Class SVNDiffWindow

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

public class SVNDiffWindow extends 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
Version:
1.3
Author:
TMate Software Ltd.
See Also:
  • Field Details

    • SVN_HEADER

      @Deprecated public static final byte[] SVN_HEADER
      Deprecated.
      Use SVNDeltaCompression.None instead.
      Bytes of the delta header of an uncompressed diff window.
    • SVN1_HEADER

      @Deprecated public static final byte[] SVN1_HEADER
      Deprecated.
      Use SVNDeltaCompression.Zlib instead.
      Bytes of the delta header of a compressed diff window.
      Since:
      1.1, new in Subversion 1.4
    • SVN2_HEADER

      public static final byte[] SVN2_HEADER
      Deprecated.
      Use SVNDeltaCompression.LZ4 instead.
      Bytes of the delta header of an LZ4 compressed diff window.
      Since:
      1.10, new in Subversion 1.10
    • 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 Details

    • 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:
  • Method Details

    • 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 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

      public 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:
    • 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

      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:
    • setData

      public void setData(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 String toString()
      Gives a string representation of this object.
      Overrides:
      toString in class 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(OutputStream os, boolean writeHeader) throws 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:
      IOException - if an I/O error occurs
    • writeTo

      @Deprecated public void writeTo(OutputStream os, boolean writeHeader, boolean compress) throws IOException
      Throws:
      IOException
      Since:
      1.1
    • writeTo

      public void writeTo(OutputStream os, boolean writeHeader, org.tmatesoft.svn.core.internal.delta.SVNDeltaCompression compression) throws 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, depending on compression algorithm
      compression - compression algorithm to use when writing window bytes (again if writeHeader is true)
      Throws:
      IOException
      Since:
      1.10
    • 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(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(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