12 lines
717 B
Plaintext
12 lines
717 B
Plaintext
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Flex is a tool for generating scanners. A scanner, sometimes called a
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tokenizer, is a program which recognizes lexical patterns in text. The
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flex program reads user-specified input files, or its standard input
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if no file names are given, for a description of a scanner to generate.
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The description is in the form of pairs of regular expressions and C
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code, called rules. Flex generates a C source file named, "lex.yy.c",
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which defines the function yylex(). The file "lex.yy.c" can be compiled
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and linked to produce an executable. When the executable is run, it
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analyzes its input for occurrences of text matching the regular
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expressions for each rule. Whenever it finds a match, it executes the
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corresponding C code.
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