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OpenSpace/include/openspace/properties/templateproperty.h
2024-02-06 15:53:24 +01:00

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/*****************************************************************************************
* *
* OpenSpace *
* *
* Copyright (c) 2014-2024 *
* *
* 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 *
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* 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___TEMPLATEPROPERTY___H__
#define __OPENSPACE_CORE___TEMPLATEPROPERTY___H__
#include <openspace/properties/property.h>
namespace openspace::properties {
/**
* This subclass of Property handles a single parameter value that is of type `T`. It
* provides all the necessary methods to automatically access the value. One notable
* instantiation of this class is StringProperty, using `T = std::string` while
* NumericalProperty is a templated subclass dealing with numerical parameter types.
*
* The accessor operator and assignment operators are overloaded, so that the
* TemplateProperty can be used just in the same way as a regular member variable. In the
* case that these cannot not be used inline, the Property::get method will work.
*
* Each instantiation of this class should provide a constructor that deals with the
* default value for that specific type `T`, so that a property can be created from just a
* Property::PropertyInfo object.
*
* \tparam T The type of value that is stored in this TemplateProperty
*
* \see Property
* \see NumericalProperty
*/
template <typename T>
class TemplateProperty : public Property {
public:
using ValueType = T;
/**
* The constructor initializing the TemplateProperty with the provided PropertyInfo
* \p info and and the default value \p value.
*
* \param info The PropertyInfo structure that contains all the required static
* information for initializing this Property.
* \param value The default value of the Property
*
* \pre \p info.identifier must not be empty
* \pre \p info.guiName must not be empty
*/
TemplateProperty(Property::PropertyInfo info, T value);
/**
* Returns the class name for this TemplateProperty. This method has to be specialized
* for each new type.
*
* \return The class name for the TemplateProperty
*/
virtual std::string_view className() const override = 0;
/**
* Returns the stored value packed into a `std::any` object.
*
* \return The stored value packed into a `std::any` object
*/
virtual std::any get() const override;
/**
* Sets the value from the provided ghoul::any object. If the types between `T` and
* `value` disagree, an error is logged and the stored value remains unchanged.
*
* \param value The value that is used to set this Property
*/
virtual void set(std::any value) final;
/**
* Returns the `std::type_info` describing the template parameter `T`. It can be used
* to test against a ghoul::any value before trying to assign it.
*
* \return The type info object describing the template parameter `T`
*/
virtual const std::type_info& type() const override;
/**
* This method encodes the stored value into a Lua object and pushes that object onto
* the stack.
*
* \param state The Lua state onto which the encoded object will be pushed
* \return `true` if the encoding succeeded; `false` otherwise
*/
virtual bool getLuaValue(lua_State* state) const override;
/**
* Sets the value of this TemplateProperty by decoding the object at the top of the
* stack and, if successful, assigning it using the Property::set method. If the
* decoding is successful, the new value is set, otherwise it remains unchanged.
*
* \param state The Lua state from which the value will be decoded
*/
virtual void setLuaValue(lua_State* state) override;
/// \see Property::typeLua
virtual int typeLua() const override = 0;
/**
* This method encodes the stored value into a std::string object. The resulting
* encoding must also be a valid JSON representation fo the property.
*
* \return The string representation of the stored property value
*/
virtual std::string stringValue() const override;
/**
* This operator allows the TemplateProperty to be used almost transparently as if it
* was of the type `T`. It makes assignments such as `T v = property;` possible by
* allowing implicit casts (even though, internally, not casts are performed. This
* method is next to zero overhead).
*
* \return The internal representation of the Property
*/
operator T();
/**
* This operator allows the TemplateProperty to be used almost transparently as if it
* was of the type `T`. It makes assignments such as `T v = property;` possible by
* allowing implicit casts (even though, internally, not casts are performed. This
* method is next to zero overhead).
*
* \return The internal representation of the Property
*/
operator T() const;
/**
* The assignment operator allows the TemplateProperty's value to be set without using
* the TemplateProperty::set method. It will be done internally by this method and it
* allows assignments such as `prop = T(1)`.
*
* \param val The value that should be set
*/
TemplateProperty<T>& operator=(T val);
/**
* This method sets the stored value to the provided value `val`, moving it into
* place. The move only happens if the provided value `val` is different from the
* stored value, which needs an operator== to exist for the type `T`. If the value is
* different, the listeners are notified.
*
* \param val The new value for this TemplateProperty
*/
virtual void setValue(T val);
/**
* Returns the currently stored value.
*
* \return The currently stored value
*/
T value() const;
protected:
/**
* Decodes the object at the top of the stack to a value of the type `T` and returns
* it. This method has to be specialized for each new type.
*
* \param state The Lua state from which the value will be decoded
* \return The decoded value
*/
virtual T fromLuaConversion(lua_State* state) const = 0;
/**
* Encodes the stored value into a Lua object and pushes that object onto the stack.
* This method has to be specialized for each new type.
*
* \param state The Lua state onto which the encoded object will be pushed
*/
virtual void toLuaConversion(lua_State* state) const = 0;
/**
* Encodes the stored value into a std::string object, in a format that is a valid
* JSON representation of the property. This method has to be specialized for each new
* type.
*
* \return The resulting encoding
*/
virtual std::string toStringConversion() const = 0;
/// The value that this TemplateProperty currently stores
T _value;
};
} // namespace openspace::properties
#include "openspace/properties/templateproperty.inl"
#endif // __OPENSPACE_CORE___TEMPLATEPROPERTY___H__