org.eclipse.jgit.treewalk

Class AbstractTreeIterator

java.lang.Object

org.eclipse.jgit.treewalk.AbstractTreeIterator

Direct Known Subclasses:

CanonicalTreeParser, DirCacheIterator, EmptyTreeIterator, WorkingTreeIterator

public abstract class AbstractTreeIterator
extends Object

Walks a Git tree (directory) in Git sort order.

A new iterator instance should be positioned on the first entry, or at eof. Data for the first entry (if not at eof) should be available immediately.

Implementors must walk a tree in the Git sort order, which has the following odd sorting:

1. A.c
2. A/c
3. A0c

In the second item, A is the name of a subtree and c is a file within that subtree. The other two items are files in the root level tree.

See Also:

CanonicalTreeParser

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	DEFAULT_PATH_SIZE Default size for the path buffer.
protected int	mode Mode bits for the current entry.
protected byte[]	path Path buffer for the current entry.
protected int	pathLen Total length of the current entry's complete path from the root.
protected int	pathOffset Position within path this iterator starts writing at.
protected static byte[]	zeroid A dummy object id buffer that matches the zero ObjectId.

Constructor Summary

Constructors

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

Method Summary

Methods

Modifier and Type	Method and Description
abstract void	back(int delta) Move to prior entry, populating this iterator with the entry data.
EmptyTreeIterator	createEmptyTreeIterator() Create a new iterator as though the current entry were a subtree.
abstract AbstractTreeIterator	createSubtreeIterator(ObjectReader reader) Create a new iterator for the current entry's subtree.
AbstractTreeIterator	createSubtreeIterator(ObjectReader reader, MutableObjectId idBuffer) Create a new iterator for the current entry's subtree.
protected void	ensurePathCapacity(int capacity, int len) Ensure that path is capable to hold at least capacity bytes
abstract boolean	eof() Is this tree iterator at its EOF point (no more entries)?
abstract boolean	first() Is this tree iterator positioned on its first entry?
FileMode	getEntryFileMode()
ObjectId	getEntryObjectId() Get the object id of the current entry.
void	getEntryObjectId(MutableObjectId out) Obtain the ObjectId for the current entry.
byte[]	getEntryPathBuffer() Get the current entry path buffer.
int	getEntryPathHashCode() Get the current entry's path hash code.
int	getEntryPathLength()
String	getEntryPathString()
int	getEntryRawMode()
void	getName(byte[] buffer, int offset) Get the name component of the current entry path into the provided buffer.
int	getNameLength()
int	getNameOffset() JGit internal API for use by DirCacheCheckout
protected void	growPath(int len) Grow the path buffer larger.
abstract boolean	hasId()
abstract byte[]	idBuffer() Get the byte array buffer object IDs must be copied out of.
boolean	idEqual(AbstractTreeIterator otherIterator) Check if the current entry of both iterators has the same id.
abstract int	idOffset() Get the position within idBuffer() of this entry's ObjectId.
abstract void	next(int delta) Move to next entry, populating this iterator with the entry data.
int	pathCompare(AbstractTreeIterator p) Compare the path of this current entry to another iterator's entry.
int	pathCompare(byte[] buf, int pos, int end, int pathMode) Compare the path of this current entry to a raw buffer.
void	reset() Position this iterator on the first entry.
void	skip() Advance to the next tree entry, populating this iterator with its data.
void	stopWalk() Indicates to the iterator that no more entries will be read.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_PATH_SIZE

protected static final int DEFAULT_PATH_SIZE

Default size for the path buffer.

See Also:

Constant Field Values

zeroid

protected static final byte[] zeroid

A dummy object id buffer that matches the zero ObjectId.

mode

protected int mode

Mode bits for the current entry.

A numerical value from FileMode is usually faster for an iterator to obtain from its data source so this is the preferred representation.

See Also:

FileMode

path

protected byte[] path

Path buffer for the current entry.

This buffer is pre-allocated at the start of walking and is shared from parent iterators down into their subtree iterators. The sharing allows the current entry to always be a full path from the root, while each subtree only needs to populate the part that is under their control.

pathOffset

protected final int pathOffset

Position within path this iterator starts writing at.

This is the first offset in path that this iterator must populate during next(int). At the root level (when parent is null) this is 0. For a subtree iterator the index before this position should have the value '/'.

pathLen

protected int pathLen

Total length of the current entry's complete path from the root.

This is the number of bytes within path that pertain to the current entry. Values at this index through the end of the array are garbage and may be randomly populated from prior entries.

Constructor Detail

AbstractTreeIterator

protected AbstractTreeIterator()

Create a new iterator with no parent.

AbstractTreeIterator

protected AbstractTreeIterator(String prefix)

Create a new iterator with no parent and a prefix.

The prefix path supplied is inserted in front of all paths generated by this iterator. It is intended to be used when an iterator is being created for a subsection of an overall repository and needs to be combined with other iterators that are created to run over the entire repository namespace.

Parameters:

prefix - position of this iterator in the repository tree. The value may be null or the empty string to indicate the prefix is the root of the repository. A trailing slash ('/') is automatically appended if the prefix does not end in '/'.

AbstractTreeIterator

protected AbstractTreeIterator(byte[] prefix)

Create a new iterator with no parent and a prefix.

