/**
* Copyright (c) 2012, The National Archives <pronom@nationalarchives.gsi.gov.uk>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following
* conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of the The National Archives nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package uk.gov.nationalarchives.droid.command.filter;
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.Token;
import org.antlr.runtime.TokenStream;
import org.antlr.runtime.tree.CommonTree;
import org.antlr.runtime.tree.CommonTreeAdaptor;
import org.antlr.runtime.tree.TreeAdaptor;
import uk.gov.nationalarchives.droid.dql.DqlLexer;
import uk.gov.nationalarchives.droid.dql.DqlParser;
/**
* Utility classs for antlr.
* @author rflitcroft
*
*/
public final class AntlrUtils {
private AntlrUtils() { }
/**
* Parses a DQL string into an syntax tree.
* @param dql the DQl to parse
* @return an AST
* @throws RecognitionException if eth DQl could not be parsed.
*/
static CommonTree parseDqlToAbstractSytntaxTree(String dql) throws RecognitionException {
ANTLRStringStream input = new ANTLRStringStream(dql);
DqlLexer lexer = new DqlLexer(input);
TokenStream tokens = new CommonTokenStream(lexer);
DqlParser parser = new DqlParser(tokens) {
@Override
public void emitErrorMessage(String msg) {
throw new DqlParseException(msg);
}
};
final TreeAdaptor adaptor = new CommonTreeAdaptor() {
@Override
public Object create(Token payload) {
return new CommonTree(payload);
}
};
parser.setTreeAdaptor(adaptor);
DqlParser.criterion_return ret = parser.criterion();
CommonTree tree = (CommonTree) ret.getTree();
return tree;
}
}