tools/intersect-diffs.py

   1 #!/usr/bin/env python
   2 ##  Copyright (c) 2012 The WebM project authors. All Rights Reserved.
   3 ##
   4 ##  Use of this source code is governed by a BSD-style license
   5 ##  that can be found in the LICENSE file in the root of the source
   6 ##  tree. An additional intellectual property rights grant can be found
   7 ##  in the file PATENTS.  All contributing project authors may
   8 ##  be found in the AUTHORS file in the root of the source tree.
   9 ##
  10 """Calculates the "intersection" of two unified diffs.
  11
  12 Given two diffs, A and B, it finds all hunks in B that had non-context lines
  13 in A and prints them to stdout. This is useful to determine the hunks in B that
  14 are relevant to A. The resulting file can be applied with patch(1) on top of A.
  15 """
  16
  17 __author__ = "jkoleszar@google.com"
  18
  19 import sys
  20
  21 import diff
  22
  23
  24 def FormatDiffHunks(hunks):
  25     """Re-serialize a list of DiffHunks."""
  26     r = []
  27     last_header = None
  28     for hunk in hunks:
  29         this_header = hunk.header[0:2]
  30         if last_header != this_header:
  31             r.extend(hunk.header)
  32             last_header = this_header
  33         else:
  34             r.extend(hunk.header[2])
  35         r.extend(hunk.lines)
  36         r.append("\n")
  37     return "".join(r)
  38
  39
  40 def ZipHunks(rhs_hunks, lhs_hunks):
  41     """Join two hunk lists on filename."""
  42     for rhs_hunk in rhs_hunks:
  43         rhs_file = rhs_hunk.right.filename.split("/")[1:]
  44
  45         for lhs_hunk in lhs_hunks:
  46             lhs_file = lhs_hunk.left.filename.split("/")[1:]
  47             if lhs_file != rhs_file:
  48                 continue
  49             yield (rhs_hunk, lhs_hunk)
  50
  51
  52 def main():
  53     old_hunks = [x for x in diff.ParseDiffHunks(open(sys.argv[1], "r"))]
  54     new_hunks = [x for x in diff.ParseDiffHunks(open(sys.argv[2], "r"))]
  55     out_hunks = []
  56
  57     # Join the right hand side of the older diff with the left hand side of the
  58     # newer diff.
  59     for old_hunk, new_hunk in ZipHunks(old_hunks, new_hunks):
  60         if new_hunk in out_hunks:
  61             continue
  62         old_lines = old_hunk.right
  63         new_lines = new_hunk.left
  64
  65         # Determine if this hunk overlaps any non-context line from the other
  66         for i in old_lines.delta_line_nums:
  67             if i in new_lines:
  68                 out_hunks.append(new_hunk)
  69                 break
  70
  71     if out_hunks:
  72         print FormatDiffHunks(out_hunks)
  73         sys.exit(1)
  74
  75 if __name__ == "__main__":
  76     main()