class Poco::XML::DOMBuilder
Overview
This class builds a tree representation of an XML document, according to the W3C Document Object Model, Level 1 and 2 specifications. More…
#include <DOMBuilder.h> class DOMBuilder: protected Poco::XML::DTDHandler, protected Poco::XML::ContentHandler, protected Poco::XML::LexicalHandler { public: // construction DOMBuilder( XMLReader& xmlReader, NamePool* pNamePool = 0 ); // methods virtual Document* parse(const XMLString& uri); virtual Document* parse(InputSource* pInputSource); virtual Document* parseMemoryNP( const char* xml, std::size_t size ); protected: // methods virtual void notationDecl( const XMLString& name, const XMLString* publicId, const XMLString* systemId ); virtual void unparsedEntityDecl( const XMLString& name, const XMLString* publicId, const XMLString& systemId, const XMLString& notationName ); virtual void setDocumentLocator(const Locator* loc); virtual void startDocument(); virtual void endDocument(); virtual void startElement( const XMLString& uri, const XMLString& localName, const XMLString& qname, const Attributes& attrList ); virtual void endElement( const XMLString& uri, const XMLString& localName, const XMLString& qname ); virtual void characters( const XMLChar ch [], int start, int length ); virtual void ignorableWhitespace( const XMLChar ch [], int start, int length ); virtual void processingInstruction( const XMLString& target, const XMLString& data ); virtual void startPrefixMapping( const XMLString& prefix, const XMLString& uri ); virtual void endPrefixMapping(const XMLString& prefix); virtual void skippedEntity(const XMLString& name); virtual void startDTD( const XMLString& name, const XMLString& publicId, const XMLString& systemId ); virtual void endDTD(); virtual void startEntity(const XMLString& name); virtual void endEntity(const XMLString& name); virtual void startCDATA(); virtual void endCDATA(); virtual void comment( const XMLChar ch [], int start, int length ); void appendNode(AbstractNode* pNode); void setupParse(); };
Inherited Members
public: // methods virtual void notationDecl( const XMLString& name, const XMLString* publicId, const XMLString* systemId ) = 0; virtual void unparsedEntityDecl( const XMLString& name, const XMLString* publicId, const XMLString& systemId, const XMLString& notationName ) = 0; virtual void setDocumentLocator(const Locator* loc) = 0; virtual void startDocument() = 0; virtual void endDocument() = 0; virtual void startElement( const XMLString& uri, const XMLString& localName, const XMLString& qname, const Attributes& attrList ) = 0; virtual void endElement( const XMLString& uri, const XMLString& localName, const XMLString& qname ) = 0; virtual void characters( const XMLChar ch [], int start, int length ) = 0; virtual void ignorableWhitespace( const XMLChar ch [], int start, int length ) = 0; virtual void processingInstruction( const XMLString& target, const XMLString& data ) = 0; virtual void startPrefixMapping( const XMLString& prefix, const XMLString& uri ) = 0; virtual void endPrefixMapping(const XMLString& prefix) = 0; virtual void skippedEntity(const XMLString& name) = 0; virtual void startDTD( const XMLString& name, const XMLString& publicId, const XMLString& systemId ) = 0; virtual void endDTD() = 0; virtual void startEntity(const XMLString& name) = 0; virtual void endEntity(const XMLString& name) = 0; virtual void startCDATA() = 0; virtual void endCDATA() = 0; virtual void comment( const XMLChar ch [], int start, int length ) = 0;
Detailed Documentation
This class builds a tree representation of an XML document, according to the W3C Document Object Model, Level 1 and 2 specifications.
The actual XML parsing is done by an XMLReader, which must be supplied to the DOMBuilder.
Construction
DOMBuilder( XMLReader& xmlReader, NamePool* pNamePool = 0 )
Creates a DOMBuilder using the given XMLReader.
If a NamePool is given, it becomes the Document ‘s NamePool.
