<section xmlns="http://docbook.org/ns/docbook" version="5.0"
xml:id="appendix.porting.doc" xreflabel="Documentation Hacking">
<?dbhtml filename="documentation_hacking.html"?>
<info><title>Writing and Generating Documentation</title>
<keywordset>
<keyword>ISO C++</keyword>
<keyword>documentation</keyword>
<keyword>style</keyword>
<keyword>docbook</keyword>
<keyword>doxygen</keyword>
</keywordset>
</info>
<section xml:id="doc.intro">
<info>
<title>Introduction</title>
</info>
<para>
Documentation for the GNU C++ Library is created from three
independent sources: a manual, a FAQ, and an API reference.
</para>
<para>
The sub-directory <filename class="directory">doc</filename>
within the main source directory contains
<filename>Makefile.am</filename> and
<filename>Makefile.in</filename>, which provide rules for
generating documentation, described in excruciating detail
below. The <filename class="directory">doc</filename>
sub-directory also contains three directories: <filename
class="directory">doxygen</filename>, which contains scripts and
fragments for <command>doxygen</command>, <filename
class="directory">html</filename>, which contains an html
version of the manual, and <filename
class="directory">xml</filename>, which contains an xml version
of the manual.
</para>
<para>
Diverging from established documentation conventions in the rest
of the GCC project, libstdc++ does not use Texinfo as a markup
language. Instead, Docbook is used to create the manual and the
FAQ, and Doxygen is used to construct the API
reference. Although divergent, this conforms to the GNU Project
recommendations as long as the output is of sufficient quality,
as per
<link xmlns:xlink="http://www.w3.org/1999/xlink"
xlink:href="http://www.gnu.org/prep/standards/standards.html#Documentation">
GNU Manuals</link>.
</para>
</section>
<section xml:id="doc.generation">
<info>
<title>Generating Documentation</title>
</info>
<para>
Certain Makefile rules are required by the GNU Coding
Standards. These standard rules generate HTML, PDF, XML, or man
files. For each of the generative rules, there is an additional
install rule that is used to install any generated documentation
files into the prescribed installation directory. Files are
installed into <filename class="directory">share/doc</filename>
or <filename class="directory">share/man</filename> directories.
</para>
<para>
The standard Makefile rules are conditionally supported, based
on the results of examining the host environment for
prerequisites at configuration time. If requirements are not
found, the rule is aliased to a dummy rule that does nothing,
and produces no documentation. If the requirements are found,
the rule forwards to a private rule that produces the requested
documentation.
</para>
<para>
For more details on what prerequisites were found and where,
please consult the file <filename>config.log</filename> in the
libstdc++ build directory. Compare this log to what is expected
for the relevant Makefile conditionals:
<literal>BUILD_INFO</literal>, <literal>BUILD_XML</literal>,
<literal>BUILD_HTML</literal>, <literal>BUILD_MAN</literal>,
<literal>BUILD_PDF</literal>, and <literal>BUILD_EPUB</literal>.
</para>
<para>
Supported Makefile rules:
</para>
<variablelist>
<varlistentry>
<term>
<emphasis>make html</emphasis>
</term>
<term>
<emphasis>make install-html</emphasis>
</term>
<listitem>
<para>
Generates multi-page HTML documentation, and installs it
in the following directories:
</para>
<para>
<filename>doc/libstdc++/libstdc++-api.html</filename>
</para>
<para>
<filename>doc/libstdc++/libstdc++-manual.html</filename>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<emphasis>make pdf</emphasis>
</term>
<term>
<emphasis>make install-pdf</emphasis>
</term>
<listitem>
<para>
Generates indexed PDF documentation, and installs it as
the following files:
</para>
<para>
<filename>doc/libstdc++/libstdc++-api.pdf</filename>
</para>
<para>
<filename>doc/libstdc++/libstdc++-manual.pdf</filename>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<emphasis>make man</emphasis>
</term>
<term>
<emphasis>make install-man</emphasis>
</term>
<listitem>
<para>
Generates man pages, and installs it in the following directory:
</para>
<para>
<filename class="directory">man/man3/</filename>
</para>
<para>
The generated man pages are namespace-qualified, so to look at
the man page for <classname>vector</classname>, one would use
<command>man std::vector</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<emphasis>make epub</emphasis>
</term>
<term>
<emphasis>make install-epub</emphasis>
</term>
<listitem>
<para>
Generates documentation in the ebook/portable electronic
reader format called Epub, and installs it as the
following file.
