(?:^\+\+\+[ ](b/(?P<b_file>.+?)|/dev/null)\t?(?:\n|$))?

    """, re.VERBOSE | re.MULTILINE)

    _hg_header_re = re.compile(r"""

        # has already been split on this:

        # ^diff[ ]--git

            [ ]a/(?P<a_path>.+?)[ ]b/(?P<b_path>.+?)\n

        (?:^old[ ]mode[ ](?P<old_mode>\d+)\n

           ^new[ ]mode[ ](?P<new_mode>\d+)(?:\n|$))?

        (?:^similarity[ ]index[ ](?P<similarity_index>\d+)%(?:\n|$))?

        (?:^rename[ ]from[ ](?P<rename_from>.+)\n

           ^rename[ ]to[ ](?P<rename_to>.+)(?:\n|$))?

        (?:^copy[ ]from[ ](?P<copy_from>.+)\n

           ^copy[ ]to[ ](?P<copy_to>.+)(?:\n|$))?

        (?:^new[ ]file[ ]mode[ ](?P<new_file_mode>.+)(?:\n|$))?

        (?:^deleted[ ]file[ ]mode[ ](?P<deleted_file_mode>.+)(?:\n|$))?

        (?:^index[ ](?P<a_blob_id>[0-9A-Fa-f]+)

            \.\.(?P<b_blob_id>[0-9A-Fa-f]+)[ ]?(?P<b_mode>.+)?(?:\n|$))?

        (?:^(?P<bin_patch>GIT[ ]binary[ ]patch)(?:\n|$))?

        (?:^---[ ](a/(?P<a_file>.+?)|/dev/null)\t?(?:\n|$))?

        (?:^\+\+\+[ ](b/(?P<b_file>.+?)|/dev/null)\t?(?:\n|$))?

    """, re.VERBOSE | re.MULTILINE)

    #used for inline highlighter word split

    _token_re = re.compile(r'()(&gt;|&lt;|&amp;|<u>\t</u>| <i></i>|\W+?)')

    _escape_re = re.compile(r'(&)|(<)|(>)|(\t)|(?<=.)( \n| $)')

    def __init__(self, diff, vcs='hg', format='gitdiff', diff_limit=None):

        """

        :param diff:   a text in diff format

        :param vcs: type of version controll hg or git

        :param format: format of diff passed, `udiff` or `gitdiff`

        :param diff_limit: define the size of diff that is considered "big"

            based on that parameter cut off will be triggered, set to None

            to show full diff

        """

        if not isinstance(diff, basestring):

            raise Exception('Diff must be a basestring got %s instead' % type(diff))

        self._diff = diff

        self._format = format

        self.adds = 0

        self.removes = 0

        # calculate diff size

        self.diff_size = len(diff)

        self.diff_limit = diff_limit

        self.cur_diff_size = 0

        self.parsed = False

        self.parsed_diff = []

        self.vcs = vcs

        if format == 'gitdiff':

            self.differ = self._highlight_line_difflib

            self._parser = self._parse_gitdiff

        else:

            self.differ = self._highlight_line_udiff

            self._parser = self._parse_udiff

    def _copy_iterator(self):

        """

        make a fresh copy of generator, we should not iterate thru

        an original as it's needed for repeating operations on

        this instance of DiffProcessor

        """

        self.__udiff, iterator_copy = tee(self.__udiff)

        return iterator_copy

    def _escaper(self, string):

        """

        Escaper for diff escapes special chars and checks the diff limit

        :param string:

        """

        self.cur_diff_size += len(string)

        # escaper gets iterated on each .next() call and it checks if each

        # parsed line doesn't exceed the diff limit

        if self.diff_limit is not None and self.cur_diff_size > self.diff_limit:

            raise DiffLimitExceeded('Diff Limit Exceeded')

        def substitute(m):

            groups = m.groups()

            if groups[0]:

                return '&'

            if groups[1]:

                return '<'

            if groups[2]:

                return '>'

            if groups[3]:

                return '<u>\t</u>'

            if groups[4]:

                return ' <i></i>'

            assert False

        return self._escape_re.sub(substitute, safe_unicode(string))

    def _line_counter(self, l):

        """

        Checks each line and bumps total adds/removes for this diff

        :param l:

        """

        if l.startswith('+') and not l.startswith('+++'):

            self.adds += 1

        elif l.startswith('-') and not l.startswith('---'):

            self.removes += 1

        return safe_unicode(l)

    def _highlight_line_difflib(self, line, next_):

        """

        Highlight inline changes in both lines.

