Scala example source code file (ReplayPrefixOneCharInputStream.java)

This example Scala source code file (ReplayPrefixOneCharInputStream.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

inputstream, invalid, ioexception, replayprefixonecharinputstream, string, utf-16, utf-32, utf-8

The ReplayPrefixOneCharInputStream.java Scala example source code

package scala.tools.jline.internal;

import java.io.IOException;
import java.io.InputStream;
import java.text.MessageFormat;

/**
 * This is awkward and inefficient, but probably the minimal way to add UTF-8 support to JLine
 *
 * @author <a href="mailto:Marc.Herbert@continuent.com">Marc Herbert</a>
 * @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
 * @since 2.0
 */
public final class ReplayPrefixOneCharInputStream
    extends InputStream
{
    private byte firstByte;

    private int byteLength;

    private InputStream wrappedStream;

    private int byteRead;

    private final String encoding;

    public ReplayPrefixOneCharInputStream(final String encoding) {
        assert encoding != null;
        this.encoding = encoding;
    }

    public String getEncoding() {
        return encoding;
    }

    public void setInput(final int recorded, final InputStream wrapped) throws IOException {
        this.byteRead = 0;
        this.firstByte = (byte) recorded;
        this.wrappedStream = wrapped;

        byteLength = 1;
        if (encoding.equalsIgnoreCase("UTF-8")) {
            setInputUTF8(recorded, wrapped);
        }
        else if (encoding.equalsIgnoreCase("UTF-16")) {
            byteLength = 2;
        }
        else if (encoding.equalsIgnoreCase("UTF-32")) {
            byteLength = 4;
        }
    }


    public void setInputUTF8(final int recorded, final InputStream wrapped) throws IOException {
        // 110yyyyy 10zzzzzz
        if ((firstByte & (byte) 0xE0) == (byte) 0xC0) {
            this.byteLength = 2;
        }
        // 1110xxxx 10yyyyyy 10zzzzzz
        else if ((firstByte & (byte) 0xF0) == (byte) 0xE0) {
            this.byteLength = 3;
        }
        // 11110www 10xxxxxx 10yyyyyy 10zzzzzz
        else if ((firstByte & (byte) 0xF8) == (byte) 0xF0) {
            this.byteLength = 4;
        }
        else {
            throw new IOException(MessageFormat.format("Invalid UTF-8 first byte: {0}", firstByte));
        }
    }

    public int read() throws IOException {
        if (available() == 0) {
            return -1;
        }

        byteRead++;

        if (byteRead == 1) {
            return firstByte;
        }

        return wrappedStream.read();
    }

    /**
     * InputStreamReader is greedy and will try to read bytes in advance. We
     * do NOT want this to happen since we use a temporary/"losing bytes"
     * InputStreamReader above, that's why we hide the real
     * wrappedStream.available() here.
     */
    public int available() {
        return byteLength - byteRead;
    }
}