Split the two command implementations into separate libraries (#2012)

This will allow us at the user code side to determine to include old commands, new commands or both.

wpilibOldCommands/src/main/native/include/frc/commands/Subsystem.h

@@ -0,0 +1,199 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2011-2019 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 <memory>
+#include <string>
+
+#include <wpi/StringRef.h>
+#include <wpi/Twine.h>
+
+#include "frc/ErrorBase.h"
+#include "frc/smartdashboard/Sendable.h"
+#include "frc/smartdashboard/SendableHelper.h"
+
+namespace frc {
+
+class Command;
+
+class Subsystem : public ErrorBase,
+                  public Sendable,
+                  public SendableHelper<Subsystem> {
+  friend class Scheduler;
+
+ public:
+  /**
+   * Creates a subsystem with the given name.
+   *
+   * @param name the name of the subsystem
+   */
+  explicit Subsystem(const wpi::Twine& name);
+
+  Subsystem(Subsystem&&) = default;
+  Subsystem& operator=(Subsystem&&) = default;
+
+  /**
+   * Sets the default command. If this is not called or is called with null,
+   * then there will be no default command for the subsystem.
+   *
+   * <b>WARNING:</b> This should <b>NOT</b> be called in a constructor if the
+   * subsystem is a singleton.
+   *
+   * @param command the default command (or null if there should be none)
+   */
+  void SetDefaultCommand(Command* command);
+
+  /**
+   * Returns the default command (or null if there is none).
+   *
+   * @return the default command
+   */
+  Command* GetDefaultCommand();
+
+  /**
+   * Returns the default command name, or empty string is there is none.
+   *
+   * @return the default command name
+   */
+  wpi::StringRef GetDefaultCommandName();
+
+  /**
+   * Sets the current command.
+   *
+   * @param command the new current command
+   */
+  void SetCurrentCommand(Command* command);
+
+  /**
+   * Returns the command which currently claims this subsystem.
+   *
+   * @return the command which currently claims this subsystem
+   */
+  Command* GetCurrentCommand() const;
+
+  /**
+   * Returns the current command name, or empty string if no current command.
+   *
+   * @return the current command name
+   */
+  wpi::StringRef GetCurrentCommandName() const;
+
+  /**
+   * When the run method of the scheduler is called this method will be called.
+   */
+  virtual void Periodic();
+
+  /**
+   * Initialize the default command for this subsystem.
+   *
+   * This is meant to be the place to call SetDefaultCommand in a subsystem and
+   * will be called on all the subsystems by the CommandBase method before the
+   * program starts running by using the list of all registered Subsystems
+   * inside the Scheduler.
+   *
+   * This should be overridden by a Subsystem that has a default Command
+   */
+  virtual void InitDefaultCommand();
+
+  /**
+   * Gets the name of this Subsystem.
+   *
+   * @return Name
+   */
+  std::string GetName() const;
+
+  /**
+   * Sets the name of this Subsystem.
+   *
+   * @param name name
+   */
+  void SetName(const wpi::Twine& name);
+
+  /**
+   * Gets the subsystem name of this Subsystem.
+   *
+   * @return Subsystem name
+   */
+  std::string GetSubsystem() const;
+
+  /**
+   * Sets the subsystem name of this Subsystem.
+   *
+   * @param subsystem subsystem name
+   */
+  void SetSubsystem(const wpi::Twine& subsystem);
+
+  /**
+   * Associate a Sendable with this Subsystem.
+   * Also update the child's name.
+   *
+   * @param name name to give child
+   * @param child sendable
+   */
+  void AddChild(const wpi::Twine& name, std::shared_ptr<Sendable> child);
+
+  /**
+   * Associate a Sendable with this Subsystem.
+   * Also update the child's name.
+   *
+   * @param name name to give child
+   * @param child sendable
+   */
+  void AddChild(const wpi::Twine& name, Sendable* child);
+
+  /**
+   * Associate a Sendable with this Subsystem.
+   * Also update the child's name.
+   *
+   * @param name name to give child
+   * @param child sendable
+   */
+  void AddChild(const wpi::Twine& name, Sendable& child);
+
+  /**
+   * Associate a {@link Sendable} with this Subsystem.
+   *
+   * @param child sendable
+   */
+  void AddChild(std::shared_ptr<Sendable> child);
+
+  /**
+   * Associate a {@link Sendable} with this Subsystem.
+   *
+   * @param child sendable
+   */
+  void AddChild(Sendable* child);
+
+  /**
+   * Associate a {@link Sendable} with this Subsystem.
+   *
+   * @param child sendable
+   */
+  void AddChild(Sendable& child);
+
+ private:
+  /**
+   * Call this to alert Subsystem that the current command is actually the
+   * command.
+   *
+   * Sometimes, the Subsystem is told that it has no command while the Scheduler
+   * is going through the loop, only to be soon after given a new one. This will
+   * avoid that situation.
+   */
+  void ConfirmCommand();
+
+  Command* m_currentCommand = nullptr;
+  bool m_currentCommandChanged = true;
+  Command* m_defaultCommand = nullptr;
+  bool m_initializedDefaultCommand = false;
+
+ public:
+  void InitSendable(SendableBuilder& builder) override;
+};
+
+}  // namespace frc