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RE: [xml-dev] from xpath to surrounding context?

From: "Evan Owens" <Evan.Owens@-------.--->
To: "Mukul Gandhi" <gandhi.mukul@-----.--->
Date: 11/8/2007 5:02:00 PM
Thanks!  We need to output the markup as well as the text (for
diagnostic purposes) but this will get us started in the right
direction.   

-----Original Message-----
From: Mukul Gandhi [mailto:gandhi.mukul@g...] 
Sent: Thursday, November 08, 2007 12:27 AM
To: Evan Owens
Cc: xml-dev@l...
Subject: Re: [xml-dev] from xpath to surrounding context?

Here is a custom utility for this requirement using XSLT 2.0, and Saxon.

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                       xmlns:xs="http://www.w3.org/2001/XMLSchema"
                       xmlns:saxon="http://saxon.sf.net/"
                       xmlns:fn="http://custom-functions"
                       version="2.0">
	
  <xsl:output method="text" />

  <xsl:variable name="xpath" select="'xpath expression ...'" />

  <xsl:template match="/">
    <xsl:variable name="beforeText"
select="fn:beforeNow(saxon:evaluate($xpath), 40)" />
    <xsl:variable name="afterText"
select="fn:afterNow(saxon:evaluate($xpath), 40)" />
    <xsl:value-of select="$beforeText" />
    <xsl:text>&#xa;</xsl:text>
    <xsl:value-of select="$xpath" />
    <xsl:text>&#xa;</xsl:text>
    <xsl:value-of select="$afterText" />
  </xsl:template>

  <xsl:function name="fn:beforeNow" as="xs:string">
    <xsl:param name="items" as="item()*" />
    <xsl:param name="x" as="xs:integer" />

    <xsl:variable name="length"
select="string-length(string-join($items/preceding::text(),''))" />
    <xsl:variable name="result"
select="substring(string-join($items/preceding::text(),''), $length -
$x, $length)" />

    <xsl:sequence select="$result" />

  </xsl:function>

  <xsl:function name="fn:afterNow" as="xs:string">
    <xsl:param name="items" as="item()*" />
    <xsl:param name="x" as="xs:integer" />

    <xsl:variable name="length"
select="string-length(string-join($items/following::text(),''))" />
    <xsl:variable name="result"
select="substring(string-join($items/following::text(),''), 0, $x)" />

    <xsl:sequence select="$result" />

  </xsl:function>

</xsl:stylesheet>

Hope you could adapt this in your environment.

On Nov 7, 2007 7:09 PM, Evan Owens <Evan.Owens@p...> wrote:
>
> Given an xpath expression that points into a document, can anyone 
> suggest a clever way to extract an arbitrary chunk of the document 
> immediately before and after that point?  Say, 40 characters before
and after?
>
> Here's the use case: we have an error report that is generated as part

> of an XSLT batch transformation process.  The error message include 
> the xpath that describes the element that caused the problem; e.g., 
> /ART[1]/BM[1]/BIBL[1]/BIB[5]/NOTE[1]/P[1].  The users of the report 
> have requested that we add a bit of context to help them assess the 
> errors without having to open every single file...a preview snippet as
it were.
>
> It doesn't have to be a pure XML solution nor does it have to be 
> extremely efficient in processor time.  These are not large documents 
> and it would be okay to reread the files as part of the error report
generation.
>
> Thanks in advance for any suggestions as to ways to tackle this
problem.
>
> Evan Owens


--
Regards,
Mukul Gandhi

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