Summary

TABULATOR RDF PARSER Version 0.1 Parser believed to be in full positive RDF/XML parsing compliance with the possible exception of handling deprecated RDF attributes appropriately. Parser is believed to comply fully with other W3C and industry standards where appropriate (DOM, ECMAScript, &c.) Author: David Sheets SVN ID: $Id$ W3C® SOFTWARE NOTICE AND LICENSE http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231 This work (and included software, documentation such as READMEs, or other related items) is being provided by the copyright holders under the following license. By obtaining, using and/or copying this work, you (the licensee) agree that you have read, understood, and will comply with the following terms and conditions. Permission to copy, modify, and distribute this software and its documentation, with or without modification, for any purpose and without fee or royalty is hereby granted, provided that you include the following on ALL copies of the software and documentation or portions thereof, including modifications: 1. The full text of this NOTICE in a location viewable to users of the redistributed or derivative work. 2. Any pre-existing intellectual property disclaimers, notices, or terms and conditions. If none exist, the W3C Software Short Notice should be included (hypertext is preferred, text is permitted) within the body of any redistributed or derivative code. 3. Notice of any changes or modifications to the files, including the date changes were made. (We recommend you provide URIs to the location from which the code is derived.) THIS SOFTWARE AND DOCUMENTATION IS PROVIDED "AS IS," AND COPYRIGHT HOLDERS MAKE NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF THE SOFTWARE OR DOCUMENTATION WILL NOT INFRINGE ANY THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS. COPYRIGHT HOLDERS WILL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF ANY USE OF THE SOFTWARE OR DOCUMENTATION. The name and trademarks of copyright holders may NOT be used in advertising or publicity pertaining to the software without specific, written prior permission. Title to copyright in this software and any associated documentation will at all times remain with copyright holders.

/**
 * @fileoverview
 * TABULATOR RDF PARSER
 *
 * Version 0.1
 *  Parser believed to be in full positive RDF/XML parsing compliance
 *  with the possible exception of handling deprecated RDF attributes
 *  appropriately. Parser is believed to comply fully with other W3C
 *  and industry standards where appropriate (DOM, ECMAScript, &c.)
 *
 *  Author: David Sheets <dsheets@mit.edu>
 *  SVN ID: $Id$
 *
 * W3C® SOFTWARE NOTICE AND LICENSE
 * http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
 * This work (and included software, documentation such as READMEs, or
 * other related items) is being provided by the copyright holders under
 * the following license. By obtaining, using and/or copying this work,
 * you (the licensee) agree that you have read, understood, and will
 * comply with the following terms and conditions.
 * 
 * Permission to copy, modify, and distribute this software and its
 * documentation, with or without modification, for any purpose and
 * without fee or royalty is hereby granted, provided that you include
 * the following on ALL copies of the software and documentation or
 * portions thereof, including modifications:
 * 
 * 1. The full text of this NOTICE in a location viewable to users of
 * the redistributed or derivative work.
 * 2. Any pre-existing intellectual property disclaimers, notices, or terms and
 * conditions. If none exist, the W3C Software Short Notice should be
 * included (hypertext is preferred, text is permitted) within the body
 * of any redistributed or derivative code.
 * 3. Notice of any changes or modifications to the files, including the
 * date changes were made. (We recommend you provide URIs to the location
 * from which the code is derived.)
 * 
 * THIS SOFTWARE AND DOCUMENTATION IS PROVIDED "AS IS," AND COPYRIGHT
 * HOLDERS MAKE NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO, WARRANTIES OF MERCHANTABILITY OR FITNESS
 * FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF THE SOFTWARE OR
 * DOCUMENTATION WILL NOT INFRINGE ANY THIRD PARTY PATENTS, COPYRIGHTS,
 * TRADEMARKS OR OTHER RIGHTS.
 * 
 * COPYRIGHT HOLDERS WILL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL
 * OR CONSEQUENTIAL DAMAGES ARISING OUT OF ANY USE OF THE SOFTWARE OR
 * DOCUMENTATION.
 * 
 * The name and trademarks of copyright holders may NOT be used in
 * advertising or publicity pertaining to the software without specific,
 * written prior permission. Title to copyright in this software and any
 * associated documentation will at all times remain with copyright
 * holders.
 */
/**
 * @class Class defining an RDFParser resource object tied to an RDFStore
 *  
 * @author David Sheets <dsheets@mit.edu>
 * @version 0.1
 * 
 * @constructor
 * @param {RDFStore} store An RDFStore object
 */
function RDFParser(store) {
    /** Standard namespaces that we know how to handle @final
     *  @member RDFParser
     */
    RDFParser.ns = {'RDF':
		       "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
		       'RDFS':
		       "http://www.w3.org/2000/01/rdf-schema#"}
    /** DOM Level 2 node type magic numbers @final
     *  @member RDFParser
     */
    RDFParser.nodeType = {'ELEMENT': 1, 'ATTRIBUTE': 2, 'TEXT': 3,
			     'CDATA_SECTION': 4, 'ENTITY_REFERENCE': 5,
			     'ENTITY': 6, 'PROCESSING_INSTRUCTION': 7,
			     'COMMENT': 8, 'DOCUMENT': 9, 'DOCUMENT_TYPE': 10,
			     'DOCUMENT_FRAGMENT': 11, 'NOTATION': 12}

