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"""Module with functions which are supposed to be as fast as possible"""

from stat import S_ISDIR

__all__ = ('tree_to_stream', 'tree_entries_from_data', 'traverse_trees_recursive',

'traverse_tree_recursive')

def tree_to_stream(entries, write):

"""Write the give list of entries into a stream using its write method

:param entries: **sorted** list of tuples with (binsha, mode, name)

:param write: write method which takes a data string"""

ord_zero = ord('0')

bit_mask = 7 # 3 bits set

for binsha, mode, name in entries:

mode_str = ''

for i in xrange(6):

mode_str = chr(((mode >> (i * 3)) & bit_mask) + ord_zero) + mode_str

# END for each 8 octal value

# git slices away the first octal if its zero

if mode_str[0] == '0':

mode_str = mode_str[1:]

# END save a byte

# here it comes: if the name is actually unicode, the replacement below

# will not work as the binsha is not part of the ascii unicode encoding -

# hence we must convert to an utf8 string for it to work properly.

# According to my tests, this is exactly what git does, that is it just

# takes the input literally, which appears to be utf8 on linux.

if isinstance(name, unicode):

name = name.encode("utf8")

write("%s %s\0%s" % (mode_str, name, binsha))

# END for each item

def tree_entries_from_data(data):

"""Reads the binary representation of a tree and returns tuples of Tree items

:param data: data block with tree data

:return: list(tuple(binsha, mode, tree_relative_path), ...)"""

ord_zero = ord('0')

len_data = len(data)

i = 0

out = list()

while i < len_data:

mode = 0

# read mode

# Some git versions truncate the leading 0, some don't

# The type will be extracted from the mode later

while data[i] != ' ':

# move existing mode integer up one level being 3 bits

# and add the actual ordinal value of the character

mode = (mode << 3) + (ord(data[i]) - ord_zero)

i += 1

# END while reading mode

# byte is space now, skip it

i += 1

# parse name, it is NULL separated

ns = i

while data[i] != '\0':

i += 1

# END while not reached NULL

# default encoding for strings in git is utf8

# Only use the respective unicode object if the byte stream was encoded

name = data[ns:i]

name_enc = name.decode("utf-8")

if len(name) > len(name_enc):

name = name_enc

# END handle encoding

# byte is NULL, get next 20

i += 1

sha = data[i:i + 20]

i = i + 20

out.append((sha, mode, name))

# END for each byte in data stream

return out

def _find_by_name(tree_data, name, is_dir, start_at):

"""return data entry matching the given name and tree mode

or None.

Before the item is returned, the respective data item is set

None in the tree_data list to mark it done"""

try:

item = tree_data[start_at]

if item and item[2] == name and S_ISDIR(item[1]) == is_dir:

tree_data[start_at] = None

return item

except IndexError:

pass

# END exception handling

for index, item in enumerate(tree_data):

if item and item[2] == name and S_ISDIR(item[1]) == is_dir:

tree_data[index] = None

return item

# END if item matches

# END for each item

return None

def _to_full_path(item, path_prefix):

"""Rebuild entry with given path prefix"""

if not item:

return item

return (item[0], item[1], path_prefix + item[2])

def traverse_trees_recursive(odb, tree_shas, path_prefix):

"""

:return: list with entries according to the given binary tree-shas.

The result is encoded in a list

of n tuple|None per blob/commit, (n == len(tree_shas)), where

* [0] == 20 byte sha

* [1] == mode as int

* [2] == path relative to working tree root

The entry tuple is None if the respective blob/commit did not

exist in the given tree.

:param tree_shas: iterable of shas pointing to trees. All trees must

be on the same level. A tree-sha may be None in which case None

:param path_prefix: a prefix to be added to the returned paths on this level,

set it '' for the first iteration

:note: The ordering of the returned items will be partially lost"""

trees_data = list()

nt = len(tree_shas)

for tree_sha in tree_shas:

if tree_sha is None:

data = list()

else:

data = tree_entries_from_data(odb.stream(tree_sha).read())

# END handle muted trees

trees_data.append(data)

# END for each sha to get data for

out = list()

out_append = out.append

# find all matching entries and recursively process them together if the match

# is a tree. If the match is a non-tree item, put it into the result.

# Processed items will be set None

for ti, tree_data in enumerate(trees_data):

for ii, item in enumerate(tree_data):

if not item:

continue

# END skip already done items

entries = [None for n in range(nt)]

entries[ti] = item

sha, mode, name = item # its faster to unpack

is_dir = S_ISDIR(mode) # type mode bits

# find this item in all other tree data items

# wrap around, but stop one before our current index, hence

# ti+nt, not ti+1+nt

for tio in range(ti + 1, ti + nt):

tio = tio % nt

entries[tio] = _find_by_name(trees_data[tio], name, is_dir, ii)

# END for each other item data

# if we are a directory, enter recursion

if is_dir:

out.extend(traverse_trees_recursive(

odb, [((ei and ei[0]) or None) for ei in entries], path_prefix + name + '/'))

else:

out_append(tuple(_to_full_path(e, path_prefix) for e in entries))

# END handle recursion

# finally mark it done

tree_data[ii] = None

# END for each item

# we are done with one tree, set all its data empty

del(tree_data[:])

# END for each tree_data chunk

return out

def traverse_tree_recursive(odb, tree_sha, path_prefix):

"""

:return: list of entries of the tree pointed to by the binary tree_sha. An entry

has the following format:

* [0] 20 byte sha

* [1] mode as int

* [2] path relative to the repository

:param path_prefix: prefix to prepend to the front of all returned paths"""

entries = list()

data = tree_entries_from_data(odb.stream(tree_sha).read())

# unpacking/packing is faster than accessing individual items

for sha, mode, name in data:

if S_ISDIR(mode):

entries.extend(traverse_tree_recursive(odb, sha, path_prefix + name + '/'))

else:

entries.append((sha, mode, path_prefix + name))

# END for each item

return entries

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