doc-en/reference/xml/examples.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<chapter xml:id="xml.examples" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 &reftitle.examples;
 <section xml:id="example.xml-structure">
  <title>XML Element Structure Example</title>
  <para>
   This first example displays the structure of the start elements in
   a document with indentation.
   <example>
    <title>Show XML Element Structure</title>
    <programlisting role="php">
<![CDATA[
<?php
$file = "data.xml";
$depth = 0;

function startElement($parser, $name, $attrs)
{
    global $depth;

    for ($i = 0; $i < $depth; $i++) {
        echo "  ";
    }
    echo "$name\n";
    $depth++;
}

function endElement($parser, $name)
{
    global $depth;
    $depth--;
}

$xml_parser = xml_parser_create();
xml_set_element_handler($xml_parser, "startElement", "endElement");
if (!($fp = fopen($file, "r"))) {
    die("could not open XML input");
}

while ($data = fread($fp, 4096)) {
    if (!xml_parse($xml_parser, $data, feof($fp))) {
        die(sprintf("XML error: %s at line %d",
                    xml_error_string(xml_get_error_code($xml_parser)),
                    xml_get_current_line_number($xml_parser)));
    }
}
xml_parser_free($xml_parser);
?>
]]>
    </programlisting>
   </example>
  </para>
 </section>

 <section xml:id="example.xml-map-tags">
  <title>XML Tag Mapping Example</title>
  <para>
   <example>
    <title>Map XML to HTML</title>
    <para>
     This example maps tags in an XML document directly to HTML
     tags.  Elements not found in the "map array" are ignored.  Of
     course, this example will only work with a specific XML
     document type.
    </para>
    <programlisting role="php">
<![CDATA[
<?php
$file = "data.xml";
$map_array = array(
    "BOLD"     => "B",
    "EMPHASIS" => "I",
    "LITERAL"  => "TT"
);

function startElement($parser, $name, $attrs) 
{
    global $map_array;
    if (isset($map_array[$name])) {
        echo "<$map_array[$name]>";
    }
}

function endElement($parser, $name) 
{
    global $map_array;
    if (isset($map_array[$name])) {
        echo "</$map_array[$name]>";
    }
}

function characterData($parser, $data) 
{
    echo $data;
}

$xml_parser = xml_parser_create();
// use case-folding so we are sure to find the tag in $map_array
xml_parser_set_option($xml_parser, XML_OPTION_CASE_FOLDING, true);
xml_set_element_handler($xml_parser, "startElement", "endElement");
xml_set_character_data_handler($xml_parser, "characterData");
if (!($fp = fopen($file, "r"))) {
    die("could not open XML input");
}

while ($data = fread($fp, 4096)) {
    if (!xml_parse($xml_parser, $data, feof($fp))) {
        die(sprintf("XML error: %s at line %d",
                    xml_error_string(xml_get_error_code($xml_parser)),
                    xml_get_current_line_number($xml_parser)));
    }
}
xml_parser_free($xml_parser);
?>
]]>
    </programlisting>
   </example>
  </para>
 </section>

 <section xml:id="example.xml-external-entity">
  <title>XML External Entity Example</title>
  <para>
   This example highlights XML code.  It illustrates how to use an
   external entity reference handler to include and parse other
   documents, as well as how PIs can be processed, and a way of
   determining "trust" for PIs containing code.
  </para>
  <para>
   XML documents that can be used for this example are found below
   the example (<filename>xmltest.xml</filename> and
   <filename>xmltest2.xml</filename>.)
  </para>
  <para>
   <example>
    <title>External Entity Example</title>
    <programlisting role="php">
<![CDATA[
<?php
$file = "xmltest.xml";

function trustedFile($file) 
{
    // only trust local files owned by ourselves
    if (!preg_match("@^([a-z][a-z0-9+.-]*)\:\/\/@i", $file) 
        && fileowner($file) == getmyuid()) {
            return true;
    }
    return false;
}

function startElement($parser, $name, $attribs) 
{
    echo "&lt;<font color=\"#0000cc\">$name</font>";
    if (count($attribs)) {
        foreach ($attribs as $k => $v) {
            echo " <font color=\"#009900\">$k</font>=\"<font 
                   color=\"#990000\">$v</font>\"";
        }
    }
    echo "&gt;";
}

function endElement($parser, $name) 
{
    echo "&lt;/<font color=\"#0000cc\">$name</font>&gt;";
}

