arabica/SAX/XMLReader.h
2003-08-27 14:26:32 +00:00

417 lines
14 KiB
C++

#ifndef XMLReaderH // -*- C++ -*-
#define XMLReaderH
// XMLReader.h
// $Id$
#include <string>
#include <memory>
#include <SAX/ContentHandler.h>
#include <SAX/EntityResolver.h>
#include <SAX/DTDHandler.h>
#include <SAX/ErrorHandler.h>
#include <SAX/InputSource.h>
namespace SAX
{
/**
* Interface for reading an XML document using callbacks.
*
* <p>XMLReader is the interface that an XML parser's SAX2 driver must
* implement. This interface allows an application to set and
* query features and properties in the parser, to register
* event handlers for document processing, and to initiate
* a document parse.</p>
*
* <p>All SAX interfaces are assumed to be synchronous: the
* {@link #parse parse} methods must not return until parsing
* is complete, and readers must wait for an event-handler callback
* to return before reporting the next event.</p>
*
* <p>This interface replaces the (now deprecated) SAX 1.0 {@link
* basic_Parser Parser} interface. The XMLReader interface
* contains two important enhancements over the old Parser
* interface:</p>
*
* <ol>
* <li>it adds a standard way to query and set features and
* properties; and</li>
* <li>it adds Namespace support, which is required for many
* higher-level XML standards.</li>
* </ol>
*
* <p>There are adapters available to convert a SAX1 Parser to
* a SAX2 XMLReader and vice-versa.</p>
*
* @since SAX 2.0
* @author Jez Higgins,
* <a href="mailto:jez@jezuk.co.uk">jez@jezuk.co.uk</a>
* @version 2.0
* @see basic_XMLFilter
* @see basic_helpers.ParserAdapter
* @see basic_helpers.XMLReaderAdapter
*/
template<class string_type>
class basic_XMLReader
{
public:
typedef string_type stringT;
typedef basic_EntityResolver<stringT> EntityResolverT;
typedef basic_DTDHandler<stringT> DTDHandlerT;
typedef basic_ContentHandler<stringT> ContentHandlerT;
typedef basic_InputSource<stringT> InputSourceT;
typedef basic_ErrorHandler<stringT> ErrorHandlerT;
virtual ~basic_XMLReader() { }
/////////////////////////////////////////////////
// Configuration
/**
* Look up the value of a feature.
*
* <p>The feature name is any fully-qualified URI. It is
* possible for an XMLReader to recognize a feature name but
* to be unable to return its value; this is especially true
* in the case of an adapter for a SAX1 Parser, which has
* no way of knowing whether the underlying parser is
* performing validation or expanding external entities.</p>
*
* <p>All XMLReaders are required to recognize the
* http://xml.org/sax/features/namespaces and the
* http://xml.org/sax/features/namespace-prefixes feature names.</p>
*
* <p>Some feature values may be available only in specific
* contexts, such as before, during, or after a parse.</p>
*
* <p>Typical usage is something like this:</p>
*
* <pre>
* XMLReader r = new MySAXDriver();
*
* // try to activate validation
* try {
* r.setFeature("http://xml.org/sax/features/validation", true);
* } catch (SAXException e) {
* System.err.println("Cannot activate validation.");
* }
*
* // register event handlers
* r.setContentHandler(new MyContentHandler());
* r.setErrorHandler(new MyErrorHandler());
*
* // parse the first document
* try {
* r.parse("http://www.foo.com/mydoc.xml");
* } catch (IOException e) {
* System.err.println("I/O exception reading XML document");
* } catch (SAXException e) {
* System.err.println("XML exception reading document.");
* }
* </pre>
*
* <p>Implementors are free (and encouraged) to invent their own features,
* using names built on their own URIs.</p>
*
* @param name The feature name, which is a fully-qualified URI.
* @return The current state of the feature (true or false).
* @see #setFeature
*/
virtual bool getFeature(const stringT& name) const = 0;
/**
* Set the state of a feature.
