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CMStateSet.javaAPI DocApache Xerces 3.0.19469Fri Sep 14 20:33:52 BST 2007org.apache.xerces.impl.dtd.models

CMStateSet

public class CMStateSet extends Object
This class is a very simple bitset class. The DFA content model code needs to support a bit set, but the java BitSet class is way, way overkill. Our bitset never needs to be expanded after creation, hash itself, etc... Since the vast majority of content models will never require more than 64 bits, and since allocation of anything in Java is expensive, this class provides a hybrid implementation that uses two ints for instances that use 64 bits or fewer. It has a byte array reference member which will only be used if more than 64 bits are required. Note that the code that uses this class will never perform operations on sets of different sizes, so that check does not have to be made here.
xerces.internal
version
$Id: CMStateSet.java 446752 2006-09-15 21:55:19Z mrglavas $

Fields Summary
int
fBitCount
int
fByteCount
int
fBits1
int
fBits2
byte[]
fByteArray
Constructors Summary
public CMStateSet(int bitCount)

        // Store the required bit count and insure its legal
        fBitCount = bitCount;
        if (fBitCount < 0)
            throw new RuntimeException("ImplementationMessages.VAL_CMSI");

        //
        //  See if we need to allocate the byte array or whether we can live
        //  within the 64 bit high performance scheme.
        //
        if (fBitCount > 64)
        {
            fByteCount = fBitCount / 8;
            if (fBitCount % 8 != 0)
                fByteCount++;
            fByteArray = new byte[fByteCount];
        }

        // Init all the bits to zero
        zeroBits();
Methods Summary
public booleanequals(java.lang.Object o)

	if (!(o instanceof CMStateSet)) return false;
	return isSameSet((CMStateSet)o);
public final booleangetBit(int bitToGet)

        if (bitToGet >= fBitCount)
            throw new RuntimeException("ImplementationMessages.VAL_CMSI");

        if (fBitCount < 65)
        {
            final int mask = (0x1 << (bitToGet % 32));
            if (bitToGet < 32)
                return (fBits1 & mask) != 0;
            else
                return (fBits2 & mask) != 0;
        }
         else
        {
            // Create the mask and byte values
            final byte mask = (byte)(0x1 << (bitToGet % 8));
            final int ofs = bitToGet >> 3;

            // And access the right bit and byte
            return ((fByteArray[ofs] & mask) != 0);
        }
public inthashCode()

        if (fBitCount < 65)
        {
            return fBits1+ fBits2 * 31;
        }
         else
        {
            int hash = 0;
            for (int index = fByteCount - 1; index >= 0; index--)
                hash = fByteArray[index] + hash * 31;
            return hash;
        }
public final voidintersection(org.apache.xerces.impl.dtd.models.CMStateSet setToAnd)

        if (fBitCount < 65)
        {
            fBits1 &= setToAnd.fBits1;
            fBits2 &= setToAnd.fBits2;
        }
         else
        {
            for (int index = fByteCount - 1; index >= 0; index--)
                fByteArray[index] &= setToAnd.fByteArray[index];
        }
public final booleanisEmpty()

        if (fBitCount < 65)
        {
            return ((fBits1 == 0) && (fBits2 == 0));
        }
         else
        {
            for (int index = fByteCount - 1; index >= 0; index--)
            {
                if (fByteArray[index] != 0)
                    return false;
            }
        }
        return true;
final booleanisSameSet(org.apache.xerces.impl.dtd.models.CMStateSet setToCompare)

        if (fBitCount != setToCompare.fBitCount)
            return false;

        if (fBitCount < 65)
        {
            return ((fBits1 == setToCompare.fBits1)
            &&      (fBits2 == setToCompare.fBits2));
        }

        for (int index = fByteCount - 1; index >= 0; index--)
        {
            if (fByteArray[index] != setToCompare.fByteArray[index])
                return false;
        }
        return true;
public final voidsetBit(int bitToSet)

        if (bitToSet >= fBitCount)
            throw new RuntimeException("ImplementationMessages.VAL_CMSI");

        if (fBitCount < 65)
        {
            final int mask = (0x1 << (bitToSet % 32));
            if (bitToSet < 32)
            {
                fBits1 &= ~mask;
                fBits1 |= mask;
            }
             else
            {
                fBits2 &= ~mask;
                fBits2 |= mask;
            }
        }
         else
        {
            // Create the mask and byte values
            final byte mask = (byte)(0x1 << (bitToSet % 8));
            final int ofs = bitToSet >> 3;

            // And access the right bit and byte
            fByteArray[ofs] &= ~mask;
            fByteArray[ofs] |= mask;
        }
public final voidsetTo(org.apache.xerces.impl.dtd.models.CMStateSet srcSet)

        // They have to be the same size
        if (fBitCount != srcSet.fBitCount)
            throw new RuntimeException("ImplementationMessages.VAL_CMSI");
        
        if (fBitCount < 65)
        {
            fBits1 = srcSet.fBits1;
            fBits2 = srcSet.fBits2;
        }
         else
        {
            for (int index = fByteCount - 1; index >= 0; index--)
                fByteArray[index] = srcSet.fByteArray[index];
        }
public java.lang.StringtoString()

        StringBuffer strRet = new StringBuffer();
        try
        {
            strRet.append('{");
            for (int index = 0; index < fBitCount; index++) {
                if (getBit(index)) {
                    strRet.append(' ").append(index);
                }
            }
            strRet.append(" }");
        }

        catch(RuntimeException exToCatch)
        {
            //
            //  We know this won't happen but we have to catch it to avoid it
            //  having to be in our 'throws' list.
            //
        }
        return strRet.toString();
public final voidunion(org.apache.xerces.impl.dtd.models.CMStateSet setToOr)

        if (fBitCount < 65)
        {
            fBits1 |= setToOr.fBits1;
            fBits2 |= setToOr.fBits2;
        }
         else
        {
            for (int index = fByteCount - 1; index >= 0; index--)
                fByteArray[index] |= setToOr.fByteArray[index];
        }
public final voidzeroBits()

        if (fBitCount < 65)
        {
            fBits1 = 0;
            fBits2 = 0;
        }
         else
        {
            for (int index = fByteCount - 1; index >= 0; index--)
                fByteArray[index] = 0;
        }