What you’re looking for is Pumping lemma for regular languages. Here is an example with your exact problem: Examples: Let L = {ambm | m ≥ 1}. Then L is not regular. Proof: Let n be as in Pumping Lemma. Let w = anbn. Let w = xyz be as in Pumping Lemma. Thus, xy2z … Read more
It’s feasible but it is a bad idea. Iterator blocks were created to help you write custom iterators for collections, not for solving the general-purpose problem of implementing state machines. If you want to write a state machine, just write a state machine. It’s not hard. If you want to write a lot of state … Read more
I don’t really get the question. The State Design pattern is pretty clear. See the Design Patterns book. class SuperState( object ): def someStatefulMethod( self ): raise NotImplementedError() def transitionRule( self, input ): raise NotImplementedError() class SomeState( SuperState ): def someStatefulMethod( self ): actually do something() def transitionRule( self, input ): return NextState() That’s pretty … Read more
A rather convenient way to help look at this to use python’s little-known re.DEBUG flag on any pattern: >>> re.compile(r'<([A-Z][A-Z0-9]*)\b[^>]*>(.*?)</\1>’, re.DEBUG) literal 60 subpattern 1 in range (65, 90) max_repeat 0 65535 in range (65, 90) range (48, 57) at at_boundary max_repeat 0 65535 not_literal 62 literal 62 subpattern 2 min_repeat 0 65535 any None … Read more
The heart of a state machine is the transition table, which takes a state and a symbol (what you’re calling an event) to a new state. That’s just a two-index array of states. For sanity and type safety, declare the states and symbols as enumerations. I always add a “length” member in some way (language-specific) … Read more