tools/intersect-diffs.py

   1 #!/usr/bin/env python
   2 ##
   3 ## Copyright (c) 2016, Alliance for Open Media. All rights reserved
   4 ##
   5 ## This source code is subject to the terms of the BSD 2 Clause License and
   6 ## the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
   7 ## was not distributed with this source code in the LICENSE file, you can
   8 ## obtain it at www.aomedia.org/license/software. If the Alliance for Open
   9 ## Media Patent License 1.0 was not distributed with this source code in the
  10 ## PATENTS file, you can obtain it at www.aomedia.org/license/patent.
  11 ##
  12 """Calculates the "intersection" of two unified diffs.
  13
  14 Given two diffs, A and B, it finds all hunks in B that had non-context lines
  15 in A and prints them to stdout. This is useful to determine the hunks in B that
  16 are relevant to A. The resulting file can be applied with patch(1) on top of A.
  17 """
  18
  19 __author__ = "jkoleszar@google.com"
  20
  21 import sys
  22
  23 import diff
  24
  25
  26 def FormatDiffHunks(hunks):
  27     """Re-serialize a list of DiffHunks."""
  28     r = []
  29     last_header = None
  30     for hunk in hunks:
  31         this_header = hunk.header[0:2]
  32         if last_header != this_header:
  33             r.extend(hunk.header)
  34             last_header = this_header
  35         else:
  36             r.extend(hunk.header[2])
  37         r.extend(hunk.lines)
  38         r.append("\n")
  39     return "".join(r)
  40
  41
  42 def ZipHunks(rhs_hunks, lhs_hunks):
  43     """Join two hunk lists on filename."""
  44     for rhs_hunk in rhs_hunks:
  45         rhs_file = rhs_hunk.right.filename.split("/")[1:]
  46
  47         for lhs_hunk in lhs_hunks:
  48             lhs_file = lhs_hunk.left.filename.split("/")[1:]
  49             if lhs_file != rhs_file:
  50                 continue
  51             yield (rhs_hunk, lhs_hunk)
  52
  53
  54 def main():
  55     old_hunks = [x for x in diff.ParseDiffHunks(open(sys.argv[1], "r"))]
  56     new_hunks = [x for x in diff.ParseDiffHunks(open(sys.argv[2], "r"))]
  57     out_hunks = []
  58
  59     # Join the right hand side of the older diff with the left hand side of the
  60     # newer diff.
  61     for old_hunk, new_hunk in ZipHunks(old_hunks, new_hunks):
  62         if new_hunk in out_hunks:
  63             continue
  64         old_lines = old_hunk.right
  65         new_lines = new_hunk.left
  66
  67         # Determine if this hunk overlaps any non-context line from the other
  68         for i in old_lines.delta_line_nums:
  69             if i in new_lines:
  70                 out_hunks.append(new_hunk)
  71                 break
  72
  73     if out_hunks:
  74         print FormatDiffHunks(out_hunks)
  75         sys.exit(1)
  76
  77 if __name__ == "__main__":
  78     main()