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Refactor child pointer logic to the factory 

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1766492 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Nick Burch 2016-10-25 09:33:37 +00:00
parent 3f1965ea27
commit 6816899106
6 changed files with 104 additions and 64 deletions
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4
src/scratchpad/src/org/apache/poi/hdgf/pointers/Pointer.java
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@ -45,6 +45,10 @@ public abstract class Pointer {
}
public abstract int getSizeInBytes();
public abstract int getNumPointersOffset(byte[] data);
public abstract int getNumPointers(int offset, byte[] data);
public abstract int getPostNumPointersSkip();
public abstract boolean destinationHasStrings();
public abstract boolean destinationHasPointers();
public abstract boolean destinationHasChunks();

53
src/scratchpad/src/org/apache/poi/hdgf/pointers/PointerFactory.java
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@ -31,6 +31,9 @@ public final class PointerFactory {
}
public int getVersion() { return version; }
/**
* Creates a single Pointer from the data at the given offset
*/
public Pointer createPointer(byte[] data, int offset) {
Pointer p;
if(version >= 6) {
@ -57,39 +60,25 @@ public final class PointerFactory {
}
/**
* In a {@link PointerContainingStream}, where would the
* number of child pointers be stored for this kind of Pointer?
* Parsers the {@link PointerContainingStream} contents and
* creates all the child Pointers for it
*/
public int identifyNumPointersOffset(Pointer pointer, byte[] data) {
if (pointer instanceof PointerV6) {
// V6 stores it as the first value in the stream
return (int)LittleEndian.getUInt(data, 0);
} else if (pointer instanceof PointerV5) {
// V5 uses fixed offsets
switch (pointer.type) {
case 0x1d:
case 0x4e:
return 0x24-6;
case 0x1e:
return 0x3c-6;
case 0x14:
return 0x88-6;
}
return 10;
} else {
throw new IllegalArgumentException("Unsupported Pointer type " + pointer);
}
}
public int identifyNumPointers(Pointer pointer, int offset, byte[] data) {
if (pointer instanceof PointerV6) {
// V6 stores it a 32 bit number at the offset
return (int)LittleEndian.getUInt(data, offset);
} else if (pointer instanceof PointerV5) {
// V5 stores it as a 16 bit number at the offset
return LittleEndian.getShort(data, offset);
} else {
throw new IllegalArgumentException("Unsupported Pointer type " + pointer);
public Pointer[] createContainerPointers(Pointer parent, byte[] data) {
// Where in the stream does the "number of pointers" offset live?
int numPointersOffset = parent.getNumPointersOffset(data);
// How many do we have?
int numPointers = parent.getNumPointers(numPointersOffset, data);
// How much to skip for the num pointers + any extra data?
int skip = parent.getPostNumPointersSkip();
// Create
int pos = numPointersOffset + skip;
Pointer[] childPointers = new Pointer[numPointers];
for(int i=0; i<numPointers; i++) {
childPointers[i] = this.createPointer(data, pos);
pos += childPointers[i].getSizeInBytes();
}
return childPointers;
}
}

31
src/scratchpad/src/org/apache/poi/hdgf/pointers/PointerV5.java
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@ -17,6 +17,8 @@
package org.apache.poi.hdgf.pointers;
import org.apache.poi.util.LittleEndian;
/**
* A Pointer from v5
*/
@ -43,4 +45,33 @@ public final class PointerV5 extends Pointer {
* With v6 pointers, the on-disk size is 16 bytes
*/
public int getSizeInBytes() { return 16; }
/**
* Depends on the type only, not stored
*/
public int getNumPointersOffset(byte[] data) {
switch (type) {
case 0x1d:
case 0x4e:
return 0x24-6;
case 0x1e:
return 0x3c-6;
case 0x14:
return 0x88-6;
}
return 10;
}
/**
* 16 bit int at the given offset
*/
public int getNumPointers(int offset, byte[] data) {
// V5 stores it as a 16 bit number at the offset
return LittleEndian.getShort(data, offset);
}
/**
* Just the 2 bytes of the number of pointers
*/
public int getPostNumPointersSkip() {
return 2;
}
}

