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- // Formatting library for C++ - experimental format string compilation
- //
- // Copyright (c) 2012 - present, Victor Zverovich and fmt contributors
- // All rights reserved.
- //
- // For the license information refer to format.h.
- #ifndef FMT_COMPILE_H_
- #define FMT_COMPILE_H_
- #include "format.h"
- FMT_BEGIN_NAMESPACE
- namespace detail {
- template <typename Char, typename InputIt>
- FMT_CONSTEXPR inline counting_iterator copy_str(InputIt begin, InputIt end,
- counting_iterator it) {
- return it + (end - begin);
- }
- template <typename OutputIt> class truncating_iterator_base {
- protected:
- OutputIt out_;
- size_t limit_;
- size_t count_ = 0;
- truncating_iterator_base() : out_(), limit_(0) {}
- truncating_iterator_base(OutputIt out, size_t limit)
- : out_(out), limit_(limit) {}
- public:
- using iterator_category = std::output_iterator_tag;
- using value_type = typename std::iterator_traits<OutputIt>::value_type;
- using difference_type = std::ptrdiff_t;
- using pointer = void;
- using reference = void;
- FMT_UNCHECKED_ITERATOR(truncating_iterator_base);
- OutputIt base() const { return out_; }
- size_t count() const { return count_; }
- };
- // An output iterator that truncates the output and counts the number of objects
- // written to it.
- template <typename OutputIt,
- typename Enable = typename std::is_void<
- typename std::iterator_traits<OutputIt>::value_type>::type>
- class truncating_iterator;
- template <typename OutputIt>
- class truncating_iterator<OutputIt, std::false_type>
- : public truncating_iterator_base<OutputIt> {
- mutable typename truncating_iterator_base<OutputIt>::value_type blackhole_;
- public:
- using value_type = typename truncating_iterator_base<OutputIt>::value_type;
- truncating_iterator() = default;
- truncating_iterator(OutputIt out, size_t limit)
- : truncating_iterator_base<OutputIt>(out, limit) {}
- truncating_iterator& operator++() {
- if (this->count_++ < this->limit_) ++this->out_;
- return *this;
- }
- truncating_iterator operator++(int) {
- auto it = *this;
- ++*this;
- return it;
- }
- value_type& operator*() const {
- return this->count_ < this->limit_ ? *this->out_ : blackhole_;
- }
- };
- template <typename OutputIt>
- class truncating_iterator<OutputIt, std::true_type>
- : public truncating_iterator_base<OutputIt> {
- public:
- truncating_iterator() = default;
- truncating_iterator(OutputIt out, size_t limit)
- : truncating_iterator_base<OutputIt>(out, limit) {}
- template <typename T> truncating_iterator& operator=(T val) {
- if (this->count_++ < this->limit_) *this->out_++ = val;
- return *this;
- }
- truncating_iterator& operator++() { return *this; }
- truncating_iterator& operator++(int) { return *this; }
- truncating_iterator& operator*() { return *this; }
- };
- // A compile-time string which is compiled into fast formatting code.
- class compiled_string {};
- template <typename S>
- struct is_compiled_string : std::is_base_of<compiled_string, S> {};
- /**
- \rst
- Converts a string literal *s* into a format string that will be parsed at
- compile time and converted into efficient formatting code. Requires C++17
- ``constexpr if`` compiler support.
- **Example**::
- // Converts 42 into std::string using the most efficient method and no
- // runtime format string processing.
- std::string s = fmt::format(FMT_COMPILE("{}"), 42);
- \endrst
- */
- #if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
- # define FMT_COMPILE(s) \
- FMT_STRING_IMPL(s, fmt::detail::compiled_string, explicit)
- #else
- # define FMT_COMPILE(s) FMT_STRING(s)
- #endif
- #if FMT_USE_NONTYPE_TEMPLATE_ARGS
- template <typename Char, size_t N,
- fmt::detail_exported::fixed_string<Char, N> Str>
- struct udl_compiled_string : compiled_string {
- using char_type = Char;
- explicit constexpr operator basic_string_view<char_type>() const {
- return {Str.data, N - 1};
- }
- };
- #endif
- template <typename T, typename... Tail>
- const T& first(const T& value, const Tail&...) {
- return value;
- }
- #if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
- template <typename... Args> struct type_list {};
- // Returns a reference to the argument at index N from [first, rest...].
