Automatic Generation of Multiple Exit Parsing Subroutines
The parser construction method presented here might be characterized as the offspring of the successful marriage of LR(k) methodology  with the transition diagram systems of Conway . Like transition diagram systems, the parsers constructed by the method presented here, called the LLP(k) method, consist of small, finite state automata linked by “subroutine calls” and provide a mixed top-down/bottom-up parse. Transition diagram systems with one exit state per diagram correspond to top-down parsers and have been extensively studied [6,9,10]. Like Conway’s transition diagrams, however, LLP(k) subroutines can parse multiple non-terminals simultaneously and return an indication of what they have discovered. It has been shown  that transition diagram systems composed of such multiple exit diagrams can parse all deterministic context free languages. Further, LLP(k) parsers can be realized as directly executing (non-interpretive) subroutines. The method has been implemented . The results demonstrate the feasibility of the approach.
KeywordsProduction Chain Parse Tree Production Expression Input String Check State
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