Benchmark of different compile-time string representations

anonymous.erb.cpp

// Copyright Louis Dionne 2013-2016
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)

template <char ...s>
static auto string_maker = [] {
    struct local { char data[sizeof...(s)] = {s...}; };
    return local{};
};

template <char ...s>
decltype(string_maker<s...>()) string{};


int main() {
    <% ('a'..'f').each do |c| %>
        auto s_<%= c %> = string<
            <%= input_size.times.map { "'#{c}'" }.join(', ') %>
        >;
        (void)s_<%= c %>;
    <% end %>
}

baseline.erb.cpp

// Copyright Louis Dionne 2013-2016
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)

template <char ...>
int string = 0;


int main() {
    <% ('a'..'f').each do |c| %>
        auto s_<%= c %> = string<
            <%= input_size.times.map { "'#{c}'" }.join(', ') %>
        >;
        (void)s_<%= c %>;
    <% end %>
}

chart.erb.json

<%
  def benchmark(variant)
    time_compilation("#{variant}.erb.cpp", (1...1000).step(25))
  end
%>

{
  "title": {
    "text": "Compile-time behavior of creating a string"
  },
  "xAxis": {
    "title": { "text": "Size of the string" }
  },
  "series": [
    {
      "name": "baseline",
      "data": <%= benchmark("baseline") %>
    }, {
      "name": "anonymous type",
      "data": <%= benchmark("anonymous") %>
    }, {
      "name": "struct",
      "data": <%= benchmark("struct") %>
    }
  ]
}

struct.erb.cpp

// Copyright Louis Dionne 2013-2016
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)


template <char ...s>
struct string {
    char value[sizeof...(s)] = {s...};
};


int main() {
    <% ('a'..'f').each do |c| %>
        auto s_<%= c %> = string<
            <%= input_size.times.map { "'#{c}'" }.join(', ') %>
        >{};
        (void)s_<%= c %>;
    <% end %>
}