*
* <p>The feature name is any fully-qualified URI. It is
* possible for an XMLReader to recognize a feature name but
* to be unable to set its value; this is especially true
* in the case of an adapter for a SAX1 {@link basic_Parser Parser},
* which has no way of affecting whether the underlying parser is
* validating, for example.</p>
*
* <p>All XMLReaders are required to support setting
* http://xml.org/sax/features/namespaces to true and
* http://xml.org/sax/features/namespace-prefixes to false.</p>
*
* <p>Some feature values may be immutable or mutable only
* in specific contexts, such as before, during, or after
* a parse.</p>
*
* @param name The feature name, which is a fully-qualified URI.
* @param value The requested value of the feature (true or false).
* @exception SAXNotRecognizedException When the
* XMLReader does not recognize the feature name.
* @exception SAXNotSupportedException When the
* XMLReader recognizes the feature name but
* cannot set the requested value.
* @see #getFeature
* @see FeatureNames
* @see http://www.saxproject.org/apidoc/org/xml/sax/package-summary.html#package_description for a list of SAX2 features.
*/
virtual void setFeature(const stringT& name, bool value) = 0;
/////////////////////////////////////////////////
// Event Handlers
/**
* Allow an application to register an entity resolver.
*
* <p>If the application does not register an entity resolver,
* the XMLReader will perform its own default resolution.</p>
*
* <p>Applications may register a new or different resolver in the
* middle of a parse, and the SAX parser must begin using the new
* resolver immediately.</p>
*
* @param resolver The entity resolver.
* @see #getEntityResolver
*/
virtual void setEntityResolver(EntityResolverT& resolver) = 0;
/**
* Return the current entity resolver.
*
* @return The current entity resolver, or null if none
* has been registered.
* @see #setEntityResolver
*/
virtual EntityResolverT* getEntityResolver() const = 0;
/**
* Allow an application to register a DTD event handler.
*
* <p>If the application does not register a DTD handler, all DTD
* events reported by the SAX parser will be silently ignored.</p>
*
* <p>Applications may register a new or different handler in the
* middle of a parse, and the SAX parser must begin using the new
* handler immediately.</p>
*
* @param handler The DTD handler.
* @see #getDTDHandler
*/
virtual void setDTDHandler(DTDHandlerT& handler) = 0;
/**
* Return the current DTD handler.
*
* @return The current DTD handler, or null if none
* has been registered.
* @see #setDTDHandler
*/
virtual DTDHandlerT* getDTDHandler() const = 0;
/**
* Allow an application to register a content event handler.
*
* <p>If the application does not register a content handler, all
* content events reported by the SAX parser will be silently
* ignored.</p>
*
* <p>Applications may register a new or different handler in the
* middle of a parse, and the SAX parser must begin using the new
* handler immediately.</p>
*
* @param handler The content handler.
* @see #getContentHandler
*/
virtual void setContentHandler(ContentHandlerT& handler) = 0;
/**
* Return the current content handler.
*
* @return The current content handler, or null if none
* has been registered.
* @see #setContentHandler
*/
virtual ContentHandlerT* getContentHandler() const = 0;
/**
* Allow an application to register an error event handler.
*
* <p>If the application does not register an error handler, all
* error events reported by the SAX parser will be silently
* ignored; however, normal processing may not continue. It is
* highly recommended that all SAX applications implement an
* error handler to avoid unexpected bugs.</p>
*
* <p>Applications may register a new or different handler in the
* middle of a parse, and the SAX parser must begin using the new
* handler immediately.</p>
*
* @param handler The error handler.
* @see #getErrorHandler
*/
virtual void setErrorHandler(ErrorHandlerT& handler) = 0;
/**
* Return the current error handler.
*
* @return The current error handler, or null if none
* has been registered.
* @see #setErrorHandler
*/
virtual ErrorHandlerT* getErrorHandler() const = 0;
//////////////////////////////////////////////////
// Parsing
/**
* Parse an XML document from a system identifier (URI).
*
* <p>This method is a shortcut for the common case of reading a
* document from a system identifier. It is the exact
* equivalent of the following:</p>
*
* <pre>
* InputSource is(systemId);
* parse(is);
* </pre>
*
* <p>If the system identifier is a URL, it must be fully resolved
* by the application before it is passed to the parser.</p>
*
* @param systemId The system identifier (URI).
* @see #parse(basic_InputSource&)
*/
void parse(const stringT& systemId)
{
InputSourceT is(systemId);
parse(is);
} // parser
/**
* Parse an XML document.
