foonathan / array Goto Github PK

Hi,

I'm trying to invoke LLVM's argument parser programaticaly (i.e. not from main with main args) and I was wondering if the array library could help me there. The issue is that llvm::ParseCommandLineOptions takes raw argc and argv arguments directly, where argv is a char**. I was trying to implement my argument parser so that it can be invoked from a sane C++ API (Say, using a vector of string views), and I was wondering if any of the array lib views could be converted directly or indirectly to a char**.

Thanks in advance.

where order of elements isn't imported

==>

where order of elements isn't important* << perhaps?

Just an idea, but it kind of looks like Bip buffer implementation would fit on top of block storage concept here quite well.
Key word being 'contiguous memory container'. ( https://github.com/willemt/bipbuffer , https://www.codeproject.com/Articles/3479/The-Bip-Buffer-The-Circular-Buffer-with-a-Twist )

I'll try take a stab at getting something working, any pointers for the interface design ?

In flat_set::assign, the container only provides the basic exception guarantee if memory cannot be stolen from the input and the ::reserve() allocation throws. In addition, since input_view does not specify that its value_type is nothrow move or copyable, the operation may again fail during the translation of elements from the view into the set.

array_.clear();
array_.reserve(input.size()); // <-- might throw here, leaving the container empty

// insert all elements individually
for (auto& element : input.view())
{
    if (input.will_copy())
        insert(element); // <-- could also throw here, leaving a partially filled container
    else
    {
        // safe, according to precondition of input view,
        // we're allowed to move them
        auto& non_const = const_cast<Key&>(element);
        insert(std::move(non_const)); // <-- or here
    }
}

It looks like you are already aware of this, given the TODO comments in flat_map's assign* functions:

template <typename InputIt>
void assign_pair_range(InputIt begin, InputIt end)
{
    // TODO: exception safety
    clear();
    insert_pair_range(begin, end);
}

A simple solution to add strong exception safety would be to create a new flat_set from the input range and swap if there was no exception thrown.

Something like https://ned14.github.io/outcome/use-matrix/, for fools like me who feel overwhelmed by the feature list.