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XPath and trees

XPath and trees. Elena Pierazzo 2006-2007. XPath. A language to describe how to locate a part of an XML document Used in many XML-based technologies and tools. XML documents: a tree view. <p> Here is some <hi type=" ital " > highlighted </hi> text. </p>. node. link.

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XPath and trees

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  1. XPath and trees Elena Pierazzo 2006-2007

  2. XPath • A language to describe how to locate a part of an XML document • Used in many XML-based technologies and tools

  3. XML documents: a tree view <p>Here is some <hi type="ital">highlighted</hi> text.</p> node link

  4. Or a genealogical chart Parent of <p> Ancestor of <hi>, @type, text nodes Child of / Siblings, descendant of /

  5. Other examples Let’s see some more examples

  6. Paths and Steps one step’s path <xsl:template match=“section”> <xsl:template match=“section/title”> / step operator (= child of) two steps’ path

  7. Abbreviated Syntax • / = child of E.g.: “section/title” Not the same as: /section/title • // = descendant of E.g.: “body//title” • * = any node E.g.: body/*/title • . = current node E.g.: .//para Not the same as //para

  8. XPath at work <AUTHOR TYPE="main">  <NAME><FIRST>Professor Christopher</FIRST><LAST>Gantley</LAST></NAME>  <AFFIL>University of Northumbria</AFFIL>  <EMAIL>c.gantley@unnx.ac.uk</EMAIL></AUTHOR><AUTHOR>  <NAME><FIRST>Megan</FIRST><LAST>Graham</LAST></NAME>  <AFFIL>Institute of Image Research, University of Northumbria</AFFIL>  <EMAIL>megan.graham@unnx.ac.uk</EMAIL></AUTHOR>

  9. We want obtain: Gantley, Professor Christopher <xsl:template match="NAME"><Ii><xsl:apply-templates select="LAST"/>, <xsl:apply-templates select="FIRST"/></i></xsl:template> Children of the contextual node Contextual node

  10. The select attribute • Has different meaning! • <xsl:template match=“node and descendant”> • <xsl:apply-templates select=“selected node”> • <xsl:value-of select=“text”>  forthcoming!

  11. Processing the text: value-of As it was: http://www.cch.kcl.ac.uk/legacy/teaching/av2001/xslt/class_mats/chap1/examples/eeyore.xsl How we can making it better: <xsl:template match="story"><html><head><title>Winnie-the-Pooh: <xsl:value-of select="/story/title"/></title></head><body><xsl:apply-templates/></body></html></xsl:template> Just text, not other nodes

  12. More examples • XML document: chap 2 > examples > abst10.xml • "Finished" template: chap 2 > examples > abstrs.xsl

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