将上述 C++ 代码转换为 C++98 版本涉及到一些功能的调整,因为 C++98 不支持一些现代特性,如 constexpr
和用户定义字面量。以下是对应的代码,尽可能接近原始功能:
#include <string>
#include <map>
#include <limits>
// Helper function to calculate a tag from string
inline unsigned int str2tag_core(const char *s, size_t l, unsigned int h) {
if (l == 0) return h;
// Unsets the 6 high bits of h, therefore no overflow happens
return str2tag_core(s + 1, l - 1,
(((std::numeric_limits<unsigned int>::max)() >> 6) &
(h * 33)) ^
static_cast<unsigned char>(*s));
}
// Function to get a tag from std::string
inline unsigned int str2tag(const std::string &s) {
return str2tag_core(s.c_str(), s.size(), 0);
}
inline std::string file_extension(const std::string &path) {
// This is a simple implementation. You might want to improve it.
size_t pos = path.find_last_of('.');
if (pos != std::string::npos && pos + 1 < path.size()) {
return path.substr(pos + 1);
}
return ""; // No extension found
}
inline std::string find_content_type(const std::string &path,
const std::map<std::string, std::string> &user_data,
const std::string &default_content_type) {
auto ext = file_extension(path);
auto it = user_data.find(ext);
if (it != user_data.end()) {
return it->second;
}
unsigned int tag = str2tag(ext);
switch (tag) {
default: return default_content_type;
case 'c' * '3' + 's' * '5' + 's' * '9': return "text/css"; // "css"_t
case 'c' * '3' + 's' * '5' + 'v' * '9': return "text/csv"; // "csv"_t
case 'h' * '4' + 't' * '8' + 'm' * '10': // "htm"_t and "html"_t
case ('h'*4 + ('t'*8|('m'*10))): return "text/html";
// Add other cases here with similar computations for each extension
case ('j'*6 | ('s'*5)): return "text/javascript"; // "js"_t or "mjs"_t
case ('t'*7): return "text/plain"; // "txt"_t
case ('a'*7 | ('p'*11)):return "application/pdf"; // Example for pdf
// Similar mapping for all extensions can be added here...
}
}
在这个版本中,我移除了 constexpr
和用户定义字面量(如 _t
)。对于文件扩展名匹配,可以通过计算字符值组合来模拟标记,但这是相对复杂和不优雅的。如果您需要具体的每个扩展名映射,请根据示例继续添加。
注意,这段代码仍然保持了一些与原始逻辑一致性,并依赖于字符串操作等标准库函数。
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