text: #pragma once
  /*
  * Copyright 2016 Huy Cuong Nguyen
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
  
  #include <utility>
  #include <stdexcept>
  
  namespace ZXing {
  
  template <typename T>
  class Nullable final
  {
  	bool m_hasValue = false;
  	T m_value;
  
  public:
  	Nullable() = default;
  	Nullable(const T &value) : m_hasValue(true), m_value(value) {}
  	Nullable(T &&value) : m_hasValue(true), m_value(std::move(value)) {}
  	Nullable(std::nullptr_t) {}
  	
  	Nullable<T> & operator=(const T &value) {
  		m_hasValue = true;
  		m_value = value;
  		return *this;
  	}
  
  	Nullable<T> & operator=(T &&value) {
  		m_hasValue = true;
  		m_value = std::move(value);
  		return *this;
  	}
  
  	Nullable<T> & operator=(std::nullptr_t) {
  		m_hasValue = false;
  		m_value = T();
  		return *this;
  	}
  
  	operator T() const {
  		if (!m_hasValue) {
  			// throw std::logic_error("Access empty value");
  		}
  		return m_value;
  	}
  	
  	bool hasValue() const {
  		return m_hasValue;
  	}
  	
  	const T & value() const {
  		return m_value;
  	}
  	
  	T & value() {
  		return m_value;
  	}
  
  	friend inline bool operator==(const Nullable &a, const Nullable &b) {
  		return a.m_hasValue == b.m_hasValue && (!a.m_hasValue || a.m_value == b.m_value);
  	}
  	friend inline bool operator!=(const Nullable &a, const Nullable &b) {
  		return !(a == b);
  	}
  
  	friend inline bool operator==(const Nullable &a, const T &v) {
  		return a.m_hasValue && a.m_value == v;
  	}
  	friend inline bool operator!=(const Nullable &a, const T &v) {
  		return !(a == v);
  	}
  
  	friend inline bool operator==(const T &v, const Nullable &a) {
  		return a.m_hasValue && a.m_value == v;
  	}
  	friend inline bool operator!=(const T &v, const Nullable &a) {
  		return !(v == a);
  	}
  
  	friend inline bool operator==(const Nullable &a, std::nullptr_t) {
  		return !a.m_hasValue;
  	}
  	friend inline bool operator!=(const Nullable &a, std::nullptr_t) {
  		return a.m_hasValue;
  	}
  
  	friend inline bool operator==(std::nullptr_t, const Nullable &a) {
  		return !a.m_hasValue;
  	}
  	friend inline bool operator!=(std::nullptr_t, const Nullable &a) {
  		return a.m_hasValue;
  	}
  
  	friend inline void swap(Nullable &a, Nullable &b) {
  		using std::swap;
  		swap(a.m_value, b.m_value);
  		swap(a.m_hasValue, b.m_hasValue);
  	}
  };
  
  } // ZXing
  