[commands] Change grouping decorator impl to flatten nested group structures (#3335)

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

@@ -107,7 +107,7 @@ class Command {
    * @param duration the timeout duration
    * @return the command with the timeout added
    */
-  ParallelRaceGroup WithTimeout(units::second_t duration) &&;
+  virtual ParallelRaceGroup WithTimeout(units::second_t duration) &&;
 
   /**
    * Decorates this command with an interrupt condition.  If the specified
@@ -118,7 +118,7 @@ class Command {
    * @param condition the interrupt condition
    * @return the command with the interrupt condition added
    */
-  ParallelRaceGroup WithInterrupt(std::function<bool()> condition) &&;
+  virtual ParallelRaceGroup WithInterrupt(std::function<bool()> condition) &&;
 
   /**
    * Decorates this command with a runnable to run before this command starts.
@@ -127,7 +127,7 @@ class Command {
    * @param requirements the required subsystems
    * @return the decorated command
    */
-  SequentialCommandGroup BeforeStarting(
+  virtual SequentialCommandGroup BeforeStarting(
       std::function<void()> toRun,
       std::initializer_list<Subsystem*> requirements) &&;
 
@@ -138,7 +138,7 @@ class Command {
    * @param requirements the required subsystems
    * @return the decorated command
    */
-  SequentialCommandGroup BeforeStarting(
+  virtual SequentialCommandGroup BeforeStarting(
       std::function<void()> toRun,
       wpi::span<Subsystem* const> requirements = {}) &&;
 
@@ -149,7 +149,7 @@ class Command {
    * @param requirements the required subsystems
    * @return the decorated command
    */
-  SequentialCommandGroup AndThen(
+  virtual SequentialCommandGroup AndThen(
       std::function<void()> toRun,
       std::initializer_list<Subsystem*> requirements) &&;
 
@@ -160,7 +160,7 @@ class Command {
    * @param requirements the required subsystems
    * @return the decorated command
    */
-  SequentialCommandGroup AndThen(
+  virtual SequentialCommandGroup AndThen(
       std::function<void()> toRun,
       wpi::span<Subsystem* const> requirements = {}) &&;
 
@@ -170,7 +170,7 @@ class Command {
    *
    * @return the decorated command
    */
-  PerpetualCommand Perpetually() &&;
+  virtual PerpetualCommand Perpetually() &&;
 
   /**
    * Decorates this command to run "by proxy" by wrapping it in a
@@ -180,7 +180,7 @@ class Command {
    *
    * @return the decorated command
    */
-  ProxyScheduleCommand AsProxy();
+  virtual ProxyScheduleCommand AsProxy();
 
   /**
    * Schedules this command.

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

@@ -65,6 +65,8 @@ class PerpetualCommand : public CommandHelper<CommandBase, PerpetualCommand> {
 
   void End(bool interrupted) override;
 
+  PerpetualCommand Perpetually() && override;
+
  private:
   std::unique_ptr<Command> m_command;
 };

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

@@ -84,6 +84,15 @@ class SequentialCommandGroup
 
   bool RunsWhenDisabled() const override;
 
+  SequentialCommandGroup BeforeStarting(
+      std::function<void()> toRun,
+      wpi::ArrayRef<Subsystem*> requirements = {}) &&
+      override;
+
+  SequentialCommandGroup AndThen(std::function<void()> toRun,
+                                 wpi::ArrayRef<Subsystem*> requirements = {}) &&
+      override;
+
  private:
   void AddCommands(std::vector<std::unique_ptr<Command>>&& commands) final;