    /**
     * Frame class for namespace and base URI lookups
     * Base lookups will always resolve because the parser knows
     * the default base.
     *
     * @private
     */
    this['frameFactory'] = function (parser, parent, element) {
	return {'NODE': 1,
		'ARC': 2,
		'parent': parent,
		'parser': parser,
		'store': parser['store'],
		'element': element,
		'lastChild': 0,
		'base': null,
		'lang': null,
		'node': null,
		'nodeType': null,
		'listIndex': 1,
		'rdfid': null,
		'datatype': null,
		'collection': false,

	/** Terminate the frame and notify the store that we're done */
		'terminateFrame': function () {
		    if (this['collection']) {
			this['node']['close']()
		    }
		},
	
	/** Add a symbol of a certain type to the this frame */
		'addSymbol': function (type, uri) {
		    uri = URIjoin(uri, this['base'])
		    this['node'] = this['store']['sym'](uri)
		    this['nodeType'] = type
		},
	
	/** Load any constructed triples into the store */
		'loadTriple': function () {
		    if (this['parent']['parent']['collection']) {
			this['parent']['parent']['node']['append'](this['node'])
		    }
		    else {
			this['store']['add'](this['parent']['parent']['node'],
				       this['parent']['node'],
				       this['node'],
				       this['parser']['why'])
		    }
		    if (this['parent']['rdfid'] != null) { // reify
			var triple = this['store']['sym'](
			    URIjoin("#"+this['parent']['rdfid'],this['base']))
			this['store']['add'](triple,
					     this['store']['sym'](
						 RDFParser['ns']['RDF']
						     +"type"),
					     this['store']['sym'](
						 RDFParser['ns']['RDF']
						     +"Statement"),
					     this['parser']['why'])
			this['store']['add'](triple,
					     this['store']['sym'](
						 RDFParser['ns']['RDF']
						     +"subject"),
					     this['parent']['parent']['node'],
					     this['parser']['why'])
			this['store']['add'](triple,
					     this['store']['sym'](
						 RDFParser['ns']['RDF']
						     +"predicate"),
					     this['parent']['node'],
					     this['parser']['why'])
			this['store']['add'](triple,
					     this['store']['sym'](
						 RDFParser['ns']['RDF']
						     +"object"),
					     this['node'],
					     this['parser']['why'])
		    }
		},

	/** Check if it's OK to load a triple */
		'isTripleToLoad': function () {
		    return (this['parent'] != null
			    && this['parent']['parent'] != null
			    && this['nodeType'] == this['NODE']
			    && this['parent']['nodeType'] == this['ARC']
			    && this['parent']['parent']['nodeType']
			    == this['NODE'])
		},

