# Poco::XML

# class DeclHandler

Library: XML
Package: SAX
Header: Poco/SAX/DeclHandler.h

## Description

This is an optional extension handler for SAX2 to provide information about DTD declarations in an XML document. XML readers are not required to support this handler, and this handler is not included in the core SAX2 distribution.

Note that data-related DTD declarations (unparsed entities and notations) are already reported through the DTDHandler interface. If you are using the declaration handler together with a lexical handler, all of the events will occur between the startDTD and the endDTD events. To set the DeclHandler for an XML reader, use the setProperty method with the propertyId "http://xml.org/sax/properties/declaration-handler". If the reader does not support declaration events, it will throw a SAXNotRecognizedException or a SAXNotSupportedException when you attempt to register the handler.

## Member Summary

Member Functions: attributeDecl, elementDecl, externalEntityDecl, internalEntityDecl

## Destructor

### ~DeclHandler

virtual ~DeclHandler();

## Member Functions

### attributeDecl

virtual void attributeDecl(
const XMLString & eName,
const XMLString & aName,
const XMLString * valueDefault,
const XMLString * value
) = 0;

Report an attribute type declaration.

Only the effective (first) declaration for an attribute will be reported. The type will be one of the strings "CDATA", "ID", "IDREF", "IDREFS", "NMTOKEN", "NMTOKENS", "ENTITY", "ENTITIES", a parenthesized token group with the separator "|" and all whitespace removed, or the word "NOTATION" followed by a space followed by a parenthesized token group with all whitespace removed.

The value will be the value as reported to applications, appropriately normalized and with entity and character references expanded.

### elementDecl

virtual void elementDecl(
const XMLString & name,
const XMLString & model
) = 0;

Report an element type declaration.

The content model will consist of the string "EMPTY", the string "ANY", or a parenthesised group, optionally followed by an occurrence indicator. The model will be normalized so that all parameter entities are fully resolved and all whitespace is removed,and will include the enclosing parentheses. Other normalization (such as removing redundant parentheses or simplifying occurrence indicators) is at the discretion of the parser.

### externalEntityDecl

virtual void externalEntityDecl(
const XMLString & name,
const XMLString * publicId,
const XMLString & systemId
) = 0;

Report an external entity declaration.

Only the effective (first) declaration for each entity will be reported.

If the system identifier is a URL, the parser must resolve it fully before passing it to the application.

### internalEntityDecl

virtual void internalEntityDecl(
const XMLString & name,
const XMLString & value
) = 0;

Report an internal entity declaration.

Only the effective (first) declaration for each entity will be reported. All parameter entities in the value will be expanded, but general entities will not.