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utf8ienc.dtx
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utf8ienc.dtx
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% \iffalse meta-comment
%
% Copyright (C) 1993-2022
% The LaTeX Project and any individual authors listed elsewhere
% in this file.
%
% This file is part of the LaTeX base system.
% -------------------------------------------
%
% It may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either version 1.3c
% of this license or (at your option) any later version.
% The latest version of this license is in
% https://www.latex-project.org/lppl.txt
% and version 1.3c or later is part of all distributions of LaTeX
% version 2008 or later.
%
% This file has the LPPL maintenance status "maintained".
%
% The list of all files belonging to the LaTeX base distribution is
% given in the file `manifest.txt'. See also `legal.txt' for additional
% information.
%
% The list of derived (unpacked) files belonging to the distribution
% and covered by LPPL is defined by the unpacking scripts (with
% extension .ins) which are part of the distribution.
%
% \fi
%
% \iffalse
%<*driver>
\documentclass{ltxdoc}
\usepackage[latin1,utf8]{inputenc}% force utf8 to be re-loaded, to get version info
\GetFileInfo{utf8.def}
\title{Providing some UTF-8 support via \texttt{inputenc}}
\date{\fileversion\space\filedate{} printed \today}
\author{%
David Carlisle \and Frank Mittelbach \and
Chris Rowley\thanks{Borrowing heavily from tables by Sebastian Rahtz; some table
and code cleanup by Javier Bezos}}
\begin{document}
\MaintainedByLaTeXTeam{latex}
\maketitle
\tableofcontents
\DocInput{utf8ienc.dtx}
\end{document}
%</driver>
% \fi
%
% \newpage
%
% \section{Introduction}
%
%
% \subsection{Background and general stuff}
%
% For many reasons what this package provides is a long way from any
% type of `Unicode compliance'.
%
% In stark contrast to 8-bit character sets, with 16 or more bits it can
% easily be very inefficient to support the full range.\footnote{In
% fact, \LaTeX's current 8-bit support does not go so far as to make
% all 8-bit characters into valid input.} Moreover, useful support of
% character input by a typesetting system overwhelmingly means finding
% an acceptable visual representation of a sequence of characters and
% this, for \LaTeX{}, means having available a suitably encoded 8-bit
% font.
%
% Unfortunately it is not possible to predict exactly what valid UTF-8
% octet sequences will appear in a particular file so it is best to
% make all the unsupported but valid sequences produce a reasonably
% clear and noticeable error message.
%
% There are two directions from which to approach the question of what
% to load. One is to specify the ranges of Unicode characters that will
% result in some sensible typesetting; this requires the provider to
% ensure that suitable fonts are loaded and that these input characters
% generate the correct typesetting via the encodings of those fonts. The
% other is to inspect the font encodings to be used and use these to
% define which input Unicode characters should be supported.
%
% For Western European languages, at least, going in either direction
% leads to many straightforward decisions and a few that are more
% subjective. In both cases some of the specifications are \TeX{}
% specific whilst most are independent of the particular typesetting
% software in use.
%
% As we have argued elsewhere, \LaTeX{} needs to refer to characters via
% `seven-bit-text' names and, so far, these have been chosen by
% reference to historical sources such as Plain \TeX{} or Adobe encoding
% descriptions. It is unclear whether this ad hoc naming structure should
% simply be extended or whether it would be useful to
% supplement it with standardised internal Unicode character names such as
% one or more of the following:\footnote{Burkhard und Holger Mittelbach
% spielen mit mir! Sie haben etwas hier geschrieben.}
%
% \begin{verbatim}
% \ltxutwochar <4 hex digits>
%
% \ltxuchar {<hex digits>}
% B H U R R R
%
% \ltxueightchartwo <2 utf8 octets as 8-bit char tokens>
% \ltxueightcharthree <3 utf8 octets ...>
% \ltxueightcharfour <4 utf8 octets ...>
% \end{verbatim}
%
%
% \subsection{More specific stuff}
%
% In addition to setting up the mechanism for reading UTF-8 characters
% and specifying the \LaTeX-level support available, this package
% contains support for some default historically expected \TeX-related
% characters and some example `Unicode definition files' for standard
% font encodings.
%
%
% \subsection{Notes}
%
% This package does not support Unicode combining characters as \TeX{}
% is not really equipped to make this possible.
%
% No attempt is made to be useful beyond Latin, and maybe Cyrillic,
% for European languages (as of now).
%
%
% \subsection{Basic operation of the code}
%
% The \texttt{inputenc} package makes the upper 8-bit characters active and
% assigns to all of them an error message. It then waits for the
% input encoding files to change this set-up. Similarly, whenever
% |\inputencoding| is encountered in a document, first the upper
% 8-bit characters are set back to produce an error and then the
% definitions for the new input encoding are loaded, changing some of the
% previous settings.
