NAME

docbook2latex.xps - an XPathScript stylesheet for LaTeX.

SYNOPSIS

  xpathscript yourdoc.xml docbook2latex.xps > yourdoc.tex

DESCRIPTION

This is docbook2latex.xps version number $Revision: 32928 $, by IDEALX (http://www.idealx.org/docbook2latex/).

Using Matt Sergeant's XPathScript framework (see "SEE ALSO"), this stylesheet translates Docbook XML into LaTeX for beautiful typesetting of Docbook articles (reports, books and other kinds of whole documents defined by the DTD are not supported yet).

Provided you have the Perl dependencies installed (XML::XPathScript, from CPAN, as well as all sub-dependencies of those), the command shown in the synopsis will turn any (DTD-conformant) mydoc.xml into pure LaTeX (that is, using only packages included in the TeTeX distribution to compile). Every unknown Unicode character or XML tag present in the document will trigger appropriate warnings, but the stylesheet will recover nicely and still produce a valid LaTeX output.

This stylesheet supports french and english typesetting, on a per-tag basis.

Of course, I bet you won't be pleased with the aesthetics of the result, or maybe there are some tags (from the 400+ in Docbook) or characters (from the 30000+ in Unicode) that aren't typeset and that you absolutely want. So read on...

USER DOCUMENTATION

CUSTOMIZING AND ADDING FUNCTIONALITY

You could just modify the stylesheet: there are plenty of comments, but grasping the big picture at once can be difficult. Fortunately, XPathScript allows for overload-oriented customization; the same philosophy is followed throughout this stylesheet, so that there are a number graft points (beside whole XML tags, as specified in the XPathScript documentation) where you can modify part of the stylesheet behaviour without interfering with the overall functionality. Working knowledge of XPathScript is assumed (see "SEE ALSO").

An example

Cut-and-paste the following text into test.xps, then run xpathscript mydoc.xml test.xps:

<% our $inhibitOutput; $inhibitOutput++; %>

<!--#include file="docbook2latex.xps"-->

<% $inhibitOutput--; %>

  <%
  # Change the style to add fancy headers and the word "draft" behind
  # every page
  push(@packages,"fancyhdr");
  push(@packages,[ "draftcopy" => "all", "english" ]);

  # override the varname tag to display as sans-serif
  delete $t->{varname}; $t->{varname}->{testcode}=sub {
          my ($self, $return)=@_;
          $return->{pre}='\textss{';
          $return->{post}='}';
          return 0;
  };

  # double the ruler on top of each table.
  our $typeset_tableframe;
  my $ORIG_typeset_tableframe=$typeset_tableframe;
  $typeset_tableframe=sub {
     return '\hline'.($ORIG_typeset_tableframe(@_));
  }

%>

<%= $inhibitOutput ? "" : apply_templates() %>

Modification points

The modification points fall into 3 categories: configuration variables, overridable templates and overridable function references. The example above shows how to override all three.

Environment variables

There is no standard method yet for passing arguments to an XML::XPathScript stylesheet. Waiting for something better, the UNIX environment is used instead. At present, no environment variable is recognized and any customization must be done by a cascading stylesheet (but in order to get customization e.g. for outputting variadic documents, said stylesheet may need to read the environment).

Configuration variables

There are package-global variables that are read at runtime to customize the stylesheet's behaviour. Examples are $fancytables (if true, use the longtable package to typeset tables) and @packages (the list of TeX packages to invoke in the preamble). The list of such configuration variables is shown in "REFERENCE MANUAL".

Overridable templates

As stated in the XPathScript documentation, the $t variable (which is in scope from every < % ... % > construct) holds a reference to a hash of XML element handlers keyed by element name, which can be replaced with your own (see http://axkit.org/docs/xpathscript/guide.dkb?section=6). The code in the templates is fully context-dependent, in that it only ever reads data from the XML document to reach a typesetting decision, and does not use any muddy global variables to pass sticky state information around (the only exception is that a function is allowed to cache its results). This means it is perfectly OK to replace only some of the element handlers with your own, without messing up with the way the others work. Beware though that some tags are not rendered as part of the apply_templates() mechanism, but are treated in an ad-hoc way by the stylesheet - for example, <title> tags are always rendered in TeX as part of the parent <section>, <table>, <figure> or such.

