RawCharSequence.java

/*
 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org> and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.eclipse.jgit.util;

/**
 * A rough character sequence around a raw byte buffer.
 * <p>
 * Characters are assumed to be 8-bit US-ASCII.
 */
public final class RawCharSequence implements CharSequence {
    /** A zero-length character sequence. */
    public static final RawCharSequence EMPTY = new RawCharSequence(null, 0, 0);

    final byte[] buffer;

    final int startPtr;

    final int endPtr;

    /**
     * Create a rough character sequence around the raw byte buffer.
     *
     * @param buf
     *            buffer to scan.
     * @param start
     *            starting position for the sequence.
     * @param end
     *            ending position for the sequence.
     */
    public RawCharSequence(byte[] buf, int start, int end) {
        buffer = buf;
        startPtr = start;
        endPtr = end;
    }

    /** {@inheritDoc} */
    @Override
    public char charAt(int index) {
        return (char) (buffer[startPtr + index] & 0xff);
    }

    /** {@inheritDoc} */
    @Override
    public int length() {
        return endPtr - startPtr;
    }

    /** {@inheritDoc} */
    @Override
    public CharSequence subSequence(int start, int end) {
        return new RawCharSequence(buffer, startPtr + start, startPtr + end);
    }

    /** {@inheritDoc} */
    @Override
    public String toString() {
        final int n = length();
        final StringBuilder b = new StringBuilder(n);
        for (int i = 0; i < n; i++)
            b.append(charAt(i));
        return b.toString();
    }
}