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/* IdFunction.java --
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Copyright (C) 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.xml.xpath;
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import java.util.Collection;
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import java.util.List;
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import javax.xml.namespace.QName;
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import org.w3c.dom.Node;
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/**
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* The <code>id</code> function selects elements by their unique ID.
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* When the argument to id is of type node-set, then the result is
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* the union of the result of applying id to the string-value of each of the
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* nodes in the argument node-set. When the argument to id is of any other
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* type, the argument is converted to a string as if by a call to the string
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* function; the string is split into a whitespace-separated list of tokens
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* (whitespace is any sequence of characters matching the production S); the
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* result is a node-set containing the elements in the same document as the
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* context node that have a unique ID equal to any of the tokens in the
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* list.
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*
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* @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
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*/
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public final class IdFunction
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extends Pattern
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{
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final Expr arg;
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IdFunction(List args)
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{
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this((Expr) args.get(0));
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}
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public IdFunction(Expr arg)
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{
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this.arg = arg;
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}
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public boolean matches(Node context)
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{
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Object ret = evaluate(context, 1, 1);
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return !((Collection) ret).isEmpty();
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}
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public Object evaluate(Node context, int pos, int len)
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{
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Object val = arg.evaluate(context, pos, len);
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return _id(context, val);
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}
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public Expr clone(Object context)
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{
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return new IdFunction(arg.clone(context));
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}
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public boolean references(QName var)
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{
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return arg.references(var);
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}
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public String toString()
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{
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return "id(" + arg + ")";
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}
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}
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