        """

        if line['action'] == 'del':

            old, new = line, next_

        else:

            old, new = next_, line

        oldwords = self._token_re.split(old['line'])

        newwords = self._token_re.split(new['line'])

        sequence = difflib.SequenceMatcher(None, oldwords, newwords)

        oldfragments, newfragments = [], []

        for tag, i1, i2, j1, j2 in sequence.get_opcodes():

            oldfrag = ''.join(oldwords[i1:i2])

            newfrag = ''.join(newwords[j1:j2])

            if tag != 'equal':

                if oldfrag:

                    oldfrag = '<del>%s</del>' % oldfrag

                if newfrag:

                    newfrag = '<ins>%s</ins>' % newfrag

            oldfragments.append(oldfrag)

            newfragments.append(newfrag)

        old['line'] = "".join(oldfragments)

        new['line'] = "".join(newfragments)

    def _highlight_line_udiff(self, line, next_):

        """

        Highlight inline changes in both lines.

        """

        start = 0

        limit = min(len(line['line']), len(next_['line']))

        while start < limit and line['line'][start] == next_['line'][start]:

            start += 1

        end = -1

        limit -= start

        while -end <= limit and line['line'][end] == next_['line'][end]:

            end -= 1

        end += 1

        if start or end:

            def do(l):

                last = end + len(l['line'])

                if l['action'] == 'add':

                    tag = 'ins'

                else:

                    tag = 'del'

                l['line'] = '%s<%s>%s</%s>%s' % (

                    l['line'][:start],

                    tag,

                    l['line'][start:last],

                    tag,

                    l['line'][last:]

                )

            do(line)

            do(next_)

    def _get_header(self, diff_chunk):

        """

        parses the diff header, and returns parts, and leftover diff

        parts consists of 14 elements::

            a_path, b_path, similarity_index, rename_from, rename_to,

            old_mode, new_mode, new_file_mode, deleted_file_mode,

            a_blob_id, b_blob_id, b_mode, a_file, b_file

        :param diff_chunk:

        """

        match = None

        if self.vcs == 'git':

            match = self._git_header_re.match(diff_chunk)

        elif self.vcs == 'hg':

            match = self._hg_header_re.match(diff_chunk)

        if match is None:

            raise Exception('VCS type %s is not supported' % self.vcs)

        groups = match.groupdict()

        rest = diff_chunk[match.end():]

        if rest and not rest.startswith('@') and not rest.startswith('literal '):

            raise Exception('cannot parse diff header: %r followed by %r' % (diff_chunk[:match.end()], rest[:1000]))

        return groups, difflines

    def _clean_line(self, line, command):

        if command in ['+', '-', ' ']:

            #only modify the line if it's actually a diff thing

            line = line[1:]

        return line

    def _parse_gitdiff(self, inline_diff=True):

        _files = []

        diff_container = lambda arg: arg

        ##split the diff in chunks of separate --git a/file b/file chunks

        for raw_diff in ('\n' + self._diff).split('\ndiff --git')[1:]:

            head, diff = self._get_header(raw_diff)

            op = None

            stats = {

                'added': 0,

                'deleted': 0,

                'binary': False,

                'ops': {},

            }

            if head['deleted_file_mode']:

                op = 'D'

                stats['binary'] = True

                stats['ops'][DEL_FILENODE] = 'deleted file'

            elif head['new_file_mode']:

                op = 'A'

                stats['binary'] = True

                stats['ops'][NEW_FILENODE] = 'new file %s' % head['new_file_mode']

            else:  # modify operation, can be cp, rename, chmod

                # CHMOD

                if head['new_mode'] and head['old_mode']:

                    op = 'M'

                    stats['binary'] = True

                    stats['ops'][CHMOD_FILENODE] = ('modified file chmod %s => %s'

                                        % (head['old_mode'], head['new_mode']))

                # RENAME

                if (head['rename_from'] and head['rename_to']

                      and head['rename_from'] != head['rename_to']):

                    op = 'R'

                    stats['binary'] = True

                    stats['ops'][RENAMED_FILENODE] = ('file renamed from %s to %s'

                                    % (head['rename_from'], head['rename_to']))

                # COPY

                if head.get('copy_from') and head.get('copy_to'):

                    op = 'M'

                    stats['binary'] = True

                    stats['ops'][COPIED_FILENODE] = ('file copied from %s to %s'

                                        % (head['copy_from'], head['copy_to']))

                # FALL BACK: detect missed old style add or remove

                if op is None:

                    if not head['a_file'] and head['b_file']:

                        op = 'A'

                        stats['binary'] = True

                        stats['ops'][NEW_FILENODE] = 'new file'

                    elif head['a_file'] and not head['b_file']:

                        op = 'D'

                        stats['binary'] = True

                        stats['ops'][DEL_FILENODE] = 'deleted file'

                # it's not ADD not DELETE

                if op is None:

                    op = 'M'

                    stats['binary'] = True

                    stats['ops'][MOD_FILENODE] = 'modified file'

