gnu.xml.pipeline

Class DomConsumer.Handler

Enclosing Class:
DomConsumer
Implemented Interfaces:
ContentHandler, DeclHandler, DTDHandler, LexicalHandler
Known Direct Subclasses:
Consumer.Backdoor

public static class DomConsumer.Handler
extends Object
implements ContentHandler, LexicalHandler, DTDHandler, DeclHandler

Class used to intercept various parsing events and use them to populate a DOM document. Subclasses would typically know and use backdoors into specific DOM implementations, used to implement DTD-related functionality.

Note that if this ever throws a DOMException (runtime exception) that will indicate a bug in the DOM (e.g. doesn't support something per specification) or the parser (e.g. emitted an illegal name, or accepted illegal input data).

Field Summary

protected DomConsumer
consumer

Constructor Summary

Handler(DomConsumer consumer)
Subclasses may use SAX2 events to provide additional behaviors in the resulting DOM.

Method Summary

void
attributeDecl(String eName, String aName, String type, String mode, String value)
Report an attribute type declaration.
boolean
canPopulateEntityRefs()
May be overridden by subclasses to return true, indicating that entity reference nodes can be populated and then made read-only.
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.
protected Text
createText(boolean isCDATA, ch[] , int start, int length)
Subclasses may overrride this method to provide a more efficient way to construct text nodes.
void
elementDecl(String name, String model)
Report an element type declaration.
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
endEntity(String name)
Report the end of an entity.
void
endPrefixMapping(String prefix)
End the scope of a prefix-URI mapping.
void
externalEntityDecl(String name, String publicId, String SystemId)
Report a parsed external entity declaration.
protected Document
getDocument()
Returns the document under construction.
protected Node
getTop()
Returns the current node being populated.
void
ignorableWhitespace(ch[] , int start, int length)
Receive notification of ignorable whitespace in element content.
void
internalEntityDecl(String name, String value)
Report an internal entity declaration.
void
notationDecl(String name, String publicId, String SystemId)
void
processingInstruction(String target, String data)
Receive notification of a processing instruction.
void
setDocumentLocator(Locator locator)
Receive an object for locating the origin of SAX document events.
void
skippedEntity(String name)
Receive notification of a skipped entity.
void
startCDATA()
Report the start of a CDATA section.
void
startDTD(String name, 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
startEntity(String name)
Report the beginning of some internal and external XML entities.
void
startPrefixMapping(String prefix, String uri)
Begin the scope of a prefix-URI Namespace mapping.
void
unparsedEntityDecl(String name, String publicId, String SystemId, String notationName)

Methods inherited from class java.lang.Object

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

Field Details

consumer

protected DomConsumer consumer

Constructor Details

Handler

protected Handler(DomConsumer consumer)
            throws SAXException
Subclasses may use SAX2 events to provide additional behaviors in the resulting DOM.

Method Details

attributeDecl

public void attributeDecl(String eName,
                          String aName,
                          String type,
                          String mode,
                          String value)
            throws SAXException
Report an attribute type declaration.

Only the effective (first) declaration for an attribute will be reported. The type will be one of the strings "CDATA", "ID", "IDREF", "IDREFS", "NMTOKEN", "NMTOKENS", "ENTITY", "ENTITIES", a parenthesized token group with the separator "|" and all whitespace removed, or the word "NOTATION" followed by a space followed by a parenthesized token group with all whitespace removed.

The value will be the value as reported to applications, appropriately normalized and with entity and character references expanded.

Specified by:
attributeDecl in interface DeclHandler
Parameters:
eName - The name of the associated element.
aName - The name of the attribute.
type - A string representing the attribute type.
mode - A string representing the attribute defaulting mode ("#IMPLIED", "#REQUIRED", or "#FIXED") or null if none of these applies.
value - A string representing the attribute's default value, or null if there is none.
Throws:
SAXException - The application may raise an exception.

canPopulateEntityRefs

public boolean canPopulateEntityRefs()
May be overridden by subclasses to return true, indicating that entity reference nodes can be populated and then made read-only.