</para>
<para>
<filename>doc/libstdc++/libstdc++-manual.epub</filename>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<emphasis>make xml</emphasis>
</term>
<term>
<emphasis>make install-xml</emphasis>
</term>
<listitem>
<para>
Generates single-file XML documentation, and installs it
as the following files:
</para>
<para>
<filename>doc/libstdc++/libstdc++-api-single.xml</filename>
</para>
<para>
<filename>doc/libstdc++/libstdc++-manual-single.xml</filename>
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
Makefile rules for several other formats are explicitly not
supported, and are always aliased to dummy rules. These
unsupported formats are: <emphasis>info</emphasis>,
<emphasis>ps</emphasis>, and <emphasis>dvi</emphasis>.
</para>
</section>
<section xml:id="doc.doxygen"><info><title>Doxygen</title></info>
<section xml:id="doxygen.prereq"><info><title>Prerequisites</title></info>
<table frame="all" xml:id="table.doxygen_prereq">
<title>Doxygen Prerequisites</title>
<tgroup cols="3" align="center" colsep="1" rowsep="1">
<colspec colname="c1"/>
<colspec colname="c2"/>
<colspec colname="c3"/>
<thead>
<row>
<entry>Tool</entry>
<entry>Version</entry>
<entry>Required By</entry>
</row>
</thead>
<tbody>
<row>
<entry>coreutils</entry>
<entry>8.5</entry>
<entry>all</entry>
</row>
<row>
<entry>bash</entry>
<entry>4.1</entry>
<entry>all</entry>
</row>
<row>
<entry>doxygen</entry>
<entry>1.7.6.1</entry>
<entry>all</entry>
</row>
<row>
<entry>graphviz</entry>
<entry>2.26</entry>
<entry>graphical hierarchies</entry>
</row>
<row>
<entry>pdflatex</entry>
<entry>2007-59</entry>
<entry>pdf output</entry>
</row>
</tbody>
</tgroup>
</table>
<para>
Prerequisite tools are Bash 2.0 or later,
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.doxygen.nl">Doxygen</link>, and
the <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.gnu.org/software/coreutils/">GNU
coreutils</link>. (GNU versions of find, xargs, and possibly
sed and grep are used, just because the GNU versions make
things very easy.)
</para>
<para>
To generate the pretty pictures and hierarchy
graphs, the
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.graphviz.org">Graphviz</link> package
will need to be installed. For PDF
output, <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://tug.org/applications/pdftex/">
pdflatex</link> is required as well as a number of TeX packages
such as <package>texlive-xtab</package> and
<package>texlive-tocloft</package>.
</para>
<para>
Be warned the PDF file generated via doxygen is extremely
large. At last count, the PDF file is over three thousand
pages. Generating this document taxes the underlying TeX
formatting system, and will require the expansion of TeX's memory
capacity. Specifically, the <literal>pool_size</literal>
variable in the configuration file <filename>texmf.cnf</filename> may
need to be increased by a minimum factor of two. Alternatively, using
<userinput>LATEX_CMD=lualatex</userinput> might allow the docs to be
build without running out of memory.
</para>
</section>
<section xml:id="doxygen.rules"><info><title>Generating the Doxygen Files</title></info>
<para>
The following Makefile rules run Doxygen to generate HTML
docs, XML docs, XML docs as a single file, PDF docs, and the
man pages. These rules are not conditional! If the required
tools are not found, or are the wrong versions, the rule may
end in an error.
</para>
<para>
<screen><userinput>make doc-html-doxygen</userinput></screen>
</para>
<para>
<screen><userinput>make doc-xml-doxygen</userinput></screen>
</para>
<para>
<screen><userinput>make doc-xml-single-doxygen</userinput></screen>
</para>
<para>
<screen><userinput>make doc-pdf-doxygen</userinput></screen>
</para>
<para>
<screen><userinput>make doc-man-doxygen</userinput></screen>
</para>
<para>
Generated files are output into separate sub directories of
<filename class="directory">doc/doxygen/</filename> in the
build directory, based on the output format. For instance, the
HTML docs will be in <filename class="directory">doc/doxygen/html</filename>.
