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#!/usr/bin/env python
## Copyright (c) 2012 The WebM project authors. All Rights Reserved.
##
## Use of this source code is governed by a BSD-style license
## that can be found in the LICENSE file in the root of the source
## tree. An additional intellectual property rights grant can be found
## in the file PATENTS. All contributing project authors may
## be found in the AUTHORS file in the root of the source tree.
##
"""Calculates the "intersection" of two unified diffs.
Given two diffs, A and B, it finds all hunks in B that had non-context lines
in A and prints them to stdout. This is useful to determine the hunks in B that
are relevant to A. The resulting file can be applied with patch(1) on top of A.
"""
__author__ = "jkoleszar@google.com"
import re
import sys
class DiffLines(object):
"""A container for one half of a diff."""
def __init__(self, filename, offset, length):
self.filename = filename
self.offset = offset
self.length = length
self.lines = []
self.delta_line_nums = []
def Append(self, line):
l = len(self.lines)
if line[0] != " ":
self.delta_line_nums.append(self.offset + l)
self.lines.append(line[1:])
assert l+1 <= self.length
def Complete(self):
return len(self.lines) == self.length
def __contains__(self, item):
return item >= self.offset and item <= self.offset + self.length - 1
class DiffHunk(object):
"""A container for one diff hunk, consisting of two DiffLines."""
def __init__(self, header, file_a, file_b, start_a, len_a, start_b, len_b):
self.header = header
self.left = DiffLines(file_a, start_a, len_a)
self.right = DiffLines(file_b, start_b, len_b)
self.lines = []
def Append(self, line):
"""Adds a line to the DiffHunk and its DiffLines children."""
if line[0] == "-":
self.left.Append(line)
elif line[0] == "+":
self.right.Append(line)
elif line[0] == " ":
self.left.Append(line)
self.right.Append(line)
else:
assert False, ("Unrecognized character at start of diff line "
"%r" % line[0])
self.lines.append(line)
def Complete(self):
return self.left.Complete() and self.right.Complete()
def __repr__(self):
return "DiffHunk(%s, %s, len %d)" % (
self.left.filename, self.right.filename,
max(self.left.length, self.right.length))
def ParseDiffHunks(stream):
"""Walk a file-like object, yielding DiffHunks as they're parsed."""
file_regex = re.compile(r"(\+\+\+|---) (\S+)")
range_regex = re.compile(r"@@ -(\d+)(,(\d+))? \+(\d+)(,(\d+))?")
hunk = None
while True:
line = stream.readline()
if not line:
break
if hunk is None:
# Parse file names
diff_file = file_regex.match(line)
if diff_file:
if line.startswith("---"):
a_line = line
a = diff_file.group(2)
continue
if line.startswith("+++"):
b_line = line
b = diff_file.group(2)
continue
# Parse offset/lengths
diffrange = range_regex.match(line)
if diffrange:
if diffrange.group(2):
start_a = int(diffrange.group(1))
len_a = int(diffrange.group(3))
else:
start_a = 1
len_a = int(diffrange.group(1))
if diffrange.group(5):
start_b = int(diffrange.group(4))
len_b = int(diffrange.group(6))
else:
start_b = 1
len_b = int(diffrange.group(4))
header = [a_line, b_line, line]
hunk = DiffHunk(header, a, b, start_a, len_a, start_b, len_b)
else:
# Add the current line to the hunk
hunk.Append(line)
# See if the whole hunk has been parsed. If so, yield it and prepare
# for the next hunk.
if hunk.Complete():
yield hunk
hunk = None
# Partial hunks are a parse error
assert hunk is None
def FormatDiffHunks(hunks):
"""Re-serialize a list of DiffHunks."""
r = []
last_header = None
for hunk in hunks:
this_header = hunk.header[0:2]
if last_header != this_header:
r.extend(hunk.header)
last_header = this_header
else:
r.extend(hunk.header[2])
r.extend(hunk.lines)
r.append("\n")
return "".join(r)
def ZipHunks(rhs_hunks, lhs_hunks):
"""Join two hunk lists on filename."""
for rhs_hunk in rhs_hunks:
rhs_file = rhs_hunk.right.filename.split("/")[1:]
for lhs_hunk in lhs_hunks:
lhs_file = lhs_hunk.left.filename.split("/")[1:]
if lhs_file != rhs_file:
continue
yield (rhs_hunk, lhs_hunk)
def main():
old_hunks = [x for x in ParseDiffHunks(open(sys.argv[1], "r"))]
new_hunks = [x for x in ParseDiffHunks(open(sys.argv[2], "r"))]
out_hunks = []
# Join the right hand side of the older diff with the left hand side of the
# newer diff.
for old_hunk, new_hunk in ZipHunks(old_hunks, new_hunks):
if new_hunk in out_hunks:
continue
old_lines = old_hunk.right
new_lines = new_hunk.left
# Determine if this hunk overlaps any non-context line from the other
for i in old_lines.delta_line_nums:
if i in new_lines:
out_hunks.append(new_hunk)
break
if out_hunks:
print FormatDiffHunks(out_hunks)
sys.exit(1)
if __name__ == "__main__":
main()
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