            # a real non-binary diff

            if head['a_file'] or head['b_file']:

                try:

                    chunks, _stats = self._parse_lines(diff)

                    stats['binary'] = False

                    stats['added'] = _stats[0]

                    stats['deleted'] = _stats[1]

                    # explicit mark that it's a modified file

                    if op == 'M':

                        stats['ops'][MOD_FILENODE] = 'modified file'

                except DiffLimitExceeded:

                    diff_container = lambda _diff: \

                        LimitedDiffContainer(self.diff_limit,

                                            self.cur_diff_size, _diff)

                    break

            else:  # GIT binary patch (or empty diff)

                # GIT Binary patch

                if head['bin_patch']:

                    stats['ops'][BIN_FILENODE] = 'binary diff not shown'

                chunks = []

            if op == 'D' and chunks:

                # a way of seeing deleted content could perhaps be nice - but

                # not with the current UI

                chunks = []

            chunks.insert(0, [{

                'old_lineno': '',

                'new_lineno': '',

                'action':     'context',

                'line':       msg,

                } for _op, msg in stats['ops'].iteritems()

                  if _op not in [MOD_FILENODE]])

            _files.append({

                'filename':         head['b_path'],

                'old_revision':     head['a_blob_id'],

                'new_revision':     head['b_blob_id'],

                'chunks':           chunks,

                'operation':        op,

                'stats':            stats,

            })

        if not inline_diff:

            return diff_container(_files)

        # highlight inline changes

        for diff_data in _files:

            for chunk in diff_data['chunks']:

                lineiter = iter(chunk)

                try:

                    while 1:

                        line = lineiter.next()

                        if line['action'] not in ['unmod', 'context']:

                            nextline = lineiter.next()

                            if nextline['action'] in ['unmod', 'context'] or \

                               nextline['action'] == line['action']:

                                continue

                            self.differ(line, nextline)

                except StopIteration:

                    pass

        return diff_container(_files)

    def _parse_udiff(self, inline_diff=True):

        raise NotImplementedError()

    def _parse_lines(self, diff):

        """

        Parse the diff and return data for the template.

        """

        stats = [0, 0]

        (old_line, old_end, new_line, new_end) = (None, None, None, None)

        try:

            chunks = []

            line = diff.next()

            while True:

                lines = []

                chunks.append(lines)

                match = self._chunk_re.match(line)

                if not match:

                    raise Exception('error parsing diff @@ line %r' % line)

                gr = match.groups()

                (old_line, old_end,

                 new_line, new_end) = [int(x or 1) for x in gr[:-1]]

                old_line -= 1

                new_line -= 1

                context = len(gr) == 5

                old_end += old_line

                new_end += new_line

                if context:

                    # skip context only if it's first line

                    if int(gr[0]) > 1:

                        lines.append({

                            'old_lineno': '...',

                            'new_lineno': '...',

                            'action':     'context',

                            'line':       line,

                        })

                line = diff.next()

                while old_line < old_end or new_line < new_end:

                    if not line:

                        raise Exception('error parsing diff - empty line at -%s+%s' % (old_line, new_line))

                    affects_old = affects_new = False

                    command = line[0]

                    if command == '+':

                        affects_new = True

                        action = 'add'

diff --git a/oh no b/oh yes

rename from oh no

rename to oh yes

--- a/oh no	

+++ b/oh yes	

 1

-2+ 2

-3 

+2

+3

 4

@@ -5,3 +6,4 @@

 5

 6

 7

+8

        ('file', 'M',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {CHMOD_FILENODE: 'modified file chmod 100755 => 100644'}}),

    ],

    'hg_diff_rename_file.diff': [

        ('file_renamed', 'R',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {RENAMED_FILENODE: 'file renamed from file to file_renamed'}}),

    ],

    'hg_diff_rename_and_chmod_file.diff': [

        ('README', 'R',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {CHMOD_FILENODE: 'modified file chmod 100644 => 100755',

                  RENAMED_FILENODE: 'file renamed from README.rst to README'}}),

    ],

    'hg_diff_binary_and_normal.diff': [

        ('img/baseline-10px.png', 'A',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {NEW_FILENODE: 'new file 100644',

                  BIN_FILENODE: 'binary diff not shown'}}),

        ('img/baseline-20px.png', 'D',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {DEL_FILENODE: 'deleted file',