The rule of thumb for overriding templates is: a template for some tag is overridable if and only if it exist()s in the $t hash, and is not listed in the @abstracttags variable provided by the stylesheet as package-global for this purpose.

Overridable function references

In some particularly tedious places of the stylesheet (e.g. for tables), there is a function reference in a package-global variable that holds a function that will be called for typesetting something. For example, &$typeset_tablerow(something) will be called to typeset a row in a table. The list of such function references and their prototypes and expected semantics is described in "REFERENCE MANUAL", so that you may code your own replacements for those in use in this stylesheet.

Unicode guidelines

By far the greatest pain when enhancing this stylesheet (and even before, when writing it...) is Unicode support. XML input through XML::Parser always happens in Unicode, as per the XML standard; Perl stores the result in its new polymorphic strings (with UTF-8 as the in-memory representation) which exhibit the "contamination problem" (see "XML::XPathScript::Toys::translate_node"). LaTeX barfs on Unicode input, of course. Therefore, there needs to be a kind of "unicode firewall" throughout the stylesheet(s) that correctly transcodes every kind of Unicode input into LaTeX (which for our purpose is a subset of Latin1 since we use the inputenc package).

  • Text nodes explicitly computed by user code should be converted using extra utf8tolatin1() or utf8totex() calls (which see) :

      $t->{pre}.=findnodes("/article/articleinfo/title/text()"); # WRONG

    would produce a bogus XML::XPath::Node::Text=SCALAR(0xdeadbeef), while

      $t->{pre}.=findvalue("/article/articleinfo/title/text()"); # WRONG

    as suggested by the XPathScript documentation, would UTF8-taint the result.

    Use this instead:

      my ($node)=findnodes("/article/articleinfo/title/text()"); # WARNING,
         # scalar context would not work - see Quirks.
      $t->{pre}=utf8totex($node);

    or even simpler, use "apply_templates_under" that was created for this very purpose:

      my $rendered=apply_templates_under("/article/articleinfo/title");
  • Element nodes should never be converted to text directly:

        $t->{pre}.=findnodes("/some/path",$self);  # WRONG, as
         # would be any variation thereof with findvalue() or such

    Use something like "apply_templates_under" instead to recurse into their substructure. The rationale is that outputting stringified element nodes only has meaning if the output is XML too, or tagless UTF-8 at the very least, and has no meaning for TeX.

  • XPath values that are not nodes should be dealt with using the UTF8-to-something-else functions:

      $t->{pre}.=utf8totex(findvalue('@url',$self));
    
      my $filename=utf8tolatin1(findvalue('@fileref',$graphicnode));
  • If you don't copy the part of the document into the output but are merely testing something about it, then Unicode won't hurt you. For example, in

       $t->{pre}.="\\textbf{" if (findvalue("@role",$self) eq "strong");

    Here findvalue("@role",$self) is UTF-8 but you won't ever have to bother since it does not make its way to the output stream. The test works as expected ("strong" is promoted to Unicode but this does not change its value), the Boolean test result is not tainted (it never is), and therefore the result, "\\textbf{" is Latin1 as it should.

Quirks

Bugs and oddities were spotted in various places of the Perl XML support software (XML::XPath version 1.12), and the following workarounds were used to circumvent them. You may find it useful to do likewise in your own extensions:

  • the clever object model in XML::XPath with shadow objets geared at good garbage collection gets in the way for the matches() function, which only works toward ancestors of the node (as of version 1.12);

  • findnodes() in scalar context returns an object which is not a node, but an XML::XPath::NodeSet. Be careful to always call it in list context if you are interested in nodes and not NodeSets; if you just want one node, say

       my ($attrnode)=findnodes('@url',$xrefnode);
  • apply_templates() with no arguments does what the spec does, which is exactly what you don't want (re-render the whole document through the stylesheet!). Use apply_templates_under instead:

       $t->{pre}.=apply_templates(findnodes("para",$node)); # WRONG if
                        # findnodes() yields no results
    
       $t->{pre}.=apply_templates_under("para",$node); # OK
  • findnodes() performed on a backward axis (ex 'preceding::') in array context should return the value in reverse document order (according to the XPath spec and reasonable expectation), but doesn't in versions 1.12 and 1.13. The manpage is not clear as to whether this is a bug or a feature. In order to accomodate both possible outcomes of this behaviour (stays the same or is reversed) in future versions of XML::XPath, the reorder_backaxis() function compensates this (see "reorder_backaxis").

