# Pyrogram - Telegram MTProto API Client Library for Python

# Copyright (C) 2017-present Dan <https://github.com/delivrance>

#

# This file is part of Pyrogram.

#

# Pyrogram is free software: you can redistribute it and/or modify

# it under the terms of the GNU Lesser General Public License as published

# by the Free Software Foundation, either version 3 of the License, or

# (at your option) any later version.

#

# Pyrogram 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 Lesser General Public License for more details.

#

# You should have received a copy of the GNU Lesser General Public License

# along with Pyrogram. If not, see <http://www.gnu.org/licenses/>.

import re

from struct import unpack

# SMP = Supplementary Multilingual Plane: https://en.wikipedia.org/wiki/Plane_(Unicode)#Overview

SMP_RE = re.compile(r"[\U00010000-\U0010FFFF]")

def add_surrogates(text):

# Replace each SMP code point with a surrogate pair

return SMP_RE.sub(

lambda match: # Split SMP in two surrogates

"".join(chr(i) for i in unpack("<HH", match.group().encode("utf-16le"))),

text

)

def remove_surrogates(text):

# Replace each surrogate pair with a SMP code point

return text.encode("utf-16", "surrogatepass").decode("utf-16")

def replace_once(source: str, old: str, new: str, start: int):

return source[:start] + source[start:].replace(old, new, 1)