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.TH plex 1 "10 Jan 2000" "Free Pascal" "Pascal lexical analyzer generator"
.SH NAME
plex \- The Pascal Lex lexical analyzer generator.
.SH USAGE
.B lex [options] lex-file[.l] [output-file[.pas]]
.SH OPTIONS
.TP
.B \-v
.I Verbose:
.BR plex
generates a readable description of the generated
lexical analyzer, written to lex-file with new extension
.I .lst
.TP
.B \-o
.I Optimize:
.BR plex
optimizes DFA tables to produce a minimal DFA.
.SH DESCRIPTION
.BR plex
is a program generator that is used to generate the Turbo Pascal source
code for a lexical analyzer subroutine from the specification of an input
language by a regular expression grammar.
.BR plex
parses the source grammar contained in lex-file (with default suffix .l)
and writes the constructed lexical analyzer subroutine to the specified
output-file (with default suffix .pas); if no output file is specified, output
goes to lex-file with new suffix .pas. If any errors are found during
compilation, error messages are written to the list file (lex-file with new
suffix .lst).
The generated output file contains a lexical analyzer routine, yylex,
implemented as:
.RS
function yylex : Integer;
.RE
This routine has to be called by your main program to execute the lexical
analyzer. The return value of the yylex routine usually denotes the number
of a token recognized by the lexical analyzer (see the return routine in the
LexLib unit). At end-of-file the yylex routine normally returns 0.
The code template for the yylex routine may be found in the yylex.cod
file. This file is needed by TP Lex when it constructs the output file. It
must be present either in the current directory or in the directory from which
TP Lex was executed (TP Lex searches these directories in the indicated
order). (NB: For the Linux/Free Pascal version, the code template is searched
in some directory defined at compile-time instead of the execution path,
usually /usr/lib/fpc/lexyacc.)
The TP Lex library (LexLib) unit is required by programs using Lex-generated
lexical analyzers; you will therefore have to put an appropriate uses clause
into your program or unit that contains the lexical analyzer routine. The
LexLib unit also provides various useful utility routines; see the file
lexlib.pas for further information.
.SH MORE INFORMATION
For more information, see the documentation that comes with plex and yacc.
.SH AUTHOR
Albert Graeff (<ag@muwiinfa.geschichte.uni-mainz.de>, <Dr.Graef@t-online.de>)
.SH SEE ALSO
.BR ppc386 (1)
.BR pyacc (1)
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