RqlQueryResultParser

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nl.aidministrator.rdf.client.rql
Class RqlQueryResultParser

java.lang.Object
  nl.aidministrator.rdf.client.rql.RqlQueryResultParser

All Implemented Interfaces:: org.xml.sax.ContentHandler

public class RqlQueryResultParser
extends java.lang.Object
implements org.xml.sax.ContentHandler

Parser for parsing the query results from RQL queries. This parser is used by the SesameProxy. This is a SAX-based parser. An RDF triples based parser would have been nicer but is more difficult to implement as there are no guarantees for the order in which an RDF parser reports statements.

Field Summary

private java.lang.StringBuffer _chars
          Buffer used to store characters reported in consecutive calls to characters().

private nl.aidministrator.rdf.client.model.Intersection _intersect
          Variable used to build an Intersection result over multiple calls to startElement().

private QueryResultListener _listener
          The object to report the query results to.

private boolean _tupleValueParsed
          Flag indicating whether a value has parsed for the current rdf:li element.

private java.lang.String _xmlLang
          Optional value of an "xml:lang" attribute for literal values.

private int _xmlTreeDepth
          The depth of current XML element in the XML tree.

Constructor Summary

RqlQueryResultParser(QueryResultListener list)


Method Summary

void characters(char[] ch, int start, int length)
          Receive notification of character data.

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

void endElement(java.lang.String ns, java.lang.String lName, java.lang.String qName)
          Receive notification of the end of an element.

void endPrefixMapping(java.lang.String prefix)
          End the scope of a prefix-URI mapping.

void ignorableWhitespace(char[] ch, int start, int length)
          Receive notification of ignorable whitespace in element content.

void processingInstruction(java.lang.String target, java.lang.String data)
          Receive notification of a processing instruction.

void setDocumentLocator(org.xml.sax.Locator locator)
          Receive an object for locating the origin of SAX document events.

void skippedEntity(java.lang.String name)
          Receive notification of a skipped entity.

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

void startElement(java.lang.String ns, java.lang.String lName, java.lang.String qName, org.xml.sax.Attributes atts)
          Receive notification of the beginning of an element.

void startPrefixMapping(java.lang.String prefix, java.lang.String uri)
          Begin the scope of a prefix-URI Namespace mapping.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

_listener

private QueryResultListener _listener

The object to report the query results to.

_chars

private java.lang.StringBuffer _chars

Buffer used to store characters reported in consecutive calls to characters().

_xmlTreeDepth

private int _xmlTreeDepth

The depth of current XML element in the XML tree.

_xmlLang

private java.lang.String _xmlLang

Optional value of an "xml:lang" attribute for literal values.

_intersect

private nl.aidministrator.rdf.client.model.Intersection _intersect

Variable used to build an Intersection result over multiple calls to startElement().

_tupleValueParsed

private boolean _tupleValueParsed

Flag indicating whether a value has parsed for the current rdf:li element. When no value has been parsed yet when the end element for rdf:li is reported, the value should be an empty string.

Constructor Detail

RqlQueryResultParser

public RqlQueryResultParser(QueryResultListener list)

Method Detail

characters

public void characters(char[] ch,
                       int start,
                       int length)

Description copied from interface: org.xml.sax.ContentHandler

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 55 method rather than this one (validating parsers must do so).

Specified by:: characters in interface org.xml.sax.ContentHandler

startElement

public void startElement(java.lang.String ns,
                         java.lang.String lName,
                         java.lang.String qName,
                         org.xml.sax.Attributes atts)

Description copied from interface: org.xml.sax.ContentHandler

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 55 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:

the Namespace URI;
the local name; and
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() 55 , attribute values may have characters that need more than one char value.

Specified by:: startElement in interface org.xml.sax.ContentHandler

endElement

public void endElement(java.lang.String ns,
                       java.lang.String lName,
                       java.lang.String qName)

Description copied from interface: org.xml.sax.ContentHandler

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 55 event for every endElement event (even when the element is empty).

For information on the names, see startElement.

Specified by:: endElement in interface org.xml.sax.ContentHandler

ignorableWhitespace

public void ignorableWhitespace(char[] ch,
                                int start,
                                int length)

Description copied from interface: org.xml.sax.ContentHandler

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 org.xml.sax.ContentHandler

startDocument

public void startDocument()

Description copied from interface: org.xml.sax.ContentHandler

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 55 ).