- template <int N, typename T, typename... Args>
- constexpr const auto& get([[maybe_unused]] const T& first,
- [[maybe_unused]] const Args&... rest) {
- static_assert(N < 1 + sizeof...(Args), "index is out of bounds");
- if constexpr (N == 0)
- return first;
- else
- return detail::get<N - 1>(rest...);
- }
- template <typename Char, typename... Args>
- constexpr int get_arg_index_by_name(basic_string_view<Char> name,
- type_list<Args...>) {
- return get_arg_index_by_name<Args...>(name);
- }
- template <int N, typename> struct get_type_impl;
- template <int N, typename... Args> struct get_type_impl<N, type_list<Args...>> {
- using type =
- remove_cvref_t<decltype(detail::get<N>(std::declval<Args>()...))>;
- };
- template <int N, typename T>
- using get_type = typename get_type_impl<N, T>::type;
- template <typename T> struct is_compiled_format : std::false_type {};
- template <typename Char> struct text {
- basic_string_view<Char> data;
- using char_type = Char;
- template <typename OutputIt, typename... Args>
- constexpr OutputIt format(OutputIt out, const Args&...) const {
- return write<Char>(out, data);
- }
- };
- template <typename Char>
- struct is_compiled_format<text<Char>> : std::true_type {};
- template <typename Char>
- constexpr text<Char> make_text(basic_string_view<Char> s, size_t pos,
- size_t size) {
- return {{&s[pos], size}};
- }
- template <typename Char> struct code_unit {
- Char value;
- using char_type = Char;
- template <typename OutputIt, typename... Args>
- constexpr OutputIt format(OutputIt out, const Args&...) const {
- return write<Char>(out, value);
- }
- };
- // This ensures that the argument type is convertible to `const T&`.
- template <typename T, int N, typename... Args>
- constexpr const T& get_arg_checked(const Args&... args) {
- const auto& arg = detail::get<N>(args...);
- if constexpr (detail::is_named_arg<remove_cvref_t<decltype(arg)>>()) {
- return arg.value;
- } else {
- return arg;
- }
- }
- template <typename Char>
- struct is_compiled_format<code_unit<Char>> : std::true_type {};
- // A replacement field that refers to argument N.
- template <typename Char, typename T, int N> struct field {
- using char_type = Char;
- template <typename OutputIt, typename... Args>
- constexpr OutputIt format(OutputIt out, const Args&... args) const {
- return write<Char>(out, get_arg_checked<T, N>(args...));
- }
- };
- template <typename Char, typename T, int N>
- struct is_compiled_format<field<Char, T, N>> : std::true_type {};
- // A replacement field that refers to argument with name.
- template <typename Char> struct runtime_named_field {
- using char_type = Char;
- basic_string_view<Char> name;
- template <typename OutputIt, typename T>
- constexpr static bool try_format_argument(
- OutputIt& out,
- // [[maybe_unused]] due to unused-but-set-parameter warning in GCC 7,8,9
- [[maybe_unused]] basic_string_view<Char> arg_name, const T& arg) {
- if constexpr (is_named_arg<typename std::remove_cv<T>::type>::value) {
- if (arg_name == arg.name) {
- out = write<Char>(out, arg.value);
- return true;
- }
- }
- return false;
- }
- template <typename OutputIt, typename... Args>
- constexpr OutputIt format(OutputIt out, const Args&... args) const {
- bool found = (try_format_argument(out, name, args) || ...);
- if (!found) {
- FMT_THROW(format_error("argument with specified name is not found"));
- }
- return out;
- }
- };
- template <typename Char>
- struct is_compiled_format<runtime_named_field<Char>> : std::true_type {};
- // A replacement field that refers to argument N and has format specifiers.
