AsciiStringUtil Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/AsciiStringUtil.java lines 24–291

final class AsciiStringUtil {

    /**
     * Convert the {@link AsciiString} to a lower case.
     *
     * @param string the {@link AsciiString} to convert
     * @return the new {@link AsciiString} in lower case
     */
    static AsciiString toLowerCase(final AsciiString string) {
        final byte[] byteArray = string.array();
        final int offset = string.arrayOffset();
        final int length = string.length();
        if (!containsUpperCase(byteArray, offset, length)) {
            return string;
        }
        final byte[] newByteArray = PlatformDependent.allocateUninitializedArray(length);
        toLowerCase(byteArray, offset, newByteArray);
        return new AsciiString(newByteArray, false);
    }

    private static boolean containsUpperCase(final byte[] byteArray, int offset, final int length) {
        if (!PlatformDependent.isUnaligned()) {
            return linearContainsUpperCase(byteArray, offset, length);
        }

        final int longCount = length >>> 3;
        for (int i = 0; i < longCount; ++i) {
            final long word = PlatformDependent.getLong(byteArray, offset);
            if (SWARUtil.containsUpperCase(word)) {
                return true;
            }
            offset += Long.BYTES;
        }
        return unrolledContainsUpperCase(byteArray, offset, length & 7);
    }

    private static boolean linearContainsUpperCase(final byte[] byteArray, final int offset, final int length) {
        final int end = offset + length;
        for (int idx = offset; idx < end; ++idx) {
            if (isUpperCase(byteArray[idx])) {
                return true;
            }
        }
        return false;
    }

    private static boolean unrolledContainsUpperCase(final byte[] byteArray, int offset, final int byteCount) {
        assert byteCount >= 0 && byteCount < 8;
        if ((byteCount & Integer.BYTES) != 0) {
            final int word = PlatformDependent.getInt(byteArray, offset);
            if (SWARUtil.containsUpperCase(word)) {
                return true;
            }
            offset += Integer.BYTES;
        }
        if ((byteCount & Short.BYTES) != 0) {
            if (isUpperCase(PlatformDependent.getByte(byteArray, offset))) {
                return true;
            }
            if (isUpperCase(PlatformDependent.getByte(byteArray, offset + 1))) {
                return true;
            }
            offset += Short.BYTES;
        }
        if ((byteCount & Byte.BYTES) != 0) {
            return isUpperCase(PlatformDependent.getByte(byteArray, offset));
        }
        return false;
    }

    private static void toLowerCase(final byte[] src, final int srcOffset, final byte[] dst) {
        if (!PlatformDependent.isUnaligned()) {
            linearToLowerCase(src, srcOffset, dst);
            return;
        }

        final int length = dst.length;
        final int longCount = length >>> 3;
        int offset = 0;
        for (int i = 0; i < longCount; ++i) {
            final long word = PlatformDependent.getLong(src, srcOffset + offset);