</para>
<para>
Careful observers will see that the Makefile rules simply call
a script from the source tree, <filename>run_doxygen</filename>, which
does the actual work of running Doxygen and then (most
importantly) massaging the output files. If for some reason
you prefer to not go through the Makefile, you can call this
script directly. (Start by passing <literal>--help</literal>.)
</para>
<para>
If you wish to tweak the Doxygen settings, do so by editing
<filename>doc/doxygen/user.cfg.in</filename>. Notes to fellow
library hackers are written in triple-# comments.
</para>
</section>
<section xml:id="doxygen.debug">
<info><title>Debugging Generation</title></info>
<para>
Sometimes, mis-configuration of the pre-requisite tools can
lead to errors when attempting to build the
documentation. Here are some of the obvious errors, and ways
to fix some common issues that may appear quite cryptic.
</para>
<para>
First, if using a rule like <code>make pdf</code>, try to
narrow down the scope of the error to either docbook
(<code>make doc-pdf-docbook</code>) or doxygen (<code>make
doc-pdf-doxygen</code>).
</para>
<para>
Working on the doxygen path only, closely examine the
contents of the following build directory: <filename
class="directory">build/target/libstdc++-v3/doc/doxygen/latex</filename>.
Pay attention to three files enclosed within, annotated as follows.
</para>
<itemizedlist>
<listitem>
<para>
<emphasis>refman.tex</emphasis>
</para>
<para>
The actual latex file, or partial latex file. This is generated
via <command>doxygen</command>, and is the LaTeX version of the
Doxygen XML file <filename>libstdc++-api.xml</filename>. Go to a specific
line, and look at the generated LaTeX, and try to deduce what
markup in <filename>libstdc++-api.xml</filename> is causing it.
</para>
</listitem>
<listitem>
<para>
<emphasis>refman.log</emphasis>
</para>
<para>
A log created by <command>latex</command> as it processes the
<filename>refman.tex</filename> file. If generating the PDF fails
look at the end of this file for errors such as:
<screen>
! LaTeX Error: File `xtab.sty' not found.
</screen>
This indicates a required TeX package is missing. For the example
above the <package>texlive-xtab</package> package needs to be
installed.
</para>
</listitem>
<listitem>
<para>
<emphasis>refman.out</emphasis>
</para>
<para>
A log of the compilation of the converted LaTeX form to PDF. This
is a linear list, from the beginning of the
<filename>refman.tex</filename> file: the last entry of this file
should be the end of the LaTeX file. If it is truncated, then you
know that the last entry is the last part of the generated LaTeX
source file that is valid. Often this file contains an error with
a specific line number of <filename>refman.tex</filename> that is
incorrect, or will have clues at the end of the file with the dump
of the memory usage of LaTeX.
</para>
</listitem>
</itemizedlist>
<para>
If the error at hand is not obvious after examination, a
fall-back strategy is to start commenting out the doxygen
input sources, which can be found in
<filename>doc/doxygen/user.cfg.in</filename>, look for the
<literal>INPUT</literal> tag. Start by commenting out whole
directories of header files, until the offending header is
identified. Then, read the latex log files to try and find
surround text, and look for that in the offending header.
</para>
</section>
<section xml:id="doxygen.markup"><info><title>Markup</title></info>
<para>
In general, libstdc++ files should be formatted according to
the rules found in the
<link linkend="contrib.coding_style">Coding Standard</link>. Before
any doxygen-specific formatting tweaks are made, please try to
make sure that the initial formatting is sound.
</para>
<para>
Adding Doxygen markup to a file (informally called
<quote>doxygenating</quote>) is very simple. See the
<link xmlns:xlink="http://www.w3.org/1999/xlink"
xlink:href="https://www.doxygen.nl/download.html#latestman">Doxygen
manual</link> for details.
We try to use a very-recent version of Doxygen.
</para>
<para>
For classes, use
<classname>deque</classname>/<classname>vector</classname>/<classname>list</classname>
and <classname>std::pair</classname> as examples. For
functions, see their member functions, and the free functions
in <filename class="headerfile">stl_algobase.h</filename>. Member
functions of other container-like types should read similarly to
these member functions.
</para>
<para>
Some commentary to accompany
the first list in the <link xmlns:xlink="http://www.w3.org/1999/xlink"
xlink:href="https://www.doxygen.nl/manual/docblocks.html">Special
Documentation Blocks</link> section of the Doxygen manual:
</para>
<orderedlist inheritnum="ignore" continuation="restarts">
<listitem>
<para>For longer comments, use the Javadoc style...</para>
</listitem>
<listitem>
<para>
...not the Qt style. The intermediate *'s are preferred.
