Package org.eclipse.jgit.treewalk

Class EmptyTreeIterator

java.lang.Object

org.eclipse.jgit.treewalk.AbstractTreeIterator

org.eclipse.jgit.treewalk.EmptyTreeIterator

public class EmptyTreeIterator
extends AbstractTreeIterator

Iterator over an empty tree (a directory with no files).

Field Summary

Fields inherited from class org.eclipse.jgit.treewalk.AbstractTreeIterator

attributesNode, DEFAULT_PATH_SIZE, mode, parent, path, pathLen, pathOffset, zeroid

Constructor Summary

Constructors

Constructor	Description
EmptyTreeIterator()	Create a new iterator with no parent.
EmptyTreeIterator(AbstractTreeIterator p, byte[] childPath, int childPathOffset)	Create an iterator for a subtree of an existing iterator.

Method Summary

Modifier and Type	Method	Description
void	back(int delta)	Move to prior entry, populating this iterator with the entry data.
AbstractTreeIterator	createSubtreeIterator(ObjectReader reader)	Create a new iterator for the current entry's subtree.
boolean	eof()	Is this tree iterator at its EOF point (no more entries)?
boolean	first()	Is this tree iterator positioned on its first entry?
ObjectId	getEntryObjectId()	Get the object id of the current entry.
boolean	hasId()	Whether the entry has a valid ObjectId.
byte[]	idBuffer()	Get the byte array buffer object IDs must be copied out of.
int	idOffset()	Get the position within AbstractTreeIterator.idBuffer() of this entry's ObjectId.
protected boolean	needsStopWalk()	Whether the iterator implements AbstractTreeIterator.stopWalk().
void	next(int delta)	Move to next entry, populating this iterator with the entry data.
void	reset()	Position this iterator on the first entry.
void	stopWalk()	Indicates to the iterator that no more entries will be read.

Methods inherited from class org.eclipse.jgit.treewalk.AbstractTreeIterator

createEmptyTreeIterator, createSubtreeIterator, ensurePathCapacity, findFile, findFile, getEntryFileMode, getEntryObjectId, getEntryPathBuffer, getEntryPathHashCode, getEntryPathLength, getEntryPathString, getEntryRawMode, getName, getNameLength, getNameOffset, growPath, idEqual, isWorkTree, pathCompare, pathCompare, skip, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

EmptyTreeIterator

public EmptyTreeIterator()

Create a new iterator with no parent.

EmptyTreeIterator

public EmptyTreeIterator(AbstractTreeIterator p,
                         byte[] childPath,
                         int childPathOffset)

Create an iterator for a subtree of an existing iterator.

The caller is responsible for setting up the path of the child iterator.

Parameters:

p - parent tree iterator.

childPath - path array to be used by the child iterator. This path must contain the path from the top of the walk to the first child and must end with a '/'.

childPathOffset - position within childPath where the child can insert its data. The value at childPath[childPathOffset-1] must be '/'.

Method Detail

createSubtreeIterator

public AbstractTreeIterator createSubtreeIterator(ObjectReader reader)
                                           throws IncorrectObjectTypeException,
                                                  IOException

Create a new iterator for the current entry's subtree.

The parent reference of the iterator must be this, otherwise the caller would not be able to exit out of the subtree iterator correctly and return to continue walking this.

Specified by:

createSubtreeIterator in class AbstractTreeIterator

Parameters:

reader - reader to load the tree data from.

Returns:

a new parser that walks over the current subtree.

Throws:

IncorrectObjectTypeException - the current entry is not actually a tree and cannot be parsed as though it were a tree.

IOException - a loose object or pack file could not be read.

hasId

public boolean hasId()

Whether the entry has a valid ObjectId.

Specified by:

hasId in class AbstractTreeIterator

Returns:

true if the entry has a valid ObjectId.

getEntryObjectId

public ObjectId getEntryObjectId()

Get the object id of the current entry.