%
% The 8-bit input encodings currently supported by \texttt{inputenc}
% all use declarations such as |\DeclareInputText| and the like to map an
% 8-bit number to some \LaTeX{} internal form, e.g.~to |\"a|.
%
% The situation when supporting UTF-8 as the input encoding is
% different, however. Here we only have to set up the actions of
% those 8-bit numbers that can be the first octet in a UTF-8
% representation of a Unicode character. But we cannot simply set
% this to some internal \LaTeX{} form since the Unicode character
% consists of more than one octet; instead we have to define this
% starting octet to parse the right number of further octets that
% together form the UTF-8 representation of some Unicode character.
%
% Therefore when switching to \texttt{utf8} within the
% \texttt{inputenc} framework the characters with numbers (hex)
% from \texttt{"C2} to \texttt{"DF} are defined to parse for a
% second octet following, the characters from \texttt{"E0} to
% \texttt{"EF} are defined to parse for two more octets and finally
% the characters from \texttt{"F0} to \texttt{"F3} are defined to
% parse for three additional octets. These additional octets are
% always in the range \texttt{"80} to \texttt{"B9}.
%
% Thus, when such a character is encountered in the document (so
% long as expansion is not prohibited) a defined number of
% additional octets (8-bit characters) are read and from them a
% unique control sequence name is immediately constructed.
%
% This control sequence is either defined (good) or undefined
% (likely); in the latter case the user gets an error message
% saying that this UTF-8 sequence (or, better, Unicode character)
% is not supported.
%
% If the control sequence is set up to do something useful then it will
% expand to a \LaTeX{} internal form: e.g.~for the utf8 sequence of
% two octets \texttt{"C3 "A4} we get |\"a| as the
% internal form which then, depending on the font encoding,
% eventually resolves to the single glyph `latin-a-umlaut' or to
% the composite glyph `latin-a with an umlaut accent'.
%
% These mappings from (UTF-8 encoded) Unicode characters to \LaTeX{}
% internal forms are made indirectly. The code below provides a
% declaration |\DeclareUnicodeCharacter| which maps Unicode numbers
% (as hexadecimal) to \LaTeX{} internal forms.
%
% This mapping needs to be set up only once so it is done at
% |\begin{document}| by looking at the list of font encodings that
% are loaded by the document and providing mappings related to
% those font encodings whenever these are available. Thus at most
% only those Unicode characters that can be represented by the glyphs
% available in these encodings will be defined.
%
% Technically this is done by loading one file per encoding,
% if available, that is supposed to provide the necessary mapping
% information.
%
%
% \MaybeStop{}
%
%
%
%
% \section{Coding}
%
% \subsection{Housekeeping}
%
% The usual introductory bits and pieces:
%
% \begin{macrocode}
%<utf8>\ProvidesFile{utf8.def}
%<test>\ProvidesFile{utf8-test.tex}
%<+lcy> \ProvidesFile{lcyenc.dfu}
%<+ly1> \ProvidesFile{ly1enc.dfu}
%<+oms> \ProvidesFile{omsenc.dfu}
%<+ot1> \ProvidesFile{ot1enc.dfu}
%<+ot2> \ProvidesFile{ot2enc.dfu}
%<+t1> \ProvidesFile{t1enc.dfu}
%<+t2a> \ProvidesFile{t2aenc.dfu}
%<+t2b> \ProvidesFile{t2benc.dfu}
%<+t2c> \ProvidesFile{t2cenc.dfu}
%<+ts1> \ProvidesFile{ts1enc.dfu}
%<+x2> \ProvidesFile{x2enc.dfu}
%<+all> \ProvidesFile{utf8enc.dfu}
%<-utf8-2018> [2022/06/07 v1.3c UTF-8 support]
% \end{macrocode}
%
% \begin{macrocode}
%<*utf8>
% \end{macrocode}
% This is a temporary fix for the e-p\TeX{} / e-up\TeX{} engines that do not yet
% have a |\ifincsname| primitive. Once this is available the extra file will
% be dropped.
% \changes{v1.2h}{2019/07/09}{Temp rollback fix for e-pTeX}
% \begin{macrocode}
\ifx\ifincsname\@undefined % old e-pTeX or e-upTeX engines
\input utf8-2018.def
\expandafter\@firstofone
\else
\expandafter\@gobble
\fi
\endinput
% \end{macrocode}
%
% \begin{macrocode}
\makeatletter
% \end{macrocode}
% We restore the |\catcode| of space (which is set to ignore in
% \texttt{inputenc}) while reading \texttt{.def} files. Otherwise
% we would need to explicitly use |\space| all over the place in
% error and log messages.
