tupleinput.java

berkeley db 4.6.21的源码。berkeley db是一个简单的数据库管理系统

     * @return the value read from the buffer.
     *
     * @throws IndexOutOfBoundsException if not enough bytes are available in
     * the buffer.
     */
    public final double readSortedDouble()
        throws IndexOutOfBoundsException {

        long val = readUnsignedLong();
        val ^= (val < 0) ? 0x8000000000000000L : 0xffffffffffffffffL;
        return Double.longBitsToDouble(val);
    }

    /**
     * Reads an unsigned byte (one byte) value from the buffer.
     * Reads values that were written using {@link
     * TupleOutput#writeUnsignedByte}.
     *
     * @return the value read from the buffer.
     *
     * @throws IndexOutOfBoundsException if not enough bytes are available in
     * the buffer.
     */
    public final int readUnsignedByte()
        throws IndexOutOfBoundsException {

        int c = readFast();
        if (c < 0) {
            throw new IndexOutOfBoundsException();
        }
        return c;
    }

    /**
     * Reads an unsigned short (two byte) value from the buffer.
     * Reads values that were written using {@link
     * TupleOutput#writeUnsignedShort}.
     *
     * @return the value read from the buffer.
     *
     * @throws IndexOutOfBoundsException if not enough bytes are available in
     * the buffer.
     */
    public final int readUnsignedShort()
        throws IndexOutOfBoundsException {

        int c1 = readFast();
        int c2 = readFast();
        if ((c1 | c2) < 0) {
             throw new IndexOutOfBoundsException();
        }
        return ((c1 << 8) | c2);
    }

    // --- end DataInput compatible methods ---

    /**
     * Reads an unsigned int (four byte) value from the buffer.
     * Reads values that were written using {@link
     * TupleOutput#writeUnsignedInt}.
     *
     * @return the value read from the buffer.
     *
     * @throws IndexOutOfBoundsException if not enough bytes are available in
     * the buffer.
     */
    public final long readUnsignedInt()
        throws IndexOutOfBoundsException {

        long c1 = readFast();
        long c2 = readFast();
        long c3 = readFast();
        long c4 = readFast();
        if ((c1 | c2 | c3 | c4) < 0) {
	    throw new IndexOutOfBoundsException();
        }
        return ((c1 << 24) | (c2 << 16) | (c3 << 8) | c4);
    }

    /**
     * This method is private since an unsigned long cannot be treated as
     * such in Java, nor converted to a BigInteger of the same value.
     */
    private final long readUnsignedLong()
        throws IndexOutOfBoundsException {

        long c1 = readFast();
        long c2 = readFast();
        long c3 = readFast();
        long c4 = readFast();
        long c5 = readFast();
        long c6 = readFast();
        long c7 = readFast();
        long c8 = readFast();
        if ((c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8) < 0) {
             throw new IndexOutOfBoundsException();
        }
        return ((c1 << 56) | (c2 << 48) | (c3 << 40) | (c4 << 32) |
                (c5 << 24) | (c6 << 16) | (c7 << 8)  | c8);
    }

    /**
     * Reads the specified number of bytes from the buffer, converting each
     * unsigned byte value to a character of the resulting string.
     * Reads values that were written using {@link TupleOutput#writeBytes}.
     * Only characters with values below 0x100 may be read using this method.
     *
     * @param length is the number of bytes to be read.
     *
     * @return the value read from the buffer.
     *
     * @throws IndexOutOfBoundsException if not enough bytes are available in
     * the buffer.
     */
    public final String readBytes(int length)
        throws IndexOutOfBoundsException {

        StringBuffer buf = new StringBuffer(length);
        for (int i = 0; i < length; i++) {
            int c = readFast();
            if (c < 0) {
                throw new IndexOutOfBoundsException();
            }
            buf.append((char) c);
        }
        return buf.toString();
    }

    /**
     * Reads the specified number of characters from the buffer, converting
     * each two byte unsigned value to a character of the resulting string.
     * Reads values that were written using {@link TupleOutput#writeChars}.
     *
     * @param length is the number of characters to be read.
     *
     * @return the value read from the buffer.
     *
     * @throws IndexOutOfBoundsException if not enough bytes are available in
     * the buffer.
     */
    public final String readChars(int length)
        throws IndexOutOfBoundsException {

        StringBuffer buf = new StringBuffer(length);
        for (int i = 0; i < length; i++) {
            buf.append(readChar());
        }
        return buf.toString();
    }

    /**
     * Reads the specified number of bytes from the buffer, converting each
     * unsigned byte value to a character of the resulting array.
     * Reads values that were written using {@link TupleOutput#writeBytes}.
     * Only characters with values below 0x100 may be read using this method.
     *
     * @param chars is the array to receive the data and whose length is used
     * to determine the number of bytes to be read.
     *
     * @throws IndexOutOfBoundsException if not enough bytes are available in
     * the buffer.
     */
    public final void readBytes(char[] chars)
        throws IndexOutOfBoundsException {

        for (int i = 0; i < chars.length; i++) {
            int c = readFast();
            if (c < 0) {
                throw new IndexOutOfBoundsException();
            }
            chars[i] = (char) c;
        }
    }