See also "Unicode guidelines" which may, as a whole, be considered as a big quirk of its own, and also "Stylesheet Guidelines" in XML::XPathScript.

PROGRAMMING FAQ

I get a strange error about an XPath query with pieces of LaTeX inside, which is nowhere to be found in my source...

This is because your {testcode} routine did not return a satisfactory value. Remember: you have to return -1 ("do not render the subtree of this node, I did it already, just output $t->{pre} and $t->{post} side by side"), 1 ("please render the subtree in full"), 0 ("render nothing at all please") or an XPath expression ("only render those subnodes that match this expression").

Forgetting the return altogether is a common mistake: in the following code, "\end{stuff}" would be the return value, thus causing the reported behaviour:

$t->{sometag}->{testcode}=sub { my ($node,$t)=@_; $t->{pre}="\\begin{stuff}"; $t->{post}="\\end{stuff}"; };

I get an internal error in an XML::XPath module. What next?

Please keep in mind that some XPath expressions, although syntactically correct, lead to errors. Consider the following snippet:

   my $targetname=findvalue("name(id($label))");

It is an error for the XPath function name() to be called with anything but one stringifiable argument. Thus, if $label does not exist, you are screwed - and the evaluation of the XPath expression will produce a most cryptic error. Rewrite your code into this:

   my ($targetnode)=findnodes("id($label)");
   return "" if (! $targetnode);
   my $targetname=findvalue("name()",$targetnode);

(but the real solution in this particular case is of course to validate your document against the DTD beforehand - that would have spotted the inexisting reference $label was supposed to point to.)

REFERENCE MANUAL

Support functions and global variables

This stylesheet defines a number of convenience functions and global variables that can be reused inside your own extensions.

Basic pipework

warn_at($node, $message);
die_at($node, $message);

Same as warn() and die(), but produce appropriate messages indicating the point of the error, using get_xpath_of_node().

my $text=framederror($error);
my $text=centerederror($error);

Typesets an error text in a 0.4\columnwidth wide framed box, which provides fancy error messages in place of missing images, bogus tables, etc. instead of quitting the stylesheet abruptly. The centerederror() function adds a centering environment around the box.

@nodes=reorder_backaxis("forward",@nodes);
@nodes=reorder_backaxis("backward",@nodes);

Assuming that @nodes was obtained through a call to findnodes on a backward axis (which has ordering issues, see "Quirks"), Do The Right Thing and reverse them if needed (e.g. when you want your nodes backwards w.r.t. document order and the XML::XPath du jour provides them forwards, or vice versa). Will die if the behaviour of the XML::XPath version in use is unknown (right now, we are backward compatible, pun intended, with all versions up to 1.13).

my $outputtext=apply_templates_under( [ $xpath ] , [ $node ] );

Same as "apply_templates" in XML::XPathScript, but allows for "skipping" node types that are not handled directly (for example because they are abstract - see @abstracttags). apply_templates_under($node) applies the templates to all children of $node (excluding $node itself), and returns the concatenation of all results; apply_templates_under($xpath, $node) applies the templates to those nodes that match $xpath starting from $node, and returns the concatenation of all results.

call_template($node,$t,$template);

Calls a template from a "testcode" routine, and updates $t accordingly as if calling the appropriate "testcode" entry in $template, a standard XML::XPathScript template structure. Returns the same value as said testcode would. This function is useful for overloading templates in cascaded stylesheets:

  my $oldtemplate=delete $t->{someelement};
  $t->{someelement}->{testcode}=sub {
     my ($node,$t)=@_;
     return call_template($node,$t,$oldtemplate);
  };

(the above example is trivial, as it does exactly the same thing as the old template would. But you get the idea).

