mirror of
https://github.com/fmtlib/fmt.git
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290 lines
9.0 KiB
C++
290 lines
9.0 KiB
C++
// Formatting library for C++ - experimental range support
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//
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// Copyright (c) 2012 - present, Victor Zverovich
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// All rights reserved.
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//
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// For the license information refer to format.h.
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//
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// Copyright (c) 2018 - present, Remotion (Igor Schulz)
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// All Rights Reserved
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// {fmt} support for ranges, containers and types tuple interface.
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#ifndef FMT_RANGES_H_
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#define FMT_RANGES_H_
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#include <type_traits>
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#include "format.h"
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// output only up to N items from the range.
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#ifndef FMT_RANGE_OUTPUT_LENGTH_LIMIT
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# define FMT_RANGE_OUTPUT_LENGTH_LIMIT 256
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#endif
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FMT_BEGIN_NAMESPACE
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template <typename Char> struct formatting_base {
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template <typename ParseContext>
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FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
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return ctx.begin();
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}
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};
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template <typename Char, typename Enable = void>
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struct formatting_range : formatting_base<Char> {
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static FMT_CONSTEXPR_DECL const std::size_t range_length_limit =
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FMT_RANGE_OUTPUT_LENGTH_LIMIT; // output only up to N items from the
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// range.
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Char prefix;
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Char delimiter;
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Char postfix;
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formatting_range() : prefix('{'), delimiter(','), postfix('}') {}
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static FMT_CONSTEXPR_DECL const bool add_delimiter_spaces = true;
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static FMT_CONSTEXPR_DECL const bool add_prepostfix_space = false;
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};
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template <typename Char, typename Enable = void>
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struct formatting_tuple : formatting_base<Char> {
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Char prefix;
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Char delimiter;
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Char postfix;
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formatting_tuple() : prefix('('), delimiter(','), postfix(')') {}
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static FMT_CONSTEXPR_DECL const bool add_delimiter_spaces = true;
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static FMT_CONSTEXPR_DECL const bool add_prepostfix_space = false;
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};
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namespace internal {
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template <typename RangeT, typename OutputIterator>
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OutputIterator copy(const RangeT& range, OutputIterator out) {
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for (auto it = range.begin(), end = range.end(); it != end; ++it)
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*out++ = *it;
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return out;
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}
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template <typename OutputIterator>
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OutputIterator copy(const char* str, OutputIterator out) {
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while (*str) *out++ = *str++;
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return out;
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}
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template <typename OutputIterator>
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OutputIterator copy(char ch, OutputIterator out) {
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*out++ = ch;
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return out;
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}
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/// Return true value if T has std::string interface, like std::string_view.
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template <typename T> class is_like_std_string {
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template <typename U>
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static auto check(U* p)
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-> decltype((void)p->find('a'), p->length(), (void)p->data(), int());
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template <typename> static void check(...);
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public:
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static FMT_CONSTEXPR_DECL const bool value =
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!std::is_void<decltype(check<T>(FMT_NULL))>::value;
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};
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template <typename Char>
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struct is_like_std_string<fmt::basic_string_view<Char>> : std::true_type {};
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template <typename... Ts> struct conditional_helper {};
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template <typename T, typename _ = void> struct is_range_ : std::false_type {};
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#if !FMT_MSC_VER || FMT_MSC_VER > 1800
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template <typename T>
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struct is_range_<
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T, typename std::conditional<
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false,
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conditional_helper<decltype(internal::declval<T>().begin()),
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decltype(internal::declval<T>().end())>,
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void>::type> : std::true_type {};
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#endif
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/// tuple_size and tuple_element check.
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template <typename T> class is_tuple_like_ {
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template <typename U>
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static auto check(U* p) -> decltype(
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std::tuple_size<U>::value,
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(void)internal::declval<typename std::tuple_element<0, U>::type>(),
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int());
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template <typename> static void check(...);
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public:
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static FMT_CONSTEXPR_DECL const bool value =
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!std::is_void<decltype(check<T>(FMT_NULL))>::value;
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};
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// Check for integer_sequence
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#if defined(__cpp_lib_integer_sequence) || FMT_MSC_VER >= 1900
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template <typename T, T... N>
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using integer_sequence = std::integer_sequence<T, N...>;
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template <std::size_t... N> using index_sequence = std::index_sequence<N...>;
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template <std::size_t N>
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using make_index_sequence = std::make_index_sequence<N>;
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#else
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template <typename T, T... N> struct integer_sequence {
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typedef T value_type;
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static FMT_CONSTEXPR std::size_t size() { return sizeof...(N); }
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};
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template <std::size_t... N>
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using index_sequence = integer_sequence<std::size_t, N...>;
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template <typename T, std::size_t N, T... Ns>
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struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
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template <typename T, T... Ns>
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struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
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template <std::size_t N>
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using make_index_sequence = make_integer_sequence<std::size_t, N>;
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#endif
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template <class Tuple, class F, size_t... Is>
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void for_each(index_sequence<Is...>, Tuple&& tup, F&& f) FMT_NOEXCEPT {
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using std::get;
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// using free function get<I>(T) now.
