Detemplatize parse

include/fmt/base.h

@@ -1006,7 +1006,7 @@ struct format_specs : basic_specs {
  * You can use the `format_parse_context` type alias for `char` instead.
  */
 FMT_EXPORT
-template <typename Char> class parse_context {
+template <typename Char = char> class parse_context {
  private:
   basic_string_view<Char> format_str_;
   int next_arg_id_;

include/fmt/chrono.h

@@ -2098,7 +2098,7 @@ struct formatter<weekday, Char> : private formatter<std::tm, Char> {
   bool use_tm_formatter_ = false;
 
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin(), end = ctx.end();
     if (it != end && *it == 'L') {
       ++it;
@@ -2127,7 +2127,7 @@ struct formatter<day, Char> : private formatter<std::tm, Char> {
   bool use_tm_formatter_ = false;
 
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin(), end = ctx.end();
     use_tm_formatter_ = it != end && *it != '}';
     return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
@@ -2152,7 +2152,7 @@ struct formatter<month, Char> : private formatter<std::tm, Char> {
   bool use_tm_formatter_ = false;
 
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin(), end = ctx.end();
     if (it != end && *it == 'L') {
       ++it;
@@ -2181,7 +2181,7 @@ struct formatter<year, Char> : private formatter<std::tm, Char> {
   bool use_tm_formatter_ = false;
 
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin(), end = ctx.end();
     use_tm_formatter_ = it != end && *it != '}';
     return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
@@ -2205,7 +2205,7 @@ struct formatter<year_month_day, Char> : private formatter<std::tm, Char> {
   bool use_tm_formatter_ = false;
 
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin(), end = ctx.end();
     use_tm_formatter_ = it != end && *it != '}';
     return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
@@ -2236,7 +2236,7 @@ struct formatter<std::chrono::duration<Rep, Period>, Char> {
   basic_string_view<Char> format_str_;
 
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin(), end = ctx.end();
     if (it == end || *it == '}') return it;
 
@@ -2321,7 +2321,7 @@ template <typename Char> struct formatter<std::tm, Char> {
   }
 
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin(), end = ctx.end();
     if (it == end || *it == '}') return it;
 

include/fmt/format.h

@@ -4015,8 +4015,7 @@ template <> struct formatter<bytes> {
   detail::dynamic_format_specs<> specs_;
 
  public:
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const char* {
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
     return parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx,
                               detail::type::string_type);
   }
@@ -4055,8 +4054,7 @@ template <typename T> struct formatter<group_digits_view<T>> : formatter<T> {
   detail::dynamic_format_specs<> specs_;
 
  public:
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const char* {
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
     return parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx,
                               detail::type::int_type);
   }
@@ -4083,8 +4081,7 @@ template <typename T, typename Char> struct nested_view {
 
 template <typename T, typename Char>
 struct formatter<nested_view<T, Char>, Char> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return ctx.begin();
   }
   template <typename FormatContext>
@@ -4103,7 +4100,7 @@ template <typename T, typename Char = char> struct nested_formatter {
  public:
   constexpr nested_formatter() : width_(0) {}
 
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin(), end = ctx.end();
     if (it == end) return it;
     auto specs = format_specs();

include/fmt/ranges.h

@@ -266,12 +266,12 @@ template <range_format K>
 using range_format_constant = std::integral_constant<range_format, K>;
 
 // These are not generic lambdas for compatibility with C++11.
-template <typename ParseContext> struct parse_empty_specs {
+template <typename Char> struct parse_empty_specs {
   template <typename Formatter> FMT_CONSTEXPR void operator()(Formatter& f) {
     f.parse(ctx);
     detail::maybe_set_debug_format(f, true);
   }
-  ParseContext& ctx;
+  parse_context<Char>& ctx;
 };
 template <typename FormatContext> struct format_tuple_element {
   using char_type = typename FormatContext::char_type;
@@ -327,8 +327,7 @@ struct formatter<Tuple, Char,
     closing_bracket_ = close;
   }
 
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin();
     auto end = ctx.end();
     if (it != end && detail::to_ascii(*it) == 'n') {
@@ -338,7 +337,7 @@ struct formatter<Tuple, Char,
     }
     if (it != end && *it != '}') report_error("invalid format specifier");
     ctx.advance_to(it);
-    detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
+    detail::for_each(formatters_, detail::parse_empty_specs<Char>{ctx});
     return it;
   }
 
@@ -449,8 +448,7 @@ struct range_formatter<
     closing_bracket_ = close;
   }
 
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin();
     auto end = ctx.end();
     detail::maybe_set_debug_format(underlying_, true);
@@ -549,8 +547,7 @@ struct formatter<
                                   detail::string_literal<Char, '}'>{});
   }
 
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return range_formatter_.parse(ctx);
   }
 
