Function compute_common_dim

src/common_dims.cpp:93–161

};

static bool compute_common_dim(std::vector<std::size_t>& cd_dims,
                               common_dim_state& state1,
                               common_dim_state& state2)
{
    assert(state1.get() < state2.get());
    auto d2    = state2.get();
    auto dims  = state1.dims_for(d2);
    auto naxes = distance(dims);

    if(naxes == 0)
        return false;

    // Check if state1 has a remainder from previous split
    bool has_remainder = (state1.rem != 1);

    // Compute the product of dimensions, adjusting for remainder if needed
    auto n = elements(dims);
    if(has_remainder and naxes > 0)
    {
        n = n / *dims.begin() * (*dims.begin() / state1.rem);
    }

    // If not divisible then we can't compute a common dim
    if((d2 % n) != 0)
        return false;

    auto rem = d2 / n;
    auto start_pos = cd_dims.size();

    // Add axes mappings
    if(has_remainder)
    {
        // state1: dimension was split, keep axes together
        state1.add_axes(naxes, start_pos);
        // state2: axes should include the previous remainder dimension
        state2.add_axes(rem == 1 ? naxes : naxes + 1, start_pos - 1);
    }
    else
    {
        // state1: separate axes for each dimension
        state1.add_multi_axes(naxes, start_pos);
        // state2: normal axes mapping
        state2.add_axes(rem == 1 ? naxes : naxes + 1, start_pos);
    }

    // Add dimensions to cd_dims
    if(has_remainder and naxes > 0)
    {
        // Adjust the first dimension by dividing by the remainder
        cd_dims.push_back(*dims.begin() / state1.rem);
        cd_dims.insert(cd_dims.end(), std::next(dims.begin()), dims.end());
    }
    else
    {
        cd_dims.insert(cd_dims.end(), dims.begin(), dims.end());
    }

    // Add remainder dimension if needed