ErrorFilteredConsumer.java

/*******************************************************************************
 * Copyright (c) 2012-2017 Codenvy, S.A.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Codenvy, S.A. - initial API and implementation
 *******************************************************************************/
package org.eclipse.che.api.core.util;

import java.io.IOException;

import static org.eclipse.che.api.core.util.ErrorFilteredConsumer.ErrorIndicator.DEFAULT_ERROR_INDICATOR;

/**
 * Consumes all output and redirect to another consumer
 * only those lines which contain errors.
 *
 * @author Anatolii Bazko
 */
public class ErrorFilteredConsumer implements LineConsumer {

    private final ErrorIndicator errorIndicator;
    private final LineConsumer   lineConsumer;

    public ErrorFilteredConsumer(ErrorIndicator errorIndicator, LineConsumer lineConsumer) {
        this.errorIndicator = errorIndicator;
        this.lineConsumer = lineConsumer;
    }

    public ErrorFilteredConsumer(LineConsumer lineConsumer) {
        this(DEFAULT_ERROR_INDICATOR, lineConsumer);
    }

    @Override
    public void writeLine(String line) throws IOException {
        if (errorIndicator.isError(line)) {
            lineConsumer.writeLine(line);
        }
    }

    @Override
    public void close() throws IOException {
        lineConsumer.close();
    }

    /**
     * Indicates if line contains a error message.
     */
    @FunctionalInterface
    public interface ErrorIndicator {
        boolean isError(String line);

        ErrorIndicator DEFAULT_ERROR_INDICATOR = line -> line.startsWith("[STDERR]");
    }
}