Overrides:

getEntryObjectId in class AbstractTreeIterator

Returns:

an object id for the current entry.

idBuffer

public byte[] idBuffer()

Get the byte array buffer object IDs must be copied out of.

The id buffer contains the bytes necessary to construct an ObjectId for the current entry of this iterator. The buffer can be the same buffer for all entries, or it can be a unique buffer per-entry. Implementations are encouraged to expose their private buffer whenever possible to reduce garbage generation and copying costs.

Specified by:

idBuffer in class AbstractTreeIterator

Returns:

byte array the implementation stores object IDs within.

See Also:

AbstractTreeIterator.getEntryObjectId()

idOffset

public int idOffset()

Get the position within AbstractTreeIterator.idBuffer() of this entry's ObjectId.

Specified by:

idOffset in class AbstractTreeIterator

Returns:

offset into the array returned by AbstractTreeIterator.idBuffer() where the ObjectId must be copied out of.

reset

public void reset()

Position this iterator on the first entry. The default implementation of this method uses back(1) until first() is true. This is most likely not the most efficient method of repositioning the iterator to its first entry, so subclasses are strongly encouraged to override the method.

Overrides:

reset in class AbstractTreeIterator

first

public boolean first()

Is this tree iterator positioned on its first entry?

An iterator is positioned on the first entry if back(1) would be an invalid request as there is no entry before the current one.

An empty iterator (one with no entries) will be first() && eof().

Specified by:

first in class AbstractTreeIterator

Returns:

true if the iterator is positioned on the first entry.

eof

public boolean eof()

Is this tree iterator at its EOF point (no more entries)?

An iterator is at EOF if there is no current entry.

Specified by:

eof in class AbstractTreeIterator

Returns:

true if we have walked all entries and have none left.

next

public void next(int delta)
          throws CorruptObjectException

Move to next entry, populating this iterator with the entry data.

The delta indicates how many moves forward should occur. The most common delta is 1 to move to the next entry.

Implementations must populate the following members:

• AbstractTreeIterator.mode
• AbstractTreeIterator.path (from AbstractTreeIterator.pathOffset to AbstractTreeIterator.pathLen)
• AbstractTreeIterator.pathLen

as well as any implementation dependent information necessary to accurately return data from AbstractTreeIterator.idBuffer() and AbstractTreeIterator.idOffset() when demanded.

Specified by:

next in class AbstractTreeIterator

Parameters:

delta - number of entries to move the iterator by. Must be a positive, non-zero integer.

Throws:

CorruptObjectException - the tree is invalid.

back

public void back(int delta)
          throws CorruptObjectException

Move to prior entry, populating this iterator with the entry data.

The delta indicates how many moves backward should occur.The most common delta is 1 to move to the prior entry.

Implementations must populate the following members:

• AbstractTreeIterator.mode
• AbstractTreeIterator.path (from AbstractTreeIterator.pathOffset to AbstractTreeIterator.pathLen)
• AbstractTreeIterator.pathLen

as well as any implementation dependent information necessary to accurately return data from AbstractTreeIterator.idBuffer() and AbstractTreeIterator.idOffset() when demanded.

Specified by:

back in class AbstractTreeIterator

Parameters:

delta - number of entries to move the iterator by. Must be a positive, non-zero integer.

Throws:

CorruptObjectException - the tree is invalid.

stopWalk

public void stopWalk()

Indicates to the iterator that no more entries will be read.

This is only invoked by TreeWalk when the iteration is aborted early due to a StopWalkException being thrown from within a TreeFilter.

Overrides:

stopWalk in class AbstractTreeIterator

needsStopWalk

protected boolean needsStopWalk()

Whether the iterator implements AbstractTreeIterator.stopWalk().

Overrides:

needsStopWalk in class AbstractTreeIterator

Returns:

true if the iterator implements AbstractTreeIterator.stopWalk().