	/** Add a symbolic node to this frame */
		'addNode': function (uri) {
		    this['addSymbol'](this['NODE'],uri)
		    if (this['isTripleToLoad']()) {
			this['loadTriple']()
		    }
		},

	/** Add a collection node to this frame */
		'addCollection': function () {
		    this['nodeType'] = this['NODE']
		    this['node'] = this['store']['collection']()
		    this['collection'] = true
		    if (this['isTripleToLoad']()) {
			this['loadTriple']()
		    }
		},

	/** Add a collection arc to this frame */
		'addCollectionArc': function () {
		    this['nodeType'] = this['ARC']
		},

	/** Add a bnode to this frame */
		'addBNode': function (id) {
		    if (id != null) {
			if (this['parser']['bnodes'][id] != null) {
			    this['node'] = this['parser']['bnodes'][id]
			} else {
			    this['node'] = this['parser']['bnodes'][id] = this['store']['bnode']()
			}
		    } else { this['node'] = this['store']['bnode']() }
		    
		    this['nodeType'] = this['NODE']
		    if (this['isTripleToLoad']()) {
			this['loadTriple']()
		    }
		},

	/** Add an arc or property to this frame */
		'addArc': function (uri) {
		    if (uri == RDFParser['ns']['RDF']+"li") {
			uri = RDFParser['ns']['RDF']+"_"+this['parent']['listIndex']++
		    }
		    this['addSymbol'](this['ARC'], uri)
		},

	/** Add a literal to this frame */
		'addLiteral': function (value) {
		    if (this['parent']['datatype']) { var lang = "" }
		    else { var lang = this['lang'] }
		    this['node'] = this['store']['literal'](
			value, lang, this['parent']['datatype'])
		    this['nodeType'] = this['NODE']
		    if (this['isTripleToLoad']()) {
			this['loadTriple']()
		    }
		}
	       }
    }

    /** Our triple store reference @private */
    this['store'] = store
    /** Our identified blank nodes @private */
    this['bnodes'] = {}
    /** A context for context-aware stores @private */
    this['why'] = null
    /** Reification flag */
    this.reify = false
    /** Force RDF in parsing flag */
    this.forceRDF = false

    /**
     * Build our initial scope frame and parse the DOM into triples
     * @param {DOMTree} document The DOM to parse
     * @param {String} base The base URL to use 
     * @param {Object} why The context to which this resource belongs
     */
    this.parse = function (document, base, why) {
	var children = document['childNodes']

	// clean up for the next run
	this['cleanParser']()

	// figure out the root element
	if (document['nodeType'] == RDFParser['nodeType']['DOCUMENT']) {
	    for (var c=0; c<children['length']; c++) {
		if (children[c]['nodeType']
		    == RDFParser['nodeType']['ELEMENT']) {
		    var root = children[c]
		    break
		}
	    }	    
	}
	else if (document['nodeType'] == RDFParser['nodeType']['ELEMENT']) {
	    var root = document
	}
	else {
	    throw new Error("RDFParser: can't find root in " + base
			    + ". Halting. ")
	    return false
	}
	
	this['why'] = why

	// we're unsure if it's RDF
	if (!this['forceRDF']
	    && root['namespaceURI'] != RDFParser['ns']['RDF']) {
	    throw new Error("RDFParser: " + base
			    + " might not be RDF. Halting. "
			    + "Parser expected either assurance"
			    + " of RDF or root node with namespace"
			    + " of " + RDFParser['ns']['RDF']);
	    return false
	}

