support bazel complie this project and format code.

This commit is contained in:
zhangxing
2023-03-30 00:15:11 +08:00
committed by light-city
parent 1f86192576
commit 3c8a3f259b
641 changed files with 10349 additions and 9523 deletions

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//
// Created by light on 20-1-6.
//
#include <iostream>
#include "structData.h"
template<class T>
struct hasSerialize {
// 编译时比较
typedef char yes[1];
typedef char no[2];
// 允许我们检查序列化确实是一种方法
// 第二个参数必须是第一个参数的类型
// 例如: reallyHas<int,10> 替换为 reallyHas<int,int 10> 并起作用
// 注意:它仅适用于整数常量和指针(因此函数指针可以使用)
// 例如reallyHas<std::string (C::*)(), &C::serialize> 替换为
// reallyHas<std::string (C::*)(), std::string (C::*)() &C::serialize> 并起作用
template<typename U, U u>
struct reallyHas;
// std::string (C::*)() 是函数指针声明
template<typename C>
static yes &test(reallyHas<std::string (C::*)(), &C::serialize> * /*unused*/) {}
// ()()const 函数指针 -> std::string serialize() const
template<typename C>
static yes &test(reallyHas<std::string (C::*)() const, &C::serialize> * /*unused*/) {}
// The famous C++ sink-hole.
// Note that sink-hole must be templated too as we are testing test<T>(0).
// If the method serialize isn't available, we will end up in this method.
template<typename>
static no &test(...) { /* dark matter */ }
//用作测试的返回值的常数。
//由于编译时评估的大小,因此实际上在这里完成了测试。
static const bool value = sizeof(test<T>(0)) == sizeof(yes);
};
template<bool B, class T = void> // Default template version.
struct enable_if {
}; // This struct doesn't define "type" and the substitution will fail if you try to access it.
template<class T> // A specialisation used if the expression is true.
struct enable_if<true, T> {
typedef T type;
}; // This struct do have a "type" and won't fail on access.
template<class T>
typename enable_if<hasSerialize<T>::value, std::string>::type serialize(const T &obj) {
return obj.serialize();
}
template<class T>
typename enable_if<!hasSerialize<T>::value, std::string>::type serialize(const T &obj) {
return to_string(obj);
}
int main() {
// Usage:
// enable_if<true, int>::type t1; // Compiler happy. t's type is int.
// enable_if<hasSerialize<B>::value, int>::type t2; // Compiler happy. t's type is int.
//
// enable_if<false, int>::type t3; // Compiler unhappy. no type named 'type' in 'enable_if<false, int>';
// enable_if<hasSerialize<A>::value, int>::type t4; // no type named 'type' in 'enable_if<false, int>';
A a;
B b;
C c;
// The following lines work like a charm!
std::cout << serialize(a) << std::endl;
std::cout << serialize(b) << std::endl;
std::cout << serialize(c) << std::endl;
}