _WIN32
+#pragma warning(pop)
+#endif

wpilibNewCommands/src/test/java/edu/wpi/first/wpilibj2/command/RepeatCommandTest.java

@@ -0,0 +1,71 @@
+// 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.
+
+package edu.wpi.first.wpilibj2.command;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import edu.wpi.first.hal.HAL;
+import edu.wpi.first.wpilibj.simulation.DriverStationSim;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import org.junit.jupiter.api.Test;
+
+class RepeatCommandTest {
+  @Test
+  void callsMethodsCorrectly() {
+    HAL.initialize(500, 0);
+    // enable so that we don't need to mess with `runsWhenDisabled` for each command
+    DriverStationSim.setEnabled(true);
+
+    var initCounter = new AtomicInteger(0);
+    var exeCounter = new AtomicInteger(0);
+    var isFinishedCounter = new AtomicInteger(0);
+    var endCounter = new AtomicInteger(0);
+    var isFinishedHook = new AtomicBoolean(false);
+
+    final var command =
+        new RepeatCommand(
+            new FunctionalCommand(
+                initCounter::incrementAndGet,
+                exeCounter::incrementAndGet,
+                interrupted -> endCounter.incrementAndGet(),
+                () -> {
+                  isFinishedCounter.incrementAndGet();
+                  return isFinishedHook.get();
+                }));
+
+    assertEquals(0, initCounter.get());
+    assertEquals(0, exeCounter.get());
+    assertEquals(0, isFinishedCounter.get());
+    assertEquals(0, endCounter.get());
+
+    CommandScheduler.getInstance().schedule(command);
+    assertEquals(1, initCounter.get());
+    assertEquals(0, exeCounter.get());
+    assertEquals(0, isFinishedCounter.get());
+    assertEquals(0, endCounter.get());
+
+    isFinishedHook.set(false);
+    CommandScheduler.getInstance().run();
+    assertEquals(1, initCounter.get());
+    assertEquals(1, exeCounter.get());
+    assertEquals(1, isFinishedCounter.get());
+    assertEquals(0, endCounter.get());
+
+    isFinishedHook.set(true);
+    CommandScheduler.getInstance().run();
+    assertEquals(2, initCounter.get());
+    assertEquals(2, exeCounter.get());
+    assertEquals(2, isFinishedCounter.get());
+    assertEquals(1, endCounter.get());
+
+    isFinishedHook.set(false);
+    CommandScheduler.getInstance().run();
+    assertEquals(2, initCounter.get());
+    assertEquals(3, exeCounter.get());
+    assertEquals(3, isFinishedCounter.get());
+    assertEquals(1, endCounter.get());
+  }
+}

wpilibNewCommands/src/test/native/cpp/frc2/command/RepeatCommandTest.cpp

@@ -0,0 +1,62 @@
+// 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 "CommandTestBase.h"
+#include "frc2/command/FunctionalCommand.h"
+#include "frc2/command/RepeatCommand.h"
+
+using namespace frc2;
+class RepeatCommandTest : public CommandTestBase {};
+
+TEST_F(RepeatCommandTest, CallsMethodsCorrectly) {
+  CommandScheduler scheduler = GetScheduler();
+
+  int initCounter = 0;
+  int exeCounter = 0;
+  int isFinishedCounter = 0;
+  int endCounter = 0;
+  bool isFinishedHook = false;
+
+  auto command =
+      FunctionalCommand([&initCounter] { initCounter++; },
+                        [&exeCounter] { exeCounter++; },
+                        [&endCounter](bool interrupted) { endCounter++; },
+                        [&isFinishedCounter, &isFinishedHook] {
+                          isFinishedCounter++;
+                          return isFinishedHook;
+                        })
+          .Repeat();
+
+  EXPECT_EQ(0, initCounter);
+  EXPECT_EQ(0, exeCounter);
+  EXPECT_EQ(0, isFinishedCounter);
+  EXPECT_EQ(0, endCounter);
+
+  scheduler.Schedule(&command);
+  EXPECT_EQ(1, initCounter);
+  EXPECT_EQ(0, exeCounter);
+  EXPECT_EQ(0, isFinishedCounter);
+  EXPECT_EQ(0, endCounter);
+
+  isFinishedHook = false;
+  scheduler.Run();
+  EXPECT_EQ(1, initCounter);
+  EXPECT_EQ(1, exeCounter);
+  EXPECT_EQ(1, isFinishedCounter);
+  EXPECT_EQ(0, endCounter);
+
+  isFinishedHook = true;
+  scheduler.Run();
+  EXPECT_EQ(2, initCounter);
+  EXPECT_EQ(2, exeCounter);
+  EXPECT_EQ(2, isFinishedCounter);
+  EXPECT_EQ(1, endCounter);
+
+  isFinishedHook = false;
+  scheduler.Run();
+  EXPECT_EQ(2, initCounter);
+  EXPECT_EQ(3, exeCounter);
+  EXPECT_EQ(3, isFinishedCounter);
+  EXPECT_EQ(1, endCounter);
+}