If $template has no "testcode" tag, the functionality is emulated (e.g. $t->{pre} is set from $template->{pre} etc.)

%uniconvs

A hash whose keys are numeric Unicode codes (see "SEE ALSO") and whose values are the corresponding LaTeX sequences to render the character. %uniconvs need not contain space, tab, newline nor any Latin1 character (those are done automatically), but it doesn't hurt if it does.

One must call reload_uniconvs() after modifying this variable.

$uniunknown

The sequence of characters rendered in place of an unknown character.

reload_uniconvs();

Refreshes the internal variables of this stylesheet (namely, a regexp cache). To be called whenever %uniconvs is modified.

my $textinlatin1 = utf8tolatin1($textinunicode);

Returns a Unicode-untainted, Latin1-only copy of its input (which may be a text node or a stringifiable object). Unicode characters above 0x0fe in $textinunicode are removed.

my $textinlatex = utf8totex($textinunicode, $significantspace);
my $textinlatex = utf8totex($textinunicode, $translations);

Converts an UTF8-encoded string, stringifiable object or text node (that is, most kinds of stuff coming down from the XML data model) into a form that is GROKked by LaTeX using the inputenc package (most Latin1 characters are supported directly). This function first uses the %uniconvs configuration variable (see above), then a direct Latin1 mapping if the character is either whitespace or in Latin1 range. If this also fails, $uniunknown is rendered and an appropriate warning is emitted. Unless $significantspace is set to a true value, sequences of consecutive whitespace are collapsed to one and purely whitespace strings are converted to the empty string.

If $translations is additionnally a hash reference, it may supply additional character transliterations that will override those in %uniconvs. This is most useful for verbatim modes.

my $labelstring = langofnode($node);

Returns the language that prevails in node $node (as defined by the closest ancestor having a "lang" tag). Returns the empty string if no ancestor has a "lang" tag.

my $text= flatten_textnodes ($node);
my $text= flatten_textnodes ($node,$xpath);

Returns a text version of $node's content, obtained by concatenating all text subnodes in $node, normalizing all whitespace to just one space, and suppressing ISO Latin1 accents. The return value is in Latin1. This is used for example in the <indexterm> template, to get alphabetic sorting right in makeindex. $xpath, if specified, is an XPath expression to filter the right text subnodes in $node (the default is ".//text()").

General LaTeX support

Functions and global variables in there deal with day-to-day LaTeX, excluding character set issues (dealt with in "Basic pipework") and tables (see "LaTeX tables").

$documentclass
@documentclass_args

The arguments to the opening \documentclass{} macro call. By default, docbook2latex produces a 11pt, twoside, a4paper report (that is, $documentclass="report" and @documentclass_args = ("11pt", "twoside", "a4paper")).

$dvidriver or $ENV{DVIDRIVER}

The name of the DVI driver used for rendering this document, such as dvipdfm or dvips. This variable also helps making decisions for rendering images (the <graphic> tag for example). This stylesheet indeed has support for both PostScript® and PDF document rendering, but unfortunately not through the same TeX output file (due to restrictions on LaTeX's side) so the DVI driver has to be chosen at XML-to-LaTeX conversion time.

As a not-really-functional-style but oh-so-convenient temporary kludge (pending a standard means of passing stylesheet arguments on the xpathscript command line), $ENV{DVIDRIVER} is the default value of $dvidriver, that is, one can change this parameter through the environment, without even altering the stylesheet.

@abstracttags

The list of tags that are abstract, that is, that should never have apply_templates() applied to them directly. An example is <title> tags that cannot be rendered properly alone, but only as part of their parent <section>, <table> or the like. This variable is read-only and only serves as a convenience to the programmer (``is it of any use for me to overload this tag in $t ?''), modifying it has no effect.

$fancytables

If set to a true value (the default), tables are typeset using the longtable and multirows LaTeX packages. If set to a false value, plain tabulars are used instead.

$glosstermsinindex

If set to a true value (the default), then <glossterm> nodes that do not appear in a <glosslist> will be included automatically in the index with a status of preferred entries (equivalent to <indexterm significance="preferred">).

