001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017package org.apache.logging.log4j.core.pattern;
018
019import java.util.List;
020
021import org.apache.logging.log4j.core.LogEvent;
022import org.apache.logging.log4j.core.config.Configuration;
023import org.apache.logging.log4j.core.config.plugins.Plugin;
024import org.apache.logging.log4j.core.layout.PatternLayout;
025
026/**
027 * VariablesNotEmpty pattern converter.
028 */
029@Plugin(name = "notEmpty", category = PatternConverter.CATEGORY)
030@ConverterKeys({ "notEmpty", "varsNotEmpty", "variablesNotEmpty", })
031public final class VariablesNotEmptyReplacementConverter extends LogEventPatternConverter {
032
033    private final List<PatternFormatter> formatters;
034
035    /**
036     * Construct the converter.
037     * 
038     * @param formatters
039     *            The PatternFormatters to generate the text to manipulate.
040     */
041    private VariablesNotEmptyReplacementConverter(final List<PatternFormatter> formatters) {
042        super("notEmpty", "notEmpty");
043        this.formatters = formatters;
044    }
045
046    /**
047     * Gets an instance of the class.
048     *
049     * @param config
050     *            The current Configuration.
051     * @param options
052     *            pattern options, may be null.
053     * @return instance of class.
054     */
055    public static VariablesNotEmptyReplacementConverter newInstance(final Configuration config,
056            final String[] options) {
057        if (options.length != 1) {
058            LOGGER.error("Incorrect number of options on varsNotEmpty. Expected 1 received " + options.length);
059            return null;
060        }
061        if (options[0] == null) {
062            LOGGER.error("No pattern supplied on varsNotEmpty");
063            return null;
064        }
065        final PatternParser parser = PatternLayout.createPatternParser(config);
066        final List<PatternFormatter> formatters = parser.parse(options[0]);
067        return new VariablesNotEmptyReplacementConverter(formatters);
068    }
069
070    /**
071     * {@inheritDoc}
072     */
073    @Override
074    public void format(final LogEvent event, final StringBuilder toAppendTo) {
075        final StringBuilder buf = new StringBuilder();
076        int emptyVars = 0;
077        int vars = 0;
078        for (final PatternFormatter formatter : formatters) {
079            final int start = buf.length();
080            formatter.format(event, buf);
081            final boolean isVariable = formatter.getConverter().isVariable();
082            vars += isVariable ? 1 : 0;
083            if (isVariable && buf.length() - start == 0) {
084                emptyVars++;
085            }
086        }
087        if (vars > 0 && emptyVars != vars) {
088            toAppendTo.append(buf.toString());
089        }
090    }
091}