ranges.h

Go to the documentation of this file.

// Formatting library for C++ - the core API
//
// Copyright (c) 2012 - present, Victor Zverovich
// All rights reserved.
//
// For the license information refer to format.h.
//
// Copyright (c) 2018 - present, Remotion (Igor Schulz)
// All Rights Reserved
// {fmt} support for ranges, containers and types tuple interface.

#ifndef FMT_RANGES_H_
#define FMT_RANGES_H_

#include "format.h"
#include <type_traits>

// output only up to N items from the range.
#ifndef FMT_RANGE_OUTPUT_LENGTH_LIMIT
# define FMT_RANGE_OUTPUT_LENGTH_LIMIT 256
#endif

FMT_BEGIN_NAMESPACE

template <typename Char>
struct formatting_base {
  template <typename ParseContext>
  FMT_CONSTEXPR auto parse(ParseContext &ctx) -> decltype(ctx.begin()) {
    return ctx.begin();
  }
};

template <typename Char, typename Enable = void>
struct formatting_range : formatting_base<Char> {
  static FMT_CONSTEXPR_DECL const std::size_t range_length_limit =
      FMT_RANGE_OUTPUT_LENGTH_LIMIT; // output only up to N items from the range.
  Char prefix;
  Char delimiter;
  Char postfix;
  formatting_range() : prefix('{'), delimiter(','), postfix('}') {}
  static FMT_CONSTEXPR_DECL const bool add_delimiter_spaces = true;
  static FMT_CONSTEXPR_DECL const bool add_prepostfix_space = false;
};

template <typename Char, typename Enable = void>
struct formatting_tuple : formatting_base<Char> {
  Char prefix;
  Char delimiter;
  Char postfix;
  formatting_tuple() : prefix('('), delimiter(','), postfix(')') {}
  static FMT_CONSTEXPR_DECL const bool add_delimiter_spaces = true;
  static FMT_CONSTEXPR_DECL const bool add_prepostfix_space = false;
};

namespace internal {

template <typename RangeT, typename OutputIterator>
void copy(const RangeT &range, OutputIterator out) {
  for (auto it = range.begin(), end = range.end(); it != end; ++it)
    *out++ = *it;
}

template <typename OutputIterator>
void copy(const char *str, OutputIterator out) {
  const char *p_curr = str;
  while (*p_curr) {
    *out++ = *p_curr++;
  }
}

template <typename OutputIterator>
void copy(char ch, OutputIterator out) {
  *out++ = ch;
}

/// Return true value if T has std::string interface, like std::string_view.
template <typename T>
class is_like_std_string {
  template <typename U>
  static auto check(U *p) ->
    decltype(p->find('a'), p->length(), p->data(), int());
  template <typename>
  static void check(...);

 public:
  static FMT_CONSTEXPR_DECL const bool value =
    !std::is_void<decltype(check<T>(FMT_NULL))>::value;
};

template <typename Char>
struct is_like_std_string<fmt::basic_string_view<Char>> : std::true_type {};

template <typename... Ts>
struct conditional_helper {};

template <typename T, typename _ = void>
struct is_range_ : std::false_type {};

#if !FMT_MSC_VER || FMT_MSC_VER > 1800
template <typename T>
struct is_range_<T, typename std::conditional<
                    false,
                    conditional_helper<decltype(internal::declval<T>().begin()),
                                       decltype(internal::declval<T>().end())>,
                    void>::type> : std::true_type {};
#endif

/// tuple_size and tuple_element check.
template <typename T>
class is_tuple_like_ {
  template <typename U>
  static auto check(U *p) ->
    decltype(std::tuple_size<U>::value,
      internal::declval<typename std::tuple_element<0, U>::type>(), int());
  template <typename>
  static void check(...);

 public:
  static FMT_CONSTEXPR_DECL const bool value =
    !std::is_void<decltype(check<T>(FMT_NULL))>::value;
};

// Check for integer_sequence
#if defined(__cpp_lib_integer_sequence) || FMT_MSC_VER >= 1900
template <typename T, T... N>
using integer_sequence = std::integer_sequence<T, N...>;
template <std::size_t... N>
using index_sequence = std::index_sequence<N...>;
template <std::size_t N>
using make_index_sequence = std::make_index_sequence<N>;
#else
template <typename T, T... N>
struct integer_sequence {
  typedef T value_type;

  static FMT_CONSTEXPR std::size_t size() {
    return sizeof...(N);
  }
};

template <std::size_t... N>
using index_sequence = integer_sequence<std::size_t, N...>;

template <typename T, std::size_t N, T... Ns>
struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
template <typename T, T... Ns>
struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};

template <std::size_t N>
using make_index_sequence = make_integer_sequence<std::size_t, N>;
#endif

