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from __future__ import annotations
from collections.abc import Sequence
import functools
import re
DECODE_DEFAULT_CHARS = ";/?:@&=+$,#"
DECODE_COMPONENT_CHARS = ""
decode_cache: dict[str, list[str]] = {}
def get_decode_cache(exclude: str) -> Sequence[str]:
if exclude in decode_cache:
return decode_cache[exclude]
cache: list[str] = []
decode_cache[exclude] = cache
for i in range(128):
ch = chr(i)
cache.append(ch)
for i in range(len(exclude)):
ch_code = ord(exclude[i])
cache[ch_code] = "%" + ("0" + hex(ch_code)[2:].upper())[-2:]
return cache
# Decode percent-encoded string.
#
def decode(string: str, exclude: str = DECODE_DEFAULT_CHARS) -> str:
cache = get_decode_cache(exclude)
repl_func = functools.partial(repl_func_with_cache, cache=cache)
return re.sub(r"(%[a-f0-9]{2})+", repl_func, string, flags=re.IGNORECASE)
def repl_func_with_cache(match: re.Match, cache: Sequence[str]) -> str:
seq = match.group()
result = ""
i = 0
l = len(seq) # noqa: E741
while i < l:
b1 = int(seq[i + 1 : i + 3], 16)
if b1 < 0x80:
result += cache[b1]
i += 3 # emulate JS for loop statement3
continue
if (b1 & 0xE0) == 0xC0 and (i + 3 < l):
# 110xxxxx 10xxxxxx
b2 = int(seq[i + 4 : i + 6], 16)
if (b2 & 0xC0) == 0x80:
all_bytes = bytes((b1, b2))
try:
result += all_bytes.decode()
except UnicodeDecodeError:
result += "\ufffd" * 2
i += 3
i += 3 # emulate JS for loop statement3
continue
if (b1 & 0xF0) == 0xE0 and (i + 6 < l):
# 1110xxxx 10xxxxxx 10xxxxxx
b2 = int(seq[i + 4 : i + 6], 16)
b3 = int(seq[i + 7 : i + 9], 16)
if (b2 & 0xC0) == 0x80 and (b3 & 0xC0) == 0x80:
all_bytes = bytes((b1, b2, b3))
try:
result += all_bytes.decode()
except UnicodeDecodeError:
result += "\ufffd" * 3
i += 6
i += 3 # emulate JS for loop statement3
continue
if (b1 & 0xF8) == 0xF0 and (i + 9 < l):
# 111110xx 10xxxxxx 10xxxxxx 10xxxxxx
b2 = int(seq[i + 4 : i + 6], 16)
b3 = int(seq[i + 7 : i + 9], 16)
b4 = int(seq[i + 10 : i + 12], 16)
if (b2 & 0xC0) == 0x80 and (b3 & 0xC0) == 0x80 and (b4 & 0xC0) == 0x80:
all_bytes = bytes((b1, b2, b3, b4))
try:
result += all_bytes.decode()
except UnicodeDecodeError:
result += "\ufffd" * 4
i += 9
i += 3 # emulate JS for loop statement3
continue
result += "\ufffd"
i += 3 # emulate JS for loop statement3
return result
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