</para>
</listitem>
<listitem>
<para>
Use the triple-slash style only for one-line comments (the
<quote>brief</quote> mode).
</para>
</listitem>
<listitem>
<para>
This is disgusting. Don't do this.
</para>
</listitem>
</orderedlist>
<para>
Some specific guidelines:
</para>
<para>
Use the @-style of commands, not the !-style. Please be
careful about whitespace in your markup comments. Most of the
time it doesn't matter; doxygen absorbs most whitespace, and
both HTML and *roff are agnostic about whitespace. However,
in <pre> blocks and @code/@endcode sections, spacing can
have <quote>interesting</quote> effects.
</para>
<para>
Use either kind of grouping, as
appropriate. <filename>doxygroups.cc</filename> exists for this
purpose. See <filename class="headerfile">stl_iterator.h</filename>
for a good example of the <quote>other</quote> kind of grouping.
</para>
<para>
Markdown can be used for formatting text. Doxygen is configured to
support this, and it is a good compromise between readable comments
in the C++ source and nice formatting in the generated HTML.
Please format the names of function parameters in either code font
or italics. Use underscores or @e for emphasis when necessary.
Use backticks or @c to refer to other standard names.
(Examples of all these abound in the present code.)
</para>
<para>
Complicated math functions should use the multi-line format.
An example from <filename class="headerfile">random.h</filename>:
</para>
<para>
<literallayout class="normal">
/**
* @brief A model of a linear congruential random number generator.
*
* @f[
* x_{i+1}\leftarrow(ax_{i} + c) \bmod m
* @f]
*/
</literallayout>
</para>
<para>
One area of note is the markup required for
<literal>@file</literal> markup in header files. Two details
are important: for filenames that have the same name in
multiple directories, include part of the installed path to
disambiguate. For example:
</para>
<para>
<literallayout class="normal">
/** @file debug/vector
* This file is a GNU debug extension to the Standard C++ Library.
*/
</literallayout>
</para>
<para>
The other relevant detail for header files is the use of a
libstdc++-specific doxygen alias that helps distinguish
between public header files (like <filename class="headerfile">random</filename>)
from implementation or private header files (like
<filename class="headerfile">bits/c++config.h</filename>.) This alias is spelled
<literal>@headername</literal> and can take one or two
arguments that detail the public header file or files that
should be included to use the contents of the file. All header
files that are not intended for direct inclusion must use
<literal>headername</literal> in the <literal>file</literal>
block. An example:
</para>
<para>
<literallayout class="normal">
/** @file bits/basic_string.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{string}
*/
</literallayout>
</para>
<para>
Be careful about using certain, special characters when
writing Doxygen comments. Single and double quotes, and
separators in filenames are two common trouble spots. When in
doubt, consult the following table.
</para>
<table frame="all" xml:id="table.doxygen_cmp">
<title>HTML to Doxygen Markup Comparison</title>
<tgroup cols="2" align="left" colsep="1" rowsep="1">
<colspec colname="c1"/>
<colspec colname="c2"/>
<thead>
<row>
<entry>HTML</entry>
<entry>Doxygen</entry>
<entry>Markdown</entry>
</row>
</thead>
<tbody>
<row>
<entry>\</entry>
<entry>\\</entry>
<entry>\\</entry>
</row>
<row>
<entry>"</entry>
<entry>\"</entry>
<entry>\"</entry>
</row>
<row>
<entry>'</entry>
<entry>\'</entry>
<entry>\'</entry>
</row>
<row>
<entry><i></entry>
<entry>@a word</entry>
<entry>_word_ or *word*</entry>
</row>
<row>
<entry><b></entry>
<entry>@b word</entry>
<entry>**word** or __word__</entry>
</row>
<row>
<entry><code></entry>
<entry>@c word</entry>
<entry>`word`</entry>
</row>
<row>
<entry><em></entry>
<entry>@a word</entry>
<entry>_word_ or *word*</entry>
</row>
<row>
<entry><em></entry>
<entry><em>two words or more</em></entry>
<entry>_two words or more_</entry>
</row>
</tbody>
</tgroup>
</table>
</section>
</section>
<section xml:id="doc.docbook"><info><title>Docbook</title></info>
<section xml:id="docbook.prereq"><info><title>Prerequisites</title></info>
<table frame="all" xml:id="table.docbook_prereq">
<title>Docbook Prerequisites</title>