template <class Tuple, class F, size_t... Is>
void for_each(index_sequence<Is...>, Tuple &&tup, F &&f) FMT_NOEXCEPT {
  using std::get;
  // using free function get<I>(T) now.
  const int _[] = {0, ((void)f(get<Is>(tup)), 0)...};
  (void)_;  // blocks warnings
}

template <class T>
FMT_CONSTEXPR make_index_sequence<std::tuple_size<T>::value> 
get_indexes(T const &) { return {}; }

template <class Tuple, class F>
void for_each(Tuple &&tup, F &&f) {
  const auto indexes = get_indexes(tup);
  for_each(indexes, std::forward<Tuple>(tup), std::forward<F>(f));
}

template<typename Arg>
FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&, 
  typename std::enable_if<
    !is_like_std_string<typename std::decay<Arg>::type>::value>::type* = nullptr) {
  return add_space ? " {}" : "{}";
}

template<typename Arg>
FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&, 
  typename std::enable_if<
    is_like_std_string<typename std::decay<Arg>::type>::value>::type* = nullptr) {
  return add_space ? " \"{}\"" : "\"{}\"";
}

FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char*) {
  return add_space ? " \"{}\"" : "\"{}\"";
}
FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t*) {
    return add_space ? L" \"{}\"" : L"\"{}\"";
}

FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char) {
    return add_space ? " '{}'" : "'{}'";
}
FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t) {
    return add_space ? L" '{}'" : L"'{}'";
}

}  // namespace internal

template <typename T>
struct is_tuple_like {
  static FMT_CONSTEXPR_DECL const bool value =
    internal::is_tuple_like_<T>::value && !internal::is_range_<T>::value;
};

template <typename TupleT, typename Char>
struct formatter<TupleT, Char, 
    typename std::enable_if<fmt::is_tuple_like<TupleT>::value>::type> {
private:
  // C++11 generic lambda for format()
  template <typename FormatContext>
  struct format_each {
    template <typename T>
    void operator()(const T& v) {
      if (i > 0) {
        if (formatting.add_prepostfix_space) {
          *out++ = ' ';
        }
        internal::copy(formatting.delimiter, out);
      }
      format_to(out,
                internal::format_str_quoted(
                    (formatting.add_delimiter_spaces && i > 0), v),
                v);
      ++i;
    }

    formatting_tuple<Char>& formatting;
    std::size_t& i;
    typename std::add_lvalue_reference<decltype(std::declval<FormatContext>().out())>::type out;
  };

public:
  formatting_tuple<Char> formatting;

  template <typename ParseContext>
  FMT_CONSTEXPR auto parse(ParseContext &ctx) -> decltype(ctx.begin()) {
    return formatting.parse(ctx);
  }

  template <typename FormatContext = format_context>
  auto format(const TupleT &values, FormatContext &ctx) -> decltype(ctx.out()) {
    auto out = ctx.out();
    std::size_t i = 0;
    internal::copy(formatting.prefix, out);

    internal::for_each(values, format_each<FormatContext>{formatting, i, out});
    if (formatting.add_prepostfix_space) {
      *out++ = ' ';
    }
    internal::copy(formatting.postfix, out);

    return ctx.out();
  }
};

template <typename T>
struct is_range {
  static FMT_CONSTEXPR_DECL const bool value =
    internal::is_range_<T>::value && !internal::is_like_std_string<T>::value;
};

template <typename RangeT, typename Char>
struct formatter<RangeT, Char,
    typename std::enable_if<fmt::is_range<RangeT>::value>::type> {

  formatting_range<Char> formatting;

  template <typename ParseContext>
  FMT_CONSTEXPR auto parse(ParseContext &ctx) -> decltype(ctx.begin()) {
    return formatting.parse(ctx);
  }

  template <typename FormatContext>
  typename FormatContext::iterator format(
      const RangeT &values, FormatContext &ctx) {
    auto out = ctx.out();
    internal::copy(formatting.prefix, out);
    std::size_t i = 0;
    for (auto it = values.begin(), end = values.end(); it != end; ++it) {
      if (i > 0) {
        if (formatting.add_prepostfix_space) {
          *out++ = ' ';
        }
        internal::copy(formatting.delimiter, out);
      }
      format_to(out,
                internal::format_str_quoted(
                    (formatting.add_delimiter_spaces && i > 0), *it),
                *it);
      if (++i > formatting.range_length_limit) {
        format_to(out, " ... <other elements>");
        break;
      }
    }
    if (formatting.add_prepostfix_space) {
      *out++ = ' ';
    }
    internal::copy(formatting.postfix, out);
    return ctx.out();
  }
};

FMT_END_NAMESPACE

#endif // FMT_RANGES_H_