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axyz/include/Engine/Core/ComponentWrapper.h
T

128 lines
4.5 KiB
C++

#ifndef ComponentWrapper_h__
#define ComponentWrapper_h__
#include <boost/shared_array.hpp>
#include "../Common.h"
#include "Entity.h"
#include "ComponentInfo.h"
#include "Util/Any.h"
template <typename T, typename Enable = void>
struct ComponentField { };
template <typename T>
struct ComponentField<T, typename std::enable_if<std::is_trivially_copyable<T>::value>::type>
{
static T& Get(const ComponentInfo::Field_t& info, char* data) { return *reinterpret_cast<T*>(data); }
static void Set(const ComponentInfo::Field_t& info, char* data, const T& value) { Get(data) = value; }
};
template <>
struct ComponentField<std::string, void>
{
static std::string& Get(const ComponentInfo::Field_t& info, char* data) { return **reinterpret_cast<std::string**>(data); }
static void Set(const ComponentInfo::Field_t& info, char* data, const std::string& value) { Get(info, data) = value; }
};
struct ComponentWrapper
{
ComponentWrapper(const ComponentInfo& componentInfo, char* data)
: Info(componentInfo)
, EntityID(*reinterpret_cast<::EntityID*>(data))
, Data(data + sizeof(::EntityID))
{ }
const ComponentInfo& Info;
const ::EntityID EntityID;
char* Data;
ComponentInfo::EnumType Enum(const char* fieldName, const char* enumKey)
{
return Info.Meta->FieldEnumDefinitions.at(fieldName).at(enumKey);
}
template <typename T>
T& Field(std::string name)
{
const ComponentInfo::Field_t& field = Info.Fields.at(name);
if (sizeof(T) > field.Stride) {
std::stringstream message;
message << "Type size of \"" << typeid(T).name() << "\" doesn't match size of component field \"" << Info.Name << "." << name << "\"!";
throw new std::runtime_error(message.str().c_str());
}
return *reinterpret_cast<T*>(&Data[field.Offset]);
}
template <typename T>
void SetField(std::string name, const T value) { Field<T>(name) = value; }
//template <typename T>
//void SetField(std::string name, T& value) { Field<T>(name) = value; }
// Specialization for string literals
template <std::size_t N>
void SetField(std::string name, const char(&value)[N]) { Field<std::string>(name) = std::string(value); }
void Copy(ComponentWrapper& destination)
{
// Copy trivial data
memcpy(destination.Data, Data, Info.Stride);
// Duplicate strings
SolidifyStrings(destination);
}
// When component data has been copied, strings need to be reconstructed or they'll refer to the same data!
static void SolidifyStrings(ComponentWrapper& component)
{
for (auto& name : component.Info.StringFields) {
std::size_t offset = component.Info.Fields.at(name).Offset;
auto& value = *reinterpret_cast<const std::string*>(component.Data + offset);
new (component.Data + offset) std::string(value);
}
}
struct SubscriptProxy
{
friend struct ComponentWrapper;
private:
SubscriptProxy(ComponentWrapper* component, std::string propertyName)
: m_Component(component)
, m_PropertyName(propertyName)
{ }
ComponentWrapper* m_Component;
std::string m_PropertyName;
public:
// Return the integer value of an enum type key for this field
ComponentInfo::EnumType Enum(const char* enumKey) { return m_Component->Enum(m_PropertyName.c_str(), enumKey); }
template <typename T>
operator T&() { return m_Component->Field<T>(m_PropertyName); }
template <typename T>
void operator=(const T val) { m_Component->SetField<T>(m_PropertyName, val); }
// TODO: Pass by reference and rvalue (universal reference?)
//template <typename T>
//void operator=(T& val) { m_Component->SetField<T>(m_PropertyName, val); }
// Specialization for string literals
template <std::size_t N>
void operator=(const char(&val)[N]) { m_Component->SetField<N>(m_PropertyName, val); }
};
SubscriptProxy operator[](std::string propertyName) { return SubscriptProxy(this, propertyName); }
};
// A component wrapper that "owns" its data through a shared pointer
struct SharedComponentWrapper : ComponentWrapper
{
SharedComponentWrapper(const ComponentInfo& componentInfo, boost::shared_array<char> data)
: ComponentWrapper(componentInfo, data.get())
, m_DataReference(data)
{ }
private:
boost::shared_array<char> m_DataReference;
};
#endif