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const int _[] = {0, ((void)f(get<Is>(tup)), 0)...};
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(void)_; // blocks warnings
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}
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template <class T>
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FMT_CONSTEXPR make_index_sequence<std::tuple_size<T>::value> get_indexes(
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T const&) {
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return {};
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}
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template <class Tuple, class F> void for_each(Tuple&& tup, F&& f) {
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const auto indexes = get_indexes(tup);
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for_each(indexes, std::forward<Tuple>(tup), std::forward<F>(f));
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}
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template <typename Arg, FMT_ENABLE_IF(!is_like_std_string<
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typename std::decay<Arg>::type>::value)>
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FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&) {
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return add_space ? " {}" : "{}";
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}
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template <typename Arg, FMT_ENABLE_IF(is_like_std_string<
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typename std::decay<Arg>::type>::value)>
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FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const Arg&) {
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return add_space ? " \"{}\"" : "\"{}\"";
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}
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FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char*) {
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return add_space ? " \"{}\"" : "\"{}\"";
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}
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FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t*) {
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return add_space ? L" \"{}\"" : L"\"{}\"";
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}
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FMT_CONSTEXPR const char* format_str_quoted(bool add_space, const char) {
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return add_space ? " '{}'" : "'{}'";
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}
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FMT_CONSTEXPR const wchar_t* format_str_quoted(bool add_space, const wchar_t) {
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return add_space ? L" '{}'" : L"'{}'";
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}
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} // namespace internal
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template <typename T> struct is_tuple_like {
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static FMT_CONSTEXPR_DECL const bool value =
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internal::is_tuple_like_<T>::value && !internal::is_range_<T>::value;
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};
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template <typename TupleT, typename Char>
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struct formatter<
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TupleT, Char,
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typename std::enable_if<fmt::is_tuple_like<TupleT>::value>::type> {
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private:
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// C++11 generic lambda for format()
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template <typename FormatContext> struct format_each {
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template <typename T> void operator()(const T& v) {
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if (i > 0) {
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if (formatting.add_prepostfix_space) {
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*out++ = ' ';
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}
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out = internal::copy(formatting.delimiter, out);
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}
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out = format_to(out,
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internal::format_str_quoted(
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(formatting.add_delimiter_spaces && i > 0), v),
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v);
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++i;
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}
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formatting_tuple<Char>& formatting;
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std::size_t& i;
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typename std::add_lvalue_reference<decltype(
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std::declval<FormatContext>().out())>::type out;
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};
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public:
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formatting_tuple<Char> formatting;
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template <typename ParseContext>
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FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
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return formatting.parse(ctx);
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}
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template <typename FormatContext = format_context>
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auto format(const TupleT& values, FormatContext& ctx) -> decltype(ctx.out()) {
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auto out = ctx.out();
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std::size_t i = 0;
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internal::copy(formatting.prefix, out);
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internal::for_each(values, format_each<FormatContext>{formatting, i, out});
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if (formatting.add_prepostfix_space) {
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*out++ = ' ';
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}
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internal::copy(formatting.postfix, out);
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return ctx.out();
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}
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};
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template <typename T> struct is_range {
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static FMT_CONSTEXPR_DECL const bool value =
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internal::is_range_<T>::value && !internal::is_like_std_string<T>::value;
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};
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template <typename RangeT, typename Char>
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struct formatter<RangeT, Char,
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typename std::enable_if<fmt::is_range<RangeT>::value>::type> {
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formatting_range<Char> formatting;
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template <typename ParseContext>
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FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
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return formatting.parse(ctx);
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}
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template <typename FormatContext>
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typename FormatContext::iterator format(const RangeT& values,
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FormatContext& ctx) {
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auto out = internal::copy(formatting.prefix, ctx.out());
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std::size_t i = 0;
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for (auto it = values.begin(), end = values.end(); it != end; ++it) {
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if (i > 0) {
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if (formatting.add_prepostfix_space) *out++ = ' ';
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out = internal::copy(formatting.delimiter, out);
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}
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out = format_to(out,
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internal::format_str_quoted(
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(formatting.add_delimiter_spaces && i > 0), *it),
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*it);
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if (++i > formatting.range_length_limit) {
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out = format_to(out, " ... <other elements>");
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break;
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}
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}
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if (formatting.add_prepostfix_space) *out++ = ' ';
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return internal::copy(formatting.postfix, out);
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}
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};
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FMT_END_NAMESPACE
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#endif // FMT_RANGES_H_
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