<tgroup cols="3" align="center" colsep="1" rowsep="1">
<colspec colname="c1"/>
<colspec colname="c2"/>
<colspec colname="c3"/>
<thead>
<row>
<entry>Tool</entry>
<entry>Version</entry>
<entry>Required By</entry>
</row>
</thead>
<tbody>
<row>
<entry>docbook5-style-xsl</entry>
<entry>1.76.1</entry>
<entry>all</entry>
</row>
<row>
<entry>xsltproc</entry>
<entry>1.1.26</entry>
<entry>all</entry>
</row>
<row>
<entry>xmllint</entry>
<entry>2.7.7</entry>
<entry>validation</entry>
</row>
<row>
<entry>dblatex</entry>
<entry>0.3</entry>
<entry>pdf output</entry>
</row>
<row>
<entry>pdflatex</entry>
<entry>2007-59</entry>
<entry>pdf output</entry>
</row>
<row>
<entry>docbook2X</entry>
<entry>0.8.8</entry>
<entry>info output</entry>
</row>
<row>
<entry>epub3 stylesheets</entry>
<entry>b3</entry>
<entry>epub output</entry>
</row>
</tbody>
</tgroup>
</table>
<para>
An XML editor is recommended for editing the DocBook sources. Many
exist: some notable options
include <command>emacs</command>, <application>Kate</application>,
or <application>Conglomerate</application>.
</para>
<para>
Some editors support special <quote>XML Validation</quote>
modes that can validate the file as it is
produced. Recommended is the <command>nXML Mode</command>
for <command>emacs</command>.
</para>
<para>
Besides an editor, additional DocBook files and XML tools are
also required.
</para>
<para>
Access to the DocBook 5.0 stylesheets and schema is required. The
stylesheets are usually packaged by vendor, in something
like <filename>docbook5-style-xsl</filename>. To exactly match
generated output, please use a version of the stylesheets
equivalent
to <filename>docbook5-style-xsl-1.75.2-3</filename>. The
installation directory for this package corresponds to
the <literal>XSL_STYLE_DIR</literal>
in <filename>doc/Makefile.am</filename> and defaults
to <filename class="directory">/usr/share/sgml/docbook/xsl-ns-stylesheets</filename>.
</para>
<para>
For processing XML, an XSLT processor and some style
sheets are necessary. Defaults are <command>xsltproc</command>
provided by <filename>libxslt</filename>.
</para>
<para>
For validating the XML document, you'll need
something like <command>xmllint</command> and access to the
relevant DocBook schema. These are provided
by a vendor package like <filename>libxml2</filename> and <filename>docbook5-schemas-5.0-4</filename>
</para>
<para>
For PDF output, something that transforms valid Docbook XML to PDF is
required. Possible solutions include <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://dblatex.sourceforge.net">dblatex</link>,
<command>xmlto</command>, or <command>prince</command>. Of
these, <command>dblatex</command> is the default.
Please consult the <email>libstdc++@gcc.gnu.org</email> list when
preparing printed manuals for current best practice and
suggestions.
</para>
<para>
For Texinfo output, something that transforms valid Docbook
XML to Texinfo is required. The default choice is <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://docbook2x.sourceforge.net/">docbook2X</link>.
</para>
<para>
For epub output, the <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://sourceforge.net/projects/docbook/files/epub3/">stylesheets</link> for EPUB3 are required. These stylesheets are still in development. To validate the created file, <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://github.com/w3c/epubcheck">epubcheck</link> is necessary.
</para>
</section>
<section xml:id="docbook.rules"><info><title>Generating the DocBook Files</title></info>
<para>
The following Makefile rules generate (in order): an HTML
version of all the DocBook documentation, a PDF version of the
same, and a single XML document. These rules are not
conditional! If the required tools are not found, or are the
wrong versions, the rule may end in an error.
</para>
<para>
<screen><userinput>make doc-html-docbook</userinput></screen>
</para>
<para>
<screen><userinput>make doc-pdf-docbook</userinput></screen>
</para>
<para>
<screen><userinput>make doc-xml-single-docbook</userinput></screen>
</para>
<para>
Generated files are output into separate sub-directores of
<filename class="directory">doc/docbook/</filename> in the
build directory, based on the output format. For instance, the
HTML docs will be in <filename
class="directory">doc/docbook/html</filename>.
