gnu.xml.pipeline

Class WellFormednessFilter

Implemented Interfaces:
ContentHandler, DeclHandler, DTDHandler, EventConsumer, LexicalHandler

public final class WellFormednessFilter
extends EventFilter

This filter reports fatal exceptions in the case of event streams that are not well formed. The rules currently tested include:

Other checks for event stream correctness may be provided in the future. For example, insisting that entity boundaries nest correctly, namespace scopes nest correctly, namespace values never contain relative URIs, attributes don't have "<" characters; and more.

Field Summary

Fields inherited from class gnu.xml.pipeline.EventFilter

DECL_HANDLER, FEATURE_URI, LEXICAL_HANDLER, PROPERTY_URI

Constructor Summary

WellFormednessFilter()
Swallows all events after performing well formedness checks.
WellFormednessFilter(EventConsumer consumer)
Passes events through to the specified consumer, after first processing them.

Method Summary

void
characters(ch[] , int start, int length)
Receive notification of character data.
void
comment(ch[] , int start, int length)
Report an XML comment anywhere in the document.
void
endCDATA()
Report the end of a CDATA section.
void
endDTD()
Report the end of DTD declarations.
void
endDocument()
Receive notification of the end of a document.
void
endElement(String uri, String localName, String qName)
Receive notification of the end of an element.
void
ignorableWhitespace(ch[] , int start, int length)
Receive notification of ignorable whitespace in element content.
void
notationDecl(String name, String publicId, String systemId)
void
processingInstruction(String target, String data)
Receive notification of a processing instruction.
void
reset()
Resets state as if any preceding event stream was well formed.
void
setDocumentLocator(Locator locator)
Throws an exception when called after startDocument.
void
startCDATA()
Report the start of a CDATA section.
void
startDTD(String root, String publicId, String systemId)
Report the start of DTD declarations, if any.
void
startDocument()
Receive notification of the beginning of a document.
void
startElement(String uri, String localName, String qName, Attributes atts)
Receive notification of the beginning of an element.
void
unparsedEntityDecl(String name, String publicId, String systemId, String notationName)

Methods inherited from class gnu.xml.pipeline.EventFilter

attributeDecl, bind, chainTo, characters, comment, elementDecl, endCDATA, endDTD, endDocument, endElement, endEntity, endPrefixMapping, externalEntityDecl, getContentHandler, getDTDHandler, getDocumentLocator, getErrorHandler, getNext, getProperty, ignorableWhitespace, internalEntityDecl, notationDecl, processingInstruction, setContentHandler, setDTDHandler, setDocumentLocator, setErrorHandler, setProperty, skippedEntity, startCDATA, startDTD, startDocument, startElement, startEntity, startPrefixMapping, unparsedEntityDecl

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

WellFormednessFilter

public WellFormednessFilter()
Swallows all events after performing well formedness checks.

WellFormednessFilter

public WellFormednessFilter(EventConsumer consumer)
Passes events through to the specified consumer, after first processing them.

Method Details

characters

public void characters(ch[] ,
                       int start,
                       int length)
            throws SAXException
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 Java char value. There are two 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.

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 Java 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).

Specified by:
characters in interface ContentHandler
Overrides:
characters in interface EventFilter
Parameters:
start - the start position in the array
length - the number of characters to read from the array
Throws:
SAXException - any SAX exception, possibly wrapping another exception

comment

public void comment(ch[] ,
                    int start,
                    int length)
            throws SAXException
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).

Specified by:
comment in interface LexicalHandler
Overrides:
comment in interface EventFilter
Parameters:
start - The starting position in the array.
length - The number of characters to use from the array.
Throws:
SAXException - The application may raise an exception.

endCDATA

public void endCDATA()
            throws SAXException
Report the end of a CDATA section.
Specified by:
endCDATA in interface LexicalHandler
Overrides:
endCDATA in interface EventFilter
Throws:
SAXException - The application may raise an exception.

endDTD

public void endDTD()
            throws SAXException
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.

Specified by:
endDTD in interface LexicalHandler
Overrides:
endDTD in interface EventFilter
Throws:
SAXException - The application may raise an exception.

endDocument

public void endDocument()
            throws SAXException
Receive notification of the end of a document.

There is an apparent contradiction between the documentation for this method and the documentation for ErrorHandler.fatalError(SAXParseException). Until this ambiguity is resolved in a future major release, clients should make no assumptions about whether endDocument() will or will not be invoked when the parser has reported a fatalError() or thrown an exception.

