ContentHandler Class Referenceabstract

Receive notification of general document events. More...

`#include <xercesc/sax2/ContentHandler.hpp>`

Inheritance diagram for ContentHandler:

## Public Member Functions

Constructors and Destructor
| ContentHandler ()
| Default constructor.
virtual | ~ContentHandler ()
| Destructor.

## The virtual document handler interface

virtual void | characters (const XMLCh *const chars, const XMLSize_t length)=0
| Receive notification of character data.
virtual void | endDocument ()=0
| Receive notification of the end of a document.
virtual void | endElement (const XMLCh *const uri, const XMLCh *const localname, const XMLCh *const qname)=0
| Receive notification of the end of an element.
virtual void | ignorableWhitespace (const XMLCh *const chars, const XMLSize_t length)=0
| Receive notification of ignorable whitespace in element content.
virtual void | processingInstruction (const XMLCh *const target, const XMLCh *const data)=0
| Receive notification of a processing instruction.
virtual void | setDocumentLocator (const Locator *const locator)=0
| Receive an object for locating the origin of SAX document events.
virtual void | startDocument ()=0
| Receive notification of the beginning of a document.
virtual void | startElement (const XMLCh *const uri, const XMLCh *const localname, const XMLCh *const qname, const Attributes &attrs)=0
| Receive notification of the beginning of an element.
virtual void | startPrefixMapping (const XMLCh *const prefix, const XMLCh *const uri)=0
| Receive notification of the start of an namespace prefix mapping.
virtual void | endPrefixMapping (const XMLCh *const prefix)=0
| Receive notification of the end of an namespace prefix mapping.
virtual void | skippedEntity (const XMLCh *const name)=0
| Receive notification of a skipped entity.

## Detailed Description

Receive notification of general document events.

This is the main interface that most SAX2 applications implement: if the application needs to be informed of basic parsing events, it implements this interface and registers an instance with the SAX2 parser using the setDocumentHandler method. The parser uses the instance to report basic document-related events like the start and end of elements and character data.

The order of events in this interface is very important, and mirrors the order of information in the document itself. For example, all of an element's content (character data, processing instructions, and/or subelements) will appear, in order, between the startElement event and the corresponding endElement event.

Application writers who do not want to implement the entire interface while can derive a class from Sax2HandlerBase, which implements the default functionality; parser writers can instantiate Sax2HandlerBase to obtain a default handler. The application can find the location of any document event using the Locator interface supplied by the Parser through the setDocumentLocator method.

See also
  Parser::setDocumentHandler
  Locator::Locator
  Sax2HandlerBase::Sax2HandlerBase

## Constructor & Destructor Documentation

## ContentHandler()

ContentHandler::ContentHandler | ( |  | ) |

Default constructor.

## ~ContentHandler()

virtual ContentHandler::~ContentHandler | ( |  | ) |

virtual

Destructor.

## Member Function Documentation

## characters()

virtual void ContentHandler::characters | ( | const XMLCh *const | chars,
|  | const XMLSize_t | length
| ) |  |

pure virtual

Receive notification of character data.

The Parser will call this method to report each chunk of character data. SAX parsers may return all contiguous character data in a single chunk, or they may split it into several chunks; however, all of the characters in any single event must come from the same external entity, so that the Locator provides useful information.

The application must not attempt to read from the array outside of the specified range.

Note that some parsers will report whitespace using the ignorableWhitespace() method rather than this one (validating parsers must do so).

Parameters

  chars | The characters from the XML document.
  length | The number of characters to read from the array.

Exceptions

  SAXException | Any SAX exception, possibly wrapping another exception.

See also
  ignorableWhitespace
  Locator::Locator

Implemented in DefaultHandler.

## endDocument()

virtual void ContentHandler::endDocument | ( |  | ) |

pure virtual

Receive notification of the end of a document.

The SAX parser will invoke this method only once, and it will be the last method invoked during the parse. The parser shall not invoke this method until it has either abandoned parsing (because of an unrecoverable error) or reached the end of input.

Exceptions

  SAXException | Any SAX exception, possibly wrapping another exception.

Implemented in DefaultHandler.

## endElement()

virtual void ContentHandler::endElement | ( | const XMLCh *const | uri,
|  | const XMLCh *const | localname,
|  | const XMLCh *const | qname
| ) |  |

pure virtual

Receive notification of the end of an element.

The SAX parser will invoke this method at the end of every element in the XML document; there will be a corresponding startElement() event for every endElement() event (even when the element is empty).

Parameters

  uri | The URI of the associated namespace for this element
  localname | The local part of the element name
  qname | The QName of this element

Exceptions

  SAXException | Any SAX exception, possibly wrapping another exception.

Implemented in DefaultHandler.

## endPrefixMapping()

virtual void ContentHandler::endPrefixMapping | ( | const XMLCh *const | prefix | ) |

pure virtual

Receive notification of the end of an namespace prefix mapping.

By default, do nothing. Application writers may override this method in a subclass to take specific actions at the end of each namespace prefix mapping.

Parameters

  prefix | The namespace prefix used

Exceptions

  SAXException | Any SAX exception, possibly wrapping another exception.