</para>
<para>
The <userinput>doc-html-docbook-regenerate</userinput> target will
generate the HTML files and copy them back to the libstdc++ source tree.
This can be used to update the HTML files that are checked in to
version control.
</para>
<para>
If the Docbook stylesheets are installed in a custom location,
one can use the variable <literal>XSL_STYLE_DIR</literal> to
override the Makefile defaults. For example:
</para>
<screen>
<userinput>
make <literal>XSL_STYLE_DIR="/usr/share/xml/docbook/stylesheet/nwalsh"</literal> doc-html-docbook
</userinput>
</screen>
</section>
<section xml:id="docbook.debug">
<info><title>Debugging Generation</title></info>
<para>
Sometimes, mis-configuration of the pre-requisite tools can
lead to errors when attempting to build the
documentation. Here are some of the obvious errors, and ways
to fix some common issues that may appear quite cryptic.
</para>
<para>
First, if using a rule like <code>make pdf</code>, try to
narrow down the scope of the error to either docbook
(<code>make doc-pdf-docbook</code>) or doxygen (<code>make
doc-pdf-doxygen</code>).
</para>
<para>
Working on the docbook path only, closely examine the
contents of the following build directory:
<filename class="directory">build/target/libstdc++-v3/doc/docbook/latex</filename>.
Pay attention to three files enclosed within, annotated as follows.
</para>
<itemizedlist>
<listitem>
<para>
<emphasis>spine.tex</emphasis>
</para>
<para>
The actual latex file, or partial latex file. This is generated
via <command>dblatex</command>, and is the LaTeX version of the
DocBook XML file <filename>spine.xml</filename>. Go to a specific
line, and look at the generated LaTeX, and try to deduce what
markup in <filename>spine.xml</filename> is causing it.
</para>
</listitem>
<listitem>
<para>
<emphasis>spine.out</emphasis>
</para>
<para>
A log of the conversion from the XML form to the LaTeX form. This
is a linear list, from the beginning of the
<filename>spine.xml</filename> file: the last entry of this file
should be the end of the DocBook file. If it is truncated, then
you know that the last entry is the last part of the XML source
file that is valid. The error is after this point.
</para>
</listitem>
<listitem>
<para>
<emphasis>spine.log</emphasis>
</para>
<para>
A log of the compilation of the converted LaTeX form to pdf. This
is a linear list, from the beginning of the
<filename>spine.tex</filename> file: the last entry of this file
should be the end of the LaTeX file. If it is truncated, then you
know that the last entry is the last part of the generated LaTeX
source file that is valid. Often this file contains an error with
a specific line number of <filename>spine.tex</filename> that is
incorrect.
</para>
</listitem>
</itemizedlist>
<para>
If the error at hand is not obvious after examination, or if one
encounters the inscruitable <quote>Incomplete
\ifmmode</quote> error, a fall-back strategy is to start
commenting out parts of the XML document (regardless of what
this does to over-all document validity). Start by
commenting out each of the largest parts of the
<filename>spine.xml</filename> file, section by section,
until the offending section is identified.
</para>
</section>
<section xml:id="docbook.validation"><info><title>Editing and Validation</title></info>
<para>
After editing the xml sources, please make sure that the XML
documentation and markup is still valid. This can be
done easily, with the following validation rule:
</para>
<screen>
<userinput>make doc-xml-validate-docbook</userinput>
</screen>
<para>
This is equivalent to doing:
</para>
<screen>
<userinput>
xmllint --noout --valid <filename>xml/index.xml</filename>
</userinput>
</screen>
<para>
Please note that individual sections and chapters of the
manual can be validated by substituting the file desired for
<filename>xml/index.xml</filename> in the command
above. Reducing scope in this manner can be helpful when
validation on the entire manual fails.
</para>
<para>
All Docbook xml sources should always validate. No excuses!
</para>
</section>
<section xml:id="docbook.examples"><info><title>File Organization and Basics</title></info>
<literallayout class="normal">
<emphasis>Which files are important</emphasis>
All Docbook files are in the directory
libstdc++-v3/doc/xml
Inside this directory, the files of importance:
spine.xml - index to documentation set
manual/spine.xml - index to manual
manual/*.xml - individual chapters and sections of the manual
faq.xml - index to FAQ
api.xml - index to source level / API
All *.txml files are template xml files, i.e., otherwise empty files with
the correct structure, suitable for filling in with new information.
