Course Notes on Formal Languages and Compilers
Course Notes on Formal Languages and Compilers
Course Notes on Formal Languages and Compilers
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46<br />
8. LEXICAL ANALYSIS<br />
5<br />
10<br />
15<br />
20<br />
The following example regular expressi<strong>on</strong> defines tokens of a language. It is<br />
written in a form that each line in the regular expressi<strong>on</strong> describes a<br />
different token in the language.<br />
BEGIN |<br />
END |<br />
IF |<br />
THEN |<br />
ELSE |<br />
letter (letter | digit)* |<br />
digit digit* |<br />
< |<br />
|<br />
>=<br />
The following two pages are from “Principles of Compiler Writing” by Aho<br />
<strong>and</strong> Ullman <strong>and</strong> show n<strong>on</strong>-deterministic <strong>and</strong> deterministic finite state<br />
automata for the above regular expressi<strong>on</strong>.
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