Function vformat_to

extlibs/fmt/include/fmt/compile.h:174–235

namespace cf {
template <typename Context, typename Range, typename CompiledFormat>
auto vformat_to(Range out, CompiledFormat& cf, basic_format_args<Context> args)
    -> typename Context::iterator {
  using char_type = typename Context::char_type;
  basic_format_parse_context<char_type> parse_ctx(
      to_string_view(cf.format_str_));
  Context ctx(out.begin(), args);

  const auto& parts = cf.parts();
  for (auto part_it = std::begin(parts); part_it != std::end(parts);
       ++part_it) {
    const auto& part = *part_it;
    const auto& value = part.val;

    using format_part_t = format_part<char_type>;
    switch (part.part_kind) {
    case format_part_t::kind::text: {
      const auto text = value.str;
      auto output = ctx.out();
      auto&& it = reserve(output, text.size());
      it = std::copy_n(text.begin(), text.size(), it);
      ctx.advance_to(output);
      break;
    }

    case format_part_t::kind::arg_index:
      advance_to(parse_ctx, part.arg_id_end);
      internal::format_arg<Range>(parse_ctx, ctx, value.arg_index);
      break;

    case format_part_t::kind::arg_name:
      advance_to(parse_ctx, part.arg_id_end);
      internal::format_arg<Range>(parse_ctx, ctx, value.str);
      break;

    case format_part_t::kind::replacement: {
      const auto& arg_id_value = value.repl.arg_id.val;
      const auto arg = value.repl.arg_id.kind == arg_id_kind::index
                           ? ctx.arg(arg_id_value.index)
                           : ctx.arg(arg_id_value.name);

      auto specs = value.repl.specs;

      handle_dynamic_spec<width_checker>(specs.width, specs.width_ref, ctx);
      handle_dynamic_spec<precision_checker>(specs.precision,
                                             specs.precision_ref, ctx);

      error_handler h;
      numeric_specs_checker<error_handler> checker(h, arg.type());
      if (specs.align == align::numeric) checker.require_numeric_argument();
      if (specs.sign != sign::none) checker.check_sign();
      if (specs.alt) checker.require_numeric_argument();
      if (specs.precision >= 0) checker.check_precision();

      advance_to(parse_ctx, part.arg_id_end);
      ctx.advance_to(
          visit_format_arg(arg_formatter<Range>(ctx, nullptr, &specs), arg));
      break;
    }