% \changes{v1.1d}{2004/05/08}{Explicitly set catcode of space}
% \begin{macrocode}
\catcode`\ \saved@space@catcode
% \end{macrocode}
%
%
%
% \subsection{Parsing UTF-8 input}
%
% A UTF-8 char (that is not actually a 7-bit char, i.e.~a single
% octet) is parsed as follows: each starting octet is an active
% \TeX{} character token; each of these is defined below to be a
% macro with one to three arguments nominally (depending on the
% starting octet). It calls one of |\UTFviii@two@octets|,
% |\UTFviii@three@octets|, or |\UTFviii@four@octets| which then
% actually picks up the remaining octets as the argument(s).
%
% \begin{itemize}
% \item When typesetting we pick up the necessary number of additional
% octets, check if they form a command that \LaTeX{} knows about
% (via \cs{csname} \texttt{u8:}\cs{string}
% \verb=#1=\cs{string} \verb=#2...=\cs{endcsname}) and if so use that
% for typesetting. \cs{string} is needed as the octets may (all?) be
% active and we want the literal values in the name.
%
% \item If the UTF-8 character is going to be part of a label, then it is
% essentially becoming part of some csname and with the
% test \cs{ifincsname} we can find this out. If so, we render the whole
% sequence off octets harmless by using \cs{string} too when the
% starting octet executes (\cs{UTF@...@octets@string}).
%
% \item Another possible case is that \cs{protect} has \emph{not} the meaning
% of \cs{typeset@protect}. In that case we may do a \cs{write} or we may do
% a \cs{protected@edef} or \ldots{} In all such cases we want to keep the
% sequence of octets unchanged, but we can't use \cs{string} this time, since at
% least in the case of \cs{protect@edef} the result may later be
% typeset after all (in fact that is quite likely) and so at that
% point the starting octet needs to be an active character again
% (the others could be stringified). So for this case we use \cs{noexpand}
% ((\cs{UTF@...s@octets@noexpand}).
% \end{itemize}
%
% \begin{macro}{\UTFviii@two@octets}
% \changes{v1.2a}{2018/03/24}{Macros made `\cs{long} for improved error messages}%
% Putting that all together the code for a start octet of a two
% byte sequence would then look like this:
% \begin{macrocode}
\long\def\UTFviii@two@octets{%
\ifincsname
\expandafter \UTF@two@octets@string
\else
\ifx \protect\@typeset@protect \else
\expandafter\expandafter\expandafter \UTF@two@octets@noexpand
\fi
\fi
\UTFviii@two@octets@combine
}
% \end{macrocode}
% \cs{ifcsname} is tested first because that can be true even if we
% are otherwise doing typesetting. If this is the case we use
% \cs{string} on the whole octet
% sequence. \cs{UTF@two@octets@string} not only does this but also
% gets rid of the command \cs{UTFviii@two@octets@combine} in the input
% stream by picking it up as a first argument and dropping it.
%
% If this is not the case and we are doing typesetting (i.e.,
% \cs{protect} is \cs{typeset@protect}), then we execute
% \cs{UTFviii@two@octets@combine} which picks up all octets and typesets
% the character (or generates an error if it doesn't know how to
% typeset it).
%
% However, if we are not doing typesetting, then we execute the
% command \cs{UTFviii@two@octets@noexpand} which works like
% \cs{UTF@two@octets@string} but uses \cs{noexpand} instead of
% \cs{string}. This way the sequence is temporary rendered harmless,
% e.g., would display as is or stays put inside a
% \cs{protected@edef}. But if the result is later reused the
% starting octet is still active and so will be able to construct
% the UTF-8 character again.
% \end{macro}
%
%
% \begin{macro}{\UTFviii@three@octets}
% \changes{v1.2a}{2018/03/24}{Macros made `\cs{long} for improved error messages}%
% \begin{macro}{\UTFviii@four@octets}
% \changes{v1.2a}{2018/03/24}{Macros made `\cs{long} for improved
% error messages}
% The definitions for the other starting octets
% are the same except that they pick up more octets after them.
% \begin{macrocode}
\long\def\UTFviii@three@octets{%
\ifincsname
\expandafter \UTF@three@octets@string
\else
\ifx \protect\@typeset@protect \else
\expandafter\expandafter\expandafter \UTF@three@octets@noexpand
\fi
\fi
\UTFviii@three@octets@combine
}
% \end{macrocode}
% \begin{macrocode}
\long\def\UTFviii@four@octets{%
\ifincsname
\expandafter \UTF@four@octets@string
\else
\ifx \protect\@typeset@protect \else
\expandafter\expandafter\expandafter \UTF@four@octets@noexpand
\fi
\fi
\UTFviii@four@octets@combine
}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\UTFviii@two@octets@noexpand}
% \begin{macro}{\UTFviii@three@octets@noexpand}
% \begin{macro}{\UTFviii@four@octets@noexpand}
% \changes{v1.3a}{2022/02/19}{Use \cs{unexpanded} rather than \cs{noexpand} so only takes one expansion step}%
% These temporarily prevent the active chars from expanding.
