src/org/apache/pig/tools/grunt/ConsoleReaderInputStream.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.pig.tools.grunt;

import java.io.IOException;
import java.io.InputStream;
import java.io.SequenceInputStream;
import java.util.Enumeration;

import jline.console.ConsoleReader;

/** Borrowed from jline.console.internal.ConsoleReaderInputStream. However,
 *  we cannot use ConsoleReaderInputStream directly since:
 *  1. ConsoleReaderInputStream is not public
 *  2. ConsoleReaderInputStream has a bug which does not deal with UTF-8 correctly
 */
public class ConsoleReaderInputStream extends SequenceInputStream {
    private static InputStream systemIn = System.in;

    public static void setIn() throws IOException {
        setIn(new ConsoleReader());
    }

    public static void setIn(final ConsoleReader reader) {
        System.setIn(new ConsoleReaderInputStream(reader));
    }

    /**
     * Restore the original {@link System#in} input stream.
     */
    public static void restoreIn() {
        System.setIn(systemIn);
    }

    public ConsoleReaderInputStream(final ConsoleReader reader) {
        super(new ConsoleEnumeration(reader));
    }

    private static class ConsoleEnumeration implements Enumeration {
        private final ConsoleReader reader;
        private ConsoleLineInputStream next = null;
        private ConsoleLineInputStream prev = null;

        public ConsoleEnumeration(final ConsoleReader reader) {
            this.reader = reader;
        }

        public Object nextElement() {
            if (next != null) {
                InputStream n = next;
                prev = next;
                next = null;

                return n;
            }

            return new ConsoleLineInputStream(reader);
        }

        public boolean hasMoreElements() {
            // the last line was null
            if ((prev != null) && (prev.wasNull == true)) {
                return false;
            }

            if (next == null) {
                next = (ConsoleLineInputStream) nextElement();
            }

            return next != null;
        }
    }

    private static class ConsoleLineInputStream extends InputStream {
        private final ConsoleReader reader;
        private byte[] buffer = null;
        private int index = 0;
        private boolean eol = false;
        protected boolean wasNull = false;

        public ConsoleLineInputStream(final ConsoleReader reader) {
            this.reader = reader;
        }

        public int read() throws IOException {
            if (eol) {
                return -1;
            }

            if (buffer == null) {
                buffer = reader.readLine().getBytes();
            }

            if (buffer == null) {
                wasNull = true;
                return -1;
            }

            if (index >= buffer.length) {
                eol = true;
                return '\n'; // lines are ended with a newline
            }

            return buffer[index++];
        }
    }
}