Aho-Corasick string matching algorithm

Simplest example

example1 = mapM_ print $ findAll simpleSM "ushers" where
    simpleSM = makeSimpleStateMachine ["he","she","his","hers"]

Position {pIndex = 1, pLength = 3, pVal = "she"}
Position {pIndex = 2, pLength = 2, pVal = "he"}
Position {pIndex = 2, pLength = 4, pVal = "hers"}

With data

example2 = mapM_ print $ findAll sm "ushers" where
    sm = makeStateMachine [("he",0),("she",1),("his",2),("hers",3)]

Position {pIndex = 1, pLength = 3, pVal = 1}
Position {pIndex = 2, pLength = 2, pVal = 0}
Position {pIndex = 2, pLength = 4, pVal = 3}

Step-by-step state machine evaluation

example3 = mapM_ print $ next sm "ushers" where
    sm = makeSimpleStateMachine ["he","she","his","hers"]
    next _ [] = []
    next sm (s:n) = let (SMStepRes match nextSM) = stateMachineStep sm s in
        (s, match) : next nextSM n

('u',[])
('s',[])
('h',[])
('e',[(3,"she"),(2,"he")])
('r',[])
('s',[(4,"hers")])