< XQuery

Motivation

You want to view XML documents using your web browser using HTML markup.

Method

We will use an XQuery function that uses the dispatch pattern and the typeswitch function.

Sample Input

<aaa a1="A1" a2="A2" a3="A3">
    <bbb b1="B1" b2="B2" b3="B3">BBB</bbb>
    <ccc c1="C1" c2="C2" c3="C3">
       <ddd d1="D1" d2="D2" d3="D3">DDD</ddd>
       <eee>
           <fff>FFF</fff>
       </eee>
    </ccc>
</aaa>

Sample XML to HMTL Function

(: sequence dispatcher :)
declare function xml-to-html:dispatch($input as node()*, $depth as xs:integer) as item()* {
let $left-margin := concat('margin-left: ', ($depth * 5), 'px' )
for $node in $input
   return 
      typeswitch($node)
        case text() return normalize-space(<span class="d">{$node}</span>)
        case element()
           return
              <div class="element" style="{$left-margin}">
                    <span class="t">&lt;{name($node)}</span>
                    { (: for each attribute create two spans for the name and value :)
                     for $att in $node/@*
                        return
                           (
                              <span class="an"> {name($att)}=</span>,
                              <span class="av">"{string($att)}"</span>
                           )
                    }
                    {normalize-space(<span class="t">&gt;</span>)}
                    { (: now get the sub elements :)
                       for $c in $node
                          return xml-to-html:dispatch($c/node(), $depth + 1)
                    }
                    <span class="t">&lt;/{name($node)}&gt;</span>
             </div> 
        (: otherwise pass it through.  Used for comments, and PIs :)
        default return $node
};

Sample Driver

xquery version "1.0";

import module namespace xml-to-html="http://example.com/xml-to-html" at "xml-to-html.xqm";

let $title := 'View XML as HTML'

let $input :=
<aaa a1="A1" a2="A2" a3="A3">
    <bbb b1="B1" b2="B2" b3="B3">BBB</bbb>
    <ccc c1="C1" c2="C2" c3="C3">
       <ddd d1="D1" d2="D2" d3="D3">DDD</ddd>
       <eee>
           <fff>FFF</fff>
       </eee>
    </ccc>
</aaa>

let $output := xml-to-html:xml-to-html($input, 1)

return
<html>
   <head>
      <title>{$title}</title>
      <link type="text/css" rel="stylesheet" href="syntax-colors-oxygen.css"/>
   </head>
   <body>
      <div class="xml">
        {$output}
      </div>
   </body>
</html>

Sample Output

<div class="xml">
    <div class="element" style="margin-left: 5px">
        <span class="t">&lt;aaa</span>
        <span class="an">a1=</span>
        <span class="av">"A1"</span>
        <span class="an">a2=</span>
        <span class="av">"A2"</span>
        <span class="an">a3=</span>
        <span class="av">"A3"</span>&gt;<div class="element" style="margin-left: 10px">
            <span class="t">&lt;bbb</span>
            <span class="an">b1=</span>
            <span class="av">"B1"</span>
            <span class="an">b2=</span>
            <span class="av">"B2"</span>
            <span class="an">b3=</span>
            <span class="av">"B3"</span>&gt;BBB<span class="t">&lt;/bbb&gt;</span>
        </div>
        <div class="element" style="margin-left: 10px">
            <span class="t">&lt;ccc</span>
            <span class="an">c1=</span>
            <span class="av">"C1"</span>
            <span class="an">c2=</span>
            <span class="av">"C2"</span>
            <span class="an">c3=</span>
            <span class="av">"C3"</span>&gt;<div class="element" style="margin-left: 15px">
                <span class="t">&lt;ddd</span>
                <span class="an">d1=</span>
                <span class="av">"D1"</span>
                <span class="an">d2=</span>
                <span class="av">"D2"</span>
                <span class="an">d3=</span>
                <span class="av">"D3"</span>&gt;DDD<span class="t">&lt;/ddd&gt;</span>
            </div>
            <div class="element" style="margin-left: 15px">
                <span class="t">&lt;eee</span>&gt;<div class="element" style="margin-left: 20px">
                    <span class="t">&lt;fff</span>&gt;FFF<span class="t">&lt;/fff&gt;</span>
                </div>
                <span class="t">&lt;/eee&gt;</span>
            </div>
            <span class="t">&lt;/ccc&gt;</span>
        </div>
        <span class="t">&lt;/aaa&gt;</span>
    </div>
</div>

Sample CSS File

File: syntax-colors-oxygen.css

/* Begin and end tag Delimiter */
.t {color: blue;}
/* Attribute Name and equal sign */
.an {color: orange;}
/* Attribute Values and equal sign */
.av {color: orange;}
/* Element Data Content */
.d {color: black;}

Screen Image

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