~bzr-pqm/bzr/bzr.dev

import os

from subprocess import Popen, PIPE

"""

Diff and patch functionality

"""

__docformat__ = "restructuredtext"

def write_to_cmd(args, input=""):

    process = Popen(args, bufsize=len(input), stdin=PIPE, stdout=PIPE,

                    stderr=PIPE, close_fds=True)

    stdout, stderr = process.communicate(input)

    status = process.wait()

    if status < 0:

        raise Exception("%s killed by signal %i" (args[0], -status))

    return stdout, stderr, status

def patch(patch_contents, filename, output_filename=None, reverse=False):

    """Apply a patch to a file, to produce another output file.  This is should

    be suitable for our limited purposes.

    :param patch_contents: The contents of the patch to apply

    :type patch_contents: str

    :param filename: the name of the file to apply the patch to

    :type filename: str

    :param output_filename: The filename to produce.  If None, file is \

    modified in-place

    :type output_filename: str or NoneType

    :param reverse: If true, apply the patch in reverse

    :type reverse: bool

    :return: 0 on success, 1 if some hunks failed

    """

    args = ["patch", "-f", "-s", "--posix", "--binary"]

    if reverse:

        args.append("--reverse")

    if output_filename is not None:

        args.extend(("-o", output_filename))

    args.append(filename)

    stdout, stderr, status = write_to_cmd(args, patch_contents)

    return status 

def diff(orig_file, mod_str, orig_label=None, mod_label=None):

    """Compare two files, and produce a patch.

    :param orig_file: path to the old file

    :type orig_file: str

    :param mod_str: Contents of the new file

    :type mod_str: str

    :param orig_label: The label to use for the old file

    :type orig_label: str

    :param mod_label: The label to use for the new file

    :type mod_label: str

    """

    args = ["diff", "-u" ]

    if orig_label is not None and mod_label is not None:

        args.extend(("-L", orig_label, "-L", mod_label))

    args.extend(("--", orig_file, "-"))

    patch, stderr, status = write_to_cmd(args, mod_str)

    if status == 0:

        return None

    else:

        return patch

def diff3(out_file, mine_path, older_path, yours_path):

    def add_label(args, label):

        args.extend(("-L", label))

    args = ['diff3', "-E", "--merge"]

    add_label(args, "TREE")

    add_label(args, "ANCESTOR")

    add_label(args, "MERGE-SOURCE")

    args.extend((mine_path, older_path, yours_path))

    output, stderr, status = write_to_cmd(args)

    if status not in (0, 1):

        raise Exception(stderr)

    file(out_file, "wb").write(output)

    return status