Gobo Eiffel Lex is a tool for generating Eiffel programs that perform pattern-matching on text. Gelex reads a given input file for the description of the scanner to be generated. The description is in the form of pairs of regular expressions and Eiffel code, called rules. Gelex generates as output an Eiffel class equipped with routines to analyze input text for occurrences of the regular expressions. Whenever one is found, the corresponding Eiffel code is executed.