#!/usr/bin/env python
# cardinal_pythonlib/sqlalchemy/subproc.py
"""
===============================================================================
Original code copyright (C) 2009-2022 Rudolf Cardinal (rudolf@pobox.com).
This file is part of cardinal_pythonlib.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
https://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
===============================================================================
"""
import re
from typing import Any, Dict, Iterable, List
import unicodedata
# =============================================================================
# Finding
# =============================================================================
[docs]def find_nth(s: str, x: str, n: int = 0, overlap: bool = False) -> int:
r"""
Finds the position of *n*\ th occurrence of ``x`` in ``s``, or ``-1`` if
there isn't one.
- The ``n`` parameter is zero-based (i.e. 0 for the first, 1 for the
second...).
- If ``overlap`` is true, allows fragments to overlap. If not, they must be
distinct.
As per
https://stackoverflow.com/questions/1883980/find-the-nth-occurrence-of-substring-in-a-string
""" # noqa
length_of_fragment = 1 if overlap else len(x)
i = -length_of_fragment
for _ in range(n + 1):
i = s.find(x, i + length_of_fragment)
if i < 0:
break
return i
# =============================================================================
# Splitting
# =============================================================================
[docs]def split_string(x: str, n: int) -> List[str]:
"""
Split string into chunks of length n
"""
# https://stackoverflow.com/questions/9475241/split-string-every-nth-character # noqa
return [x[i : i + n] for i in range(0, len(x), n)]
# =============================================================================
# Replacement
# =============================================================================
[docs]def multiple_replace(text: str, rep: Dict[str, str]) -> str:
"""
Returns a version of ``text`` in which the keys of ``rep`` (a dict) have
been replaced by their values.
As per
https://stackoverflow.com/questions/6116978/python-replace-multiple-strings.
"""
rep = dict((re.escape(k), v) for k, v in rep.items())
pattern = re.compile("|".join(rep.keys()))
return pattern.sub(lambda m: rep[re.escape(m.group(0))], text)
[docs]def replace_in_list(
stringlist: Iterable[str], replacedict: Dict[str, str]
) -> List[str]:
"""
Returns a list produced by applying :func:`multiple_replace` to every
string in ``stringlist``.
Args:
stringlist: list of source strings
replacedict: dictionary mapping "original" to "replacement" strings
Returns:
list of final strings
"""
newlist = []
for fromstring in stringlist:
newlist.append(multiple_replace(fromstring, replacedict))
return newlist
# =============================================================================
# Mangling to ASCII
# =============================================================================
[docs]def mangle_unicode_to_ascii(s: Any) -> str:
"""
Mangle unicode to ASCII, losing accents etc. in the process.
"""
# https://stackoverflow.com/questions/1207457
if s is None:
return ""
if not isinstance(s, str):
s = str(s)
return (
unicodedata.normalize("NFKD", s)
.encode("ascii", "ignore") # gets rid of accents
.decode("ascii") # back to a string
)
# =============================================================================
# Making strings and string lists
# =============================================================================
[docs]def strnum(prefix: str, num: int, suffix: str = "") -> str:
"""
Makes a string of the format ``<prefix><number><suffix>``.
"""
return f"{prefix}{num}{suffix}"
[docs]def strnumlist(prefix: str, numbers: List[int], suffix: str = "") -> List[str]:
"""
Makes a string of the format ``<prefix><number><suffix>`` for every number
in ``numbers``, and returns them as a list.
"""
return [f"{prefix}{num}{suffix}" for num in numbers]
[docs]def strseq(prefix: str, first: int, last: int, suffix: str = "") -> List[str]:
"""
Makes a string of the format ``<prefix><number><suffix>`` for every number
from ``first`` to ``last`` inclusive, and returns them as a list.
"""
return [strnum(prefix, n, suffix) for n in range(first, last + 1)]