The prefix path supplied is inserted in front of all paths generated by this iterator. It is intended to be used when an iterator is being created for a subsection of an overall repository and needs to be combined with other iterators that are created to run over the entire repository namespace.

Parameters:

prefix - position of this iterator in the repository tree. The value may be null or the empty array to indicate the prefix is the root of the repository. A trailing slash ('/') is automatically appended if the prefix does not end in '/'.

AbstractTreeIterator

protected AbstractTreeIterator(AbstractTreeIterator p)

Create an iterator for a subtree of an existing iterator.

Parameters:

p - parent tree iterator.

AbstractTreeIterator

protected AbstractTreeIterator(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

growPath

protected void growPath(int len)

Grow the path buffer larger.

Parameters:

len - number of live bytes in the path buffer. This many bytes will be moved into the larger buffer.

ensurePathCapacity

protected void ensurePathCapacity(int capacity,
                      int len)

Ensure that path is capable to hold at least capacity bytes

Parameters:

capacity - the amount of bytes to hold

len - the amount of live bytes in path buffer

pathCompare

public int pathCompare(AbstractTreeIterator p)

Compare the path of this current entry to another iterator's entry.

Parameters:

p - the other iterator to compare the path against.

Returns:

-1 if this entry sorts first; 0 if the entries are equal; 1 if p's entry sorts first.

pathCompare

public int pathCompare(byte[] buf,
              int pos,
              int end,
              int pathMode)

Compare the path of this current entry to a raw buffer.

Parameters:

buf - the raw path buffer.

pos - position to start reading the raw buffer.

end - one past the end of the raw buffer (length is end - pos).

pathMode - the mode of the path.

Returns:

-1 if this entry sorts first; 0 if the entries are equal; 1 if p's entry sorts first.

idEqual

public boolean idEqual(AbstractTreeIterator otherIterator)

Check if the current entry of both iterators has the same id.

This method is faster than getEntryObjectId() as it does not require copying the bytes out of the buffers. A direct idBuffer() compare operation is performed.

Parameters:

otherIterator - the other iterator to test against.

Returns:

true if both iterators have the same object id; false otherwise.

hasId

public abstract boolean hasId()

Returns:

true if the entry has a valid ObjectId.

getEntryObjectId

public ObjectId getEntryObjectId()

Get the object id of the current entry.

Returns:

an object id for the current entry.

getEntryObjectId

public void getEntryObjectId(MutableObjectId out)

Obtain the ObjectId for the current entry.

Parameters:

out - buffer to copy the object id into.

getEntryFileMode

public FileMode getEntryFileMode()

Returns:

the file mode of the current entry.

getEntryRawMode

public int getEntryRawMode()

Returns:

the file mode of the current entry as bits

getEntryPathString

public String getEntryPathString()

Returns:

path of the current entry, as a string.

getEntryPathBuffer

public byte[] getEntryPathBuffer()

Get the current entry path buffer.

Note that the returned byte[] has to be used together with getEntryPathLength() (only use bytes up to this length).

Returns:

the internal buffer holding the current path.

getEntryPathLength

public int getEntryPathLength()

Returns:

length of the path in getEntryPathBuffer().

getEntryPathHashCode

public int getEntryPathHashCode()

Get the current entry's path hash code.

This method computes a hash code on the fly for this path, the hash is suitable to cluster objects that may have similar paths together.

Returns:

path hash code; any integer may be returned.

idBuffer

public abstract 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.

Returns:

byte array the implementation stores object IDs within.

See Also:

getEntryObjectId()

idOffset

public abstract int idOffset()

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

Returns:

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

createSubtreeIterator

public abstract 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.

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.

createEmptyTreeIterator

public EmptyTreeIterator createEmptyTreeIterator()

Create a new iterator as though the current entry were a subtree.

Returns:

a new empty tree iterator.

createSubtreeIterator

public AbstractTreeIterator createSubtreeIterator(ObjectReader reader,
                                         MutableObjectId idBuffer)
                                           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.

Parameters:

reader - reader to load the tree data from.

idBuffer - temporary ObjectId buffer for use by this method.

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.

reset

public void reset()
           throws CorruptObjectException

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.

Throws:

CorruptObjectException - the tree is invalid.

first

public abstract 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().

Returns:

true if the iterator is positioned on the first entry.

eof

public abstract boolean eof()

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

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

Returns:

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

next

public abstract 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:

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

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

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 abstract 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:

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

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

Parameters:

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

Throws:

CorruptObjectException - the tree is invalid.

skip

public void skip()
          throws CorruptObjectException

Advance to the next tree entry, populating this iterator with its data.

This method behaves like seek(1) but is called by TreeWalk only if a TreeFilter was used and ruled out the current entry from the results. In such cases this tree iterator may perform special behavior.

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.

getNameLength

public int getNameLength()

Returns:

the length of the name component of the path for the current entry

getNameOffset

public int getNameOffset()

JGit internal API for use by DirCacheCheckout

Returns:

start of name component part within getEntryPathBuffer()

Since:

2.0

getName

public void getName(byte[] buffer,
           int offset)

Get the name component of the current entry path into the provided buffer.

Parameters:

buffer - the buffer to get the name into, it is assumed that buffer can hold the name

offset - the offset of the name in the buffer

See Also:

getNameLength()

toString

public String toString()

Overrides:

toString in class Object