I have a quick implementation of a Brainfuck interpreter for Python in a GitHub repo. In a nutshell, though, you could keep a dictionary, where the keys are the Brainfuck characters and the values are function (or method) objects, and then dispatch on that. Something like this:
instructions = {
'+': increment,
'-': decrement,
# Other functions
}
def run(tape):
ch = next_token(tape)
if ch in instructions:
instructions[ch]()
(Not an actual implementation, just a quick illustration.)