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
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
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.

createText

protected Text createText(boolean isCDATA,
                          ch[] ,
                          int start,
                          int length)
Subclasses may overrride this method to provide a more efficient way to construct text nodes. Typically, copying the text into a single character array will be more efficient than doing that as well as allocating other needed for a String, including an internal StringBuffer. Those additional memory and CPU costs can be incurred later, if ever needed. Unfortunately the standard DOM factory APIs encourage those costs to be incurred early.

elementDecl

public void elementDecl(String name,
                        String model)
            throws SAXException
Report an element type declaration.

The content model will consist of the string "EMPTY", the string "ANY", or a parenthesised group, optionally followed by an occurrence indicator. The model will be normalized so that all parameter entities are fully resolved and all whitespace is removed,and will include the enclosing parentheses. Other normalization (such as removing redundant parentheses or simplifying occurrence indicators) is at the discretion of the parser.

Specified by:
elementDecl in interface DeclHandler
Parameters:
name - The element type name.
model - The content model as a normalized string.
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
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
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
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
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

endEntity

public void endEntity(String name)
            throws SAXException
Report the end of an entity.
Specified by:
endEntity in interface LexicalHandler
Parameters:
name - The name of the entity that is ending.
Throws:
SAXException - The application may raise an exception.

endPrefixMapping

public void endPrefixMapping(String prefix)
            throws SAXException
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.

Specified by:
endPrefixMapping in interface ContentHandler
Parameters:
prefix - the prefix that was being mapped. This is the empty string when a default mapping scope ends.
Throws:
SAXException - the client may throw an exception during processing

externalEntityDecl

public void externalEntityDecl(String name,
                               String publicId,
                               String SystemId)
            throws SAXException
Report a parsed external entity declaration.

Only the effective (first) declaration for each entity will be reported.

If the system identifier is a URL, the parser must resolve it fully before passing it to the application.

Specified by:
externalEntityDecl in interface DeclHandler
Parameters:
name - The name of the entity. If it is a parameter entity, the name will begin with '%'.
publicId - The entity's public identifier, or null if none was given.
Throws:
SAXException - The application may raise an exception.

getDocument

protected Document getDocument()
Returns the document under construction.

getTop

protected Node getTop()
Returns the current node being populated. This is usually an Element or Document, but it might be an EntityReference node if some implementation-specific code knows how to put those into the result tree and later mark them as readonly.

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
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

internalEntityDecl

public void internalEntityDecl(String name,
                               String value)
            throws SAXException
Report an internal entity declaration.

Only the effective (first) declaration for each entity will be reported. All parameter entities in the value will be expanded, but general entities will not.

Specified by:
internalEntityDecl in interface DeclHandler
Parameters:
name - The name of the entity. If it is a parameter entity, the name will begin with '%'.
value - The replacement text of the entity.
Throws:
SAXException - The application may raise an exception.

notationDecl

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

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
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

setDocumentLocator

public void setDocumentLocator(Locator locator)
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.

Specified by:
setDocumentLocator in interface ContentHandler
Parameters:
locator - an object that can return the location of any SAX document event
See Also:
Locator

skippedEntity

public void skippedEntity(String name)
            throws SAXException
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.

Specified by:
skippedEntity in interface ContentHandler
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]"
Throws:
SAXException - any SAX exception, possibly wrapping another exception

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
Throws:
SAXException - The application may raise an exception.

startDTD

public void startDTD(String name,
                     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
Parameters:
name - The document type name.
publicId - The declared public identifier for the external DTD subset, or null if none was declared.
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
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
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

startEntity

public void startEntity(String name)
            throws SAXException
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.

Specified by:
startEntity in interface LexicalHandler
Parameters:
name - The name of the entity. If it is a parameter entity, the name will begin with '%', and if it is the external DTD subset, it will be "[dtd]".
Throws:
SAXException - The application may raise an exception.

startPrefixMapping

public void startPrefixMapping(String prefix,
                               String uri)
            throws SAXException
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.

Specified by:
startPrefixMapping in interface ContentHandler
Parameters:
prefix - the Namespace prefix being declared. An empty string is used for the default element namespace, which has no prefix.
uri - the Namespace URI the prefix is mapped to
Throws:
SAXException - the client may throw an exception during processing

unparsedEntityDecl

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

DomConsumer.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.