% \begin{macrocode}
\long\def\UTF@two@octets@noexpand#1#2#3{\unexpanded{#2#3}}
\long\def\UTF@three@octets@noexpand#1#2#3#4{\unexpanded{#2#3#4}}
\long\def\UTF@four@octets@noexpand#1#2#3#4#5{\unexpanded{#2#3#4#5}}
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \begin{macro}{\UTFviii@two@octets@string}
% \begin{macro}{\UTFviii@three@octets@string}
% \begin{macro}{\UTFviii@four@octets@string}
% \changes{v1.3a}{2022/02/19}{Use \cs{detokenize} rather than \cs{string} so only takes one expansion step}%
% And the same with \cs{string} for use in \cs{csname} constructions.
% \begin{macrocode}
\long\def\UTF@two@octets@string#1#2#3{\detokenize{#2#3}}
\long\def\UTF@three@octets@string#1#2#3#4{\detokenize{#2#3#4}}
\long\def\UTF@four@octets@string#1#2#3#4#5{\detokenize{#2#3#4#5}}
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \begin{macro}{\UTFviii@two@octets@combine}
% \begin{macro}{\UTFviii@three@octets@combine}
% \begin{macro}{\UTFviii@four@octets@combine}
% From the arguments a control sequence with a name of the form
% \verb=u8:#1#2...= is constructed where the |#i| ($i>1$) are the
% arguments and |#1| is the starting octet (as a \TeX{} active character
% token). Since some or even all of these characters are active
% we need to use |\string| when building
% the \cs{csname}.
%
% The \cs{csname} thus constructed can of course be undefined but to
% avoid producing an unhelpful low-level undefined command error we
% pass it to |\UTFviii@defined| which is responsible for producing
% a more sensible error message (not yet done!!). If, however, it is
% defined we simply execute the thing (which should then expand to
% an encoding specific internal \LaTeX{} form).
% \begin{macrocode}
\long\def\UTFviii@two@octets@combine#1#2{\expandafter
\UTFviii@defined\csname u8:\string#1\string#2\endcsname}
% \end{macrocode}
%
% \begin{macrocode}
\long\def\UTFviii@three@octets@combine#1#2#3{\expandafter
\UTFviii@defined\csname u8:\string#1\string#2\string#3\endcsname}
% \end{macrocode}
%
% \begin{macrocode}
\long\def\UTFviii@four@octets@combine#1#2#3#4{\expandafter
\UTFviii@defined\csname u8:\string#1\string#2\string#3\string#4\endcsname}
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
%
% \begin{macro}{\UTFviii@defined}
% This tests whether its argument is different from |\relax|: it
% either calls for a sensible error message (not done), or it gets
% the |\fi| out of the way (in case the command has arguments) and
% executes it.
% \begin{macrocode}
\def\UTFviii@defined#1{%
\ifx#1\relax
% \end{macrocode}
% Test if the sequence is invalid UTF-8 or valid UTF-8 but without
% a \LaTeX\ definition.
% \begin{macrocode}
\if\relax\expandafter\UTFviii@checkseq\string#1\relax\relax
% \end{macrocode}
% The endline character has a special definition within the
% inputenc package (it is gobbling spaces). For this reason we
% can't produce multiline strings without some precaution.
