com.github.dakusui.cmd.io.BasicLineReader Maven / Gradle / Ivy

Go to download
package com.github.dakusui.cmd.io;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.Charset;

import org.apache.commons.lang3.ArrayUtils;

import com.github.dakusui.cmd.exceptions.CommandException;

public class BasicLineReader implements LineReader {
	private InputStreamReader isReader = null;
	private BufferedReader bReader = null;
	private char[] buf = null;
	private int maxLineSize;
	
	/**
	 * Creates an object of this class.
	 * 
	 * @param cs Character set that is assumed for the inputstream is.
	 * @param maxLineSize
	 * @param is
	 */
	public BasicLineReader(Charset cs, int maxLineSize, InputStream is) {
		this.maxLineSize = maxLineSize;
		this.isReader = new InputStreamReader(new BufferedInputStream(is), cs);
		if (maxLineSize <= 0) {
			this.bReader = new BufferedReader(this.isReader);
		}
	}

	@Override
	public String read() throws CommandException {
		String ret = null;
		try {
			if (this.maxLineSize <= 0) {
				////
				// BufferedReader mode.
				ret = bReader.readLine();
			} else {
				////
				// Custom mode
				if (buf == null) {
					this.buf = new char[this.maxLineSize];
					int len = this.isReader.read(this.buf);
					if (len == -1) return ret;
					if (len < this.buf.length) {
						this.buf = ArrayUtils.subarray(this.buf, 0, len);
					}
				}
				ret = readFromBufferAndUpdate();
			}
		} catch (IOException e) {
			throw new CommandException(e);
		}
		return ret;
	}
	
	private String readFromBufferAndUpdate() {
		int indexOfEOL = indexOfEOL(this.buf);
		String ret = null;
		if (indexOfEOL == -1) indexOfEOL = this.buf.length;
		ret = new String(ArrayUtils.subarray(this.buf, 0, indexOfEOL));
		////
		// If an EOL is at the end of the array, an empty string will be the
		// last element from the stream.
		if (indexOfEOL == this.buf.length) {
			this.buf = null;
		} else {
			this.buf = ArrayUtils.subarray(this.buf, indexOfEOL+1, this.buf.length);
			if (this.buf.length == 0) {
				this.buf = null;
			}
		}
		return ret;
	}
	
	private int indexOfEOL(char[] buf) {
		return ArrayUtils.indexOf(buf, LineConsumer.EOL);
	}
	
	@Override
	public void close() throws CommandException {
		if (this.bReader != null)
			try { bReader.close(); } catch (IOException e) {
				throw new CommandException(e);
			} finally {
				if (this.isReader != null)
					try { isReader.close(); } catch (IOException e) {
						throw new CommandException(e);
					}
			}
	}
}