Package org.tmatesoft.svn.core.io.diff

Class 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
    Version:
    1.3
    Author:
    TMate Software Ltd.
    See Also:
    SVNDiffInstruction

    • Field Summary

      Fields 
      Modifier and Type Field Description
      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

      Constructors 
      Constructor Description
      SVNDiffWindow​(long sourceViewOffset, int sourceViewLength, int targetViewLength, int instructionsLength, int newDataLength)
      Constructs an SVNDiffWindow object.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      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