PascalCase2camelCase.py

# credit https://dev.to/rrampage/snake-case-to-camel-case-and-back-using-regular-expressions-and-python-m9j
# credit https://stackoverflow.com/a/3847369
import re

REG = r"(.+?)([A-Z])"

def camel(match):
    return match.group(1).lower() + match.group(2)[0].upper() + match.group(2)[1:].lower()
lowerFirstChar = lambda s: s[:1].lower() + s[1:] if s else ''

words = """MyClass
MyClassFactory
MyClassFactoryBuilder
MyClassFactoryBuilderImpl
myInstance
myInstance2
abc
patternMatcher
Hello""".splitlines()

results = [re.sub(REG, camel, lowerFirstChar(w.strip()), 0) for w in words]
[print(w) for w in results]