[patch] Lazy evaluation for Formula.java

org.apache.poi.ss.formula.Formula.java.lazy_eval.patch (text/plain), 5.22 KB, created by Javen O'Neal on 2017-05-31 04:38:33 UTC

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Description: Lazy evaluation for Formula.java

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Creator: Javen O'Neal

Created: 2017-05-31 04:38:33 UTC

Size: 5.22 KB

patch

obsolete

>Index: src/java/org/apache/poi/ss/formula/Formula.java >=================================================================== >--- src/java/org/apache/poi/ss/formula/Formula.java (revision 1796972) >+++ src/java/org/apache/poi/ss/formula/Formula.java (working copy) >@@ -37,11 +37,12 @@ > > private static final Formula EMPTY = new Formula(new byte[0], 0); > >- /** immutable */ >- private final byte[] _byteEncoding; >- private final int _encodedTokenLen; >+ /** immutable, lazily populated */ >+ private byte[] _byteEncoding; >+ private int _encodedTokenLen = -1; >+ private Ptg[] _ptgTokens; > >- private Formula(byte[] byteEncoding, int encodedTokenLen) { >+ private Formula(final byte[] byteEncoding, final int encodedTokenLen) { > _byteEncoding = byteEncoding.clone(); > _encodedTokenLen = encodedTokenLen; > // if (false) { // set to true to eagerly check Ptg decoding >@@ -58,6 +59,14 @@ > // } > // } > } >+ >+ private Formula(final Ptg[] ptgs) { >+ // cachedTokens should only be provided by a source that promises not to mutate the array >+ // Since this class itself doesn't mutate _ptgTokens, as long as this promise is honored, >+ // _ptgTokens is immutable. >+ _ptgTokens = ptgs.clone(); >+ } >+ > /** > * Convenience method for {@link #read(int, LittleEndianInput, int)} > */ >@@ -78,9 +87,49 @@ > } > > public Ptg[] getTokens() { >+ if (_ptgTokens == null) { >+ readPtgTokensFromBytes(); >+ } >+ return _ptgTokens; >+ } >+ >+ private byte[] getEncodedBytes() { >+ if (_byteEncoding == null) { >+ readBytesFromPtgTokens(); >+ } >+ return _byteEncoding; >+ } >+ >+ private int getEncodedTokenLen() { >+ if (_getEncodedTokenLen <= 0) { >+ readBytesFromPtgTokens(); >+ } >+ return _getEncodedTokenLen; >+ } >+ >+ private void readPtgTokensFromBytes() { >+ if (_byteEncoding == null || _getEncodedTokenLen <= 0) { >+ // EMPTY >+ return; >+ } > LittleEndianInput in = new LittleEndianByteArrayInputStream(_byteEncoding); >- return Ptg.readTokens(_encodedTokenLen, in); >+ _ptgTokens = Ptg.readTokens(_encodedTokenLen, in); > } >+ >+ private void readBytesFromPtgTokens() { >+ if (_ptgTokens == null) { >+ // EMPTY >+ return; >+ } >+ final int totalSize = Ptg.getEncodedSize(_ptgTokens); >+ final byte[] encodedData = new byte[totalSize]; >+ Ptg.serializePtgs(ptgs, encodedData, 0); >+ final int encodedTokenLen = Ptg.getEncodedSizeWithoutArrayData(ptgs); >+ >+ _byteEncoding = encodedData; >+ _encodedTokenLen = encodedTokenLen; >+ } >+ > /** > * Writes The formula encoding is includes: > * <ul> >@@ -90,16 +139,18 @@ > * </ul> > */ > public void serialize(LittleEndianOutput out) { >- out.writeShort(_encodedTokenLen); >- out.write(_byteEncoding); >+ out.writeShort(getEncodedTokenLen()); >+ out.write(getEncodedBytes()); > } > > public void serializeTokens(LittleEndianOutput out) { >- out.write(_byteEncoding, 0, _encodedTokenLen); >+ out.write(getEncodedBytes(), 0, getEncodedTokenLen()); > } > public void serializeArrayConstantData(LittleEndianOutput out) { >- int len = _byteEncoding.length-_encodedTokenLen; >- out.write(_byteEncoding, _encodedTokenLen, len); >+ byte[] bytes = getEncodedBytes(); >+ int encodedLen = getEncodedTokenLen(); >+ int len = bytes.length - encodedLen; >+ out.write(bytes, encodedLen, len); > } > > >@@ -113,7 +164,7 @@ > * Note - this value is different to <tt>tokenDataLength</tt> > */ > public int getEncodedSize() { >- return 2 + _byteEncoding.length; >+ return 2 + getEncodedBytes().length; > } > /** > * This method is often used when the formula length does not appear immediately before >@@ -123,7 +174,8 @@ > * the leading ushort field, nor any trailing array constant data. > */ > public int getEncodedTokenSize() { >- return _encodedTokenLen; >+ >+ return getEncodedTokenLen(); > } > > /** >@@ -132,15 +184,11 @@ > * @param ptgs may be <code>null</code> > * @return Never <code>null</code> (Possibly empty if the supplied <tt>ptgs</tt> is <code>null</code>) > */ >- public static Formula create(Ptg[] ptgs) { >+ public static Formula create(final Ptg[] ptgs) { > if (ptgs == null || ptgs.length < 1) { > return EMPTY; > } >- int totalSize = Ptg.getEncodedSize(ptgs); >- byte[] encodedData = new byte[totalSize]; >- Ptg.serializePtgs(ptgs, encodedData, 0); >- int encodedTokenLen = Ptg.getEncodedSizeWithoutArrayData(ptgs); >- return new Formula(encodedData, encodedTokenLen); >+ return new Formula(ptgs); > } > /** > * Gets the {@link Ptg} array from the supplied {@link Formula}. >@@ -172,7 +220,7 @@ > * belongs to. <code>null</code> if this formula is not part of an array or shared formula. > */ > public CellReference getExpReference() { >- byte[] data = _byteEncoding; >+ final byte[] data = getEncodedBytes(); > if (data.length != 5) { > // tExp and tTbl are always 5 bytes long, and the only ptg in the formula > return null; >@@ -185,11 +233,11 @@ > default: > return null; > } >- int firstRow = LittleEndian.getUShort(data, 1); >- int firstColumn = LittleEndian.getUShort(data, 3); >+ final int firstRow = LittleEndian.getUShort(data, 1); >+ final int firstColumn = LittleEndian.getUShort(data, 3); > return new CellReference(firstRow, firstColumn); > } > public boolean isSame(Formula other) { >- return Arrays.equals(_byteEncoding, other._byteEncoding); >+ return Arrays.equals(getEncodedBytes(), other.getEncodedBytes()); > } > } View Attachment As Diff View Attachment As Raw

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