@packages

The list of packages to be included into the LaTeX preamble. This array may contain plain strings, or references to sub-arrays for packages that want options (the package name comes first in the sub-array, then the function - see "An example").

@sectionnames

The sequence of section-like TeX macros, from highest (e.g. 'part') to lowest (e.g. 'subparagraph'). Customizing this is likely to be a priority for those not satisfied with the aesthetics.

@tablesatbeginning

The macros for the table(s) to be generated at the beginning of the document (without the backslash). By Default "tableofcontents" is always first and then "listoffigures" and "listoftables" (in that order) are appended iff there is at least one figure (resp. table) in the document.

@tablesatend

The macros for the table(s) to be generated at the end of the document (without the backslash). Defaults to empty, or just "printindex" if there is at least one <indexterm> in the document.

$TeXkludges

The set of macro definitions that has to be present in the document in order to get it to process. We tried very hard to keep this to a minimum - but there still was quite a bit of Knuth cursing going on at IDEALX during the making of this stylesheet. If you have solutions without those, let us know.

$TeXpreamble

A variable to append to to your liking to include TeX directives into the LaTeX preamble.

$TeXbegindocument

A variable to set to your liking to include TeX directives just after the LaTeX \begin{document}. Initially set to some general typesetting directives.

$inhibitOutput

If set to one, this stylesheet doesn't apply_templates() by itself. Useful if you want to overload it (see "An example")

%boxlabels
%boxstyles

Both variables govern the rendering of tip, remark, note, example, warning, important and caution elements. Entries in %boxstyles are keyed by element names, and the matching values are the LaTeX command that is used to wrap them, without the backslash (fancybox macros are set up by default, see the LaTeX Companion page 278).

%boxlabels holds the translations of the default titles for those environments. it is a hash of hashes, whose outermost keys are two-letter language abbreviations (e.g. "en" and "fr"), and whose innermost keys are the element names.

my $TeXlength = TeXlength($docbooklength);
my $TeXlength = TeXlength($docbooklength, $starlength);

Returns the conversion of $docbooklength into a LaTeX length. If $starlength is specified, this is the value of "1*" (default is \fill).

my $TeXlength = multiply_TeX_dimension($TeXlength, $factor);

As the name implies, multiplies a TeX dimension by the given factor.

my $label = id2label($node [, $labelname ] );

Takes the attribute named $labelname ("id" by default) from $node and turns it into a string that is "more or less" unique and may be used as the argument of a \label{} or \ref{} command in TeX (e.g. bogus characters stripped). Returns undef if $node has no id (or no attribute named $labelname).

my $labelstring = thelabel($node);

Supports cross-referencing in LaTeX. If $node has an id tag, returns \label{id}, else returns the empty string. The function id2label() above is used for this purpose.

my $titleornothing = listtitle($node);

Returns a typeset title as "\paragraph*{Title}", or the empty string, depending on whether $node has a <title> child. Appropriate for paragraph-like elements that may have a title, such as <itemizedlist>, <orderedlist>, <formalpara> etc.

my $n = section_nesting_depth($node);

Returns the depth of the current section nesting, in terms of an index into @sectionnames that would be appropriate for placing a sectionning macro for $node if it were itself a section.

my $author_or_authors = render_authors($rendermode, $node);

When $node is an <article> or <book> node, returns the typeset string of the author(s) of the article or book. $rendermode is the rendering style; recognizes modes for now are "stack" (returns multiple authors as a tabular that stacks authors vertically) and "ampersand" (returns a string of the form "Johnson, Johnson \& Johnson").

my $author_or_authors = render_authors($rendermode, @author_names);

When @author_names are already typeset author names (typically using the template for author), returns the typeset string of the group of said authors according to $rendermode (see above).

my $text=render_graphic($node);
my $text=render_graphic($node, $scale);

If $node is a <graphic> or <inlinegraphic> element node object, then render the appropriate \includegraphics{} command for it (but not the surrounding TeX material for centering or making a float of it). This is shared code for <graphic> and <inlinegraphic> templates. $scale is an optional scale factor (default is 1) to multiply the document-specified dimensions with (using "multiply_TeX_dimension").

