std:: vs std::pmr:: addresses

gistfile1.cpp

#include <iostream>
#include <memory_resource>
#include <unordered_map>
#include <string>
#include <vector>

void print_string_info(const std::string& str, const std::string& name, const void* buffer_start, const void* buffer_end) {
    std::cout << name << " address: " << reinterpret_cast<uintptr_t>(str.data()) << std::endl;
    bool in_buffer = (void*)str.data() >= buffer_start && (void*)str.data() < buffer_end;
    std::cout << name << " in buffer: " << (in_buffer ? "Yes" : "No") << std::endl;
}

void print_pmr_string_info(const std::pmr::string& str, const std::string& name, const void* buffer_start, const void* buffer_end) {
    std::cout << name << " address: " << reinterpret_cast<uintptr_t>(str.data()) << std::endl;
    bool in_buffer = (void*)str.data() >= buffer_start && (void*)str.data() < buffer_end;
    std::cout << name << " in buffer: " << (in_buffer ? "Yes" : "No") << std::endl;
}

int main() {
    std::vector<char> buffer(1024); // Buffer for monotonic resource
    std::pmr::monotonic_buffer_resource resource(buffer.data(), buffer.size());

    std::cout << "=== Using std::string as key ===\n";
    std::pmr::unordered_map<std::string, int> map(&resource);
    map.emplace("long_key_string_1234567890", 42); // Long string to avoid SSO

    print_string_info(map.cbegin()->first, "std::string key", buffer.data(), buffer.data() + buffer.size());

    std::cout << "\n=== Using std::pmr::string as key ===\n";
    std::pmr::unordered_map<std::pmr::string, int> pmr_map(&resource);
    pmr_map.emplace("long_key_string_1234567890", 43); // Long string for consistency

    print_pmr_string_info(pmr_map.cbegin()->first, "std::pmr::string key", buffer.data(), buffer.data() + buffer.size());

    std::cout << "\nMonotonic buffer range: " << reinterpret_cast<uintptr_t>(buffer.data())
              << " to " << reinterpret_cast<uintptr_t>(buffer.data() + buffer.size()) << std::endl;

    return 0;
}