org.apache.metron.common.transformation.TransformationProcessor.java Source code

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Here is the source code for org.apache.metron.common.transformation.TransformationProcessor.java

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/**
 * 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.metron.common.transformation;

import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.TokenStream;
import org.apache.metron.common.dsl.ErrorListener;
import org.apache.metron.common.dsl.ParseException;
import org.apache.metron.common.dsl.VariableResolver;
import org.apache.metron.common.transformation.generated.TransformationLexer;
import org.apache.metron.common.transformation.generated.TransformationParser;

import static org.apache.commons.lang3.StringUtils.isEmpty;

public class TransformationProcessor {

    public Object parse(String rule, VariableResolver resolver) {
        if (rule == null || isEmpty(rule.trim())) {
            return null;
        }
        ANTLRInputStream input = new ANTLRInputStream(rule);
        TransformationLexer lexer = new TransformationLexer(input);
        lexer.removeErrorListeners();
        lexer.addErrorListener(new ErrorListener());
        TokenStream tokens = new CommonTokenStream(lexer);
        TransformationParser parser = new TransformationParser(tokens);

        TransformationCompiler treeBuilder = new TransformationCompiler(resolver);
        parser.addParseListener(treeBuilder);
        parser.removeErrorListeners();
        parser.addErrorListener(new ErrorListener());
        parser.transformation();
        return treeBuilder.getResult();
    }

    public boolean validate(String rule) throws ParseException {
        return validate(rule, true);
    }

    public boolean validate(String rule, boolean throwException) throws ParseException {
        try {
            parse(rule, x -> null);
            return true;
        } catch (Throwable t) {
            if (throwException) {
                throw new ParseException("Unable to parse " + rule + ": " + t.getMessage(), t);
            } else {
                return false;
            }
        }
    }
}