Compilers: principles, techniques, and tools
Compilers: principles, techniques, and tools
Generalized L.R. Parsing
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When reading a text or listening to a speech the words are processed by humans in the order they come. Intuitively there are some mental actions just after morfologic analysis of any newly recognized word. This mental action helps understanding of the given word (or positioning the word within the frame of the -- still not complete -- sentence). Within parsing of formal languages the closest to this idea is the top-down parsing that is usually used only together with LL grammars. Top-down parsing of programming languages has the advantage that it is possible to implement it by recursive descent parser -- i.e. by a system of procedures that may recursively call each other. Such a system may be "tuned" by hand made changes. The usage of LL grammars is not always possible, because of the grammars of programming languages may have left recursive symbols. Programming language grammars are intuitively "close" to LL grammars. A good model for such grammars are kind grammars studied in this contribution. Kind grammars preserve all the important features of LL grammars advantageous for parsing.