c++boostuuidboost-uuid

Check if std::string is a valid uuid using boost


I want to check if a given string is a valid UUID using boost.

This is what I have come up with by looking at the documentation on the boost website:

void validate_uuid(const std::string& value)
{
    try
    {
        boost::uuids::string_generator stringGenerator;
        (void)stringGenerator(value);
    }

    catch (const std::exception& ex)
    {
        // ...
    }
}

However, this does not always work.

If I call the function with a string that is too short for a valid UUID, an exception is thrown as expected. But if I call the function with an invalid UUID (e.g. 00000000-0000-0000-0000-00000000000K) no exception is thrown.

Please can someone clarify why this is happening.

Also, I've seen the use of boost::lexical_cast to read a string as a UUID as posted here. I'm wondering if I should follow that approach. Any advice appreciated.


Solution

  • The code you had does nothing in terms of validation. Instead it generates a UUID based on the constant passed (like a hash function).

    Looking closer I was mistaken. The missing bit of validation appears to be a check on version:

    Live On Coliru

    #include <boost/uuid/uuid.hpp>
    #include <boost/uuid/uuid_io.hpp>
    #include <boost/uuid/string_generator.hpp>
    #include <iostream>
    
    bool is_valid_uuid(std::string const& maybe_uuid, boost::uuids::uuid& result) {
        using namespace boost::uuids;
    
        try {
            result = string_generator()(maybe_uuid); 
            return result.version() != uuid::version_unknown;
        } catch(...) {
            return false;
        }
    }
    
    int main() {
        std::string maybe_uuid;
        std::cout << "Enter a UUID: ";
    
        while (std::cin >> maybe_uuid)
        {
            boost::uuids::uuid result;
            bool is_valid = is_valid_uuid(maybe_uuid, result);
            std::cout << "\n'" << maybe_uuid << "' valid: " << std::boolalpha << is_valid << "\n";
    
            if (is_valid)
                std::cout << "Parsed value: " << result << "\n";
        }
    }
    

    Sample output from Coliru: echo 00000000-0000-{0,4}000-0000-000000000000 $(uuidgen) "{$(uuidgen)}" | ./a.out:

    Enter a UUID: 
    '00000000-0000-0000-0000-000000000000' valid: false
    
    '00000000-0000-4000-0000-000000000000' valid: true
    Parsed value: 00000000-0000-4000-0000-000000000000
    
    'a2c59f5c-6c9b-4800-afb8-282fc5e743cc' valid: true
    Parsed value: a2c59f5c-6c9b-4800-afb8-282fc5e743cc
    
    '{82a31d37-6fe4-4b80-b608-c63ec5ecd578}' valid: true
    Parsed value: 82a31d37-6fe4-4b80-b608-c63ec5ecd578