*
* <p>The application can use this method to instruct the XML
* reader to begin parsing an XML document from any valid input
* source (a character stream, a byte stream, or a URI).</p>
*
* <p>Applications may not invoke this method while a parse is in
* progress (they should create a new XMLReader instead for each
* nested XML document). Once a parse is complete, an
* application may reuse the same XMLReader object, possibly with a
* different input source.</p>
*
* <p>During the parse, the XMLReader will provide information
* about the XML document through the registered event
* handlers.</p>
*
* <p>This method is synchronous: it will not return until parsing
* has ended. If a client application wants to terminate
* parsing early, it should throw an exception.</p>
*
* @param input The input source for the top-level of the
* XML document.
* @see basic_InputSource
* @see #parse(const stringT&)
* @see #setEntityResolver
* @see #setDTDHandler
* @see #setContentHandler
* @see #setErrorHandler
*/
virtual void parse(InputSourceT& input) = 0;
////////////////////////////////////////////////////
// property implementation
protected:
class PropertyBase
{
public:
virtual ~PropertyBase() { }
}; // PropertyBase
template<typename propertyTypeT>
class Property : public PropertyBase
{
public:
Property(propertyTypeT wrappee) : wrappee_(wrappee) { }
propertyTypeT get() { return wrappee_; }
private:
propertyTypeT wrappee_;
}; // class Property
public:
virtual std::auto_ptr<PropertyBase> doGetProperty(const stringT& name) = 0;
virtual void doSetProperty(const stringT& name, std::auto_ptr<PropertyBase> value) = 0;
/**
* Look up the value of a property.
*
* <p>The property name is any fully-qualified URI. It is
* possible for an XMLReader to recognize a property name but
* to be unable to return its state; this is especially true
* in the case of an adapter for a SAX1 {@link basic_Parser
* Parser}.</p>
*
* <p>XMLReaders are not required to recognize any specific
* property names, though an initial core set is documented for
* SAX2.</p>
*
* <p>Some property values may be available only in specific
* contexts, such as before, during, or after a parse.</p>
*
* <p>Implementors are free (and encouraged) to invent their own properties,
* using names built on their own URIs.</p>
*
* @param name The property name, which is a fully-qualified URI.
* @return The current value of the property.
* @exception SAXNotRecognizedException When the
* XMLReader does not recognize the property name.
* @exception SAXNotSupportedException When the
* XMLReader recognizes the property name but
* cannot determine its value at this time.
* @see #setProperty
*/
template<typename propertyTypeT>
propertyTypeT& getProperty(const stringT& name) const
{
std::auto_ptr<PropertyBase> pb = doGetProperty(name);
Property<propertyTypeT&>* prop = dynamic_cast<Property<propertyTypeT&>* >(pb.get());
if(!prop)
throw std::bad_cast("Property " + name + " is wrong type.");
return pro->get();
} // getProperty
/**
* Set the value of a property.
*
* <p>The property name is any fully-qualified URI. It is
* possible for an XMLReader to recognize a property name but
* to be unable to set its value; this is especially true
* in the case of an adapter for a SAX1 {@link basic_Parser
* Parser}.</p>
*
* <p>XMLReaders are not required to recognize setting
* any specific property names, though a core set is provided with
* SAX2.</p>
*
* <p>Some property values may be immutable or mutable only
* in specific contexts, such as before, during, or after
* a parse.</p>
*
* <p>This method is also the standard mechanism for setting
* extended handlers.</p>
*
* @param name The property name, which is a fully-qualified URI.
* @param value The requested value for the property.
* @exception SAXNotRecognizedException When the
* XMLReader does not recognize the property name.
* @exception SAXNotSupportedException When the
* XMLReader recognizes the property name but
* cannot set the requested value.
*/
template<typename propertyTypeT>
void setProperty(const stringT& name, propertyTypeT& value)
{
Property<propertyTypeT&>* prop = new Property<propertyTypeT&>(value);
doSetProperty(name, std::auto_ptr<PropertyBase>(prop));
} // setProperty
}; // class basic_XMLReader
}; // namespace SAX
/* Included to ensure that #include<SAX/XMLReader.h> defines a class called
* XMLReader.
*/
#include <SAX/ParserConfig.h>
#endif
// end of file