dataflow.py

dataflow.py

inf = float("+inf")

def fix(bottom, n=inf, unwrap=lambda x: x):
    if not callable(bottom):
        bottom_value = bottom
        bottom = lambda *args: bottom_value
    def decorator(f):
        def f_fix(*args):
            me = (f_fix, args)
            if not fix.calling:
                value, fix.values[me] = None, bottom(*args)
                i = 0
                while i < n and value != fix.values[me]:
                    fix.calling.add(me)
                    value, fix.values[me] = fix.values[me], unwrap(f(*args))
                    fix.calling.clear()
                    i += 1
                return value
            if me in fix.calling:
                return fix.values.get(me, bottom(*args))
            fix.calling.add(me)
            value = fix.values[me] = unwrap(f(*args))
            fix.calling.remove(me)
            return value
        return f_fix
    return decorator

fix.calling = set()
fix.values = {}