82 lines
1.5 KiB
Plaintext
82 lines
1.5 KiB
Plaintext
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.TH LEX 1
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.SH NAME
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lex \- generator of lexical analysis programs
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.SH SYNOPSIS
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.B lex
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[
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.B -tvn9
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]
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[
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.I file ...
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]
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.SH DESCRIPTION
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.I Lex
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generates programs to be used in simple lexical analysis of text.
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The input
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.I files
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(standard input default)
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contain regular expressions
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to be searched for and actions written in C to be executed when
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expressions are found.
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.PP
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A C source program,
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.B lex.yy.c
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is generated.
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This program, when run, copies unrecognized portions of
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the input to the output,
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and executes the associated
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C action for each regular expression that is recognized.
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.PP
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The options have the following meanings.
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.TP
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.B -t
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Place the result on the standard output instead of in file
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.BR lex.yy.c .
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.TP
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.B -v
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Print a one-line summary of statistics of the generated analyzer.
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.TP
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.B -n
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Opposite of
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.BR -v ;
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.B -n
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is default.
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.TP
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.B -9
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Adds code to be able to compile through the native C compilers.
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.SH EXAMPLES
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This program converts upper case to lower,
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removes blanks at the end of lines,
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and replaces multiple blanks by single blanks.
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.PP
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.EX
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%%
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[A-Z] putchar(yytext[0]+\'a\'-\'A\');
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[ ]+$
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[ ]+ putchar(\' \');
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.EE
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.SH FILES
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.TF /sys/lib/lex/ncform
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.TP
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.B lex.yy.c
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output
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.TP
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.B /sys/lib/lex/ncform
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template
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.SH "SEE ALSO"
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.IR yacc (1),
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.IR sed (1)
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.br
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M. E. Lesk and E. Schmidt,
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`LEX\(emLexical Analyzer Generator',
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.I
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Unix Research System Programmer's Manual,
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Tenth Edition, Volume 2.
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.SH SOURCE
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.B /sys/src/cmd/lex
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.SH BUGS
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Cannot handle
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.SM UTF.
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.PP
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The asteroid to kill this dinosaur is still in orbit.
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