                  BIN_FILENODE: 'binary diff not shown'}}),

        ('index.html', 'M',

         {'added': 3,

          'deleted': 2,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

        ('js/global.js', 'D',

         {'added': 0,

          'deleted': 75,

          'binary': False,

          'ops': {DEL_FILENODE: 'deleted file'}}),

        ('js/jquery/hashgrid.js', 'A',

         {'added': 340,

          'deleted': 0,

          'binary': False,

          'ops': {NEW_FILENODE: 'new file 100755'}}),

        ('less/docs.less', 'M',

         {'added': 34,

          'deleted': 0,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

        ('less/scaffolding.less', 'M',

         {'added': 1,

          'deleted': 3,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

        ('readme.markdown', 'M',

         {'added': 1,

          'deleted': 10,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

    ],

    'git_diff_chmod.diff': [

        ('work-horus.xls', 'M',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {CHMOD_FILENODE: 'modified file chmod 100644 => 100755'}})

    ],

    'git_diff_rename_file.diff': [

        ('file.xls', 'R',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {RENAMED_FILENODE: 'file renamed from work-horus.xls to file.xls'}})

    ],

    'git_diff_mod_single_binary_file.diff': [

        ('US Warszawa.jpg', 'M',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {MOD_FILENODE: 'modified file',

                  BIN_FILENODE: 'binary diff not shown'}})

    ],

    'git_diff_binary_and_normal.diff': [

        ('img/baseline-10px.png', 'A',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {NEW_FILENODE: 'new file 100644',

                  BIN_FILENODE: 'binary diff not shown'}}),

        ('img/baseline-20px.png', 'D',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {DEL_FILENODE: 'deleted file',

                  BIN_FILENODE: 'binary diff not shown'}}),

        ('index.html', 'M',

         {'added': 3,

          'deleted': 2,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

        ('js/global.js', 'D',

         {'added': 0,

          'deleted': 75,

          'binary': False,

          'ops': {DEL_FILENODE: 'deleted file'}}),

        ('js/jquery/hashgrid.js', 'A',

         {'added': 340,

          'deleted': 0,

          'binary': False,

          'ops': {NEW_FILENODE: 'new file 100755'}}),

        ('less/docs.less', 'M',

         {'added': 34,

          'deleted': 0,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

        ('less/scaffolding.less', 'M',

         {'added': 1,

          'deleted': 3,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

        ('readme.markdown', 'M',

         {'added': 1,

          'deleted': 10,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

    ],

    'diff_with_diff_data.diff': [

        ('vcs/backends/base.py', 'M',

         {'added': 18,

          'deleted': 2,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

        ('vcs/backends/git/repository.py', 'M',

         {'added': 46,

          'deleted': 15,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

        ('vcs/backends/hg.py', 'M',

         {'added': 22,

          'deleted': 3,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

        ('vcs/tests/test_git.py', 'M',

         {'added': 5,

          'deleted': 5,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

        ('vcs/tests/test_repository.py', 'M',

         {'added': 174,

          'deleted': 2,

          'binary': False,

          'ops': {MOD_FILENODE: 'modified file'}}),

    ],

    'hg_diff_copy_file.diff': [

        ('file2', 'M',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {COPIED_FILENODE: 'file copied from file1 to file2'}}),

    ],

    'hg_diff_copy_and_modify_file.diff': [

        ('file3', 'M',

         {'added': 1,

          'deleted': 0,

          'binary': False,

          'ops': {COPIED_FILENODE: 'file copied from file2 to file3',

                  MOD_FILENODE: 'modified file'}}),

    ],

    'hg_diff_copy_and_chmod_file.diff': [

        ('file4', 'M',

         {'added': 0,

          'deleted': 0,

          'binary': True,

          'ops': {COPIED_FILENODE: 'file copied from file3 to file4',

                  CHMOD_FILENODE: 'modified file chmod 100644 => 100755'}}),

    ],

    'hg_diff_copy_chmod_and_edit_file.diff': [

        ('file5', 'M',

         {'added': 2,

          'deleted': 1,

          'binary': False,

          'ops': {COPIED_FILENODE: 'file copied from file4 to file5',

                  CHMOD_FILENODE: 'modified file chmod 100755 => 100644',

                  MOD_FILENODE: 'modified file'}}),

    ],

    'hg_diff_rename_space_cr.diff': [

        ('oh yes', 'R',

          'deleted': 2,

          'binary': False,

          'ops': {RENAMED_FILENODE: 'file renamed from oh no to oh yes'}}),

    ],

}

class DiffLibTest(BaseTestCase):

    @parameterized.expand([(x,) for x in DIFF_FIXTURES])

    def test_diff(self, diff_fixture):

        diff = fixture.load_resource(diff_fixture, strip=False)

        diff_proc = DiffProcessor(diff)

        diff_proc_d = diff_proc.prepare()

        data = [(x['filename'], x['operation'], x['stats']) for x in diff_proc_d]

        expected_data = DIFF_FIXTURES[diff_fixture]

        self.assertListEqual(expected_data, data)