text: /*****************************************************************************************
   *                                                                                       *
   * OpenSpace                                                                             *
   *                                                                                       *
   * Copyright (c) 2014-2020                                                               *
   *                                                                                       *
   * Permission is hereby granted, free of charge, to any person obtaining a copy of this  *
   * software and associated documentation files (the "Software"), to deal in the Software *
   * without restriction, including without limitation the rights to use, copy, modify,    *
   * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to    *
   * permit persons to whom the Software is furnished to do so, subject to the following   *
   * conditions:                                                                           *
   *                                                                                       *
   * The above copyright notice and this permission notice shall be included in all copies *
   * or substantial portions of the Software.                                              *
   *                                                                                       *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,   *
   * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A         *
   * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT    *
   * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF  *
   * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE  *
   * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                                         *
   ****************************************************************************************/
  
  #ifndef __OPENSPACE_CORE___TRIGGERPROPERTY___H__
  #define __OPENSPACE_CORE___TRIGGERPROPERTY___H__
  
  #include <openspace/properties/property.h>
  
  namespace openspace::properties {
  
  /**
   * TriggerProperty that can be used to fire events into your code using the callback
   * method #onChange.
   */
  class TriggerProperty : public Property {
  public:
      /**
       * Initializes the TriggerProperty by delegating the <code>identifier</code> and
       * <code>guiName</code> to the Property constructor.
       * \param info The PropertyInfo structure that contains all the required static
       * information for initializing this Property.
       * \pre \p info.identifier must not be empty
       * \pre \p info.guiName must not be empty
       */
      TriggerProperty(PropertyInfo info);
  
      /**
       * Returns the class name <code>TriggerProperty</code>.
       * \return The class name <code>TriggerProperty</code>
       */
      std::string className() const override;
  
      /**
       * Accepts only the <code>LUA_TNIL</code> type and will notify all the listeners
       * that the event has been triggered.
       * \param state The unused Lua state
       * \return Returns always <code>true</code>
       */
      bool setLuaValue(lua_State* state) override;
  
      /**
       * Silently ignores any value that is passed into this function and will trigger the
       * listeners regardless of the value
       * \param value The ignored value
       */
      void set(std::any value) override;
  
      std::string toJson() const override;
  
      std::string jsonValue() const override;
  };
  
  } // namespace openspace::properties
  
  #endif // __OPENSPACE_CORE___TRIGGERPROPERTY___H__
  