/*
* JBoss DNA (http://www.jboss.org/dna)
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership. Some portions may be licensed
* to Red Hat, Inc. under one or more contributor license agreements.
* See the AUTHORS.txt file in the distribution for a full listing of
* individual contributors.
*
* JBoss DNA is free software. Unless otherwise indicated, all code in JBoss DNA
* is licensed to you 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.
*
* JBoss DNA 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 software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.dna.graph.query.parse;
import java.util.ArrayList;
import java.util.List;
import org.jboss.dna.common.text.ParsingException;
import org.jboss.dna.common.text.TokenStream;
import org.jboss.dna.common.text.TokenStream.Tokenizer;
import org.jboss.dna.common.util.CheckArg;
import org.jboss.dna.graph.query.model.FullTextSearch.Conjunction;
import org.jboss.dna.graph.query.model.FullTextSearch.Disjunction;
import org.jboss.dna.graph.query.model.FullTextSearch.NegationTerm;
import org.jboss.dna.graph.query.model.FullTextSearch.SimpleTerm;
import org.jboss.dna.graph.query.model.FullTextSearch.Term;
/**
* A {@link QueryParser} implementation that parses a full-text search expression. This grammar is based on the full-text search
* grammar as defined by the JCR 2.0 specification.
* <p>
* </p>
* <h3>Grammar</h3>
* <p>
* The grammar for the full-text expression is taken from the JCR 2.0 specification, and is as follows:
* </p>
*
* <pre>
* FulltextSearch ::= Disjunct {Space 'OR' Space Disjunct}
* Disjunct ::= Term {Space Term}
* Term ::= ['-'] SimpleTerm
* SimpleTerm ::= Word | '"' Word {Space Word} '"'
* Word ::= NonSpaceChar {NonSpaceChar}
* Space ::= SpaceChar {SpaceChar}
* NonSpaceChar ::= Char - SpaceChar /* Any Char except SpaceChar */
* SpaceChar ::= ' '
* Char ::= /* Any character */
* </pre>
*/
public class FullTextSearchParser {
/**
* Parse the full-text search criteria given in the supplied string.
*
* @param fullTextSearchExpression the full-text search expression; may not be null
* @return the term representation of the full-text search, or null if there are no terms
* @throws ParsingException if there is an error parsing the supplied string
* @throws IllegalArgumentException if the expression is null
*/
public Term parse( String fullTextSearchExpression ) {
CheckArg.isNotNull(fullTextSearchExpression, "fullTextSearchExpression");
Tokenizer tokenizer = TokenStream.basicTokenizer(false);
TokenStream stream = new TokenStream(fullTextSearchExpression, tokenizer, false);
return parse(stream.start());
}
/**
* Parse the full-text search criteria from the supplied token stream. This method is useful when the full-text search
* expression is included in other content.
*
* @param tokens the token stream containing the full-text search starting on the next token
* @return the term representation of the full-text search, or null if there are no terms
* @throws ParsingException if there is an error parsing the supplied string
* @throws IllegalArgumentException if the token stream is null
*/
public Term parse( TokenStream tokens ) {
CheckArg.isNotNull(tokens, "tokens");
List<Term> terms = new ArrayList<Term>();
do {
Term term = parseDisjunctedTerms(tokens);
if (term == null) break;
terms.add(term);
} while (tokens.canConsume("OR"));
if (terms.isEmpty()) return null;
return terms.size() > 1 ? new Disjunction(terms) : terms.iterator().next();
}
protected Term parseDisjunctedTerms( TokenStream tokens ) {
List<Term> terms = new ArrayList<Term>();
do {
Term term = parseTerm(tokens);
if (term == null) break;
terms.add(term);
} while (tokens.hasNext() && !tokens.matches("OR"));
if (terms.isEmpty()) return null;
return terms.size() > 1 ? new Conjunction(terms) : terms.iterator().next();
}
protected Term parseTerm( TokenStream tokens ) {
boolean negated = tokens.canConsume('-');
Term result = new SimpleTerm(removeQuotes(tokens.consume()));
return negated ? new NegationTerm(result) : result;
}
/**
* Remove any leading and trailing single- or double-quotes from the supplied text.
*
* @param text the input text; may not be null
* @return the text without leading and trailing quotes, or <code>text</code> if there were no quotes
*/
protected String removeQuotes( String text ) {
return text.replaceFirst("^['\"]+", "").replaceAll("['\"]+$", "");
}
}