% \changes{v1.1b}{2004/02/09}{No newlines allowed in error messages}
% \changes{v1.1g}{2005/09/27}{Real spaces do not show up so use \cs{space}}
% \changes{v1.1o}{2015/08/28}{Show Unicode number of character in hex}
% \changes{v1.2a}{2018/03/24}{Error message improved for non-UTF-8 sequences}%
% \changes{v1.2m}{2021/06/08}{Normalize various error messages as kernel errors}
% \begin{macrocode}
\UTFviii@undefined@err{#1}%
% \end{macrocode}
%
% \begin{macrocode}
\else
\@latex@error{Invalid UTF-8 byte sequence (\expandafter
\@gobblefour\string#1)}%
\UTFviii@invalid@help
\fi
% \end{macrocode}
%
% \begin{macrocode}
\else\expandafter
#1%
\fi
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\UTFviii@invalid@err}
% \begin{macro}{\UTFviii@invalid@help}
% \changes{v1.2a}{2018/03/24}{Macro added}%
% \changes{v1.2f}{2018/10/05}{Show invalid byte in hex}%
% \begin{macrocode}
\def\UTFviii@invalid@err#1{%
\@latex@error{Invalid UTF-8 byte "\UTFviii@hexnumber{`#1}}%
\UTFviii@invalid@help}
% \end{macrocode}
%
% \begin{macrocode}
\def\UTFviii@invalid@help{%
The document does not appear to be in UTF-8 encoding.\MessageBreak
Try adding \noexpand\UseRawInputEncoding as the first line of the file\MessageBreak
or specify an encoding such as \noexpand\usepackage[latin1]{inputenc}\MessageBreak
in the document preamble.\MessageBreak
Alternatively, save the file in UTF-8 using your editor or another tool}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\UTFviii@undefined@err}
% \changes{v1.2a}{2018/03/24}{Macro added}%
% \begin{macrocode}
\def\UTFviii@undefined@err#1{%
\@latex@error{Unicode character \expandafter
\UTFviii@splitcsname\string#1\relax
\MessageBreak
not set up for use with LaTeX}%
{You may provide a definition with\MessageBreak
\noexpand\DeclareUnicodeCharacter}%
}
% \end{macrocode}
% \end{macro}
%
%
% \begin{macro}{\UTFviii@checkseq}
% \begin{macro}{\UTFviii@check@continue}
% \changes{v1.2a}{2018/03/24}{Macro added}%
% Check that the csname consists of a valid UTF-8 sequence.
% \begin{macrocode}
\def\UTFviii@checkseq#1:#2#3{%
\ifnum`#2<"80 %
\ifx\relax#3\else1\fi
\else
\ifnum`#2<"C0 %
1 %
\else
\expandafter\expandafter\expandafter\UTFviii@check@continue
\expandafter\expandafter\expandafter#3%
\fi
\fi}
% \end{macrocode}
%
% \begin{macrocode}
\def\UTFviii@check@continue#1{%
\ifx\relax#1%
\else
\ifnum`#1<"80 1\else\ifnum`#1>"BF 1\fi\fi
\expandafter\UTFviii@check@continue
\fi
}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
%
% \begin{macro}{\UTFviii@loop}
% This bit of code derived from \texttt{xmltex} defines the active
% character corresponding to starting octets to call |\UTFviii@two@octets|
% etc as appropriate.
% The starting octet itself is passed directly as the first
% argument, the others are picked up later en route.
%
% The |\UTFviii@loop| loops through the numbers starting at
% |\count@| and ending at |\@tempcnta|${} - 1$, each time executing
% the code in |\UTFviii@tmp|.
%
% Store current settings so can restore after the loops without using a group (gh/762).
%
% \begin{macrocode}
\edef\reserved@a{%
\catcode`\noexpand\~=\the\catcode`\~\relax
\catcode`\noexpand\"=\the\catcode`\"\relax
\uccode`\noexpand\~=\the\uccode`\~\relax
\count@=\the\count@\relax
\@tempcnta=\the\@tempcnta\relax
\let\noexpand\reserved@a\relax}
% \end{macrocode}
%
% \begin{macrocode}
\catcode`\~13
\catcode`\"12
% \end{macrocode}
%
% \changes{v1.3a}{2022/02/19}{Use local protected definitions in the character definitions}%
% \begin{macrocode}
\def\UTFviii@loop{%
\uccode`\~\count@
\uppercase\expandafter{\UTFviii@tmp}%
\advance\count@\@ne
\ifnum\count@<\@tempcnta
\expandafter\UTFviii@loop
\fi}
% \end{macrocode}
%
% Handle the single byte control characters.
% \changes{v1.2a}{2018/03/24}{Loop over C0 controls added}%
% C0 controls are valid UTF-8 but defined to give the ``Character not defined error''
% They may be defined with |\DeclareUnicodeCharacter|.
% \begin{macrocode}
\def\UTFviii@tmp{\protected\edef~{\noexpand\UTFviii@undefined@err{:\string~}}}
% 0 ^^@ null
\count@"1
\@tempcnta9
% 9 ^^I tab
% 10 ^^J nl
\UTFviii@loop
\count@11
\@tempcnta12
\UTFviii@loop
% 12 ^^L
% 13 ^^M
\count@14
\@tempcnta32
\UTFviii@loop
% \end{macrocode}
%
%
% Bytes with leading bits |10| are not valid UTF-8 starting bytes
% \begin{macrocode}
\count@"80
\@tempcnta"C2
\def\UTFviii@tmp{\protected\edef~{\noexpand\UTFviii@invalid@err\string~}}
\UTFviii@loop
% \end{macrocode}
%
% Setting up 2-byte UTF-8: The starting bytes is passed as an
% active character so that it can be reprocessed later!
