/*
* Copyright 2016, Red Hat Inc. and/or its affiliates.
*
* Licensed 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 org.infinispan.objectfilter.impl.ql;
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.TokenStream;
import org.antlr.runtime.tree.CommonTree;
import org.antlr.runtime.tree.CommonTreeNodeStream;
import org.infinispan.objectfilter.ParsingException;
import org.infinispan.objectfilter.impl.logging.Log;
import org.infinispan.objectfilter.impl.ql.parse.IckleLexer;
import org.infinispan.objectfilter.impl.ql.parse.IckleParser;
import org.infinispan.objectfilter.impl.ql.parse.QueryRenderer;
import org.infinispan.objectfilter.impl.ql.parse.QueryResolver;
import org.jboss.logging.Logger;
/**
* A parser for Ickle queries. Parsing comprises these steps:
* <ul>
* <li>lexing the query</li>
* <li>parsing the query, building up an AST while doing so</li>
* <li>transforming the resulting parse tree using a QueryResolverDelegate and QueryRendererDelegate</li>
* </ul>
*
* @author Gunnar Morling
* @author anistor@redhat.com
* @since 9.0
*/
public final class QueryParser {
private static final Log log = Logger.getMessageLogger(Log.class, QueryParser.class.getName());
/**
* Parses the given query string.
*
* @param queryString the query string to parse
* @return the result of the parsing after being transformed by the processors
* @throws ParsingException in case any exception occurs during parsing
*/
public CommonTree parseQuery(String queryString, QueryResolverDelegate resolverDelegate, QueryRendererDelegate rendererDelegate) throws ParsingException {
IckleLexer lexer = new IckleLexer(new ANTLRStringStream(queryString));
CommonTokenStream tokens = new CommonTokenStream(lexer);
IckleParser parser = new IckleParser(tokens);
try {
// parser.statement() is the entry point for evaluation of any kind of statement
IckleParser.statement_return r = parser.statement();
if (parser.hasErrors()) {
throw log.getQuerySyntaxException(queryString, parser.getErrorMessages());
}
CommonTree tree = (CommonTree) r.getTree();
tree = resolve(tokens, tree, resolverDelegate);
tree = render(tokens, tree, rendererDelegate);
return tree;
} catch (RecognitionException e) {
throw log.getQuerySyntaxException(queryString, e);
}
}
// resolves the elements in given source query into an output query, by invoking {@link QueryResolverDelegate} while traversing the given query tree
private CommonTree resolve(TokenStream tokens, CommonTree tree, QueryResolverDelegate resolverDelegate) throws RecognitionException {
CommonTreeNodeStream treeNodeStream = new CommonTreeNodeStream(tree);
treeNodeStream.setTokenStream(tokens);
return (CommonTree) new QueryResolver(treeNodeStream, resolverDelegate).statement().getTree();
}
// render a given source query into an output query, by invoking {@link QueryRendererDelegate} while traversing the given query tree
private CommonTree render(TokenStream tokens, CommonTree tree, QueryRendererDelegate rendererDelegate) throws RecognitionException {
CommonTreeNodeStream treeNodeStream = new CommonTreeNodeStream(tree);
treeNodeStream.setTokenStream(tokens);
return (CommonTree) new QueryRenderer(treeNodeStream, rendererDelegate).statement().getTree();
}
}