#!/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 linesin A and prints them to stdout. This is useful to determine the hunks in B thatare relevant to A. The resulting file can be applied with patch(1) on top of A.""" __author__ = "jkoleszar@google.com" import sys import diff  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 diff.ParseDiffHunks(open(sys.argv[1], "r"))]    new_hunks = [x for x in diff.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()