Methods
virtual Document* parse(const XMLString& uri)
Parse an XML document from a location identified by an URI.
virtual Document* parse(InputSource* pInputSource)
Parse an XML document from a location identified by an InputSource.
virtual Document* parseMemoryNP( const char* xml, std::size_t size )
Parses an XML document from memory.
virtual void notationDecl( const XMLString& name, const XMLString* publicId, const XMLString* systemId )
Receive notification of a notation declaration event.
It is up to the application to record the notation for later reference, if necessary; notations may appear as attribute values and in unparsed entity declarations, and are sometime used with processing instruction target names.
At least one of publicId and systemId must be non-null. If a system identifier is present, and it is a URL, the SAX parser must resolve it fully before passing it to the application through this event.
There is no guarantee that the notation declaration will be reported before any unparsed entities that use it.
Note that publicId and systemId maybe null, therefore we pass a pointer rather than a reference.
virtual void unparsedEntityDecl( const XMLString& name, const XMLString* publicId, const XMLString& systemId, const XMLString& notationName )
Receive notification of an unparsed entity declaration event.
Note that the notation name corresponds to a notation reported by the notationDecl event. It is up to the application to record the entity for later reference, if necessary; unparsed entities may appear as attribute values.
If the system identifier is a URL, the parser must resolve it fully before passing it to the application.
Note that publicId maybe null, therefore we pass a pointer rather than a reference.
virtual void setDocumentLocator(const Locator* loc)
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()
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()
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 )
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 )
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 )
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 )
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 )
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 )
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)
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)
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.
virtual void startDTD( const XMLString& name, const XMLString& publicId, const XMLString& systemId )
Report the start of DTD declarations, if any.
This method is intended to report the beginning of the DOCTYPE declaration; if the document has no DOCTYPE declaration, this method will not be invoked.
All declarations reported through DTDHandler or DeclHandler events must appear between the startDTD and endDTD events. Declarations are assumed to belong to the internal DTD subset unless they appear between startEntity and endEntity events. Comments and processing instructions from the DTD should also be reported between the startDTD and endDTD events, in their original order of (logical) occurrence; they are not required to appear in their correct locations relative to DTDHandler or DeclHandler events, however.
Note that the start/endDTD events will appear within the start/endDocument events from ContentHandler and before the first startElement event.
virtual void endDTD()
Report the end of DTD declarations.
This method is intended to report the end of the DOCTYPE declaration; if the document has no DOCTYPE declaration, this method will not be invoked.
virtual void startEntity(const XMLString& name)
Report the beginning of some internal and external XML entities.
The reporting of parameter entities (including the external DTD subset) is optional, and SAX2 drivers that report LexicalHandler events may not implement it; you can use the http://xml.org/sax/features/lexical-handler/parameter-entities feature to query or control the reporting of parameter entities.
General entities are reported with their regular names, parameter entities have ‘’ prepended to their names, and the external DTD subset has the pseudo-entity name “[dtd]”.
When a SAX2 driver is providing these events, all other events must be properly nested within start/end entity events. There is no additional requirement that events from DeclHandler or DTDHandler be properly ordered.
Note that skipped entities will be reported through the skippedEntity event, which is part of the ContentHandler interface.
Because of the streaming event model that SAX uses, some entity boundaries cannot be reported under any circumstances:
* general entities within attribute values * parameter entities within declarations
These will be silently expanded, with no indication of where the original entity boundaries were.
Note also that the boundaries of character references (which are not really entities anyway) are not reported.
All start/endEntity events must be properly nested.
virtual void endEntity(const XMLString& name)
Report the end of an entity.
virtual void startCDATA()
Report the start of a CDATA section.
The contents of the CDATA section will be reported through the regular characters event; this event is intended only to report the boundary.
virtual void endCDATA()
Report the end of a CDATA section.
virtual void comment( const XMLChar ch [], int start, int length )
Report an XML comment anywhere in the document.
This callback will be used for comments inside or outside the document element, including comments in the external DTD subset (if read). Comments in the DTD must be properly nested inside start/endDTD and start/endEntity events (if used).