Aegisub/libaegisub/common/cajun/elements.cpp

159 lines
4.3 KiB
C++

/**********************************************
License: BSD
Project Webpage: http://cajun-jsonapi.sourceforge.net/
Author: Terry Caton
***********************************************/
#include "libaegisub/cajun/elements.h"
#include "libaegisub/cajun/visitor.h"
#include <algorithm>
#include <cassert>
namespace {
using namespace json;
class CastVisitorBase : public Visitor, public ConstVisitor {
void Visit(Array&) { }
void Visit(Object&) { }
void Visit(Integer&) { }
void Visit(Double&) { }
void Visit(String&) { }
void Visit(Boolean&) { }
void Visit(Null&) { is_null = true; }
void Visit(Array const&) { }
void Visit(Object const&) { }
void Visit(Integer const&) { }
void Visit(Double const&) { }
void Visit(String const&) { }
void Visit(Boolean const&) { }
void Visit(Null const&) { is_null = true; }
public:
bool is_null = false;
};
template<class T>
struct CastVisitor final : public CastVisitorBase {
T *element = nullptr;
void Visit(T& ele) { element = &ele; }
};
}
namespace json
{
/////////////////////////
// UnknownElement members
class UnknownElement::Imp
{
public:
virtual ~Imp() {}
virtual Imp* Clone() const = 0;
virtual bool Compare(const Imp& imp) const = 0;
virtual void Accept(ConstVisitor& visitor) const = 0;
virtual void Accept(Visitor& visitor) = 0;
};
template <typename ElementTypeT>
class UnknownElement::Imp_T final : public UnknownElement::Imp
{
public:
Imp_T(const ElementTypeT& element) : m_Element(element) { }
Imp* Clone() const { return new Imp_T<ElementTypeT>(*this); }
void Accept(ConstVisitor& visitor) const { visitor.Visit(m_Element); }
void Accept(Visitor& visitor) { visitor.Visit(m_Element); }
bool Compare(const Imp& imp) const
{
CastVisitor<const ElementTypeT> castVisitor;
imp.Accept(castVisitor);
return castVisitor.element && m_Element == *castVisitor.element;
}
private:
ElementTypeT m_Element;
};
UnknownElement::UnknownElement() : m_pImp(new Imp_T<Null>(Null())) {}
UnknownElement::UnknownElement(const UnknownElement& unknown) : m_pImp(unknown.m_pImp->Clone()) {}
UnknownElement::UnknownElement(int number) : m_pImp(new Imp_T<Integer>(number)) {}
UnknownElement::UnknownElement(const char *string) : m_pImp(new Imp_T<String>(string)) {}
UnknownElement::~UnknownElement() { }
#define DEFINE_UE_TYPE(Type) \
UnknownElement::UnknownElement(Type const& val) : m_pImp(new Imp_T<Type>(val)) { } \
UnknownElement::operator Type const&() const { return CastTo<Type>(); } \
UnknownElement::operator Type&() { return CastTo<Type>(); }
DEFINE_UE_TYPE(Object)
DEFINE_UE_TYPE(Array)
DEFINE_UE_TYPE(Integer)
DEFINE_UE_TYPE(Double)
DEFINE_UE_TYPE(Boolean)
DEFINE_UE_TYPE(String)
DEFINE_UE_TYPE(Null)
UnknownElement& UnknownElement::operator =(const UnknownElement& unknown)
{
m_pImp.reset(unknown.m_pImp->Clone());
return *this;
}
UnknownElement& UnknownElement::operator[](const std::string& key)
{
return CastTo<Object>()[key];
}
const UnknownElement& UnknownElement::operator[] (const std::string& key) const
{
// throws if we aren't an object
Object const& obj = CastTo<Object>();
Object::const_iterator it = obj.find(key);
if (it == obj.end())
throw Exception("Object member not found: " + key);
return it->second;
}
template <typename ElementTypeT>
ElementTypeT const& UnknownElement::CastTo() const
{
CastVisitor<const ElementTypeT> castVisitor;
Accept(castVisitor);
if (!castVisitor.element)
throw Exception("Bad cast");
return *castVisitor.element;
}
template <typename ElementTypeT>
ElementTypeT& UnknownElement::CastTo()
{
CastVisitor<ElementTypeT> castVisitor;
Accept(castVisitor);
// If this element is uninitialized, implicitly convert it to the desired type
if (castVisitor.is_null) {
*this = ElementTypeT();
return *this;
}
// Otherwise throw an exception
if (!castVisitor.element)
throw Exception("Bad cast");
return *castVisitor.element;
}
void UnknownElement::Accept(ConstVisitor& visitor) const { m_pImp->Accept(visitor); }
void UnknownElement::Accept(Visitor& visitor) { m_pImp->Accept(visitor); }
bool UnknownElement::operator == (const UnknownElement& element) const
{
return m_pImp->Compare(*element.m_pImp);
}
} // end namespace