LaTeX footnotes

Mostly every time some kind of tabular or minipage environment is used, the \footnote{} macro becomes nonfunctional inside it. It is still possible to typeset footnotes; the trick is page 71 of the LaTeX Companion - you have to look for it, though: instead of

  \begin{table}{|c|}
  foo\footnote{bar}
  \end{table}

one says

  \begin{table}{|c|}
  foo\footnotemark{}
  \end{table}
  \footnotetext{bar}

This looks like too tough a job for a pure context-dependent stylesheet paradigm right? Wrong :-).

@footnote_blockers

The list of element names that may typeset themselves in such a way that the \footnote{} macro does not work inside them. Stylesheet extension writers should add (or subtract, why not?) elements there according to their LaTeX design.

my $latex = render_footnote($node, $text)

Returns an appropriate LaTeX snippet for signalling a footnote as part of $node's rendering, containing $text as the text. Appropriate for implementing the templates of <footnote>, <ulink> et al. This function is not as trivial as it seems, because it handles the necessary magic of \footnotemark / \footnotetext in minipages environments (e.g. tables) where normal footnotes cannot be used because of limitations in LaTeX.

collect_trapped_footnotes($node)
collect_trapped_footnotes($node, @children)

Returns a string made up of all \footnotetext{}'s that are to appear below $node's rendering, assuming it blocks footnotes. This list is collected by rendering @children again (by default, all of $node's children) using a skewed definition of render_footnote().

LaTeX tables

my $x = table_getcolXbyname($row, $name);
my ($xstart, $xend) = table_getspanXbyname($row, $name);

Returns the 1-based x coordinate(s) of a column / span in the column /span set of a table, or dies if the named column / span does not exist. These functions cache results. $row is a row node object, and $name must match a colname attribute in an applicable colspec, resp. a spanname attribute in an applicable spanspec (see the CALS table model in "SEE ALSO"). table_getcolXbyname applies colspec overloading according to the CALS semantics (see "table_getcolspecbyX").

my $colspec = table_getcolspecbyX($row_or_entry, $x)

Returns the colspec in vigor for the specified, 1-based X coordinate, or undef if no such colspec is in the document. Overloading of <colspec> sub-elements in thead or tfoot is handled according to the CALS specification, that is, if there is any colspec at thead or tfoot model, they shadow the above ones at tgroup level entirely, and only the inner set is then taken into account (e.g. shadowing, not merging, occurs when overloading).

Note that CALS dictates that there should not be more than one colspec for a given column, so there is no discussion of list context for this function.

my $spanspec = table_getspanspecbyX($row_or_entry, $xstart, $xend)
my @several_spanspecs = table_getspanspecbyX($row_or_entry, $xstart, $xend)

Returns the. spanspec in vigor for the specified, 1-based X coordinates, or undef if no such spanspec is in the document. In list context, table_getspanspecbyX() may return several different spanspecs, in document order - in scalar context, in case of a tie, this function would only return the last relevant one in document order.

my $colspec = table_getspecbyentry($entry, $leftcolumn);
my $colspec = table_getspecbyentry($entry, $leftcolumn, $nojusthappen);

Returns the "best" (see below) <colspec> or <spanspec> element node object associated with the column or group of columns spanned by $entry, or undef if there is no such colspec or spanspec. $leftcolumn (mandatory) is to be the 1-based column number at which $entry starts (the caller, which is typically "typeset_tablerow", must know this). Useful for querying style parameters from the parent column.

$entry may either refer to the result by an explicit colname or spanname attribute in the document, or alternatively, unless $nojusthappen is set to a true value, it may also "just happen" to occupy the same column set.

In case of multiple possible outcomes to this function, the "nominative" specs have priority over the "just happening" ones, the spanspecs have priority over the colspecs, and spanspecs coming last in document order have priority in the "just happening" mode.

Overridable function references

Extension authors may wish to re-use part of this stylesheet's functionality at a sub-template level: typically, one may want to alter the outlook of tables without having to duplicate the tedious, stateful table filling algorithm that transcodes XML CALS tables into LaTeX. This stylesheet supports that by defining overridable function references at appropriate points, that extension authors may replace with their own implementation (see "Modification points").