32
src/scratchpad/src/org/apache/poi/hdgf/pointers/PointerV6.java
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@ -17,6 +17,8 @@
package org.apache.poi.hdgf.pointers;
import org.apache.poi.util.LittleEndian;
/**
* A Pointer from v6+
*/
@ -42,4 +44,34 @@ public final class PointerV6 extends Pointer {
* With v6 pointers, the on-disk size is 18 bytes
*/
public int getSizeInBytes() { return 18; }
/**
* Stored within the data
*/
public int getNumPointersOffset(byte[] data) {
return getNumPointersOffsetV6(data);
}
public static int getNumPointersOffsetV6(byte[] data) {
// V6 stores it as the first value in the stream
return (int)LittleEndian.getUInt(data, 0);
}
/**
* 32 bit int at the given offset
*/
public int getNumPointers(int offset, byte[] data) {
return getNumPointersV6(offset, data);
}
public static int getNumPointersV6(int offset, byte[] data) {
// V6 stores it a 32 bit number at the offset
return (int)LittleEndian.getUInt(data, offset);
}
/**
* 4 bytes of the number, and 4 more unknown bytes
*/
public int getPostNumPointersSkip() {
return getPostNumPointersSkipV6();
}
public static int getPostNumPointersSkipV6() {
return 8;
}
}

34
src/scratchpad/src/org/apache/poi/hdgf/streams/PointerContainingStream.java
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@ -20,8 +20,6 @@ package org.apache.poi.hdgf.streams;
import org.apache.poi.hdgf.chunks.ChunkFactory;
import org.apache.poi.hdgf.pointers.Pointer;
import org.apache.poi.hdgf.pointers.PointerFactory;
import org.apache.poi.hdgf.pointers.PointerV6;
import org.apache.poi.util.LittleEndian;
/**
* A stream that holds pointers, possibly in addition to some
@ -33,42 +31,14 @@ public class PointerContainingStream extends Stream { // TODO - instantiable sup
private ChunkFactory chunkFactory;
private PointerFactory pointerFactory;
private int numPointersLocalOffset;
protected PointerContainingStream(Pointer pointer, StreamStore store, ChunkFactory chunkFactory, PointerFactory pointerFactory) {
super(pointer, store);
this.chunkFactory = chunkFactory;
this.pointerFactory = pointerFactory;
// Find the offset to the number of child pointers we have
numPointersLocalOffset = pointerFactory.identifyNumPointersOffset(
pointer, store.getContents()
);
// Generate the objects for the pointers we contain
int numPointers = pointerFactory.identifyNumPointers(
pointer, numPointersLocalOffset, store.getContents()
);
childPointers = new Pointer[numPointers];
// Prepare to read the children
int pos = numPointersLocalOffset;
// v5 only has another (unknown) 4 byte value
// TODO Should this logic go into PointerFactory?
if (pointer instanceof PointerV6) {
pos += 4 + 4;
} else {
pos += 2;
}
// Now create the pointer objects
for(int i=0; i<numPointers; i++) {
childPointers[i] = pointerFactory.createPointer(
store.getContents(), pos
);
pos += childPointers[i].getSizeInBytes();
}
// Have the child pointers identified and created
childPointers = pointerFactory.createContainerPointers(pointer, store.getContents());
}
/**

14
src/scratchpad/testcases/org/apache/poi/hdgf/streams/StreamTest.java
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@ -18,6 +18,7 @@
package org.apache.poi.hdgf.streams;
import org.apache.poi.hdgf.pointers.Pointer;
import static org.apache.poi.hdgf.pointers.PointerV6.*;
import junit.framework.TestCase;
@ -41,7 +42,20 @@ public abstract class StreamTest extends TestCase {
public boolean destinationHasPointers() { return hasPointers; }
@Override
public boolean destinationHasStrings() { return false; }
@Override
public int getSizeInBytes() { return -1; }
@Override
public int getNumPointersOffset(byte[] data) {
return getNumPointersOffsetV6(data);
}
@Override
public int getNumPointers(int offset, byte[] data) {
return getNumPointersV6(offset, data);
}
@Override
public int getPostNumPointersSkip() {
return getPostNumPointersSkipV6();
}
}
}