    /**
     * Reads the specified number of characters from the buffer, converting
     * each two byte unsigned value to a character of the resulting array.
     * Reads values that were written using {@link TupleOutput#writeChars}.
     *
     * @param chars is the array to receive the data and whose length is used
     * to determine the number of characters to be read.
     *
     * @throws IndexOutOfBoundsException if not enough bytes are available in
     * the buffer.
     */
    public final void readChars(char[] chars)
        throws IndexOutOfBoundsException {

        for (int i = 0; i < chars.length; i++) {
            chars[i] = readChar();
        }
    }

    /**
     * Reads the specified number of UTF characters string from the data
     * buffer and converts the data from UTF to Unicode.
     * Reads values that were written using {@link
     * TupleOutput#writeString(char[])}.
     *
     * @param length is the number of characters to be read.
     *
     * @return the converted string.
     *
     * @throws IndexOutOfBoundsException if no null terminating byte is found
     * in the buffer.
     *
     * @throws IllegalArgumentException malformed UTF data is encountered.
     */
    public final String readString(int length)
        throws IndexOutOfBoundsException, IllegalArgumentException  {

        char[] chars = new char[length];
        readString(chars);
        return new String(chars);
    }

    /**
     * Reads the specified number of UTF characters string from the data
     * buffer and converts the data from UTF to Unicode.
     * Reads values that were written using {@link
     * TupleOutput#writeString(char[])}.
     *
     * @param chars is the array to receive the data and whose length is used
     * to determine the number of characters to be read.
     *
     * @throws IndexOutOfBoundsException if no null terminating byte is found
     * in the buffer.
     *
     * @throws IllegalArgumentException malformed UTF data is encountered.
     */
    public final void readString(char[] chars)
        throws IndexOutOfBoundsException, IllegalArgumentException  {

        off = UtfOps.bytesToChars(buf, off, chars, 0, chars.length, false);
    }

    /**
     * Returns the byte length of a null-terminated UTF string in the data
     * buffer, including the terminator.  Used with string values that were
     * written using {@link TupleOutput#writeString(String)}.
     *
     * @throws IndexOutOfBoundsException if no null terminating byte is found
     * in the buffer.
     *
     * @throws IllegalArgumentException malformed UTF data is encountered.
     */
    public final int getStringByteLength()
        throws IndexOutOfBoundsException, IllegalArgumentException  {

        if (available() >= 2 &&
            buf[off] == TupleOutput.NULL_STRING_UTF_VALUE &&
            buf[off + 1] == 0) {
            return 2;
        } else {
            return UtfOps.getZeroTerminatedByteLength(buf, off) + 1;
        }
    }

    /**
     * Reads a packed integer.  Note that packed integers are not appropriate
     * for sorted values (keys) unless a custom comparator is used.
     *
     * @see PackedInteger
     */
    public final int readPackedInt() {

        int len = PackedInteger.getReadIntLength(buf, off);
        int val = PackedInteger.readInt(buf, off);

        off += len;
        return val;
    }

    /**
     * Returns the byte length of a packed integer.
     *
     * @see PackedInteger
     */
    public final int getPackedIntByteLength() {
        return PackedInteger.getReadIntLength(buf, off);
    }

    /**
     * Reads a packed long integer.  Note that packed integers are not
     * appropriate for sorted values (keys) unless a custom comparator is used.
     *
     * @see PackedInteger
     */
    public final long readPackedLong() {

        int len = PackedInteger.getReadLongLength(buf, off);
        long val = PackedInteger.readLong(buf, off);

        off += len;
        return val;
    }

    /**
     * Returns the byte length of a packed long integer.
     *
     * @see PackedInteger
     */
    public final int getPackedLongByteLength() {
        return PackedInteger.getReadLongLength(buf, off);
    }

    /**
     * Reads a {@code BigInteger}.
     *
     * @see TupleOutput#writeBigInteger
     */
    public final BigInteger readBigInteger() {
        int len = readShort();
        if (len < 0) {
            len = (- len);
        }
        byte[] a = new byte[len];
        a[0] = readByte();
        readFast(a, 1, a.length - 1);
        return new BigInteger(a);
    }

    /**
     * Returns the byte length of a {@code BigInteger}.
     *
     * @see TupleOutput#writeBigInteger
     */
    public final int getBigIntegerByteLength() {
        int saveOff = off;
        int len = readShort();
        off = saveOff;
        if (len < 0) {
            len = (- len);
        }
        return len + 2;
    }
}