Pluggable LaTeX

my $outputtext = &$typeset_pageref($node,$linkend);

Typesets a reference containing a page number, to be put right after the \ref{$linkend} in the typesetting of $node, wich is an <xref>, without an intervening space. Possible values are " (page \pageref{$linkend})" (mind the leading space) or something like that, or the empty string if you don't want pagerefs. The default function tries to be smart and avoid the double closing parentheses problem when the <xref> is itself between parentheses. $linkend will be passed properly escaped, in such a way that outputting it to TeX in forms such as "\\ref{$linkend}" and "\\pageref{$linkend}" without any further transformation will produce the correct links.

my $outputtext = &$maketitle($title,\@subtitles,@authors);

This function shall typeset a titlepage (to be put just after the \begin{document}). If not set, the standard \title, \author, \maketitle mechanism of LaTeX will be used instead. zero, one or more subtitles may be passed as a list reference in the second argument.

&$typeset_bibentry($node,$t,$lang);

This function shall typeset a <biblioentry> or <biblioset>, ignoring the <biblioset> children. $node is the node to typeset in language $lang. There is a concept of $t->{pre} and $t->{post} analogous to the second argument of a testcode function; the semantics is that when an article and its proceedings are to be typeset together, the result will be made up with $tarticle->{pre}, $tproceedings->{pre}, $tproceedings->{post} and $tarticle->{post} (which is the normal way in french and in english, so that page numbers and the like appear last).

The return value is ignored. Unrecognized element children should be appropriately warned.

Pluggable table rendering

my $outputtext = &$typeset_tablerow($style,@row);

This function shall typeset a row in a table, given a style (which is either 'thead', 'tbody' or 'tfoot' --- typesetting happens in that order), and a list of hashrefs containing a description of the cells in this line: $row[0]->{height} and $row[0]->{width} contain the dimensions of the cell, and $row[0]->{cell} contains either undef (a blank cell - in this case height and width are always 1) or a reference to the XML::XPath::Element::Node object for this cell (an <entry> tag - <entrytbl>s are not supported yet).

The entries are positionned according to their upper left corner; elements in @row that have an undef ->{cell} represent coordinate points under a multiple-cell entry, to be skipped. @row is guaranteed to be of the same width as the whole table. Warning, though, many XPath functions (and functions in this stylesheet) start numbering at 1, while Perl starts numbering at 0; the code for your very own version of &$typeset_tablerow should therefore probably start like this:

    my ($style, @row)=@_;
        for(my $colnum=1; $colnum <= (scalar @row); $colnum++) {
                my $elem=$row[$colnum - 1];
        # Do stuff
    }
my $outputtext = &$typeset_tablerule($style,\@rowbefore,\@rowafter);

This function shall typeset a separator between two rows. It also gets called before the first row in a group (the second parameter is then undef), and after the last row in a group (the first parameter is undef). A group is the amount of rows represented by a whole <thead>, <tbody> or <tfoot> element. The contents of the lists pointed to by the second and third parameters (if defined) are not to be modified, and have the same structure as @row above. $style is as above.

my $outputtext = &$typeset_tableframe($tgroup,$headtxt,$bodytxt,$foottxt);

This function shall re-order $headtxt, $bodytxt and $foottxt (which are rendered TeX snippets for their respective parts of the $tgroup element node object, or undef if said <tgroup> lacks one of them) and eventually produce a valid overall TeX code for the whole table. This function is not responsible for outputting the \begin{table} or \end{table} stuff; on the other hand, it shall render the table caption and the cross-reference label(s) (in $fancytables mode only). It had better pay attention to the value of the global variable $fancytables, since the surrounding TeX table frame will be very different according to its boolean value (tabular vs. longtable).

By default, the function Does The Right Thing for multipage tables to work properly with longtable (if enabled).

my $outputtext= &$typeset_tablecolumnpattern($node,$kind,$tgroup,$width);

This function shall typeset the TeX column specification, this is, the "c|" part of "\begin{table}{c|}". The "|" after the "c" is meant: indeed, the CALS specification dictates that columns, spans and entries specify the rulings which lie on their right, except for the rightmost column (that you need not worry about; the stylesheet will take care of removing any separator material at the end of your column pattern if needed).

