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130 lines
2.0 KiB
C++
130 lines
2.0 KiB
C++
/*
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* Null.h
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*
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* Created on: 2012-8-23
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* Author: fasiondog
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*/
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#pragma once
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#ifndef NULL_H_
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#define NULL_H_
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#include "../config.h"
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#include <cstddef>
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#include <limits>
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#include <type_traits>
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namespace hku {
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/**
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* @ingroup Utilities
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* @addtogroup NullTools Null defines Null 值定义
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* @{
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*/
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/**
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* 提供指定给定类型的Null值
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*/
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template <typename T>
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class Null {
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public:
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Null() {}
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operator T() const {
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return T();
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}
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};
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/**
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* 提供int的Null值
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*/
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template <>
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class Null<int> {
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public:
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Null() {}
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operator int() {
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return (std::numeric_limits<int>::max)();
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}
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};
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/**
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* 提供unsigned int的Null值
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*/
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template <>
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class Null<unsigned int> {
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public:
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Null() {}
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operator unsigned int() {
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return (std::numeric_limits<unsigned int>::max)();
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}
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};
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/**
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* 提供long long（64位整型）的Null值
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*/
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template <>
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class Null<long long> {
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public:
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Null() {}
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operator long long() {
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return (std::numeric_limits<long long>::max)();
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}
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};
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#if !defined(_MSC_VER) && !HKU_OS_OSX
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/**
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* int64_t Null值
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*/
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template <>
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class Null<int64_t> {
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public:
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Null() {}
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operator int64_t() {
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return (std::numeric_limits<int64_t>::max)();
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}
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};
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#endif
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/**
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* 提供unsigned long long（无符号64位整型）的Null值
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*/
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template <>
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class Null<unsigned long long> {
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public:
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Null() {}
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operator unsigned long long() {
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return (std::numeric_limits<unsigned long long>::max)();
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}
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};
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#if !defined(_MSC_VER)
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/**
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* 提供size_t的Null值
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*/
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template <>
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class Null<size_t> {
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public:
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Null() {}
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operator unsigned long long() {
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return (std::numeric_limits<size_t>::max)();
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}
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};
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#endif
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/**
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* 提供double的Null值
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*/
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template <>
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class Null<double> {
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public:
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Null() {}
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operator double() {
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return (std::numeric_limits<double>::quiet_NaN)();
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// return (std::numeric_limits<double>::max)();
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}
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};
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/** @} */
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} // namespace hku
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#endif /* NULL_H_ */
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