	// our topmost frame

	var f = this['frameFactory'](this)
	f['base'] = base
	f['lang'] = ''
	
	this['parseDOM'](this['buildFrame'](f,root))
	return true
    }
    this['parseDOM'] = function (frame) {
	// a DOM utility function used in parsing
	var elementURI = function (el) {
	    return el['namespaceURI'] + el['localName']
	}
	var dig = true // if we'll dig down in the tree on the next iter

	while (frame['parent']) {
	    var dom = frame['element']
	    var attrs = dom['attributes']

	    if (dom['nodeType']
		== RDFParser['nodeType']['TEXT']) { // we have a literal
		frame['addLiteral'](dom['nodeValue'])
	    }
	    else if (elementURI(dom)
		     != RDFParser['ns']['RDF']+"RDF") { // not root
		if (frame['parent'] && frame['parent']['collection']) {
		    // we're a collection element
		    frame['addCollectionArc']()
		    frame = this['buildFrame'](frame,frame['element'])
		    frame['parent']['element'] = null
		}
                if (!frame['parent'] || !frame['parent']['nodeType']
		    || frame['parent']['nodeType'] == frame['ARC']) {
		    // we need a node
		    var about =dom['getAttributeNodeNS'](
			RDFParser['ns']['RDF'],"about")
		    var rdfid =dom['getAttributeNodeNS'](
			RDFParser['ns']['RDF'],"ID")
		    if (about && rdfid) {
			throw new Error("RDFParser: " + dom['nodeName']
					+ " has both rdf:id and rdf:about."
					+ " Halting. Only one of these"
					+ " properties may be specified on a"
					+ " node.");
		    }
		    if (about == null && rdfid) {
			frame['addNode']("#"+rdfid['nodeValue'])
			dom['removeAttributeNode'](rdfid)
		    }
		    else if (about == null && rdfid == null) {
			var bnid = dom['getAttributeNodeNS'](
			    RDFParser['ns']['RDF'],"nodeID")
			if (bnid) {
			    frame['addBNode'](bnid['nodeValue'])
			    dom['removeAttributeNode'](bnid)
			} else { frame['addBNode']() }
		    }
		    else {
			frame['addNode'](about['nodeValue'])
			dom['removeAttributeNode'](about)
		    }
		
		    // Typed nodes
		    var rdftype = dom['getAttributeNodeNS'](
			RDFParser['ns']['RDF'],"type")
		    if (RDFParser['ns']['RDF']+"Description"
			!= elementURI(dom)) {
			rdftype = {'nodeValue': elementURI(dom)}
		    }
		    if (rdftype != null) {
			this['store']['add'](frame['node'],
					     this['store']['sym'](
						 RDFParser['ns']['RDF']+"type"),
					     this['store']['sym'](
						 URIjoin(rdftype['nodeValue'],
							 frame['base'])),
					     this['why'])
			if (rdftype['nodeName']){
			    dom['removeAttributeNode'](rdftype)
			}
		    }
		    
		    // Property Attributes
		    for (var x = attrs['length']-1; x >= 0; x--) {
			this['store']['add'](frame['node'],
					     this['store']['sym'](
						 elementURI(attrs[x])),
					     this['store']['literal'](
						 attrs[x]['nodeValue'],
						 frame['lang'],""),
					     this['why'])
		    }
		}
		else { // we should add an arc (or implicit bnode+arc)
		    frame['addArc'](elementURI(dom))

		    // save the arc's rdf:ID if it has one
		    if (this['reify']) {
			var rdfid = dom['getAttributeNodeNS'](
			    RDFParser['ns']['RDF'],"ID")
			if (rdfid) {
			    frame['rdfid'] = rdfid['nodeValue']
			    dom['removeAttributeNode'](rdfid)
			}
		    }

		    var parsetype = dom['getAttributeNodeNS'](
			RDFParser['ns']['RDF'],"parseType")
		    var datatype = dom['getAttributeNodeNS'](
			RDFParser['ns']['RDF'],"datatype")
		    if (datatype) {
			frame['datatype'] = datatype['nodeValue']
			dom['removeAttributeNode'](datatype)
		    }

