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/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
#ifndef STRING_CONVERTIBLE_OPTIONAL_VALUE_H
#define STRING_CONVERTIBLE_OPTIONAL_VALUE_H
#include <string>
#include <sstream>
#include "System/Misc/NonCopyable.h"
/**
* @brief Untyped base class for TypedStringConvertibleOptionalValue.
*/
class StringConvertibleOptionalValue : public spring::noncopyable
{
public:
StringConvertibleOptionalValue() : isSet(false) {}
virtual ~StringConvertibleOptionalValue() {}
virtual std::string ToString() const = 0;
bool IsSet() const { return isSet; }
protected:
bool isSet;
};
/**
* @brief Wraps a value and detects whether it has been assigned to.
*/
template<typename T>
class TypedStringConvertibleOptionalValue : public StringConvertibleOptionalValue
{
public:
TypedStringConvertibleOptionalValue<T>& operator=(const T& x) {
value = x;
isSet = true;
return *this;
}
const T& Get() const { return value; }
std::string ToString() const override
{
std::ostringstream buf;
buf << value;
return buf.str();
}
static T FromString(const std::string& value)
{
std::istringstream buf(value);
T temp;
buf >> temp;
return temp;
}
protected:
T value;
};
/**
* @brief Specialization for std::string
*
* This exists because 1) converting from std::string to std::string is a no-op
* and 2) converting from std::string to std::string using std::istringstream
* will treat spaces as word boundaries, which we do not want.
*/
template<>
class TypedStringConvertibleOptionalValue<std::string> : public StringConvertibleOptionalValue
{
typedef std::string T;
public:
void operator=(const T& x) { value = x; isSet = true; }
const T& Get() const { return value; }
std::string ToString() const override { return value; }
static T FromString(const std::string& value) { return value; }
protected:
T value;
};
#endif // STRING_CONVERTIBLE_OPTIONAL_VALUE_H
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