[format.formatter] Reorder Formatter requirements before the

descriptions of specializations that meet those requirements.

Author: zygoloid

source/utilities.tex

@@ -20467,6 +20467,87 @@
 
 \rSec2[format.formatter]{Formatter}
 
+\rSec3[formatter.requirements]{Formatter requirements}
+
+\pnum
+\indextext{requirements!\idxnewoldconcept{Formatter}}%
+A type \tcode{F} meets the \newoldconceptdefn{Formatter} requirements if:
+
+\begin{itemize}
+\item
+it meets the
+\begin{itemize}
+\item \oldconcept{DefaultConstructible} (\tref{cpp17.defaultconstructible}),
+\item \oldconcept{CopyConstructible} (\tref{cpp17.copyconstructible}),
+\item \oldconcept{CopyAssignable} (\tref{cpp17.copyassignable}), and
+\item \oldconcept{Destructible} (\tref{cpp17.destructible})
+\end{itemize}
+requirements,
+
+\item
+it is swappable\iref{swappable.requirements} for lvalues, and
+
+\item
+the expressions shown in \tref{formatter} are valid and
+have the indicated semantics.
+\end{itemize}
+
+\pnum
+Given character type \tcode{charT}, output iterator type
+\tcode{Out}, and formatting argument type \tcode{T},
+in \tref{formatter}:
+\begin{itemize}
+\item \tcode{f} is a value of type \tcode{F},
+\item \tcode{u} is an lvalue of type \tcode{T},
+\item \tcode{t} is a value of a type convertible to (possibly const) \tcode{T},
+\item \tcode{PC} is \tcode{basic_format_parse_context<charT>},
+\item \tcode{FC} is \tcode{basic_format_context<Out, charT>},
+\item \tcode{pc} is an lvalue of type \tcode{PC}, and
+\item \tcode{fc} is an lvalue of type \tcode{FC}.
+\end{itemize}
+\tcode{pc.begin()} points to the beginning of the
+\fmtgrammarterm{format-spec}\iref{format.string}
+of the replacement field being formatted
+in the format string.
+If \fmtgrammarterm{format-spec} is empty then either
+\tcode{pc.begin() == pc.end()} or
+\tcode{*pc.begin() == '\}'}.
+
+\begin{concepttable}{\newoldconcept{Formatter} requirements}{formatter}
+{p{1.2in}p{1in}p{2.9in}}
+\topline
+\hdstyle{Expression} & \hdstyle{Return type} & \hdstyle{Requirement} \\ \capsep
+\tcode{f.parse(pc)} &
+\tcode{PC::iterator} &
+Parses \fmtgrammarterm{format-spec}\iref{format.string}
+for type \tcode{T}
+in the range \range{pc.begin()}{pc.end()}
+until the first unmatched character.
+Throws \tcode{format_error} unless the whole range is parsed
+or the unmatched character is \tcode{\}}.
+\begin{note}
+This allows formatters to emit meaningful error messages.
+\end{note}
+Stores the parsed format specifiers in \tcode{*this} and
+returns an iterator past the end of the parsed range.
+\\ \rowsep
+\tcode{f.format(t, fc)} &
+\tcode{FC::iterator} &
+Formats \tcode{t} according to the specifiers stored in \tcode{*this},
+writes the output to \tcode{fc.out()} and
+returns an iterator past the end of the output range.
+The output shall only depend on
+\tcode{t},
+\tcode{fc.locale()},
+and the range \range{pc.begin()}{pc.end()}
+from the last call to \tcode{f.parse(pc)}.
+\\ \rowsep
+\tcode{f.format(u, fc)} &
+\tcode{FC::iterator} &
+As above, but does not modify \tcode{u}.
+\\
+\end{concepttable}
+
 \rSec3[format.formatter.spec]{Formatter specializations}
 \indexlibrary{\idxcode{formatter}}%
 
@@ -20489,10 +20570,18 @@
 \begin{itemize}
 \item
 \indexlibrary{\idxcode{formatter}!specializations!character types}%
+The specializations
+\begin{codeblock}
+template<> struct formatter<char, char>;
+template<> struct formatter<char, wchar_t>;
+template<> struct formatter<wchar_t, wchar_t>;
+\end{codeblock}
+
+\item
 \indexlibrary{\idxcode{formatter}!specializations!string types}%
 For each \tcode{charT},
+the string type specializations
 \begin{codeblock}
-template<> struct formatter<charT, charT>;
 template<> struct formatter<charT*, charT>;
 template<> struct formatter<const charT*, charT>;
 template<size_t N> struct formatter<const charT[N], charT>;
@@ -20503,33 +20592,30 @@
 \end{codeblock}
 
 \item
-The specialization
+\indexlibrary{\idxcode{formatter}!specializations!arithmetic types}%
+For each \tcode{charT},
+for each cv-unqualified arithmetic type \tcode{ArithmeticT}
+other than
+\tcode{char},
+\tcode{wchar_t},
+\tcode{char8_t},
+\tcode{char16_t}, or
+\tcode{char32_t},
+a specialization
 \begin{codeblock}
-template<> struct formatter<char, wchar_t>;
+template<> struct formatter<ArithmeticT, charT>;
 \end{codeblock}
 
