/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hp.hpl.jena.reasoner.rulesys.builtins;
import com.hp.hpl.jena.graph.Node;
import com.hp.hpl.jena.graph.NodeFactory ;
import com.hp.hpl.jena.reasoner.rulesys.BuiltinException;
import com.hp.hpl.jena.reasoner.rulesys.RuleContext;
/**
* Builtin which concatenates a set of strings. It binds the last argument to
* a plain literal which is the concatenation of all the preceeding arguments.
* For a literal argument we use its lexcical form, for a URI argument its URI,
* for a bNode argument its internal ID.
*/
public class StrConcat extends BaseBuiltin {
/**
* Return a name for this builtin, normally this will be the name of the
* functor that will be used to invoke it.
*/
@Override
public String getName() {
return "strConcat";
}
/**
* Return the expected number of arguments for this functor or 0 if the number is flexible.
*/
@Override
public int getArgLength() {
return 0;
}
/**
* This method is invoked when the builtin is called in a rule body.
* @param args the array of argument values for the builtin, this is an array
* of Nodes, some of which may be Node_RuleVariables.
* @param length the length of the argument list, may be less than the length of the args array
* for some rule engines
* @param context an execution context giving access to other relevant data
* @return return true if the buildin predicate is deemed to have succeeded in
* the current environment
*/
@Override
public boolean bodyCall(Node[] args, int length, RuleContext context) {
if (length < 1)
throw new BuiltinException(this, context, "Must have at least 1 argument to " + getName());
StringBuilder buff = new StringBuilder();
for (int i = 0; i < length-1; i++) {
buff.append( lex(getArg(i, args, context), context) );
}
Node result = NodeFactory.createLiteral(buff.toString());
return context.getEnv().bind(args[length-1], result);
}
/**
* Return the appropriate lexical form of a node
*/
protected String lex(Node n, RuleContext context) {
if (n.isBlank()) {
return n.getBlankNodeLabel();
} else if (n.isURI()) {
return n.getURI();
} else if (n.isLiteral()) {
return n.getLiteralLexicalForm();
} else {
throw new BuiltinException(this, context, "Illegal node type: " + n);
}
}
}