function characterData($parser, $data) 
{
    echo "<b>$data</b>";
}

function PIHandler($parser, $target, $data) 
{
    switch (strtolower($target)) {
        case "php":
            global $parser_file;
            // If the parsed document is "trusted", we say it is safe
            // to execute PHP code inside it.  If not, display the code
            // instead.
            if (trustedFile($parser_file[$parser])) {
                eval($data);
            } else {
                printf("Untrusted PHP code: <i>%s</i>", 
                        htmlspecialchars($data));
            }
            break;
    }
}

function defaultHandler($parser, $data) 
{
    if (substr($data, 0, 1) == "&" && substr($data, -1, 1) == ";") {
        printf('<font color="#aa00aa">%s</font>', 
                htmlspecialchars($data));
    } else {
        printf('<font size="-1">%s</font>', 
                htmlspecialchars($data));
    }
}

function externalEntityRefHandler($parser, $openEntityNames, $base, $systemId,
                                  $publicId) {
    if ($systemId) {
        if (!list($parser, $fp) = new_xml_parser($systemId)) {
            printf("Could not open entity %s at %s\n", $openEntityNames,
                   $systemId);
            return false;
        }
        while ($data = fread($fp, 4096)) {
            if (!xml_parse($parser, $data, feof($fp))) {
                printf("XML error: %s at line %d while parsing entity %s\n",
                       xml_error_string(xml_get_error_code($parser)),
                       xml_get_current_line_number($parser), $openEntityNames);
                xml_parser_free($parser);
                return false;
            }
        }
        xml_parser_free($parser);
        return true;
    }
    return false;
}

function new_xml_parser($file) 
{
    global $parser_file;

    $xml_parser = xml_parser_create();
    xml_parser_set_option($xml_parser, XML_OPTION_CASE_FOLDING, 1);
    xml_set_element_handler($xml_parser, "startElement", "endElement");
    xml_set_character_data_handler($xml_parser, "characterData");
    xml_set_processing_instruction_handler($xml_parser, "PIHandler");
    xml_set_default_handler($xml_parser, "defaultHandler");
    xml_set_external_entity_ref_handler($xml_parser, "externalEntityRefHandler");
    
    if (!($fp = @fopen($file, "r"))) {
        return false;
    }
    if (!is_array($parser_file)) {
        settype($parser_file, "array");
    }
    $parser_file[$xml_parser] = $file;
    return array($xml_parser, $fp);
}

if (!(list($xml_parser, $fp) = new_xml_parser($file))) {
    die("could not open XML input");
}

echo "<pre>";
while ($data = fread($fp, 4096)) {
    if (!xml_parse($xml_parser, $data, feof($fp))) {
        die(sprintf("XML error: %s at line %d\n",
                    xml_error_string(xml_get_error_code($xml_parser)),
                    xml_get_current_line_number($xml_parser)));
    }
}
echo "</pre>";
echo "parse complete\n";
xml_parser_free($xml_parser);

?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   <example>
    <title>xmltest.xml</title>
    <programlisting role="xml">
<![CDATA[
<?xml version='1.0'?>
<!DOCTYPE chapter SYSTEM "/just/a/test.dtd" [
<!ENTITY plainEntity "FOO entity">
<!ENTITY systemEntity SYSTEM "xmltest2.xml">
]>
<chapter>
 <TITLE>Title &plainEntity;</TITLE>
 <para>
  <informaltable>
   <tgroup cols="3">
    <tbody>
     <row><entry>a1</entry><entry morerows="1">b1</entry><entry>c1</entry></row>
     <row><entry>a2</entry><entry>c2</entry></row>
     <row><entry>a3</entry><entry>b3</entry><entry>c3</entry></row>
    </tbody>
   </tgroup>
  </informaltable>
 </para>
 &systemEntity;
 <section id="about">
  <title>About this Document</title>
  <para>
   <!-- this is a comment -->
   <?php echo 'Hi!  This is PHP version ' . phpversion(); ?>
  </para>
 </section>
</chapter>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   This file is included from <filename>xmltest.xml</filename>:
   <example>
    <title>xmltest2.xml</title>
    <programlisting role="xml">
<![CDATA[
<?xml version="1.0"?>
<!DOCTYPE foo [
<!ENTITY testEnt "test entity">
]>
<foo>
   <element attrib="value"/>
   &testEnt;
   <?php echo "This is some more PHP code being executed."; ?>
</foo>
]]>
    </programlisting>
   </example>
  </para>
 </section>
</chapter>

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