# InputStreamSourceFileLocator.java

    /*******************************************************************************
     * Copyright (c) 2009, 2013 Mountainminds GmbH & Co. KG and Contributors
     * 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:
     *    Marc R. Hoffmann - initial API and implementation
     *
     *******************************************************************************/
    package org.jacoco.report;

    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.io.Reader;

    /**
     * Abstract base class for {@link ISourceFileLocator} locator implementations
     * based on {@link InputStream}s. It handles the encoding and tab width.
     */
    public abstract class InputStreamSourceFileLocator implements
    		ISourceFileLocator {

    	private final String encoding;
    	private final int tabWidth;

    	/**
    	 * Creates a new locator with the given specification.
    	 *
    	 * @param encoding
    	 *            encoding of the source files, <code>null</code> for platform
    	 *            default encoding
    	 * @param tabWidth
    	 *            tab width in source files as number of blanks
    	 *
    	 */
    	protected InputStreamSourceFileLocator(final String encoding,
    			final int tabWidth) {
    		this.encoding = encoding;
    		this.tabWidth = tabWidth;
    	}

    	public Reader getSourceFile(final String packageName, final String fileName)
    			throws IOException {
    		final InputStream in;
    		if (packageName.length() > 0) {
    			in = getSourceStream(packageName + "/" + fileName);
    		} else {
    			in = getSourceStream(fileName);
    		}

    		if (in == null) {
    			return null;
    		}

    		if (encoding == null) {
    			return new InputStreamReader(in);
    		} else {
    			return new InputStreamReader(in, encoding);
    		}
    	}

    	public int getTabWidth() {
    		return tabWidth;
    	}

    	/**
    	 * Tries to locate the given source file and opens its binary content.
    	 *
    	 * @param path
    	 *            local path to the resource
    	 * @return stream if the file could be located, <code>null</code> otherwise
    	 * @throws IOException
    	 *             in case of problems while opening the stream
    	 */
    	protected abstract InputStream getSourceStream(String path)
    			throws IOException;

    }