org.tmatesoft.svn.core.io.diff
Class SVNDiffWindow

java.lang.Object
  org.tmatesoft.svn.core.io.diff.SVNDiffWindow

public class SVNDiffWindow
extends java.lang.Object

The SVNDiffWindow class represents a diff window that contains instructions and new data of a delta to apply to a file.

Instructions are not immediately contained in a window. A diff window provides an iterator that reads and constructs one SVNDiffInstruction from provided raw bytes per one iteration. There is even an ability to use a single SVNDiffInstruction object for read and decoded instructions: for subsequent iterations an iterator simply uses the same instruction object to return as a newly read and decoded instruction.

Since:

1.2

See Also:

SVNDiffInstruction

Field Summary

static SVNDiffWindow	EMPTY An empty window (in particular, its instructions length = 0).
static byte[]	SVN_HEADER Bytes of the delta header of an uncompressed diff window.
static byte[]	SVN1_HEADER Bytes of the delta header of a compressed diff window.

Constructor Summary

SVNDiffWindow(long sourceViewOffset, int sourceViewLength, int targetViewLength, int instructionsLength, int newDataLength)
Constructs an SVNDiffWindow object.

Method Summary

int	apply(byte[] sourceBuffer, byte[] targetBuffer) Applies this window's instructions provided source and target view buffers.
void	apply(SVNDiffWindowApplyBaton applyBaton) Applies this window's instructions.
SVNDiffWindow	clone(java.nio.ByteBuffer targetData) Creates an exact copy of this window object.
int	getDataLength() Returns the total amount of new data and instruction bytes.
int	getInstructionsCount() Returns the amount of instructions of this window object.
int	getInstructionsLength() Returns the length of instructions in bytes.
int	getNewDataLength() Returns the number of new data bytes to copy to the target view.
int	getSourceViewLength() Returns the number of bytes to copy from the source view to the target one.
long	getSourceViewOffset() Returns the source view offset.
int	getTargetViewLength() Returns the length in bytes of the target view.
boolean	hasCopyFromSourceInstructions() Tells whether this window contains any copy-from-source instructions.
boolean	hasInstructions() Tells if this window is not empty, i.e. has got any instructions.
java.util.Iterator	instructions() Returns an iterator to read instructions in series.
java.util.Iterator	instructions(boolean template) Returns an iterator to read instructions in series.
SVNDiffInstruction[]	loadDiffInstructions(SVNDiffInstruction[] target) Returns an array of instructions of this window.
void	setData(java.nio.ByteBuffer buffer) Sets a byte buffer containing instruction and new data bytes of this window.
java.lang.String	toString() Gives a string representation of this object.
void	writeNewData(java.nio.ByteBuffer target, int offset, int length) Fills a target buffer with the specified number of new data bytes of this window object taken at the specified offset.
void	writeTo(java.io.OutputStream os, boolean writeHeader) Writes this window object to the provided stream.
void	writeTo(java.io.OutputStream os, boolean writeHeader, boolean compress) Formats and writes this window bytes to the specified output stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

SVN_HEADER

public static final byte[] SVN_HEADER

Bytes of the delta header of an uncompressed diff window.

SVN1_HEADER

public static final byte[] SVN1_HEADER

Bytes of the delta header of a compressed diff window.

Since:

1.1, new in Subversion 1.4

EMPTY

public static final SVNDiffWindow EMPTY

An empty window (in particular, its instructions length = 0). Corresponds to the case of an empty delta, so, it's passed to a delta consumer to create an empty file.

Constructor Detail

SVNDiffWindow

public SVNDiffWindow(long sourceViewOffset,
                     int sourceViewLength,
                     int targetViewLength,
                     int instructionsLength,
                     int newDataLength)

Constructs an SVNDiffWindow object. This constructor is used when bytes of instructions are not decoded and converted to SVNDiffInstruction objects yet, but are kept elsewhere along with new data.

Parameters:

sourceViewOffset - an offset in the source view

sourceViewLength - a number of bytes to read from the source view

targetViewLength - a length in bytes of the target view it must have after copying bytes

instructionsLength - a number of instructions bytes

newDataLength - a number of bytes of new data

See Also:

SVNDiffInstruction

Method Detail

getInstructionsLength

public int getInstructionsLength()

Returns the length of instructions in bytes.

Returns:

a number of instructions bytes

getSourceViewOffset

public long getSourceViewOffset()

Returns the source view offset.

Returns:

an offset in the source from where the source bytes must be copied

getSourceViewLength

public int getSourceViewLength()

Returns the number of bytes to copy from the source view to the target one.

Returns:

a number of source bytes to copy

getTargetViewLength

public int getTargetViewLength()

Returns the length in bytes of the target view. The length of the target view is actually the number of bytes that should be totally copied by all the instructions of this window.

Returns:

a length in bytes of the target view

getNewDataLength

public int getNewDataLength()

Returns the number of new data bytes to copy to the target view.

Returns:

a number of new data bytes

instructions

public java.util.Iterator instructions()

Returns an iterator to read instructions in series. Objects returned by an iterator's next() method are separate SVNDiffInstruction objects.

Instructions as well as new data are read from a byte buffer that is passed to this window object via the setData() method.

A call to this routine is equivalent to a call instructions(false).

Returns:

an instructions iterator

See Also:

instructions(boolean), SVNDiffInstruction

instructions

public java.util.Iterator instructions(boolean template)

Returns an iterator to read instructions in series.

