topical media & game development
lib-of-vs-libs-Poco-include-Poco-SAX-ContentHandler.h / h
//
// ContentHandler.h
//
//
//
// Library: XML
// Package: SAX
// Module: SAX
//
// SAX2 ContentHandler Interface.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
//
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
ifndef SAX_ContentHandler_INCLUDED
define SAX_ContentHandler_INCLUDED
include "Poco/XML/XML.h"
include "Poco/XML/XMLString.h"
namespace Poco {
namespace XML {
class Locator;
class Attributes;
class XML_API ContentHandler
Receive notification of the logical content of a document.
This is the main interface that most SAX applications implement: if the
application needs to be informed of basic parsing events, it implements
this interface and registers an instance with the SAX parser using the setContentHandler
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.
This interface is similar to the now-deprecated SAX 1.0 DocumentHandler
interface, but it adds support for Namespaces and for reporting skipped
entities (in non-validating XML processors).
Receive notification of the logical content of a document.
{
public:
virtual void setDocumentLocator(const Locator* loc) = 0;
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
ContentHandler 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
SAX event callbacks after startDocument returns and before endDocument is
called. The application should not attempt to use it at any other time.
virtual void startDocument() = 0;
Receive notification of the beginning of a document.
The SAX parser calls this function one time before calling all other
functions of this class (except SetDocumentLocator).
virtual void endDocument() = 0;
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.
virtual void startElement(const XMLString& uri, const XMLString& localName, const XMLString& qname, const Attributes& attrList) = 0;
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.
This event allows up to three name components for each element:
1. the Namespace URI;
2. the local name; and
3. the qualified (prefixed) name.
Any or all of these may be provided, depending on the values of the
http://xml.org/sax/features/namespaces
and the http://xml.org/sax/features/namespace-prefixes properties:
* the Namespace URI and local name are required when the namespaces
property is true (the default), and are optional when the namespaces property
is false (if one is specified, both must be);
* the qualified name is required when the namespace-prefixes property
is true, and is optional when the namespace-prefixes property is false (the
default).
Note that the attribute list provided will contain only attributes with
explicit values (specified or defaulted): #IMPLIED attributes will be omitted.
The attribute list will contain attributes used for Namespace declarations
(xmlns* attributes) only if the
http://xml.org/sax/features/namespace-prefixes
property is true (it is false by default, and support for a true value is
optional).
Like characters(), attribute values may have characters that need more than
one char value.
virtual void endElement(const XMLString& uri, const XMLString& localName, const XMLString& qname) = 0;
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).
For information on the names, see startElement.
virtual void characters(const XMLChar ch[], int start, int length) = 0;
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.
Individual characters may consist of more than one XMLChar value. There
are three important cases where this happens, because characters can't be
represented in just sixteen bits. In one case, characters are represented
in a Surrogate Pair, using two special Unicode values. Such characters are
in the so-called "Astral Planes", with a code point above U+FFFF. A second
case involves composite characters, such as a base character combining with
one or more accent characters. And most important, if XMLChar is a plain
char, characters are encoded in UTF-8.
Your code should not assume that algorithms using char-at-a-time idioms
will be working in character units; in some cases they will split characters.
This is relevant wherever XML permits arbitrary characters, such as attribute
values, processing instruction data, and comments as well as in data reported
from this method. It's also generally relevant whenever C++ code manipulates
internationalized text; the issue isn't unique to XML.
Note that some parsers will report whitespace in element content using the
ignorableWhitespace method rather than this one (validating parsers must
do so).
virtual void ignorableWhitespace(const XMLChar ch[], int start, int length) = 0;
Receive notification of ignorable whitespace in element content.
Validating Parsers must use this method to report each chunk of whitespace
in element content (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.
virtual void processingInstruction(const XMLString& target, const XMLString& data) = 0;
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 must 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.
Like characters(), processing instruction data may have characters that
need more than one char value.
virtual void startPrefixMapping(const XMLString& prefix, const XMLString& uri) = 0;
Begin the scope of a prefix-URI Namespace mapping.
The information from this event is not necessary for normal Namespace processing:
the SAX XML reader will automatically replace prefixes for element and attribute
names when the
http://xml.org/sax/features/namespaces feature is true (the
default).
There are cases, however, when applications need to use prefixes in character
data or in attribute values, where they cannot safely be expanded automatically;
the start/endPrefixMapping event supplies the information to the application
to expand prefixes in those contexts itself, if necessary.
Note that start/endPrefixMapping events are not guaranteed to be properly
nested relative to each other: all startPrefixMapping events will occur
immediately before the corresponding startElement event, and all endPrefixMapping
events will occur immediately after the corresponding endElement event,
but their order is not otherwise guaranteed.
There should never be start/endPrefixMapping events for the "xml" prefix,
since it is predeclared and immutable.
virtual void endPrefixMapping(const XMLString& prefix) = 0;
End the scope of a prefix-URI mapping.
See startPrefixMapping for details. These events will always occur immediately
after the corresponding endElement event, but the order of endPrefixMapping
events is not otherwise guaranteed.
virtual void skippedEntity(const XMLString& name) = 0;
Receive notification of a skipped entity. This is not called for entity
references within markup constructs such as element start tags or markup
declarations. (The XML recommendation requires reporting skipped external
entities. SAX also reports internal entity expansion/non-expansion, except
within markup constructs.)
The Parser will invoke this method each time the entity is skipped. Non-validating
processors may skip entities if they have not seen the declarations (because,
for example, the entity was declared in an external DTD subset). All processors
may skip external entities, depending on the values of the
http://xml.org/sax/features/external-general-entities
and the http://xml.org/sax/features/external-parameter-entities properties.
protected:
virtual ~ContentHandler();
};
} } // namespace Poco::XML
endif // SAX_ContentHandler_INCLUDED
(C) Æliens
04/09/2009
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