$Id: lib.xweb,v 1.2 2002/05/12 11:11:08 nwalsh Exp $
Copyright © 1999, 2000, 2001, 2002 Norman Walsh
Table of Contents
This is technical reference documentation for the DocBook XSL Stylesheets; it documents (some of) the parameters, templates, and other elements of the stylesheets.
This is not intended to be “user” documentation. It is provided for developers writing customization layers for the stylesheets, and for anyone who's interested in “how it works”.
Although I am trying to be thorough, this documentation is known to be incomplete. Don't forget to read the source, too :-)
Table of Contents
dot.count — Returns the number of “.” characters in a string
§1: §16 |
1| <xsl:template name="dot.count"> | <!-- Returns the number of "." characters in a string --> | <xsl:param name="string"/> | <xsl:param name="count" 5| select="0"/> | <xsl:choose> | <xsl:when test="contains($string, '.')"> | <xsl:call-template name="dot.count"> | <xsl:with-param name="string" 10| select="substring-after($string, '.')"/> | <xsl:with-param name="count" | select="$count+1"/> | </xsl:call-template> | </xsl:when> 15| <xsl:otherwise> | <xsl:value-of select="$count"/> | </xsl:otherwise> | </xsl:choose> | </xsl:template> |
copy-string — Returns “count” copies of a string
§2: §16 |
1| <xsl:template name="copy-string"> | <!-- returns 'count' copies of 'string' --> | <xsl:param name="string"/> | <xsl:param name="count" 5| select="0"/> | <xsl:param name="result"/> | | <xsl:choose> | <xsl:when test="$count>0"> 10| <xsl:call-template name="copy-string"> | <xsl:with-param name="string" | select="$string"/> | <xsl:with-param name="count" | select="$count - 1"/> 15| <xsl:with-param name="result"> | <xsl:value-of select="$result"/> | <xsl:value-of select="$string"/> | </xsl:with-param> | </xsl:call-template> 20| </xsl:when> | <xsl:otherwise> | <xsl:value-of select="$result"/> | </xsl:otherwise> | </xsl:choose> 25| </xsl:template> |
string.subst — Substitute one text string for another in a string
The string.subst template replaces all occurances of target in string with replacement and returns the result.
§3: §16 |
1| <xsl:template name="string.subst"> | <xsl:param name="string"/> | <xsl:param name="target"/> | <xsl:param name="replacement"/> 5| | <xsl:choose> | <xsl:when test="contains($string, $target)"> | <xsl:variable name="rest"> | <xsl:call-template name="string.subst"> 10| <xsl:with-param name="string" | select="substring-after($string, $target)"/> | <xsl:with-param name="target" | select="$target"/> | <xsl:with-param name="replacement" 15| select="$replacement"/> | </xsl:call-template> | </xsl:variable> | <xsl:value-of select="concat(substring-before($string, $target), $replacement, $rest)"/> | </xsl:when> 20| <xsl:otherwise> | <xsl:value-of select="$string"/> | </xsl:otherwise> | </xsl:choose> | </xsl:template> |
xpointer.idref — Extract IDREF from an XPointer
The xpointer.idref template returns the ID portion of an XPointer which is a pointer to an ID within the current document, or the empty string if it is not.
In other words, xpointer.idref returns “foo” when passed either #foo or #xpointer(id('foo')), otherwise it returns the empty string.
§4: §16 |
1| <xsl:template name="xpointer.idref">
| <xsl:param name="xpointer">http://...</xsl:param>
| <xsl:choose>
| <xsl:when test="starts-with($xpointer, '#xpointer(id(')">
5| <xsl:variable name="rest"
| select="substring-after($xpointer, '#xpointer(id(')"/>
| <xsl:variable name="quote"
| select="substring($rest, 1, 1)"/>
| <xsl:value-of select="substring-before(substring-after($xpointer, $quote), $quote)"/>
10| </xsl:when>
| <xsl:when test="starts-with($xpointer, '#')">
| <xsl:value-of select="substring-after($xpointer, '#')"/>
| </xsl:when>
| <!-- otherwise it's a pointer to some other document -->
15| </xsl:choose>
| </xsl:template> |
length-magnitude — Return the unqualified dimension from a length specification
The length-magnitude template returns the unqualified length ("20" for "20pt") from a dimension.
