Benchmark of hana::string w/ c_str() method

CMakeLists.txt

# Copyright Louis Dionne 2016
# Distributed under the Boost Software License, Version 1.0.
# (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)

set(datasets)

add_dataset(datasets hetero make hana   string1      hana.string.cpp.erb      4 "(0..50).step(10).to_a + (100..300).step(50).to_a" "which\;1")
add_dataset(datasets hetero make hana   string2      hana.string.cpp.erb      4 "(0..50).step(10).to_a + (100..300).step(50).to_a" "which\;2")

add_chart(hetero make DATASETS ${datasets})

hana.string.cpp.erb

// Copyright Louis Dionne 2016
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)

<% if env[:which] == 1 %>
    template <char ...s>
    struct string {
    private:
        static constexpr char const storage[sizeof...(s) + 1] = {s..., '\0'};

    public:
        static constexpr char const* c_str() {
            return &storage[0];
        }
    };

    template <char ...s>
    constexpr char const string<s...>::storage[sizeof...(s) + 1];
<% else %>
    template <char ...s>
    constexpr char const storage[sizeof...(s) + 1] = {s..., '\0'};

    template <char ...s>
    struct string {
    public:
        static constexpr char const* c_str() {
            return &storage<s...>[0];
        }
    };
<% end %>


template<int> struct x {};

int main() {
#if defined(METABENCH)
    <% env[:k].times do |k| %>
        <% (0..n).each do |i| %>
            auto x<%= k %>_<%= i %> = string<<%= ([(k+i) % 128] * 100).join(', ') %>>{};
        <% end %>
    <% end %>
#endif
}