If template is true then each instruction returned by the iterator is actually the same SVNDiffInstruction object, but with proper options. This prevents from allocating new memory.

On the other hand, if template is false then the iterator returns a new allocated SVNDiffInstruction object per each instruction read and decoded.

Instructions as well as new data are read from a byte buffer that is passed to this window object via the setData() method.

Parameters:

template - to use a single/multiple instruction objects

Returns:

an instructions iterator

See Also:

instructions(), SVNDiffInstruction

apply

public void apply(SVNDiffWindowApplyBaton applyBaton)
           throws SVNException

Applies this window's instructions. The source and target streams are provided by applyBaton.

If this window has got any SVNDiffInstruction.COPY_FROM_SOURCE instructions, then:

1. At first copies a source view from the source stream of applyBaton to the baton's inner source buffer. SVNDiffInstruction.COPY_FROM_SOURCE instructions of this window are relative to the bounds of that source buffer (source view, in other words).
2. Second, according to instructions, copies source bytes from the source buffer to the baton's target buffer (or target view, in other words).
3. Then, if applyBaton is supplied with an MD5 digest, updates it with those bytes in the target buffer. So, after instructions applying completes, it will be the checksum for the full text expanded.
4. The last step - appends the target buffer bytes to the baton's target stream.

SVNDiffInstruction.COPY_FROM_NEW_DATA instructions rule to copy bytes from the instructions & new data buffer provided to this window object via a call to the setData() method.

SVNDiffInstruction.COPY_FROM_TARGET instructions are relative to the bounds of the target buffer.

Parameters:

applyBaton - a baton that provides the source and target views as well as holds the source and targed streams

Throws:

SVNException

See Also:

apply(byte[], byte[])

apply

public int apply(byte[] sourceBuffer,
                 byte[] targetBuffer)

Applies this window's instructions provided source and target view buffers.

If this window has got any SVNDiffInstruction.COPY_FROM_SOURCE instructions, then appropriate bytes described by such an instruction are copied from the sourceBuffer to the targetBuffer.

SVNDiffInstruction.COPY_FROM_NEW_DATA instructions rule to copy bytes from the instructions & new data buffer provided to this window object via a call to the setData() method.

SVNDiffInstruction.COPY_FROM_TARGET instructions are relative to the bounds of the targetBuffer itself.

Parameters:

sourceBuffer - a buffer containing a source view

targetBuffer - a buffer to get a target view

Returns:

the size of the resultant target view

See Also:

apply(SVNDiffWindowApplyBaton)

setData

public void setData(java.nio.ByteBuffer buffer)

Sets a byte buffer containing instruction and new data bytes of this window.

Instructions will go before new data within the buffer and should start at buffer.position() + buffer.arrayOffset().

Applying a diff window prior to setting instruction and new data bytes may cause a NPE.

Parameters:

buffer - an input data buffer

toString

public java.lang.String toString()

Gives a string representation of this object.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of this object

hasInstructions

public boolean hasInstructions()

Tells if this window is not empty, i.e. has got any instructions.

Returns:

true if has instructions, false if has not

writeTo

public void writeTo(java.io.OutputStream os,
                    boolean writeHeader)
             throws java.io.IOException

Writes this window object to the provided stream.

If writeHeader is true then writes SVN_HEADER bytes also.

Parameters:

os - an output stream to write to

writeHeader - controls whether the header should be written or not

Throws:

java.io.IOException - if an I/O error occurs

writeTo

public void writeTo(java.io.OutputStream os,
                    boolean writeHeader,
                    boolean compress)
             throws java.io.IOException

Formats and writes this window bytes to the specified output stream.

Parameters:

os - an output stream to write the window to

writeHeader - if true a window header will be also written

compress - if true writes compressed window bytes using SVN1_HEADER to indicate that (if writeHeader is true), otherwise non-compressed window is written with SVN_HEADER (again if writeHeader is true)

Throws:

java.io.IOException

Since:

1.1

getDataLength

public int getDataLength()

Returns the total amount of new data and instruction bytes.

Returns:

new data length + instructions length

hasCopyFromSourceInstructions

public boolean hasCopyFromSourceInstructions()

Tells whether this window contains any copy-from-source instructions.

Returns:

true if this window has got at least one SVNDiffInstruction.COPY_FROM_SOURCE instruction

clone

public SVNDiffWindow clone(java.nio.ByteBuffer targetData)

Creates an exact copy of this window object.

targetData is written instruction & new data bytes and then is set to a new window object via a call to its setData() method.

Parameters:

targetData - a byte buffer to receive a copy of this wondow data

Returns:

a new window object that is an exact copy of this one

loadDiffInstructions

public SVNDiffInstruction[] loadDiffInstructions(SVNDiffInstruction[] target)

Returns an array of instructions of this window.

If target is large enough to receive all instruction objects, then it's simply filled up to the end of instructions. However if it's not, it will be expanded to receive all instructions.

Parameters:

target - an instructions receiver

Returns:

an array containing all instructions

getInstructionsCount

public int getInstructionsCount()

Returns the amount of instructions of this window object.

Returns:

a total number of instructions

writeNewData

public void writeNewData(java.nio.ByteBuffer target,
                         int offset,
                         int length)

Fills a target buffer with the specified number of new data bytes of this window object taken at the specified offset.

Parameters:

target - a buffer to copy to

offset - an offset relative to the position of the first new data byte of this window object

length - a number of new data bytes to copy