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path: root/sharedstate.git/sharedstate/sharedtext.py
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# sharedobjects.py, classes to aid activities in sharing a state
# Reinier Heeres, reinier@heeres.eu
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#
# Change log:
#   2007-06-21: rwh, first version

import types
import difflib
import logging
_logger = logging.getLogger('sharinghelper')

from sharedobject import SharedObject

def my_joinlines(list, addsep=False, separator='\n'):
    if len(list) == 0:
        return ''
    string = list[0]
    for s in list[1:]:
        if addsep:
            string += separator
        string += s
    return string

def my_splitlines(str, keepsep=False, separators=['\n']):
    list = []
    if str is None:
        return list
    ofs = 0
    startofs = 0
    while ofs < len(str):
        if str[ofs] in separators:
            if keepsep:
                list.append(str[startofs:ofs+1])
            else:
                if startofs != ofs:
                    list.append(str[startofs:ofs])
                else:
                    list.append('')
            startofs = ofs + 1
        ofs += 1
    return list

def string_to_list(str):
    list = []
    if str is not None:
        for i in str:
            list.append(i)
    return list

def list_to_string(l):
    str = ""
    for i in l:
        str += i
    return str

class SharedText(SharedObject):
    """Shared text object, generates line-by-line difference objects"""

    REPLACE = 0
    DELETE = 1
    INSERT = 2

    BY_CHAR = 0
    BY_WORD = 1
    BY_LINE = 2

    def __init__(self, name, helper, opt={}, by_what=BY_CHAR):
        SharedObject.__init__(self, name, helper, opt=opt)
        self._value = ''
        self._by_what = by_what

    def split(self, s):
        if self._by_what == SharedText.BY_CHAR:
            return string_to_list(s)
        elif self._by_what == SharedText.BY_WORD:
            return my_splitlines(s, keepsep=True, separators=['\n', ' '])
        elif self._by_what == SharedText.BY_LINE:
            return my_splitlines(s, keepsep=True)
        else:
            _logger.error('SharedText.split(): unknown splitting type')

    def join(self, l):
        if self._by_what == SharedText.BY_CHAR:
            return list_to_string(l)
        elif self._by_what == SharedText.BY_WORD:
            return my_joinlines(l)
        elif self._by_what == SharedText.BY_LINE:
            return my_joinlines(l)
        else:
            _logger.error('SharedText.split(): unknown splitting type')

    def _compatible_diffs(self, da, db):
        return True

    def diff(self, cur, old):
        """Generate a difference object between to text objects"""

        _logger.debug('Generating diff between %r and %r', cur, old)

        l1 = self.split(cur)
        l2 = self.split(old)
        sm = difflib.SequenceMatcher(None, l2, l1)
        ret = []
        for (tag, i1, i2, j1, j2) in sm.get_opcodes():
            if tag is 'replace':
                ret.append((SharedText.REPLACE, (i1, i2, j1, j2), l1[j1:j2]))
            elif tag is 'delete':
                ret.append((SharedText.DELETE, (i1, i2, j1, j2), None))
            elif tag is 'insert':
                ret.append((SharedText.INSERT, (i1, i2, j1, j2), l1[j1:j2]))
            elif tag is 'equal':
                pass
            else:
                _logger.warning('SharedText.diff(): unkown tag: %s', tag)

        if len(ret) is 0:
            return None
        else:
            return ret

    def _apply_diff_to(self, obj, diffobj):
        """Apply a diff and return an object that describes the inverse diff"""

        if diffobj is None:
            _logger.error('SharedText.apply_diff_to(): no diffobj given')
            return (None, None)

        _logger.debug('Applying %r to %r', diffobj, obj)
        ret = []
        d = 0
        l2 = self.split(obj)
        for (tag, (i1, i2, j1, j2), val) in diffobj:
            i1 -= d
            i2 -= d
#            print 'd: %r' % (d)
            if tag is SharedText.REPLACE:
                ret.append((SharedText.REPLACE, (j1, j2, i1, i2), l2[i1:i2]))
                l2[i1:i2] = val
                d -= (j2 - j1) - (i2 - i1)
            elif tag is SharedText.DELETE:
                ret.append((SharedText.INSERT, (j1, j2, i1, i2), l2[i1:i2]))
                del(l2[i1:i2])
                d += i2 - i1
            elif tag is SharedText.INSERT:
                ret.append((SharedText.DELETE, (j1, j2, i1, i2), None))
                l2[i1:i1] = val
                d -= j2 - j1

        obj = self.join(l2)
        return (obj, ret)


    def insert(self, ofs, str):
        self._value = self._value[:ofs] + str + self._value[ofs:]
        dobj = {"type": 'chars', "data": (SharedText.INSERT, ofs, str)}
        self.changed(dobj, True)

    def remove(self, ofs, len):
        del self._value[ofs:ofs+len]
        dobj = {"type": 'chars', "data": (SharedText.REMOVE, ofs, len)}
        self.changed(dobj, True)

    def replace(self, ofs, str):
        self._value[ofs:ofs+len(str)] = str
        dobj = {"type": 'chars', "data": (SharedText.REPLACE, ofs, str)}
        self.changed(dobj, True)