This function shall apply both to <colspec> nodes (in order to render the TeX table header), <spanspec> nodes (for \multicolumn patterns inside the table) and <entry> nodes (for another, one-column \multicolumn that is the only way in TeX to typeset one cell centered, for example, when all the others in the same column are left-justified). $kind will be set to either "colspec", "spanspec" or "entry", respectively. The first argument may be undef for columns that don't have a colspec, and for multicolumn cells that do not specify a spanspec. In this case, it is still possible to get typesetting data using $tgroup, which always contains an element node object pointing to the table's <tgroup> element.

By default, &$typeset_tablecolumnpattern() handles the 'colwidth' and 'align' attributes only. A width may also be specified by caller using the optional $width argument, in which case &$typeset_tablecolumnpattern() should attempt to honor it by priority.

Self-test

The integrationtest() function tests the behaviour of foreign packages that this stylesheet depends on (namely Perl itself for the UTF8-tainting issues, and XML::XPath for minor API issues). The following derived stylesheet, when run on any document, will produce a text output compatible with Test::Harness:

<% our $inhibitOutput; $inhibitOutput++; %>

<!--#include file="docbook2latex.xps"-->

<% integrationtest() %>

DOCBOOK EXTENSIONS

The tgroupstyle attribute of <tgroup> nodes is interpreted as a comma-separated list of LaTeX commands to wrap all cells with. A useful example is "footnotesize", for large tables.

NONSTANDARD DOCBOOK CONSTRUCTIONS

When using a format attribute "linespecific" in a <graphic> element, the LaTeX mechanism of selecting a file by trying various extensions is used. In this case, and contrary to what the DTD documentation says, one should omit the extension in the "fileref" attribute.

Cross references are rendered in a context-sensitive way which is much more like Perl's DWIM (Do What I Mean) than XML's OTFA (One Template Fits All): the stylesheet parses the surrounding text to determine which one of "Figure 3.2, page 42", "Figure 3.2 (page 42)" or "3.2 (page 42)" is the correct rendering for <xref linkend="FIG-3-2">. This is to overcome a design limitation in the DTD spec, which make <xref>s inappropriate for any language but english.

The words "TeX" and "LaTeX" are rendered as you might imagine they should. This is the only form of "semantic kerning" that should occur in the stylesheet, though (e.g. "---" really produces 3 dashes in the DVI and is not he same as "&mdash;" in the XML source).

BUGS / TODO / LIMITATIONS

Only a subset of DocBook is implemented. Adding tags is easy most of the time though.

MediaObject's are the only portable, kosher way of dealing with multi-format graphics (such as PostScript® vs. PNG in PDF's). They are not implemented.

Bibliography support is far from optimal and will result in bogus punctuation and label spacing every so often.

There is no support for variadic typesetting of characters according to the language (for example, &hellip; is rendered the same way under french and english, but shouldn't). Using additional character packages on-demand (that is, usepackage'ing them only when some Unicode characters are present in the input) isn't possible. Both restrictions stem from the flat Unicode character space in XML that disregards the level of strangeness of character entities (e.g. it is impossible to construct an XPath formula meaning "give me all strange characters in this document"). Building a list of all characters in the document from Perl would be a solution, although I cannot think of an efficient way of doing that.

SEE ALSO

XPathScript documentation:

  http://axkit.org/docs/xpathscript/guide.dkb

XPath documentation from W3C:

  http://www.w3.org/TR/xpath

The Docbook DTD:

  http://www.docbook.org/tdg/en/html/docbook.html

The CALS table model:

      http://www.oasis-open.org/specs/a502.htm

Unicode character table (needed to add more character support into a stylesheet):

  http://www.unicode.org/charts/charindex.html

Ditto, less complete but more LaTeX-friendly:

  http://www.bitjungle.com/~isoent/

COPYRIGHT

This program is copyright (C) Dominique Quatravaux <dom@idealx.com>, all rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

1 POD Error

The following errors were encountered while parsing the POD:

Around line 3536:

Non-ASCII character seen before =encoding in 'PostScript®'. Assuming ISO8859-1