[command] Rename PerpetualCommand to EndlessCommand (#4177)

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

@@ -252,11 +252,29 @@ public interface Command {
    * decorated without issue.
    *
    * @return the decorated command
+   * @deprecated use {@link #endlessly()} instead.
    */
+  @Deprecated(forRemoval = true, since = "2023")
   default PerpetualCommand perpetually() {
     return new PerpetualCommand(this);
   }
 
+  /**
+   * Decorates this command to run endlessly, ignoring its ordinary end conditions. The decorated
+   * command can still be interrupted or 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 EndlessCommand endlessly() {
+    return new EndlessCommand(this);
+  }
+
   /**
    * Decorates this command to run repeatedly, restarting it when it ends, until this command is
    * interrupted. The decorated command can still be canceled.

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

@@ -0,0 +1,60 @@
+// 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 endlessly, ignoring that command's end conditions. 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 EndlessCommand extends CommandBase {
+  protected final Command m_command;
+
+  /**
+   * Creates a new EndlessCommand. Will run another command endlessly, ignoring that command's end
+   * conditions, unless this command itself is interrupted.
+   *
+   * @param command the command to run endlessly
+   */
+  public EndlessCommand(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();
+  }
+
+  @Override
+  public void end(boolean interrupted) {
+    m_command.end(interrupted);
+  }
+
+  @Override
+  public boolean runsWhenDisabled() {
+    return m_command.runsWhenDisabled();
+  }
+
+  @Override
+  public EndlessCommand endlessly() {
+    return this;
+  }
+}

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

@@ -16,7 +16,10 @@ import static edu.wpi.first.wpilibj2.command.CommandGroupBase.requireUngrouped;
  * <p>As a rule, CommandGroups require the union of the requirements of their component commands.
  *
  * <p>This class is provided by the NewCommands VendorDep
+ *
+ * @deprecated Replaced by {@link EndlessCommand}.
  */
+@Deprecated(forRemoval = true, since = "2023")
 public class PerpetualCommand extends CommandBase {
   protected final Command m_command;