.\" $Header$ .TH LLGEN 1 "$Revision$" .ad .SH NAME LLgen, an extended LL(1) parser generator .SH SYNOPSIS LLgen [ \-vxw ] [ \-j[\fInum\fP] ] [ \-l\fInum\fP ] [ \-h\fInum\fP ] file ... .SH DESCRIPTION \fILLgen\fP converts a context-free grammar into a set of functions which form a recursive descent parser with no backtrack. The grammar may be ambiguous; ambiguities can be broken by user specifications. .PP \fILLgen\fP reads each \fIfile\fP in sequence. Together, these files must constitute a context-free grammar. For each file, \fILLgen\fP generates an output file, which must be compiled by the C-compiler. In addition, it generates the files \fILpars.c\fP and \fILpars.h.\fP \fILpars.h\fP contains the \fIdefine\fP statements that associate the \fILLgen\fP-assigned `token-codes' with user declared `token-names'. This allows other source files, for instance the source file containing the lexical analyzer, to access the token-codes by using the token-names. \fILpars.c\fP contains the error recovery routines and tables. It must also be compiled by the C-compiler. .PP \fILLgen\fP will only update those output files that differ from their previous version. This allows \fILLgen\fP to be used with \fImake\fP (I) convieniently. .PP To obtain a working program, the user must also supply a lexical analyzer, as well as \fImain\fP and \fILLmessage\fP, an error reporting routine; \fILex\fP (I) is a useful program for creating lexical analysers usable by \fILLgen\fP. .PP \fILLgen\fP accepts the following flags: .IP \fB\-v\fP create a file called \fILL.output\fP, which contains a description of the conflicts that were not resolved. If the flag is given more than once, \fILLgen\fP will be more "verbose". If it is given three times, a complete description of the grammar will be supplied. .IP \fB\-x\fP the sets that are computed are extended with the nonterminal symbols and these extended sets are also included in the \fILL.output\fP file. .IP \fB\-w\fP no warnings are given. .IP \fB\-j\fP[\fInum\fP] when this flag is given, \fILLgen\fP will generate dense switches, so that the compiler can generate a jump table for it. This will only be done for switches that have density between \fIlow_percentage\fP and \fIhigh_percentage\fP, as explained below. Usually, compilers generate a jumptable when the density of the switch is above a certain threshold. If you want jump tables in more cases, set \fIhigh_percentage\fP to this threshold, and \fIlow_percentage\fP to a minimum threshold. There is a time-space trade-off here. .I num is the minimum number of cases in a switch for the \fB\-j\fP option to be effective. The default value (if .I num is not given) is 8. .IP \fB\-l\fP\fInum\fP The \fIlow_percentage\fP, as described above. Default value is 10. .IP \fB\-h\fP\fInum\fP The \fIhigh_percentage\fP, as described above. Default value is 30. .SH FILES LL.output verbose output file .br Lpars.c the error recovery routines .br Lpars.h defines for token names .SH "SEE ALSO" \fIlex\fP (I) .br \fImake\fP (I) .br \fILLgen, an Extended LL(1) Parser Generator\fP by C.J.H. Jacobs. .SH DIAGNOSTICS Are intended to be self-explanatory. They are reported on standard error. A more detailed report is found in the \fILL.output\fP file. .SH AUTHOR Ceriel J. H. Jacobs