		    if (parsetype) {
			var nv = parsetype['nodeValue']
			if (nv == "Literal") {
			    frame['datatype']
				= RDFParser['ns']['RDF']+"XMLLiteral"
			    // (this.buildFrame(frame)).addLiteral(dom)
			    // should work but doesn't
			    frame = this['buildFrame'](frame)
			    frame['addLiteral'](dom)
			    dig = false
			}
			else if (nv == "Resource") {
			    frame = this['buildFrame'](frame,frame['element'])
			    frame['parent']['element'] = null
			    frame['addBNode']()
			}
			else if (nv == "Collection") {
			    frame = this['buildFrame'](frame,frame['element'])
			    frame['parent']['element'] = null
			    frame['addCollection']()
			}
			dom['removeAttributeNode'](parsetype)
		    }

		    if (attrs['length'] != 0) {
			var resource = dom['getAttributeNodeNS'](
			    RDFParser['ns']['RDF'],"resource")
			var bnid = dom['getAttributeNodeNS'](
			    RDFParser['ns']['RDF'],"nodeID")

			frame = this['buildFrame'](frame)
			if (resource) {
			    frame['addNode'](resource['nodeValue'])
			    dom['removeAttributeNode'](resource)
			} else {
			    if (bnid) {
				frame['addBNode'](bnid['nodeValue'])
				dom['removeAttributeNode'](bnid)
			    } else { frame['addBNode']() }
			}

			for (var x = attrs['length']-1; x >= 0; x--) {
			    var f = this['buildFrame'](frame)
			    f['addArc'](elementURI(attrs[x]))
			    if (elementURI(attrs[x])
				==RDFParser['ns']['RDF']+"type"){
				(this['buildFrame'](f))['addNode'](
				    attrs[x]['nodeValue'])
			    } else {
				(this['buildFrame'](f))['addLiteral'](
				    attrs[x]['nodeValue'])
			    }
			}
		    }
		    else if (dom['childNodes']['length'] == 0) {
			(this['buildFrame'](frame))['addLiteral']("")
		    }
		}
	    } // rdf:RDF

	    // dig dug
	    dom = frame['element']
	    while (frame['parent']) {
		var pframe = frame
		while (dom == null) {
		    frame = frame['parent']
		    dom = frame['element']
		}
		var candidate = dom['childNodes'][frame['lastChild']]
		if (candidate == null || !dig) {
		    frame['terminateFrame']()
		    if (!(frame = frame['parent'])) { break } // done
		    dom = frame['element']
		    dig = true
		}
		else if ((candidate['nodeType']
			  != RDFParser['nodeType']['ELEMENT']
			  && candidate['nodeType']
			  != RDFParser['nodeType']['TEXT'])
			 || (candidate['nodeType']
			     == RDFParser['nodeType']['TEXT']
			     && dom['childNodes']['length'] != 1)) {
		    frame['lastChild']++
		}
		else { // not a leaf
		    frame['lastChild']++
		    frame = this['buildFrame'](pframe,
					       dom['childNodes'][frame['lastChild']-1])
		    break
		}
	    }
	} // while
    }

    /**
     * Cleans out state from a previous parse run
     * @private
     */
    this['cleanParser'] = function () {
	this['bnodes'] = {}
	this['why'] = null
    }

    /**
     * Builds scope frame 
     * @private
     */
    this['buildFrame'] = function (parent, element) {
	var frame = this['frameFactory'](this,parent,element)
	if (parent) {
	    frame['base'] = parent['base']
	    frame['lang'] = parent['lang']
	}
	if (element == null
	    || element['nodeType'] == RDFParser['nodeType']['TEXT']) {
	    return frame
	}

	var attrs = element['attributes']

	var base = element['getAttributeNode']("xml:base")
	if (base != null) {
	    frame['base'] = base['nodeValue']
	    element['removeAttribute']("xml:base")
	}
	var lang = element['getAttributeNode']("xml:lang")
	if (lang != null) {
	    frame['lang'] = lang['nodeValue']
	    element['removeAttribute']("xml:lang")
	}

	// remove all extraneous xml and xmlns attributes
	for (var x = attrs['length']-1; x >= 0; x--) {
	    if (attrs[x]['nodeName']['substr'](0,3) == "xml") {
		element['removeAttributeNode'](attrs[x])
	    }
	}
	return frame
    }
}