//
// Created by william on 2021/8/8.
//
#include "base.h"
struct Key
{
std::string first;
std::string second;
};
struct KeyHash
{
std::size_t operator()(const Key& k) const
{
return std::hash<:string>()(k.first) ^ (std::hash<:string>()(k.second)) << 1;
}
};
struct KeyEqual
{
bool operator()(const Key& lhs, const Key& rhs) const
{
return lhs.first == rhs.first && lhs.second == rhs.second;
}
};
struct Foo
{
Foo(int val_) :
val(val_) {}
int val;
bool operator==(const Foo& rhs) const { return val == rhs.val; }
};
namespace std
{
template <>
struct hash
{
std::size_t operator()(const Foo& f) const
{
return std::hash{}(f.val);
}
};
} // namespace std
void unorderedMapTest()
{
// 创建三个 string çš„ unordered_map ï¼ˆæ˜ å°„åˆ° string ）
std::unordered_map<:string std::string> u = {
{ "RED", "#FF0000" },
{ "GREEN", "#00FF00" },
{ "BLUE", "#0000FF" }
};
// è¿ä»£å¹¶æ‰“å° unordered_map 的关键和值
for (const auto& n : u)
{
std::cout << "Key:[" << n.first << "] Value:[" << n.second << "]\n";
}
// æ·»åŠ æ–°å…¥å£åˆ° unordered_map
u["BLACK"] = "#000000";
u["WHITE"] = "#FFFFFF";
// 用关键输出值
std::cout << "The HEX of color RED is:[" << u["RED"] << "]\n";
std::cout << "The HEX of color BLACK is:[" << u["BLACK"] << "]\n";
// é»˜è®¤æž„é€ å‡½æ•°ï¼šç©º unordered_map
std::unordered_map<:string std::string> m1;
// åˆ—è¡¨æž„é€ å‡½æ•°
std::unordered_map m2 = {
{ 1, "foo" },
{ 3, "bar" },
{ 2, "baz" },
};
// å¤åˆ¶æž„é€ å‡½æ•°
std::unordered_map m3 = m2;
// ç§»åŠ¨æž„é€ å‡½æ•°
std::unordered_map m4 = std::move(m2);
// èŒƒå›´æž„é€ å‡½æ•°
std::vector<:pair>, int>> v = { {0x12, 1}, {0x01,-1} };
std::unordered_map<:bitset>, double> m5(v.begin(), v.end());
// 带定制 Key ç±»åž‹çš„æž„é€ å‡½æ•°çš„é€‰é¡¹ 1
// 定义 KeyHash 与 KeyEqual 结构体并在模æ¿ä¸ä½¿ç”¨å®ƒä»¬
std::unordered_map m6 = {
{ {"John", "Doe"}, "example"},
{ {"Mary", "Sue"}, "another"}
};
// 带定制 Key ç±»åž‹çš„æž„é€ å‡½æ•°çš„é€‰é¡¹ 2
// 为 class/struct 定义 const == è¿ç®—符并于 std 命å空间特化 std::hash 结构体
std::unordered_map m7 = {
{ Foo(1), "One"}, { 2, "Two"}, { 3, "Three"}
};
// 选项 3 ：用 lambdas
// 注æ„必须将åˆå§‹æ¡¶æ•°ä¼ é€’ç»™æž„é€ å‡½æ•°
struct Goo {int val; };
auto hash = [](const Goo &g){ return std::hash{}(g.val); };
auto comp = [](const Goo &l, const Goo &r){ return l.val == r.val; };
std::unordered_map m8(10, hash, comp);
}