Implemented in DefaultHandler.

## ignorableWhitespace()

virtual void ContentHandler::ignorableWhitespace | ( | const XMLCh *const | chars,
|  | const XMLSize_t | length
| ) |  |

pure virtual

Receive notification of ignorable whitespace in element content.

Validating Parsers must use this method to report each chunk of ignorable whitespace (see the W3C XML 1.0 recommendation, section 2.10): non-validating parsers may also use this method if they are capable of parsing and using content models.

SAX parsers may return all contiguous whitespace in a single chunk, or they may split it into several chunks; however, all of the characters in any single event must come from the same external entity, so that the Locator provides useful information.

The application must not attempt to read from the array outside of the specified range.

Parameters

  chars | The characters from the XML document.
  length | The number of characters to read from the array.

Exceptions

  SAXException | Any SAX exception, possibly wrapping another exception.

See also
  characters

Implemented in DefaultHandler.

## processingInstruction()

virtual void ContentHandler::processingInstruction | ( | const XMLCh *const | target,
|  | const XMLCh *const | data
| ) |  |

pure virtual

Receive notification of a processing instruction.

The Parser will invoke this method once for each processing instruction found: note that processing instructions may occur before or after the main document element.

A SAX parser should never report an XML declaration (XML 1.0, section 2.8) or a text declaration (XML 1.0, section 4.3.1) using this method.

Parameters

  target | The processing instruction target.
  data | The processing instruction data, or null if none was supplied.

Exceptions

  SAXException | Any SAX exception, possibly wrapping another exception.

Implemented in DefaultHandler.

## setDocumentLocator()

virtual void ContentHandler::setDocumentLocator | ( | const Locator *const | locator | ) |

pure virtual

Receive an object for locating the origin of SAX document events.

SAX parsers are strongly encouraged (though not absolutely required) to supply a locator: if it does so, it must supply the locator to the application by invoking this method before invoking any of the other methods in the DocumentHandler interface.

The locator allows the application to determine the end position of any document-related event, even if the parser is not reporting an error. Typically, the application will use this information for reporting its own errors (such as character content that does not match an application's business rules). The information returned by the locator is probably not sufficient for use with a search engine.

Note that the locator will return correct information only during the invocation of the events in this interface. The application should not attempt to use it at any other time.

Parameters

  locator | An object that can return the location of any SAX document event. The object is only 'on loan' to the client code and they are not to attempt to delete or modify it in any way!

See also
  Locator::Locator

Implemented in DefaultHandler.

## skippedEntity()

virtual void ContentHandler::skippedEntity | ( | const XMLCh *const | name | ) |

pure virtual

Receive notification of a skipped entity.

The parser will invoke this method once for each entity skipped. All processors may skip external entities, depending on the values of the features:
http://xml.org/sax/features/external-general-entities
http://xml.org/sax/features/external-parameter-entities

Note: Xerces (specifically) never skips any entities, regardless of the above features. This function is never called in the Xerces implementation of SAX2.

Introduced with SAX2

Parameters

  name | The name of the skipped entity. If it is a parameter entity, the name will begin with %, and if it is the external DTD subset, it will be the string [dtd].

Exceptions

  SAXException | Any SAX exception, possibly wrapping another exception.

Implemented in DefaultHandler.

## startDocument()

virtual void ContentHandler::startDocument | ( |  | ) |

pure virtual

Receive notification of the beginning of a document.

The SAX parser will invoke this method only once, before any other methods in this interface or in DTDHandler (except for setDocumentLocator).

Exceptions

  SAXException | Any SAX exception, possibly wrapping another exception.

Implemented in DefaultHandler.

## startElement()

virtual void ContentHandler::startElement | ( | const XMLCh *const | uri,
|  | const XMLCh *const | localname,
|  | const XMLCh *const | qname,
|  | const Attributes & | attrs
| ) |  |

pure virtual

Receive notification of the beginning of an element.

The Parser will invoke this method at the beginning of every element in the XML document; there will be a corresponding endElement() event for every startElement() event (even when the element is empty). All of the element's content will be reported, in order, before the corresponding endElement() event.

Note that the attribute list provided will contain only attributes with explicit values (specified or defaulted): #IMPLIED attributes will be omitted.

Parameters

  uri | The URI of the associated namespace for this element
  localname | The local part of the element name
  qname | The QName of this element
  attrs | The attributes attached to the element, if any.

Exceptions

  SAXException | Any SAX exception, possibly wrapping another exception.

See also
  endElement
  Attributes::Attributes

Implemented in DefaultHandler.

## startPrefixMapping()

virtual void ContentHandler::startPrefixMapping | ( | const XMLCh *const | prefix,
|  | const XMLCh *const | uri
| ) |  |

pure virtual

Receive notification of the start of an namespace prefix mapping.

By default, do nothing. Application writers may override this method in a subclass to take specific actions at the start of each namespace prefix mapping.

Parameters

  prefix | The namespace prefix used
  uri | The namespace URI used.

Exceptions

  SAXException | Any SAX exception, possibly wrapping another exception.

Implemented in DefaultHandler.

The documentation for this class was generated from the following file:

- ContentHandler.hpp