% \begin{macrocode}
\count@"C2
\@tempcnta"E0
\def\UTFviii@tmp{\protected\edef~{\noexpand\UTFviii@two@octets\noexpand~}}
\UTFviii@loop
% \end{macrocode}
%
% Setting up 3-byte UTF-8:
% \begin{macrocode}
\count@"E0
\@tempcnta"F0
\def\UTFviii@tmp{\protected\edef~{\noexpand\UTFviii@three@octets\noexpand~}}
\UTFviii@loop
% \end{macrocode}
%
% Setting up 4-byte UTF-8:
% \changes{v1.2e}{2018/09/28}{Fix "F4 lead byte}%
% \begin{macrocode}
\count@"F0
\@tempcnta"F5
\def\UTFviii@tmp{\protected\edef~{\noexpand\UTFviii@four@octets\noexpand~}}
\UTFviii@loop
% \end{macrocode}
%
% Bytes above F4 are not valid UTF-8 starting bytes as they would encode numbers beyond
% the Unicode range
% \begin{macrocode}
\count@"F5
\@tempcnta"100
\def\UTFviii@tmp{\protected\edef~{\noexpand\UTFviii@invalid@err\string~}}
\UTFviii@loop
% \end{macrocode}
%
% Restore values after the loops.
% \begin{macrocode}
\reserved@a
% \end{macrocode}
%
% \end{macro}
%
% For this case we must disable the warning generated by
% \texttt{inputenc} if it doesn't see any new |\DeclareInputText|
% commands.
% \begin{macrocode}
\@inpenc@test
% \end{macrocode}
%
%
% If this file (\texttt{utf8.def}) is not being read while setting
% up \texttt{inputenc}, i.e.~in the preamble, but when
% |\inputencoding| is called somewhere within the document, we do not
% need to input the specific Unicode mappings again. We therefore
% stop reading the file at this point.
% \begin{macrocode}
\ifx\@begindocumenthook\@undefined
\makeatother
% \end{macrocode}
% The |\fi| must be on the same line as |\endinput| or else it will
% never be seen!
% \begin{macrocode}
\endinput \fi
% \end{macrocode}
%
%
% \subsection{Mapping Unicode codes to \LaTeX{} internal forms}
%
%
% \begin{macro}{\DeclareUnicodeCharacter}
% The |\DeclareUnicodeCharacter| declaration defines a mapping from
% a Unicode character code point to a \LaTeX{} internal form. The first
% argument is the Unicode number as hexadecimal digits and the second is
% the actual \LaTeX{} internal form.
%
% We start by making sure that some characters have the right
% |\catcode| when they are used in the definitions below.
% \begin{macrocode}
\begingroup
\catcode`\"=12
\catcode`\<=12
\catcode`\.=12
\catcode`\,=12
\catcode`\;=12
\catcode`\!=12
\catcode`\~=13
% \end{macrocode}
%
% \begin{macrocode}
\gdef\DeclareUnicodeCharacter#1#2{%
\count@"#1\relax
\wlog{ \space\space defining Unicode char U+#1 (decimal \the\count@)}%
\begingroup
% \end{macrocode}
% Next we do the parsing of the number stored in |\count@| and assign the
% result to |\UTFviii@tmp|. Actually all this could be done in-line,
% the macro |\parse@XML@charref| is only there to extend this code
% to parsing Unicode numbers in other contexts one day (perhaps).
% \begin{macrocode}
\parse@XML@charref
% \end{macrocode}
%
% Here is an example of what is happening, for the pair \texttt{"C2 "A3}
% (which is the utf8 representation for the character \textsterling{}).
% After |\parse@XML@charref| we have, stored in |\UTFviii@tmp|, a
% single command with two character tokens as arguments:
% \begin{quote}
% [$t_{C2}$ and $t_{A3}$ are the characters corresponding to these
% two octets]\\
% |\UTFviii@two@octets| $t_{\rm C2}t_{\rm A3}$
% \end{quote}
% what we actually need to produce is a definition of the form
% \begin{quote}
% |\def\u8:|$t_{\rm C2}$$t_{\rm A3}$ |{|\textit{\LaTeX{} internal form}|}|\,.
% \end{quote}
% So here we temporarily redefine the prefix commands
% |\UTFviii@two@octets|, etc.~to
% generate the csname that we wish to define> the |\string|s are
% added in case these tokens are still active.
% \begin{macrocode}
\def\UTFviii@two@octets##1##2{\csname u8:##1\string##2\endcsname}%
\def\UTFviii@three@octets##1##2##3{\csname u8:##1%
\string##2\string##3\endcsname}%
\def\UTFviii@four@octets##1##2##3##4{\csname u8:##1%
\string##2\string##3\string##4\endcsname}%
% \end{macrocode}
% Now we simply:-) need to use the right number of |\expandafter|s to
% finally construct the definition: expanding |\UTFviii@tmp| once to get
% its contents, a second time to replace the prefix command by its
% |\csname| expansion, and a third time to turn the expansion into
% a csname after which the |\gdef| finally gets applied.
