SelectorParser.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.activemq.artemis.selector.impl;

import java.io.StringReader;

import org.apache.activemq.artemis.selector.filter.BooleanExpression;
import org.apache.activemq.artemis.selector.filter.ComparisonExpression;
import org.apache.activemq.artemis.selector.filter.FilterException;
import org.apache.activemq.artemis.selector.hyphenated.HyphenatedParser;
import org.apache.activemq.artemis.selector.strict.StrictParser;

/**
 */
public class SelectorParser {

   private static final LRUCache<String, Object> cache = new LRUCache<>(100);
   private static final String CONVERT_STRING_EXPRESSIONS_PREFIX = "convert_string_expressions:";
   private static final String HYPHENATED_PROPS_PREFIX = "hyphenated_props:";
   private static final String NO_CONVERT_STRING_EXPRESSIONS_PREFIX = "no_convert_string_expressions:";
   private static final String NO_HYPHENATED_PROPS_PREFIX = "no_hyphenated_props:";

   public static BooleanExpression parse(String sql) throws FilterException {
      Object result = cache.get(sql);
      if (result instanceof FilterException) {
         throw (FilterException) result;
      } else if (result instanceof BooleanExpression) {
         return (BooleanExpression) result;
      } else {
         String actual = sql;
         boolean convertStringExpressions = false;
         boolean hyphenatedProps = false;
         while (true) {
            if (actual.startsWith(CONVERT_STRING_EXPRESSIONS_PREFIX)) {
               convertStringExpressions = true;
               actual = actual.substring(CONVERT_STRING_EXPRESSIONS_PREFIX.length());
               continue;
            }
            if (actual.startsWith(HYPHENATED_PROPS_PREFIX)) {
               hyphenatedProps = true;
               actual = actual.substring(HYPHENATED_PROPS_PREFIX.length());
               continue;
            }
            if (actual.startsWith(NO_CONVERT_STRING_EXPRESSIONS_PREFIX)) {
               convertStringExpressions = false;
               actual = actual.substring(NO_CONVERT_STRING_EXPRESSIONS_PREFIX.length());
               continue;
            }
            if (actual.startsWith(NO_HYPHENATED_PROPS_PREFIX)) {
               hyphenatedProps = false;
               actual = actual.substring(NO_HYPHENATED_PROPS_PREFIX.length());
               continue;
            }
            break;
         }

         if (convertStringExpressions) {
            ComparisonExpression.CONVERT_STRING_EXPRESSIONS.set(true);
         }
         try {
            BooleanExpression e = null;
            if (hyphenatedProps) {
               HyphenatedParser parser = new HyphenatedParser(new StringReader(actual));
               e = parser.JmsSelector();
            } else {
               StrictParser parser = new StrictParser(new StringReader(actual));
               e = parser.JmsSelector();
            }
            cache.put(sql, e);
            return e;
         } catch (Throwable e) {
            FilterException fe = new FilterException(actual, e);
            cache.put(sql, fe);
            throw fe;
         } finally {
            if (convertStringExpressions) {
               ComparisonExpression.CONVERT_STRING_EXPRESSIONS.remove();
            }
         }
      }
   }

   public static void clearCache() {
      cache.clear();
   }
}