- template <typename Char, typename T, int N> struct spec_field {
- using char_type = Char;
- formatter<T, Char> fmt;
- template <typename OutputIt, typename... Args>
- constexpr FMT_INLINE OutputIt format(OutputIt out,
- const Args&... args) const {
- const auto& vargs =
- fmt::make_format_args<basic_format_context<OutputIt, Char>>(args...);
- basic_format_context<OutputIt, Char> ctx(out, vargs);
- return fmt.format(get_arg_checked<T, N>(args...), ctx);
- }
- };
- template <typename Char, typename T, int N>
- struct is_compiled_format<spec_field<Char, T, N>> : std::true_type {};
- template <typename L, typename R> struct concat {
- L lhs;
- R rhs;
- using char_type = typename L::char_type;
- template <typename OutputIt, typename... Args>
- constexpr OutputIt format(OutputIt out, const Args&... args) const {
- out = lhs.format(out, args...);
- return rhs.format(out, args...);
- }
- };
- template <typename L, typename R>
- struct is_compiled_format<concat<L, R>> : std::true_type {};
- template <typename L, typename R>
- constexpr concat<L, R> make_concat(L lhs, R rhs) {
- return {lhs, rhs};
- }
- struct unknown_format {};
- template <typename Char>
- constexpr size_t parse_text(basic_string_view<Char> str, size_t pos) {
- for (size_t size = str.size(); pos != size; ++pos) {
- if (str[pos] == '{' || str[pos] == '}') break;
- }
- return pos;
- }
- template <typename Args, size_t POS, int ID, typename S>
- constexpr auto compile_format_string(S format_str);
- template <typename Args, size_t POS, int ID, typename T, typename S>
- constexpr auto parse_tail(T head, S format_str) {
- if constexpr (POS !=
- basic_string_view<typename S::char_type>(format_str).size()) {
- constexpr auto tail = compile_format_string<Args, POS, ID>(format_str);
- if constexpr (std::is_same<remove_cvref_t<decltype(tail)>,
- unknown_format>())
- return tail;
- else
- return make_concat(head, tail);
- } else {
- return head;
- }
- }
- template <typename T, typename Char> struct parse_specs_result {
- formatter<T, Char> fmt;
- size_t end;
- int next_arg_id;
- };
- constexpr int manual_indexing_id = -1;
- template <typename T, typename Char>
- constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str,
- size_t pos, int next_arg_id) {
- str.remove_prefix(pos);
- auto ctx = compile_parse_context<Char>(str, max_value<int>(), nullptr, {},
- next_arg_id);
- auto f = formatter<T, Char>();
- auto end = f.parse(ctx);
- return {f, pos + fmt::detail::to_unsigned(end - str.data()),
- next_arg_id == 0 ? manual_indexing_id : ctx.next_arg_id()};
- }
- template <typename Char> struct arg_id_handler {
- arg_ref<Char> arg_id;
- constexpr int operator()() {
- FMT_ASSERT(false, "handler cannot be used with automatic indexing");
- return 0;
- }
- constexpr int operator()(int id) {
- arg_id = arg_ref<Char>(id);
- return 0;
- }
- constexpr int operator()(basic_string_view<Char> id) {
- arg_id = arg_ref<Char>(id);
- return 0;
- }
- constexpr void on_error(const char* message) {
- FMT_THROW(format_error(message));
- }
- };
- template <typename Char> struct parse_arg_id_result {
- arg_ref<Char> arg_id;
- const Char* arg_id_end;
- };
- template <int ID, typename Char>
- constexpr auto parse_arg_id(const Char* begin, const Char* end) {
- auto handler = arg_id_handler<Char>{arg_ref<Char>{}};
- auto arg_id_end = parse_arg_id(begin, end, handler);
- return parse_arg_id_result<Char>{handler.arg_id, arg_id_end};
- }
- template <typename T, typename Enable = void> struct field_type {
- using type = remove_cvref_t<T>;
- };
- template <typename T>
- struct field_type<T, enable_if_t<detail::is_named_arg<T>::value>> {
- using type = remove_cvref_t<decltype(T::value)>;
- };
- template <typename T, typename Args, size_t END_POS, int ARG_INDEX, int NEXT_ID,
- typename S>
- constexpr auto parse_replacement_field_then_tail(S format_str) {
- using char_type = typename S::char_type;
- constexpr auto str = basic_string_view<char_type>(format_str);
- constexpr char_type c = END_POS != str.size() ? str[END_POS] : char_type();
- if constexpr (c == '}') {
- return parse_tail<Args, END_POS + 1, NEXT_ID>(
- field<char_type, typename field_type<T>::type, ARG_INDEX>(),
- format_str);
- } else if constexpr (c != ':') {
- FMT_THROW(format_error("expected ':'"));
- } else {
- constexpr auto result = parse_specs<typename field_type<T>::type>(
- str, END_POS + 1, NEXT_ID == manual_indexing_id ? 0 : NEXT_ID);
- if constexpr (result.end >= str.size() || str[result.end] != '}') {
- FMT_THROW(format_error("expected '}'"));
- return 0;
- } else {
- return parse_tail<Args, result.end + 1, result.next_arg_id>(
- spec_field<char_type, typename field_type<T>::type, ARG_INDEX>{
- result.fmt},
- format_str);
- }
- }
- }
- // Compiles a non-empty format string and returns the compiled representation
- // or unknown_format() on unrecognized input.