% We add an irrelevant |\IeC| and braces around the definition, in
% order to avoid any space after the command being gobbled up
% when the text is written out to an auxiliary file (see
% \texttt{inputenc} for further details
% \begin{macrocode}
\expandafter\expandafter\expandafter
\expandafter\expandafter\expandafter
\expandafter
\gdef\UTFviii@tmp{\IeC{#2}}%
\endgroup
}
% \end{macrocode}
% \end{macro}
%
%
% \begin{macro}{\parse@XML@charref}
% This macro parses a Unicode number (decimal) and returns its
% UTF-8 representation as a sequence of non-active \TeX{} character
% tokens. In the
% original code it had two arguments delimited by \texttt{;} here,
% however, we supply the Unicode number implicitly.
% \begin{macrocode}
\gdef\parse@XML@charref{%
% \end{macrocode}
% We need to keep a few things local, mainly the |\uccode|'s that
% are set up below. However, the group originally used here is
% actually unnecessary since we call this macro only within another
% group; but it will be important to restore the group if this
% macro gets used for other purposes.
% \begin{macrocode}
% \begingroup
% \end{macrocode}
% The original code from \texttt{xmltex} supported the convention that a
% Unicode slot number could be given either as a decimal or as a
% hexadecimal (by starting with \texttt{x}). We do not do this so
% this code is also removed. This could be reactivated if one
% wants to support document commands that accept Unicode numbers
% (but then the first case needs to be changed from an error
% message back to something more useful again).
% \begin{macrocode}
% \uppercase{\count@\if x\noexpand#1"\else#1\fi#2}\relax
% \end{macrocode}
% As |\count@| already contains the right value we make
% |\parse@XML@charref| work without arguments.
% \changes{v1.1g}{2005/09/27}{Real spaces do not show up so use \cs{space}}
% \changes{v1.2a}{2018/03/24}{Allow control characters if active}
% In the case single byte UTF-8 sequences, only allow definition if
% the character os already active. The definition of |\UTFviii@tmp|
% looks slightly strange but is designed for the sequence of |\expandafter|
% in |\DeclareUnicodeCharacter|.
%
% \changes{v1.2o}{2021/12/13}{Use 80 not A0 to test for single byte UTF-8}
% \begin{macrocode}
\ifnum\count@<"80\relax
\ifnum\catcode\count@=13
\uccode`\~=\count@\uppercase{\def\UTFviii@tmp{\@empty\@empty~}}%
\else
\@latex@error{Cannot define non-active Unicode char value < 0080}%
\@eha
\def\UTFviii@tmp{\UTFviii@tmp}%
\fi
% \end{macrocode}
% The code below is derived from \texttt{xmltex} and generates the UTF-8 byte sequence
% for the number in |\count@|.
%
% The reverse operation (just used in error messages)
% has now been added as \cs{decode@UTFviii}.
% \begin{macrocode}
\else\ifnum\count@<"800\relax
\parse@UTFviii@a,%
\parse@UTFviii@b C\UTFviii@two@octets.,%
\else\ifnum\count@<"10000\relax
\parse@UTFviii@a;%
\parse@UTFviii@a,%
\parse@UTFviii@b E\UTFviii@three@octets.{,;}%
\else
% \end{macrocode}
%
% Test added here for out of range values, the 4-octet definitions are still set up
% so that |\DeclareUnicodeCharacter| does something sensible if the user scrolls
% past this error.
% \begin{macrocode}
\ifnum\count@>"10FFFF\relax
\@latex@error
{\UTFviii@hexnumber\count@\space too large for Unicode}%
{Values between 0 and 10FFFF are permitted}%
\fi
% \end{macrocode}
%
% \begin{macrocode}
\parse@UTFviii@a;%
\parse@UTFviii@a,%
\parse@UTFviii@a!%
\parse@UTFviii@b F\UTFviii@four@octets.{!,;}%
\fi
\fi
\fi
% \endgroup
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\parse@UTFviii@a}
% \ldots so somebody else can document this part :-)
% \changes{v1.1b}{2004/02/09}{Space in the wrong place \cs{count @64}}
% \begin{macrocode}
\gdef\parse@UTFviii@a#1{%
\@tempcnta\count@
\divide\count@ 64
\@tempcntb\count@
\multiply\count@ 64
\advance\@tempcnta-\count@
\advance\@tempcnta 128
\uccode`#1\@tempcnta
\count@\@tempcntb}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\parse@UTFviii@b}
% \ldots same here
% \begin{macrocode}
\gdef\parse@UTFviii@b#1#2#3#4{%
\advance\count@ "#10\relax
\uccode`#3\count@
\uppercase{\gdef\UTFviii@tmp{#2#3#4}}}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\decode@UTFviii}
% \changes{v1.1o}{2015/08/28}{Macro added}
% In the reverse direction, take a sequence of octets(bytes)
% representing a character in UTF-8 and construct the Unicode number.
