xml_set_notation_decl_handler()

The xml_set_notation_decl_handler() function is a PHP built-in function that sets a user-defined function as the handler for notation declarations in an XML parser. It belongs to the xml extension and works exclusively with the SAX-style parser created by xml_parser_create().

Notation declarations are rarely used in modern XML documents, but this function allows you to intercept them when they appear. It is useful when you need to process, log, or validate notation data during SAX parsing.

Note: Ensure the xml extension is enabled in your PHP environment for these functions to work.

Syntax

The syntax of the xml_set_notation_decl_handler() function is as follows:

syntax of the xml_set_notation_decl_handler() function in PHP

xml_set_notation_decl_handler($parser, $handler)

Where $parser is the XML parser on which the handler is set, and $handler is the name of the user-defined function that will handle notation declarations.

Usage Examples

Let's take a look at a practical example of using xml_set_notation_decl_handler() in PHP.

Example: Setting a Notation Declaration Handler Function

Suppose you have an XML document containing a notation declaration. You can use xml_parser_create() to create a new XML parser, set a notation declaration handler function using xml_set_notation_decl_handler(), and then parse the document, like this:

Setting a Notation Declaration Handler Function in PHP

function handle_notation_decl($parser, $notation_name, $base, $system_id, $public_id) {
    echo "Found notation: $notation_name\n";
}

$xml_parser = xml_parser_create();
xml_set_notation_decl_handler($xml_parser, "handle_notation_decl");

$xml_data = '<?xml version="1.0"?><!DOCTYPE root [<!NOTATION img SYSTEM "image.png">]><root/>';
xml_parse($xml_parser, $xml_data, true);
xml_parser_free($xml_parser);

This code creates a new XML parser using xml_parser_create(). It then sets a custom function handle_notation_decl() to handle notation declarations. Finally, it parses a sample XML string containing a <!NOTATION ...> declaration, which triggers the handler. The parser is then freed to release resources.

Conclusion

In this article, we've discussed PHP's xml_set_notation_decl_handler() function and how it can be used to set a notation declaration handler for an XML parser in PHP. We've explained what the function does, its syntax, and provided an example of how it can be used in a practical scenario. By using xml_set_notation_decl_handler() in your PHP applications, you can intercept and process notation declarations during SAX parsing.

Practice