fstringizer.py

def __extractStrings(exp):
    stack = []
    isInString = False
    currentType = ''  # exp[0] if isInString else ''
    lastI = 0
    stringState = []
    isEscape = False
    for i in range(len(exp)):
        char = exp[i]

        if i > 0 and isInString and exp[i-1] == '\\' and not isEscape:
            isEscape = True
        elif isEscape:
            isEscape = False

        if (char == "'" or char == '"' or i == len(exp)-1) and not isEscape:

            if i != len(exp)-1:
                if (isInString and currentType == char):
                    currentType = ''
                    stack.append(exp[lastI+1:i])
                elif not isInString:
                    currentType = char
                    stack.append(exp[lastI:i+1])
                else:
                    continue

            else:
                if isInString:
                    stack.append(exp[lastI+1:i])
                else:
                    currentType = char
                    stack.append(exp[lastI:i+1])

            stringState.append(isInString)
            isInString = not isInString
            lastI = i

    return stack, stringState


class __empty():
    pass


def fstringize(exp=__empty, *, debug=False):  # 'a' + time + 'b' + nick + awa

    assert exp != __empty  # If I don't give exp a default value and you just run this file, fire will raise FireExit. So I assert the default value so that just running this file can be distinguished from using command line wrongly and causing fire to raise FireExit. And then this assertion will be caught and you will be able to input your expression.

    stack1, stringState = __extractStrings(exp)

    if debug:
        print('Strings and other expressions:', stack1)
        print('Is the experssion a string:', stringState)

    stack2 = []

    for i in range(len(stack1)):
        part = stack1[i]
        if stringState[i]:
            stack2.append(part)
        else:
            part = part.strip('\'\" +')
            part = part.replace(' ', '')
            parts = part.split('+')
            for p in parts:
                stack2.append((p,))

    stack2 = list(filter(lambda part: part != ('',), stack2))

    if debug:
        print('Strings and variables:', stack2)

    fstring = ''

    for i in range(len(stack2)):
        part = stack2[i]
        if type(part) is str:
            fstring += part
        elif type(part) is tuple:
            fstring += '{' + part[0] + '}'

    return 'f'+repr(fstring).replace('\\\\', '')


if __name__ == '__main__':
    import fire
    try:
        fire.Fire(fstringize)
    except AssertionError:
        print(fstringize(input('Input your expression: ')))