Merge branch 'writetree'

1 files changed, 66 insertions, 0 deletions

diff --git a/lib/git/objects/fun.py b/lib/git/objects/fun.py
new file mode 100644
index 00000000..7882437d
--- /dev/null
+++ b/lib/git/objects/fun.py
@@ -0,0 +1,66 @@
+"""Module with functions which are supposed to be as fast as possible"""
+
+__all__ = ('tree_to_stream', 'tree_entries_from_data')
+
+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
+
+		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
+		name = data[ns:i]
+		
+		# 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