Python-OTType

A python library for Operational Transformation (OT). Basic idea follows the spec at https://github.com/ottypes/docs.

Supported Python versions : CPython 3.9 - 3.13, PyPy 3.10 - 3.11

Installation

pip install python-ottype

Basic usage:

import ottype

assert ottype.apply('asdf', [3, '123', {'d':'f'}]) == 'asd123'

OT Operations

Skip

Object type : int

Skip n characters from the current position is represented as n

assert apply('asdf', [3]) == 'asdf'

Insert

Object type : str

Insert a string s at the current position is represented as s

assert apply('asdf', ['qwer']) == 'qwerasdf'
assert apply('asdf', [2, 'qwer']) == 'asqwerdf'

Delete

Object type : dict

Delete a string s at the current position is represented as {'d': s}

assert apply('asdf', [{'d': 'as'}]) == 'df'
assert apply('asdf', [1, {'d': 'sd'}]) == 'af'

Supported Functions

OT = int | str | dict[str, str]

check(ots: Sequence[OT], *, check_unoptimized: bool = True) -> bool

Check the sequence if it only contains valid OTs. If check_unoptimized is True, only normalized sequence of OTs is accepted.

assert check(['a', 4, 'b'])
assert not check(['a', 'b'])  # is not normalized
assert not check([3])  # is not normalized

apply(doc: str, ots: Sequence[OT], *, check_unoptimized: bool = True) -> str

Apply a sequence of OTs to a string.

assert apply('abcde', [2, 'qq', {'d': 'c'}, 1, 'w']) == 'abqqdwe'

inverse_apply(doc: str, ots: Sequence[OT], *, check_unoptimized: bool = True) -> str

Inversely apply a sequence of OTs to a string.

assert inverse_apply(apply(doc, ots), ots) == doc

normalize(ots: Sequence[OT]) -> Sequence[OT]

Normalize a sequence of OTs : merge consecutive OTs and trim the last skip operation.

assert normalize([1, 2, 'as', 'df', {'d': 'qw'}, {'d': 'er'}, 3]) \
        == [3, 'asdf', {'d': 'qwer'}]

transform(ots1: Sequence[OT], ots2: Sequence[OT]) -> Sequence[OT]

Transform a sequence of OTs with the property:

assert apply(apply(doc, ots1), transform(ots2, ots1, 'left')) \
        == apply(apply(doc, ots2), transform(ots1, ots2, 'right'))

compose(ots1: Sequence[OT], ots2: Sequence[OT]) -> Sequence[OT]

Compose two sequences of OTs with the property:

assert apply(apply(doc, ots1), ots2) == apply(doc, compose(ots1, ots2))

diff(doc1: str, doc2: str) -> Sequence[OT]

Generate a sequence of OTs required to change doc1 to doc2:

assert apply(doc1, diff(doc1, doc2)) == doc2

Benchmark (at CPython 3.12.1)

Benchmark : apply operation

Benchmark : inverse_apply operation