§5: §16 |
1| <xsl:template name="length-magnitude"> | <xsl:param name="length" | select="'0pt'"/> | 5| <xsl:choose> | <xsl:when test="string-length($length) = 0"/> | <xsl:when test="substring($length,1,1) = '0' or substring($length,1,1) = '1' or substring($length,1,1) = '2' or substring($length,1,1) = '3' or substring($length,1,1) = '4' or substring($length,1,1) = '5' or substring($length,1,1) = '6' or substring($length,1,1) = '7' or substring($length,1,1) = '8' or substring($length,1,1) = '9' or substring($length,1,1) = '.'"> | <xsl:value-of select="substring($length,1,1)"/> | <xsl:call-template name="length-magnitude"> 10| <xsl:with-param name="length" | select="substring($length,2)"/> | </xsl:call-template> | </xsl:when> | </xsl:choose> 15| </xsl:template> |
length-units — Return the units from a length specification
The length-units template returns the units ("pt" for "20pt") from a length. If no units are supplied on the length, the defauilt.units are returned.
§6: §16 |
1| <xsl:template name="length-units"> | <xsl:param name="length" | select="'0pt'"/> | <xsl:param name="default.units" 5| select="'px'"/> | <xsl:variable name="magnitude"> | <xsl:call-template name="length-magnitude"> | <xsl:with-param name="length" | select="$length"/> 10| </xsl:call-template> | </xsl:variable> | | <xsl:variable name="units"> | <xsl:value-of select="substring($length, string-length($magnitude)+1)"/> 15| </xsl:variable> | | <xsl:choose> | <xsl:when test="$units = ''"> | <xsl:value-of select="$default.units"/> 20| </xsl:when> | <xsl:otherwise> | <xsl:value-of select="$units"/> | </xsl:otherwise> | </xsl:choose> 25| </xsl:template> |
length-spec — Return a fully qualified length specification
The length-spec template returns the qualified length from a dimension. If an unqualified length is given, the default.units will be added to it.
§7: §16 |
1| <xsl:template name="length-spec"> | <xsl:param name="length" | select="'0pt'"/> | <xsl:param name="default.units" 5| select="'px'"/> | | <xsl:variable name="magnitude"> | <xsl:call-template name="length-magnitude"> | <xsl:with-param name="length" 10| select="$length"/> | </xsl:call-template> | </xsl:variable> | | <xsl:variable name="units"> 15| <xsl:value-of select="substring($length, string-length($magnitude)+1)"/> | </xsl:variable> | | <xsl:value-of select="$magnitude"/> | <xsl:choose> 20| <xsl:when test="$units='cm' or $units='mm' or $units='in' or $units='pt' or $units='pc' or $units='px' or $units='em'"> | <xsl:value-of select="$units"/> | </xsl:when> | <xsl:when test="$units = ''"> | <xsl:value-of select="$default.units"/> 25| </xsl:when> | <xsl:otherwise> | <xsl:message> | <xsl:text>Unrecognized unit of measure: </xsl:text> | <xsl:value-of select="$units"/> 30| <xsl:text>.</xsl:text> | </xsl:message> | </xsl:otherwise> | </xsl:choose> | </xsl:template> |
length-in-points — Returns the size, in points, of a specified length
The length-in-points template converts a length specification to points and returns that value as an unqualified number.
There is no way for the template to infer the size of an em. It relies on the default em.size which is initially 10 (for 10pt).
Similarly, converting pixesl to points relies on the pixels.per.inch parameter which is initially 90.
§8: §16 |
1| <xsl:template name="length-in-points"> | <xsl:param name="length" | select="'0pt'"/> | <xsl:param name="em.size" 5| select="10"/> | <xsl:param name="pixels.per.inch" | select="90"/> | | <xsl:variable name="magnitude"> 10| <xsl:call-template name="length-magnitude"> | <xsl:with-param name="length" | select="$length"/> | </xsl:call-template> | </xsl:variable> 15| | <xsl:variable name="units"> | <xsl:value-of select="substring($length, string-length($magnitude)+1)"/> | </xsl:variable> | 20| <xsl:choose> | <xsl:when test="$units = 'pt'"> | <xsl:value-of select="$magnitude"/> | </xsl:when> | <xsl:when test="$units = 'cm'"> 25| <xsl:value-of select="$magnitude div 2.54 * 72.0"/> | </xsl:when> | <xsl:when test="$units = 'mm'"> | <xsl:value-of select="$magnitude div 25.4 * 72.0"/> | </xsl:when> 30| <xsl:when test="$units = 'in'"> | <xsl:value-of select="$magnitude * 72.0"/> | </xsl:when> | <xsl:when test="$units = 'pc'"> | <xsl:value-of select="$magnitude div 6.0 * 72.0"/> 35| </xsl:when> | <xsl:when test="$units = 'px'"> | <xsl:value-of select="$magnitude div $pixels.per.inch * 72.0"/> | </xsl:when> | <xsl:when test="$units = 'em'"> 40| <xsl:value-of select="$magnitude * $em.size"/> | </xsl:when> | <xsl:otherwise> | <xsl:message> | <xsl:text>Unrecognized unit of measure: </xsl:text> 45| <xsl:value-of select="$units"/> | <xsl:text>.</xsl:text> | </xsl:message> | </xsl:otherwise> | </xsl:choose> 50| </xsl:template> |
pi-attribute — Extract a pseudo-attribute from a PI
The pi-attribute template extracts a pseudo-attribute from a processing instruction. For example, given the PI “<?foo bar="1" baz='red'?>”,
<xsl:call-template name="pi-attribute">
<xsl:with-param name="pis" select="processing-instruction('foo')"/>
<xsl:with-param name="attribute" select="'baz'"/>
</xsl:call-template>will return “red”. This template returns the first matching attribute that it finds. Presented with processing instructions that contain badly formed pseudo-attributes (missing or unbalanced quotes, for example), the template may silently return erroneous results.