Specified by:: startDocument in interface org.xml.sax.ContentHandler

endDocument

public void endDocument()

Description copied from interface: org.xml.sax.ContentHandler

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(org.xml.sax.SAXParseException)>ErrorHandler.fatalError(org.xml.sax.SAXParseException) 55 . 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 org.xml.sax.ContentHandler

setDocumentLocator

public void setDocumentLocator(org.xml.sax.Locator locator)

Description copied from interface: org.xml.sax.ContentHandler

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 55 returns and before endDocument 55 is called. The application should not attempt to use it at any other time.

Specified by:: setDocumentLocator in interface org.xml.sax.ContentHandler

startPrefixMapping

public void startPrefixMapping(java.lang.String prefix,
                               java.lang.String uri)

Description copied from interface: org.xml.sax.ContentHandler

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 55 event, and all endPrefixMapping 55 events will occur immediately after the corresponding endElement 55 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 org.xml.sax.ContentHandler

endPrefixMapping

public void endPrefixMapping(java.lang.String prefix)

Description copied from interface: org.xml.sax.ContentHandler

End the scope of a prefix-URI mapping.

See startPrefixMapping 55 for details. These events will always occur immediately after the corresponding endElement 55 event, but the order of endPrefixMapping 55 events is not otherwise guaranteed.

Specified by:: endPrefixMapping in interface org.xml.sax.ContentHandler

skippedEntity

public void skippedEntity(java.lang.String name)

Description copied from interface: org.xml.sax.ContentHandler

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 org.xml.sax.ContentHandler

processingInstruction

public void processingInstruction(java.lang.String target,
                                  java.lang.String data)

Description copied from interface: org.xml.sax.ContentHandler

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() 55 , processing instruction data may have characters that need more than one char value.

Specified by:: processingInstruction in interface org.xml.sax.ContentHandler

Overview

Package

Class

Use

Deprecated

Index

Home >> All >> nl >> aidministrator >> rdf >> client >> [ rql overview ]

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SUMMARY:

JAVADOC |

SOURCE |

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Field Summary
`private java.lang.StringBuffer`	`_chars` Buffer used to store characters reported in consecutive calls to characters().
`private nl.aidministrator.rdf.client.model.Intersection`	`_intersect` Variable used to build an Intersection result over multiple calls to startElement().
`private QueryResultListener`	`_listener` The object to report the query results to.
`private boolean`	`_tupleValueParsed` Flag indicating whether a value has parsed for the current rdf:li element.
`private java.lang.String`	`_xmlLang` Optional value of an "xml:lang" attribute for literal values.
`private int`	`_xmlTreeDepth` The depth of current XML element in the XML tree.

Constructor Summary
`RqlQueryResultParser(QueryResultListener list)`

Method Summary
`void`	`characters(char[] ch, int start, int length)` Receive notification of character data.
`void`	`endDocument()` Receive notification of the end of a document.
`void`	`endElement(java.lang.String ns, java.lang.String lName, java.lang.String qName)` Receive notification of the end of an element.
`void`	`endPrefixMapping(java.lang.String prefix)` End the scope of a prefix-URI mapping.
`void`	`ignorableWhitespace(char[] ch, int start, int length)` Receive notification of ignorable whitespace in element content.
`void`	`processingInstruction(java.lang.String target, java.lang.String data)` Receive notification of a processing instruction.
`void`	`setDocumentLocator(org.xml.sax.Locator locator)` Receive an object for locating the origin of SAX document events.
`void`	`skippedEntity(java.lang.String name)` Receive notification of a skipped entity.
`void`	`startDocument()` Receive notification of the beginning of a document.
`void`	`startElement(java.lang.String ns, java.lang.String lName, java.lang.String qName, org.xml.sax.Attributes atts)` Receive notification of the beginning of an element.
`void`	`startPrefixMapping(java.lang.String prefix, java.lang.String uri)` Begin the scope of a prefix-URI Namespace mapping.

nl.aidministrator.rdf.client.rql Class RqlQueryResultParser

_listener

_chars

_xmlTreeDepth

_xmlLang

_intersect

_tupleValueParsed

RqlQueryResultParser

characters

startElement

endElement

ignorableWhitespace

startDocument

endDocument

setDocumentLocator

startPrefixMapping

endPrefixMapping

skippedEntity

processingInstruction

nl.aidministrator.rdf.client.rql
Class RqlQueryResultParser