[jira] Closed: (DIRMINA-387) Getter and putter methods for Enum and EnumSet in ByteBuffer

["Trustin Lee (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DIRMINA-387?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Trustin Lee closed DIRMINA-387.
-------------------------------

    Resolution: Fixed

> Getter and putter methods for Enum and EnumSet in ByteBuffer
> ------------------------------------------------------------
>
>                 Key: DIRMINA-387
>                 URL: https://issues.apache.org/jira/browse/DIRMINA-387
>             Project: MINA
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Trustin Lee
>            Assignee: Mike Heath
>             Fix For: 2.0.0-M1
>
>
> Mike Heath wrote:
> I've been twiddling a lot of bits with MINA and got tired of it so I
> created a utility class that converts instances of EnumSet to bit
> vectors and vice-versa.
> I thought this feature would be a good addition to MINA's ByteBuffer.
> Instead of just committing the change, I wanted to run the idea past the
> MINA community since ByteBuffer is such an integral part of the MINA
> framework.  I propose adding the following to
> org.apache.mina.common.ByteBuffer in TRUNK:
>    public <E extends Enum<E>> EnumSet<E> getEnumSet(Class<E> enumClass)
> {
>        return toEnumSet(enumClass, (long)get() & 0xFFL);
>    }
>    public <E extends Enum<E>> EnumSet<E> getEnumSetShort(Class<E>
> enumClass) {
>        return toEnumSet(enumClass, ((long)getShort()) & 0xFFFFL);
>    }
>    public <E extends Enum<E>> EnumSet<E> getEnumSetInt(Class<E>
> enumClass) {
>        return toEnumSet(enumClass, (long)getInt() & 0xFFFFFFFFL);
>    }
>    public <E extends Enum<E>> EnumSet<E> getEnumSetLong(Class<E>
> enumClass) {
>        return toEnumSet(enumClass, getLong());
>    }
>    private <E extends Enum<E>> EnumSet<E> toEnumSet(Class<E> enumClass,
> long vector) {
>        EnumSet<E> set = EnumSet.noneOf(enumClass);
>        long mask = 1;
>        for (E e : enumClass.getEnumConstants()) {
>            if ((mask & vector) == mask) {
>                set.add(e);
>            }
>            mask <<= 1;
>        }
>        return set;
>    }
>    public <E extends Enum<E>> void putEnumSet(EnumSet<E> set) {
>        put((byte)toLong(set));
>    }
>    public <E extends Enum<E>> void putEnumSetShort(EnumSet<E> set) {
>        putShort((short)toLong(set));
>    }
>    public <E extends Enum<E>> void putEnumSetInt(EnumSet<E> set) {
>        putInt((int)toLong(set));
>    }
>    public <E extends Enum<E>> void putEnumSetLong(EnumSet<E> set) {
>        putLong(toLong(set));
>    }
>    private <E extends Enum<E>> long toLong(EnumSet<E> s) {
>        long vector = 0;
>        for (E e : s) {
>            vector |= 1L << e.ordinal();
>        }
>        return vector;
>    }
> It works like this.  Suppose I have a protocol that uses an integer
> sized (32-bit) bit mask to send 32 boolean values.  Instead of masking
> off each bit to see if it's set or not, I create an enum that represents
> each value in the mask like:
> public enum MaskValues {
>    VALUE_1, // 0x00000001
>    VALUE_2, // 0x00000002
>    ...,
>    VALUE_31, // 0x40000000
>    VALUE_32  // 0x80000000
> }
> I then do:
> EnumSet<MaskValues> values = buf.getEnumSetInt(MaskValues.class);
> To see if any bit is set I can do values.contains(MaskValues.VALUE_XX)
> or to see if a group of bits are set I can do
> values.containsAll(EnumSet.of(MaskValues.VALUE_XX, MaskValues.VALUE_YY))
> and so on.  This is much easier to read then:
> int bitVector = buf.getInt();
> if (bitVector & mask == mask) { do something }
> The putXXXX methods provide a mechanism for putting an EnumSet into the
> ByteBuffer as a bit vector.
> If this functionality is desired, I'll add some Java Docs to the above
> methods and commit my code and accompanying unit tests.

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