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.

Specified by:
endDocument in interface ContentHandler
Overrides:
endDocument in interface EventFilter
Throws:
SAXException - any SAX exception, possibly wrapping another exception

endElement

public void endElement(String uri,
                       String localName,
                       String qName)
            throws SAXException
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.

Specified by:
endElement in interface ContentHandler
Overrides:
endElement in interface EventFilter
Parameters:
uri - the Namespace URI, or the empty string if the element has no Namespace URI or if Namespace processing is not being performed
localName - the local name (without prefix), or the empty string if Namespace processing is not being performed
qName - the qualified XML name (with prefix), or the empty string if qualified names are not available
Throws:
SAXException - any SAX exception, possibly wrapping another exception

ignorableWhitespace

public void ignorableWhitespace(ch[] ,
                                int start,
                                int length)
            throws SAXException
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.

Specified by:
ignorableWhitespace in interface ContentHandler
Overrides:
ignorableWhitespace in interface EventFilter
Parameters:
start - the start position in the array
length - the number of characters to read from the array
Throws:
SAXException - any SAX exception, possibly wrapping another exception

notationDecl

public void notationDecl(String name,
                         String publicId,
                         String systemId)
            throws SAXException
Specified by:
notationDecl in interface DTDHandler
Overrides:
notationDecl in interface EventFilter

processingInstruction

public void processingInstruction(String target,
                                  String data)
            throws SAXException
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.

Specified by:
processingInstruction in interface ContentHandler
Overrides:
processingInstruction in interface EventFilter
Parameters:
target - the processing instruction target
data - the processing instruction data, or null if none was supplied. The data does not include any whitespace separating it from the target
Throws:
SAXException - any SAX exception, possibly wrapping another exception

reset

public void reset()
Resets state as if any preceding event stream was well formed. Particularly useful if it ended through some sort of error, and the endDocument call wasn't made.

setDocumentLocator

public void setDocumentLocator(Locator locator)
Throws an exception when called after startDocument.
Specified by:
setDocumentLocator in interface ContentHandler
Overrides:
setDocumentLocator in interface EventFilter
Parameters:
locator - the locator, to be used in error reporting or relative URI resolution.
Throws:
IllegalStateException - when called after the document has already been started

startCDATA

public void startCDATA()
            throws SAXException
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.

Specified by:
startCDATA in interface LexicalHandler
Overrides:
startCDATA in interface EventFilter
Throws:
SAXException - The application may raise an exception.

startDTD

public void startDTD(String root,
                     String publicId,
                     String systemId)
            throws SAXException
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.

Specified by:
startDTD in interface LexicalHandler
Overrides:
startDTD in interface EventFilter
Parameters:
publicId - The declared public identifier for the external DTD subset, or null if none was declared.
systemId - The declared system identifier for the external DTD subset, or null if none was declared. (Note that this is not resolved against the document base URI.)
Throws:
SAXException - The application may raise an exception.

startDocument

public void startDocument()
            throws SAXException
Receive notification of the beginning of a document.

The SAX parser will invoke this method only once, before any other event callbacks (except for setDocumentLocator).

Specified by:
startDocument in interface ContentHandler
Overrides:
startDocument in interface EventFilter
Throws:
SAXException - any SAX exception, possibly wrapping another exception

startElement

public void startElement(String uri,
                         String localName,
                         String qName,
                         Attributes atts)
            throws SAXException
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.

Specified by:
startElement in interface ContentHandler
Overrides:
startElement in interface EventFilter
Parameters:
uri - the Namespace URI, or the empty string if the element has no Namespace URI or if Namespace processing is not being performed
localName - the local name (without prefix), or the empty string if Namespace processing is not being performed
qName - the qualified name (with prefix), or the empty string if qualified names are not available
atts - the attributes attached to the element. If there are no attributes, it shall be an empty Attributes object. The value of this object after startElement returns is undefined
Throws:
SAXException - any SAX exception, possibly wrapping another exception

unparsedEntityDecl

public void unparsedEntityDecl(String name,
                               String publicId,
                               String systemId,
                               String notationName)
            throws SAXException
Specified by:
unparsedEntityDecl in interface DTDHandler
Overrides:
unparsedEntityDecl in interface EventFilter

WellFormednessFilter.java -- Copyright (C) 1999,2000,2001 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.