Input2CharSequence.java

/* Copyright (C) 2002 Univ. of Massachusetts Amherst, Computer Science Dept.
   This file is part of "MALLET" (MAchine Learning for LanguagE Toolkit).
   http://www.cs.umass.edu/~mccallum/mallet
   This software is provided under the terms of the Common Public License,
   version 1.0, as published by http://www.opensource.org.  For further
   information, see the file `LICENSE' included with this distribution. */

/** 
 @author Andrew McCallum <a href="mailto:mccallum@cs.umass.edu">mccallum@cs.umass.edu</a>
 */

package edu.nd.nina.graph.load;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URI;

import edu.nd.nina.types.Instance;

/**
 * Pipe that can read from various kinds of text sources (either URI, File, or
 * Reader) into a CharSequence
 * 
 * @version $Id: Input2CharSequence.java,v 1.1 2007/10/22 21:37:39 mccallum Exp
 *          $
 */
public class Input2CharSequence extends Pipe {
	String encoding = null;

	public Input2CharSequence() {
	}

	public Input2CharSequence(String encoding) {
		this.encoding = encoding;
	}

	public Instance pipe(Instance carrier) {
		try {
			if (carrier.getData() instanceof URI)
				carrier.setData(pipe((URI) carrier.getData()));
			else if (carrier.getData() instanceof File)
				carrier.setData(pipe((File) carrier.getData()));
			else if (carrier.getData() instanceof Reader)
				carrier.setData(pipe((Reader) carrier.getData()));
			else if (carrier.getData() instanceof CharSequence)
				; // No conversion necessary
			else
				throw new IllegalArgumentException("Does not handle class "
						+ carrier.getData().getClass());

		} catch (java.io.IOException e) {
			throw new IllegalArgumentException("IOException " + e);
		}

		// System.out.println(carrier.getData().toString());
		return carrier;
	}

	public CharSequence pipe(URI uri) throws java.io.FileNotFoundException,
			java.io.IOException {
		if (!uri.getScheme().equals("file"))
			throw new UnsupportedOperationException(
					"Only file: scheme implemented.");
		return pipe(new File(uri.getPath()));
	}

	public CharSequence pipe(File file) throws java.io.FileNotFoundException,
			java.io.IOException {
		BufferedReader br = null;

		if (encoding == null) {
			br = new BufferedReader(new FileReader(file));
		} else {
			br = new BufferedReader(new InputStreamReader(new FileInputStream(
					file), encoding));
		}

		CharSequence cs = pipe(br);
		br.close();
		return cs;
	}

	public CharSequence pipe(Reader reader) throws java.io.IOException {
		final int BUFSIZE = 2048;
		char[] buf = new char[BUFSIZE];
		int count;
		StringBuffer sb = new StringBuffer(BUFSIZE);
		do {
			count = reader.read(buf, 0, BUFSIZE);
			if (count == -1)
				break;
			// System.out.println ("count="+count);
			sb.append(buf, 0, count);
		} while (count == BUFSIZE);
		return sb;
	}

	public CharSequence pipe(CharSequence cs) {
		return cs;
	}

}