@@ -577,8 +574,7 @@ struct formatter<
  public:
   FMT_CONSTEXPR formatter() {}
 
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin();
     auto end = ctx.end();
     if (it != end) {
@@ -592,7 +588,7 @@ struct formatter<
       }
       ctx.advance_to(it);
     }
-    detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
+    detail::for_each(formatters_, detail::parse_empty_specs<Char>{ctx});
     return it;
   }
 
@@ -637,8 +633,7 @@ struct formatter<
   formatter<string_type, Char> underlying_;
 
  public:
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return underlying_.parse(ctx);
   }
 
@@ -686,8 +681,7 @@ struct formatter<join_view<It, Sentinel, Char>, Char> {
  public:
   using nonlocking = void;
 
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const Char* {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return value_formatter_.parse(ctx);
   }
 
@@ -754,8 +748,7 @@ template <typename Char, typename... T> struct tuple_join_view : detail::view {
 
 template <typename Char, typename... T>
 struct formatter<tuple_join_view<Char, T...>, Char> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return do_parse(ctx, std::integral_constant<size_t, sizeof...(T)>());
   }
 
@@ -769,17 +762,16 @@ struct formatter<tuple_join_view<Char, T...>, Char> {
  private:
   std::tuple<formatter<typename std::decay<T>::type, Char>...> formatters_;
 
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
+  FMT_CONSTEXPR auto do_parse(parse_context<Char>& ctx,
                               std::integral_constant<size_t, 0>)
-      -> decltype(ctx.begin()) {
+      -> const Char* {
     return ctx.begin();
   }
 
-  template <typename ParseContext, size_t N>
-  FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
+  template <size_t N>
+  FMT_CONSTEXPR auto do_parse(parse_context<Char>& ctx,
                               std::integral_constant<size_t, N>)
-      -> decltype(ctx.begin()) {
+      -> const Char* {
     auto end = ctx.begin();
 #if FMT_TUPLE_JOIN_SPECIFIERS
     end = std::get<sizeof...(T) - N>(formatters_).parse(ctx);

include/fmt/std.h

@@ -122,7 +122,7 @@ template <typename Char> struct formatter<std::filesystem::path, Char> {
  public:
   FMT_CONSTEXPR void set_debug_format(bool set = true) { debug_ = set; }
 
-  template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) {
     auto it = ctx.begin(), end = ctx.end();
     if (it == end) return it;
 
@@ -235,7 +235,7 @@ struct formatter<std::optional<T>, Char,
   FMT_CONSTEXPR static void maybe_set_debug_format(U&, ...) {}
 
  public:
-  template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) {
     maybe_set_debug_format(underlying_, true);
     return underlying_.parse(ctx);
   }
@@ -281,8 +281,7 @@ template <typename T, typename E, typename Char>
 struct formatter<std::expected<T, E>, Char,
                  std::enable_if_t<is_formattable<T, Char>::value &&
                                   is_formattable<E, Char>::value>> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return ctx.begin();
   }
 
@@ -309,9 +308,7 @@ FMT_END_NAMESPACE
 FMT_BEGIN_NAMESPACE
 FMT_EXPORT
 template <> struct formatter<std::source_location> {
-  template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
-    return ctx.begin();
-  }
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) { return ctx.begin(); }
 
   template <typename FormatContext>
   auto format(const std::source_location& loc, FormatContext& ctx) const
@@ -367,8 +364,7 @@ template <typename T, typename C> struct is_variant_formattable {
 
 FMT_EXPORT
 template <typename Char> struct formatter<std::monostate, Char> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return ctx.begin();
   }
 
@@ -385,8 +381,7 @@ struct formatter<
     Variant, Char,
     std::enable_if_t<std::conjunction_v<
         is_variant_like<Variant>, is_variant_formattable<Variant, Char>>>> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return ctx.begin();
   }
 
@@ -416,8 +411,7 @@ FMT_END_NAMESPACE
 FMT_BEGIN_NAMESPACE
 FMT_EXPORT
 template <typename Char> struct formatter<std::error_code, Char> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return ctx.begin();
   }
 
@@ -508,7 +502,7 @@ template <typename Char>
 struct formatter<std::type_info, Char  // DEPRECATED! Mixing code unit types.
                  > {
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     return ctx.begin();
   }
 
@@ -529,7 +523,7 @@ struct formatter<
   bool with_typename_ = false;
 
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     auto it = ctx.begin();
     auto end = ctx.end();
     if (it == end || *it == '}') return it;
@@ -657,7 +651,7 @@ template <typename T, typename Char> struct formatter<std::complex<T>, Char> {
   }
 
  public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> decltype(ctx.begin()) {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
     if (ctx.begin() == ctx.end() || *ctx.begin() == '}') return ctx.begin();
     return parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx,
                               detail::type_constant<T, Char>::value);