bistring

The bistring library provides non-destructive versions of common string processing operations like normalization, case folding, and find/replace. Each bistring remembers the original string, and how its substrings map to substrings of the modified version.

For example:

>>> from bistring import bistr
>>> s = bistr('π•Ώπ–π–Š π––π–šπ–Žπ–ˆπ–, π–‡π–—π–”π–œπ–“ 🦊 π–π–šπ–’π–•π–˜ π–”π–›π–Šπ–— π–™π–π–Š π–‘π–†π–Ÿπ–ž 🐢')
>>> s = s.normalize('NFKD')     # Unicode normalization
>>> s = s.casefold()            # Case-insensitivity
>>> s = s.replace('🦊', 'fox')  # Replace emoji with text
>>> s = s.replace('🐢', 'dog')
>>> s = s.sub(r'[^\w\s]+', '')  # Strip everything but letters and spaces
>>> s = s[:19]                  # Extract a substring
>>> s.modified                  # The modified substring, after changes
'the quick brown fox'
>>> s.original                  # The original substring, before changes
'π•Ώπ–π–Š π––π–šπ–Žπ–ˆπ–, π–‡π–—π–”π–œπ–“ 🦊'

Demo

Try selecting some of the “original” or “modified” text below, or editing the code block!

import BiString, * as bistring from "bistring";

let s = (function() {

})();

s.original == ""

s.modified == ""