§9: §16 |
1| <xsl:template name="pi-attribute">
| <xsl:param name="pis"
| select="processing-instruction('')"/>
| <xsl:param name="attribute">filename</xsl:param>
5| <xsl:param name="count">1</xsl:param>
|
| <xsl:choose>
| <xsl:when test="$count>count($pis)">
| <!-- not found -->
10| </xsl:when>
| <xsl:otherwise>
| <xsl:variable name="pi">
| <xsl:value-of select="$pis[$count]"/>
| </xsl:variable>
15| <xsl:choose>
| <xsl:when test="contains($pi,concat($attribute, '='))">
| <xsl:variable name="rest"
| select="substring-after($pi,concat($attribute,'='))"/>
| <xsl:variable name="quote"
20| select="substring($rest,1,1)"/>
| <xsl:value-of select="substring-before(substring($rest,2),$quote)"/>
| </xsl:when>
| <xsl:otherwise>
| <xsl:call-template name="pi-attribute">
25| <xsl:with-param name="pis"
| select="$pis"/>
| <xsl:with-param name="attribute"
| select="$attribute"/>
| <xsl:with-param name="count"
30| select="$count + 1"/>
| </xsl:call-template>
| </xsl:otherwise>
| </xsl:choose>
| </xsl:otherwise>
35| </xsl:choose>
| </xsl:template> |
lookup.key — Retrieve the value associated with a particular key in a table
Given a table of space-delimited key/value pairs, the lookup.key template extracts the value associated with a particular key.
§10: §16 |
1| <xsl:template name="lookup.key"> | <xsl:param name="key" | select="''"/> | <xsl:param name="table" 5| select="''"/> | | <xsl:if test="contains($table, ' ')"> | <xsl:choose> | <xsl:when test="substring-before($table, ' ') = $key"> 10| <xsl:variable name="rest" | select="substring-after($table, ' ')"/> | <xsl:choose> | <xsl:when test="contains($rest, ' ')"> | <xsl:value-of select="substring-before($rest, ' ')"/> 15| </xsl:when> | <xsl:otherwise> | <xsl:value-of select="$rest"/> | </xsl:otherwise> | </xsl:choose> 20| </xsl:when> | <xsl:otherwise> | <xsl:call-template name="lookup.key"> | <xsl:with-param name="key" | select="$key"/> 25| <xsl:with-param name="table" | select="substring-after(substring-after($table,' '), ' ')"/> | </xsl:call-template> | </xsl:otherwise> | </xsl:choose> 30| </xsl:if> | </xsl:template> |
xpath.location — Calculate the XPath child-sequence to the current node
The xpath.location template calculates the absolute path from the root of the tree to the current element node.
§11: §16 |
1| <xsl:template name="xpath.location"> | <xsl:param name="node" | select="."/> | <xsl:param name="path" 5| select="''"/> | | <xsl:variable name="next.path"> | <xsl:value-of select="local-name($node)"/> | <xsl:if test="$path != ''">/</xsl:if> 10| <xsl:value-of select="$path"/> | </xsl:variable> | | <xsl:choose> | <xsl:when test="$node/parent::*"> 15| <xsl:call-template name="xpath.location"> | <xsl:with-param name="node" | select="$node/parent::*"/> | <xsl:with-param name="path" | select="$next.path"/> 20| </xsl:call-template> | </xsl:when> | <xsl:otherwise> | <xsl:text>/</xsl:text> | <xsl:value-of select="$next.path"/> 25| </xsl:otherwise> | </xsl:choose> | </xsl:template> |
comment-escape-string — Prepare a string for inclusion in an XML comment
The comment-escape-string template returns a string that has been transformed so that it can safely be output as an XML comment. Internal occurrences of "--" will be replaced with "- -" and a leading and/or trailing space will be added to the string, if necessary.