<emphasis>Canonical Writing Style</emphasis>
class template
function template
member function template
(via C++ Templates, Vandevoorde)
class in namespace std: allocator, not std::allocator
header file: iostream, not <iostream>
<emphasis>General structure</emphasis>
<set>
<book>
</book>
<book>
<chapter>
</chapter>
</book>
<book>
<part>
<chapter>
<section>
</section>
<sect1>
</sect1>
<sect1>
<sect2>
</sect2>
</sect1>
</chapter>
<chapter>
</chapter>
</part>
</book>
</set>
</literallayout>
</section>
<section xml:id="docbook.markup"><info><title>Markup By Example</title></info>
<para>
Complete details on Docbook markup can be found in the
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://tdg.docbook.org/tdg/5.0/ref-elements.html">DocBook Element Reference</link>.
An incomplete reference for HTML to Docbook conversion is
detailed in the table below.
</para>
<table frame="all" xml:id="table.docbook_cmp">
<title>HTML to Docbook XML Markup Comparison</title>
<tgroup cols="2" align="left" colsep="1" rowsep="1">
<colspec colname="c1"/>
<colspec colname="c2"/>
<thead>
<row>
<entry>HTML</entry>
<entry>Docbook</entry>
</row>
</thead>
<tbody>
<row>
<entry><p></entry>
<entry><para></entry>
</row>
<row>
<entry><pre></entry>
<entry><computeroutput>, <programlisting>,
<literallayout></entry>
</row>
<row>
<entry><ul></entry>
<entry><itemizedlist></entry>
</row>
<row>
<entry><ol></entry>
<entry><orderedlist></entry>
</row>
<row>
<entry><il></entry>
<entry><listitem></entry>
</row>
<row>
<entry><dl></entry>
<entry><variablelist></entry>
</row>
<row>
<entry><dt></entry>
<entry><term></entry>
</row>
<row>
<entry><dd></entry>
<entry><listitem></entry>
</row>
<row>
<entry><a href=""></entry>
<entry><ulink url=""></entry>
</row>
<row>
<entry><code></entry>
<entry><literal>, <programlisting></entry>
</row>
<row>
<entry><strong></entry>
<entry><emphasis></entry>
</row>
<row>
<entry><em></entry>
<entry><emphasis></entry>
</row>
<row>
<entry>"</entry>
<entry><quote></entry>
</row>
</tbody>
</tgroup>
</table>
<para>
And examples of detailed markup for which there are no real HTML
equivalents are listed in the table below.
</para>
<table frame="all" xml:id="table.docbook_elem">
<title>Docbook XML Element Use</title>
<tgroup cols="2" align="left" colsep="1" rowsep="1">
<colspec colname="c1"/>
<colspec colname="c2"/>
<thead>
<row>
<entry>Element</entry>
<entry>Use</entry>
</row>
</thead>
<tbody>
<row>
<entry><structname></entry>
<entry><structname>char_traits</structname></entry>
</row>
<row>
<entry><classname></entry>
<entry><classname>string</classname></entry>
</row>
<row>
<entry><function></entry>
<entry>
<para><function>clear()</function></para>
<para><function>fs.clear()</function></para>
</entry>
</row>
<row>
<entry><type></entry>
<entry><type>long long</type></entry>
</row>
<row>
<entry><varname></entry>
<entry><varname>fs</varname></entry>
</row>
<row>
<entry><literal></entry>
<entry>
<para><literal>-Weffc++</literal></para>
<para><literal>rel_ops</literal></para>
</entry>
</row>
<row>
<entry><constant></entry>
<entry>
<para><constant>_GNU_SOURCE</constant></para>
<para><constant>3.0</constant></para>
</entry>
</row>
<row>
<entry><command></entry>
<entry><command>g++</command></entry>
</row>
<row>
<entry><errortext></entry>
<entry><errortext>In instantiation of</errortext></entry>
</row>
<row>
<entry><filename></entry>
<entry>
<para><filename class="headerfile">ctype.h</filename></para>
<para><filename class="directory">/home/gcc/build</filename></para>
<para><filename class="libraryfile">libstdc++.so</filename></para>
</entry>
</row>
</tbody>
</tgroup>
</table>
</section>
</section>
</section>