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/**
* Negation
* Copyright 2014 by Michael Peter Christen
* First released 03.08.2014 at http://yacy.net
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program in the file lgpl21.txt
* If not, see <http://www.gnu.org/licenses/>.
*/
package net.yacy.cora.federate.solr.logic;
import org.apache.solr.common.SolrDocument;
public class Negation extends AbstractTerm implements Term {
private Term term;
public Negation(final Term term) {
this.term = term;
}
@Override
public Object clone() {
return new Negation(this.term);
}
@Override
public boolean equals(Object otherTerm) {
if (!(otherTerm instanceof Negation)) return false;
Negation o = (Negation) otherTerm;
return this.term.equals(o.term);
}
@Override
public int hashCode() {
return -this.term.hashCode();
}
/**
* the length attribute of a term shows if rewritten terms
* (using rules of replacement as allowed for propositional logic)
* are shorter and therefore more efficient.
* @return the number of operators plus the number of operands plus one
*/
@Override
public int weight() {
return term.weight() + 1;
}
/**
* create a Solr query string from this literal
* @return a string which is a Solr query string
*/
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append('(').append('-').append(this.term.toString()).append(')');
return sb.toString();
}
/**
* check if the key/value pair of this literal occurs in the SolrDocument
* @param doc the document to match to this literal
* @return true, if the key of this literal is contained in the document and the
* value equals (does not equal) with the value if this literal (if the signature is false)
*/
@Override
public boolean matches(SolrDocument doc) {
return !this.term.matches(doc);
}
@Override
public Term lightestRewrite() {
// TODO: this can be enhanced if negations are not attached to atoms
Term t = this.term.lightestRewrite();
return new Negation(t);
}
}
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