§12: §16 |
1| <xsl:template name="comment-escape-string"> | <xsl:param name="string" | select="''"/> | 5| <xsl:if test="starts-with($string, '-')"> | <xsl:text> </xsl:text> | </xsl:if> | | <xsl:call-template name="comment-escape-string.recursive"> 10| <xsl:with-param name="string" | select="$string"/> | </xsl:call-template> | | <xsl:if test="substring($string, string-length($string), 1) = '-'"> 15| <xsl:text> </xsl:text> | </xsl:if> | </xsl:template> |
comment-escape-string.recursive — Internal function used by comment-escape-string
The comment-escape-string.recursive template is used by comment-escape-string.
§13: §16 |
1| <xsl:template name="comment-escape-string.recursive"> | <xsl:param name="string" | select="''"/> | <xsl:choose> 5| <xsl:when test="contains($string, '--')"> | <xsl:value-of select="substring-before($string, '--')"/> | <xsl:value-of select="'- -'"/> | <xsl:call-template name="comment-escape-string.recursive"> | <xsl:with-param name="string" 10| select="substring-after($string, '--')"/> | </xsl:call-template> | </xsl:when> | <xsl:otherwise> | <xsl:value-of select="$string"/> 15| </xsl:otherwise> | </xsl:choose> | </xsl:template> |
These functions manipulate relative URI references.
The following assumptions must hold true:
All URIs are relative.
No URI contains the “../” sequence which would effectively move “up” the hierarchy.
If these assumptions do not hold, the results are unpredictable.
Table of Contents
count.uri.path.depth — Count the number of path components in a relative URI
This function counts the number of path components in a relative URI.
§14: §16 |
1| <xsl:template name="count.uri.path.depth"> | <xsl:param name="filename" | select="''"/> | <xsl:param name="count" 5| select="0"/> | | <xsl:choose> | <xsl:when test="contains($filename, '/')"> | <xsl:call-template name="count.uri.path.depth"> 10| <xsl:with-param name="filename" | select="substring-after($filename, '/')"/> | <xsl:with-param name="count" | select="$count + 1"/> | </xsl:call-template> 15| </xsl:when> | <xsl:otherwise> | <xsl:value-of select="$count"/> | </xsl:otherwise> | </xsl:choose> 20| </xsl:template> |
trim.common.uri.paths — Trim common leading path components from a relative URI
This function trims common leading path components from a relative URI.
§15: §16 |
1| <xsl:template name="trim.common.uri.paths"> | <xsl:param name="uriA" | select="''"/> | <xsl:param name="uriB" 5| select="''"/> | <xsl:param name="return" | select="'A'"/> | | <xsl:choose> 10| <xsl:when test="contains($uriA, '/') and contains($uriB, '/') and substring-before($uriA, '/') = substring-before($uriB, '/')"> | <xsl:call-template name="trim.common.uri.paths"> | <xsl:with-param name="uriA" | select="substring-after($uriA, '/')"/> | <xsl:with-param name="uriB" 15| select="substring-after($uriB, '/')"/> | <xsl:with-param name="return" | select="$return"/> | </xsl:call-template> | </xsl:when> 20| <xsl:otherwise> | <xsl:choose> | <xsl:when test="$return = 'A'"> | <xsl:value-of select="$uriA"/> | </xsl:when> 25| <xsl:otherwise> | <xsl:value-of select="$uriB"/> | </xsl:otherwise> | </xsl:choose> | </xsl:otherwise> 30| </xsl:choose> | </xsl:template> |
The lib.xsl stylesheet is just a wrapper around these functions.
§16 |
1| | <!-- ******************************************************************** | $Id: lib.xweb,v 1.2 2002/05/12 11:11:08 nwalsh Exp $ | ******************************************************************** 5| | This file is part of the XSL DocBook Stylesheet distribution. | See ../README or http://nwalsh.com/docbook/xsl/ for copyright | and other information. | 10| This module implements DTD-independent functions | | ******************************************************************** --> | | <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 15| exclude-result-prefixes="src" | version="1.0"> | | §1. dot.count | §2. copy-string 20| §3. string.subst | §4. xpointer.idref | §5. length-magnitude | §6. length-units | §7. length-spec 25| §8. length-in-points | §9. pi-attribute | §10. lookup.key | §11. xpath.location | comment-escape-string 30| comment-escape-string.recursive | §14. count.uri.path.depth | §15. trim.common.uri.paths | | </xsl:stylesheet> |