% The sequence is terminated by |\relax|.
%
% In this version, if the sequence is not valid UTF-8 you probably
% get a low level arithmetic error from |\numexpr| or stray characters
% at the end. Getting a better error message would be somewhat expensive.
% As the main use is for reporting characters in messages, this is done
% just using expansion, so |\numexpr| is used, A stub returning 0 is defined
% if |\numexpr| is not available.
% \begin{macrocode}
\ifx\numexpr\@undefined
% \end{macrocode}
%
% \begin{macrocode}
\gdef\decode@UTFviii#1{0}
% \end{macrocode}
%
% \begin{macrocode}
\else
% \end{macrocode}
%
% If the input is malformed UTF-8 there may not be enough closing ) so
% add 5 so there are always some remaining then cleanup and remove
% any remaining ones at the end. This avoids |\numexpr| parse errors
% while outputting a package error.
% \begin{macrocode}
\gdef\decode@UTFviii#1\relax{%
\expandafter\UTFviii@cleanup
\the\numexpr\dec@de@UTFviii#1\relax)))))\@empty}
% \end{macrocode}
%
% \begin{macrocode}
\gdef\UTFviii@cleanup#1)#2\@empty{#1}
% \end{macrocode}
%
% \begin{macrocode}
\gdef\dec@de@UTFviii#1{%
\ifx\relax#1%
\else
\ifnum`#1>"EF
((((`#1-"F0)%
\else
\ifnum`#1>"DF
(((`#1-"E0)%
\else
\ifnum`#1>"BF
((`#1-"C0)%
\else
\ifnum`#1>"7F
)*64+(`#1-"80)%
\else
+`#1 %
\fi
\fi
\fi
\fi
\expandafter\dec@de@UTFviii
\fi}
% \end{macrocode}
%
% \begin{macrocode}
\fi
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\UTFviii@hexnumber}
% \changes{v1.1o}{2015/08/28}{Macro added}
% Convert a number to a sequence of uppercase hex digits.
% If |\numexpr| is not available, it returns its argument unchanged.
% \begin{macrocode}
\ifx\numexpr\@undefined
% \end{macrocode}
% \begin{macrocode}
\global\let\UTFviii@hexnumber\@firstofone
\global\UTFviii@hexdigit\hexnumber@
% \end{macrocode}
% \begin{macrocode}
\else
% \end{macrocode}
% \begin{macrocode}
\gdef\UTFviii@hexnumber#1{%
\ifnum#1>15 %
\expandafter\UTFviii@hexnumber\expandafter{\the\numexpr(#1-8)/16\relax}%
\fi
\UTFviii@hexdigit{\numexpr#1\ifnum#1>0-((#1-8)/16)*16\fi\relax}%
}
% \end{macrocode}
%
% Almost but not quite |\hexnumber@|.
% \begin{macrocode}
\gdef\UTFviii@hexdigit#1{\ifcase\numexpr#1\relax
0\or1\or2\or3\or4\or5\or6\or7\or8\or9\or
A\or B\or C\or D\or E\or F\fi}
% \end{macrocode}
%
% \begin{macrocode}
\fi
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\UTFviii@splitcsname}
% \changes{v1.1o}{2015/08/28}{Macro added}
% \begin{macro}{\UTFviii@hexcodepoint}
% \changes{v1.2e}{2018/09/28}{Macro added: Format codepoint properly}
% Split a csname representing a unicode character and return
% the character and the unicode number in hex.
% \begin{macrocode}
\gdef\UTFviii@hexcodepoint#1{U+%
\ifnum#1<16 0\fi
\ifnum#1<256 0\fi
\ifnum#1<4096 0\fi
\UTFviii@hexnumber{#1}%
}%
\gdef\UTFviii@splitcsname#1:#2\relax{%
% \end{macrocode}
% \changes{v1.2b}{2018/03/26}{add percent as \cs{endlinechar} not -1 in the format}%
% Need to pre-expand the argument to ensure cleanup in case of mal-formed UTF-8.
% \begin{macrocode}
#2 (\expandafter\UTFviii@hexcodepoint\expandafter{%
\the\numexpr\decode@UTFviii#2\relax})%
}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
\endgroup
% \end{macrocode}
%
% \begin{macrocode}
\@onlypreamble\DeclareUnicodeCharacter
% \end{macrocode}
% These are preamble only as long as we don't support Unicode