001: /******************************************************************
002: * File: StrConcat.java
003: * Created by: Dave Reynolds
004: * Created on: 10 Jan 2007
005: *
006: * (c) Copyright 2007, Hewlett-Packard Development Company, LP
007: * [See end of file]
008: * $Id: StrConcat.java,v 1.2 2008/01/02 12:06:21 andy_seaborne Exp $
009: *****************************************************************/package com.hp.hpl.jena.reasoner.rulesys.builtins;
010:
011: import com.hp.hpl.jena.graph.Node;
012: import com.hp.hpl.jena.reasoner.rulesys.BuiltinException;
013: import com.hp.hpl.jena.reasoner.rulesys.RuleContext;
014:
015: /**
016: * Builtin which concatenates a set of strings. It binds the last argument to
017: * a plain literal which is the concatenation of all the preceeding arguments.
018: * For a literal argument we use its lexcical form, for a URI argument its URI,
019: * for a bNode argument its internal ID.
020: *
021: * @author <a href="mailto:der@hplb.hpl.hp.com">Dave Reynolds</a>
022: * @version $Revision: 1.2 $
023: */
024: public class StrConcat extends BaseBuiltin {
025:
026: /**
027: * Return a name for this builtin, normally this will be the name of the
028: * functor that will be used to invoke it.
029: */
030: public String getName() {
031: return "strConcat";
032: }
033:
034: /**
035: * Return the expected number of arguments for this functor or 0 if the number is flexible.
036: */
037: public int getArgLength() {
038: return 0;
039: }
040:
041: /**
042: * This method is invoked when the builtin is called in a rule body.
043: * @param args the array of argument values for the builtin, this is an array
044: * of Nodes, some of which may be Node_RuleVariables.
045: * @param length the length of the argument list, may be less than the length of the args array
046: * for some rule engines
047: * @param context an execution context giving access to other relevant data
048: * @return return true if the buildin predicate is deemed to have succeeded in
049: * the current environment
050: */
051: public boolean bodyCall(Node[] args, int length, RuleContext context) {
052: if (length < 1)
053: throw new BuiltinException(this , context,
054: "Must have at least 1 argument to " + getName());
055: StringBuffer buff = new StringBuffer();
056: for (int i = 0; i < length - 1; i++) {
057: buff.append(lex(getArg(i, args, context), context));
058: }
059: Node result = Node.createLiteral(buff.toString());
060: return context.getEnv().bind(args[length - 1], result);
061: }
062:
063: /**
064: * Return the appropriate lexical form of a node
065: */
066: protected String lex(Node n, RuleContext context) {
067: if (n.isBlank()) {
068: return n.getBlankNodeLabel();
069: } else if (n.isURI()) {
070: return n.getURI();
071: } else if (n.isLiteral()) {
072: return n.getLiteralLexicalForm();
073: } else {
074: throw new BuiltinException(this , context,
075: "Illegal node type: " + n);
076: }
077: }
078:
079: }
080:
081: /*
082: (c) Copyright 2007, 2008 Hewlett-Packard Development Company, LP
083: All rights reserved.
084:
085: Redistribution and use in source and binary forms, with or without
086: modification, are permitted provided that the following conditions
087: are met:
088:
089: 1. Redistributions of source code must retain the above copyright
090: notice, this list of conditions and the following disclaimer.
091:
092: 2. Redistributions in binary form must reproduce the above copyright
093: notice, this list of conditions and the following disclaimer in the
094: documentation and/or other materials provided with the distribution.
095:
096: 3. The name of the author may not be used to endorse or promote products
097: derived from this software without specific prior written permission.
098:
099: THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
100: IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
101: OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
102: IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
103: INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
104: NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
105: DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
106: THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
107: (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
108: THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
109: */
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