- template <typename Args, size_t POS, int ID, typename S>
- constexpr auto compile_format_string(S format_str) {
- using char_type = typename S::char_type;
- constexpr auto str = basic_string_view<char_type>(format_str);
- if constexpr (str[POS] == '{') {
- if constexpr (POS + 1 == str.size())
- FMT_THROW(format_error("unmatched '{' in format string"));
- if constexpr (str[POS + 1] == '{') {
- return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
- } else if constexpr (str[POS + 1] == '}' || str[POS + 1] == ':') {
- static_assert(ID != manual_indexing_id,
- "cannot switch from manual to automatic argument indexing");
- constexpr auto next_id =
- ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
- return parse_replacement_field_then_tail<get_type<ID, Args>, Args,
- POS + 1, ID, next_id>(
- format_str);
- } else {
- constexpr auto arg_id_result =
- parse_arg_id<ID>(str.data() + POS + 1, str.data() + str.size());
- constexpr auto arg_id_end_pos = arg_id_result.arg_id_end - str.data();
- constexpr char_type c =
- arg_id_end_pos != str.size() ? str[arg_id_end_pos] : char_type();
- static_assert(c == '}' || c == ':', "missing '}' in format string");
- if constexpr (arg_id_result.arg_id.kind == arg_id_kind::index) {
- static_assert(
- ID == manual_indexing_id || ID == 0,
- "cannot switch from automatic to manual argument indexing");
- constexpr auto arg_index = arg_id_result.arg_id.val.index;
- return parse_replacement_field_then_tail<get_type<arg_index, Args>,
- Args, arg_id_end_pos,
- arg_index, manual_indexing_id>(
- format_str);
- } else if constexpr (arg_id_result.arg_id.kind == arg_id_kind::name) {
- constexpr auto arg_index =
- get_arg_index_by_name(arg_id_result.arg_id.val.name, Args{});
- if constexpr (arg_index != invalid_arg_index) {
- constexpr auto next_id =
- ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
- return parse_replacement_field_then_tail<
- decltype(get_type<arg_index, Args>::value), Args, arg_id_end_pos,
- arg_index, next_id>(format_str);
- } else {
- if constexpr (c == '}') {
- return parse_tail<Args, arg_id_end_pos + 1, ID>(
- runtime_named_field<char_type>{arg_id_result.arg_id.val.name},
- format_str);
- } else if constexpr (c == ':') {
- return unknown_format(); // no type info for specs parsing
- }
- }
- }
- }
- } else if constexpr (str[POS] == '}') {
- if constexpr (POS + 1 == str.size())
- FMT_THROW(format_error("unmatched '}' in format string"));
- return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
- } else {
- constexpr auto end = parse_text(str, POS + 1);
- if constexpr (end - POS > 1) {
- return parse_tail<Args, end, ID>(make_text(str, POS, end - POS),
- format_str);
- } else {
- return parse_tail<Args, end, ID>(code_unit<char_type>{str[POS]},
- format_str);
- }
- }
- }
- template <typename... Args, typename S,
- FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
- constexpr auto compile(S format_str) {
- constexpr auto str = basic_string_view<typename S::char_type>(format_str);
- if constexpr (str.size() == 0) {
- return detail::make_text(str, 0, 0);
- } else {
- constexpr auto result =
- detail::compile_format_string<detail::type_list<Args...>, 0, 0>(
- format_str);
- return result;
- }
- }
- #endif // defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
- } // namespace detail
- FMT_MODULE_EXPORT_BEGIN
- #if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
- template <typename CompiledFormat, typename... Args,
- typename Char = typename CompiledFormat::char_type,
- FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