 \item
-\indexlibrary{\idxcode{formatter}!specializations!arithmetic types}%
 \indexlibrary{\idxcode{formatter}!specializations!pointer types}%
 \indexlibrary{\idxcode{formatter}!specializations!\idxcode{nullptr_t}}%
-A specialization
+For each \tcode{charT},
+the pointer type specializations
 \begin{codeblock}
-template<> struct formatter<T, charT>;
+template<> struct formatter<nullptr_t, charT>;
+template<> struct formatter<void*, charT>;
+template<> struct formatter<const void*, charT>;
 \end{codeblock}
-for each \tcode{charT},
-for each cv-unqualified type \tcode{T} that is
-\begin{itemize}
-\item \tcode{nullptr_t},
-\item \tcode{void*},
-\item \tcode{const void*},
-\item an integral type other than
-\tcode{char},
-\tcode{wchar_t},
-\tcode{char8_t},
-\tcode{char16_t}, or
-\tcode{char32_t}, or
-\item a floating-point type.
-\end{itemize}
 \end{itemize}
 The \tcode{parse} member functions of these formatters
 interpret the format specification
@@ -20590,87 +20676,6 @@
 \end{codeblock}
 \end{example}
 
-\rSec3[formatter.requirements]{Formatter requirements}
-
-\pnum
-\indextext{requirements!\idxnewoldconcept{Formatter}}%
-A type \tcode{F} meets the \newoldconceptdefn{Formatter} requirements if:
-
-\begin{itemize}
-\item
-it meets the
-\begin{itemize}
-\item \oldconcept{DefaultConstructible} (\tref{cpp17.defaultconstructible}),
-\item \oldconcept{CopyConstructible} (\tref{cpp17.copyconstructible}),
-\item \oldconcept{CopyAssignable} (\tref{cpp17.copyassignable}), and
-\item \oldconcept{Destructible} (\tref{cpp17.destructible})
-\end{itemize}
-requirements,
-
-\item
-it is swappable\iref{swappable.requirements} for lvalues, and
-
-\item
-the expressions shown in \tref{formatter} are valid and
-have the indicated semantics.
-\end{itemize}
-
-\pnum
-Given character type \tcode{charT}, output iterator type
-\tcode{Out}, and formatting argument type \tcode{T},
-in \tref{formatter}:
-\begin{itemize}
-\item \tcode{f} is a value of type \tcode{F},
-\item \tcode{u} is an lvalue of type \tcode{T},
-\item \tcode{t} is a value of a type convertible to (possibly const) \tcode{T},
-\item \tcode{PC} is \tcode{basic_format_parse_context<charT>},
-\item \tcode{FC} is \tcode{basic_format_context<Out, charT>},
-\item \tcode{pc} is an lvalue of type \tcode{PC}, and
-\item \tcode{fc} is an lvalue of type \tcode{FC}.
-\end{itemize}
-\tcode{pc.begin()} points to the beginning of the
-\fmtgrammarterm{format-spec}\iref{format.string}
-% FIXME: Which one?
-portion of the format string.
-If \fmtgrammarterm{format-spec} is empty then either
-\tcode{pc.begin() == pc.end()} or
-\tcode{*pc.begin() == '\}'}.
-
-\begin{concepttable}{\newoldconcept{Formatter} requirements}{formatter}
-{p{1.2in}p{1in}p{2.9in}}
-\topline
-\hdstyle{Expression} & \hdstyle{Return type} & \hdstyle{Requirement} \\ \capsep
-\tcode{f.parse(pc)} &
-\tcode{PC::iterator} &
-Parses \fmtgrammarterm{format-spec}\iref{format.string}
-for type \tcode{T}
-in the range \range{pc.begin()}{pc.end()}
-until the first unmatched character.
-Throws \tcode{format_error} unless the whole range is parsed
-or the unmatched character is \tcode{\}}.
-\begin{note}
-This allows formatters to emit meaningful error messages.
-\end{note}
-Stores the parsed format specifiers in \tcode{*this} and
-returns an iterator past the end of the parsed range.
-\\ \rowsep
-\tcode{f.format(t, fc)} &
-\tcode{FC::iterator} &
-Formats \tcode{t} according to the specifiers stored in \tcode{*this},
-writes the output to \tcode{fc.out()} and
-returns an iterator past the end of the output range.
-The output shall only depend on
-\tcode{t},
-\tcode{fc.locale()},
-and the range \range{pc.begin()}{pc.end()}
-from the last call to \tcode{f.parse(pc)}.
-\\ \rowsep
-\tcode{f.format(u, fc)} &
-\tcode{FC::iterator} &
-As above, but does not modify \tcode{u}.
-\\
-\end{concepttable}
-
 \rSec3[format.parse.ctx]{Class template \tcode{basic_format_parse_context}}
 
 \indexlibrary{\idxcode{basic_format_parse_context}}%