- FMT_INLINE std::basic_string<Char> format(const CompiledFormat& cf,
- const Args&... args) {
- auto s = std::basic_string<Char>();
- cf.format(std::back_inserter(s), args...);
- return s;
- }
- template <typename OutputIt, typename CompiledFormat, typename... Args,
- FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
- constexpr FMT_INLINE OutputIt format_to(OutputIt out, const CompiledFormat& cf,
- const Args&... args) {
- return cf.format(out, args...);
- }
- template <typename S, typename... Args,
- FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
- FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
- Args&&... args) {
- if constexpr (std::is_same<typename S::char_type, char>::value) {
- constexpr auto str = basic_string_view<typename S::char_type>(S());
- if constexpr (str.size() == 2 && str[0] == '{' && str[1] == '}') {
- const auto& first = detail::first(args...);
- if constexpr (detail::is_named_arg<
- remove_cvref_t<decltype(first)>>::value) {
- return fmt::to_string(first.value);
- } else {
- return fmt::to_string(first);
- }
- }
- }
- constexpr auto compiled = detail::compile<Args...>(S());
- if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
- detail::unknown_format>()) {
- return fmt::format(
- static_cast<basic_string_view<typename S::char_type>>(S()),
- std::forward<Args>(args)...);
- } else {
- return fmt::format(compiled, std::forward<Args>(args)...);
- }
- }
- template <typename OutputIt, typename S, typename... Args,
- FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
- FMT_CONSTEXPR OutputIt format_to(OutputIt out, const S&, Args&&... args) {
- constexpr auto compiled = detail::compile<Args...>(S());
- if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
- detail::unknown_format>()) {
- return fmt::format_to(
- out, static_cast<basic_string_view<typename S::char_type>>(S()),
- std::forward<Args>(args)...);
- } else {
- return fmt::format_to(out, compiled, std::forward<Args>(args)...);
- }
- }
- #endif
- template <typename OutputIt, typename S, typename... Args,
- FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
- format_to_n_result<OutputIt> format_to_n(OutputIt out, size_t n,
- const S& format_str, Args&&... args) {
- auto it = fmt::format_to(detail::truncating_iterator<OutputIt>(out, n),
- format_str, std::forward<Args>(args)...);
- return {it.base(), it.count()};
- }
- template <typename S, typename... Args,
- FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
- FMT_CONSTEXPR20 size_t formatted_size(const S& format_str,
- const Args&... args) {
- return fmt::format_to(detail::counting_iterator(), format_str, args...)
- .count();
- }
- template <typename S, typename... Args,
- FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
- void print(std::FILE* f, const S& format_str, const Args&... args) {
- memory_buffer buffer;
- fmt::format_to(std::back_inserter(buffer), format_str, args...);
- detail::print(f, {buffer.data(), buffer.size()});
- }
- template <typename S, typename... Args,
- FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
- void print(const S& format_str, const Args&... args) {
- print(stdout, format_str, args...);
- }
- #if FMT_USE_NONTYPE_TEMPLATE_ARGS
- inline namespace literals {
- template <detail_exported::fixed_string Str> constexpr auto operator""_cf() {
- using char_t = remove_cvref_t<decltype(Str.data[0])>;
- return detail::udl_compiled_string<char_t, sizeof(Str.data) / sizeof(char_t),
- Str>();
- }
- } // namespace literals
- #endif
- FMT_MODULE_EXPORT_END
- FMT_END_NAMESPACE
- #endif // FMT_COMPILE_H_
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