109 lines
3.2 KiB
Groff
109 lines
3.2 KiB
Groff
.TH TABGEN 1ACK
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.ad
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.SH NAME
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tabgen \- table generator for C-programs
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.SH SYNOPSYS
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.B tabgen \fIarguments\fP
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.SH DESCRIPTION
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.I Tabgen
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is a handy tool for generating tables for C-programs from a compact
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description. The current version is only suitable for generating character
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tables. The output is produced on standard output.
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It works by maintaining an internal table of values, printing this table
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when this is requested.
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.PP
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Each argument given to
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.I tabgen
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is either a command or a description. Descriptions are discussed first.
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.PP
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A description consists of a value (a string), directly followed by a semicolon,
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directly followed by a list of indices for which the table to be generated
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has this value. This list of indices must be in a certain \fBinputformat\fP,
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characterized by a charactet.
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Currently, there is only one inputformat, "c". In this format, the indices
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are characters. There are two special characters: '\e' and '-'. The '\e'
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behaves like in a C-string, and the '-' describes a range, unless
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it starts the list of indices.
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.PP
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Some examples of descriptions:
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.nf
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STIDF:a-zA-Z_
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STSKIP:\er \et\e013\ef
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.fi
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.PP
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These descriptions have the effect that the internal table values for
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'a' through 'z', 'A' through 'Z', and '_' are set to STIDF, and that the
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internal table values for carriage-return, space, tab, vertical-tab, and
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form-feed are set to STSKIP.
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.PP
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A command is introduced by a special character. On the command line,
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a command is introduced by a '-'. The following commands are
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recognized:
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.IP I\fIchar\fP
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switch to a different input format. This command is only there for future
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extensions.
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.IP f\fIfile\fP
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read input from the file \fIfile\fP. In a file, each line is an argument
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to \fItabgen\fP. Each line is either a command or a description. In a file,
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commands are introduced by a '%'.
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.IP F\fIformat\fP
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Values are printed in a printf format. The default value for this format
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is \fB"%s,\en"\fP. This can be changed with this command.
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.IP T\fItext\fP
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Print \fItext\fP literally at this point.
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.IP p
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Print the table as it is built at this point.
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.IP C
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Clear the table. This sets all internal table values to 0.
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.IP i\fIstr\fP
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Initialize all internal table values to \fIstr\fP. if \fIstr\fP is not
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given, this command is equivalent to the C command.
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.IP S\fInum\fP
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Set the table size to \fInum\fP entries. The default size is 128.
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.SH "AN EXAMPLE"
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.PP
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The next example is a part of the \fItabgen\fP description of the
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character tables used by the lexical analyser of the ACK Modula-2 compiler.
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This description resides in a file called char.tab.
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.I
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Tabgen
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is called as follows:
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.nf
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tabgen -fchar.tab > char.c
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.fi
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.PP
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The description as given here generates 2 tables: one indicating a class
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according to which token a character can be a start of, and one indicating
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whether a character may occur in an identifier.
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.nf
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% Comments are introduced with space or tab after the %
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%S129
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%F %s,
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% CHARACTER CLASSES
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%iSTGARB
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STSKIP: \et\e013\e014\e015
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STNL:\e012
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STSIMP:-#&()*+,/;=[]^{|}~
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STCOMP:.:<>
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STIDF:a-zA-Z
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STSTR:"'
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STNUM:0-9
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STEOI:\e200
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%T#include "class.h"
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% class.h contains #defines for STSKIP, STNL, ...
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%Tchar tkclass[] = {
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%p
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%T};
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% INIDF
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%C
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1:a-zA-Z0-9
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%Tchar inidf[] = {
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%F %s,
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%p
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%T};
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.fi
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.SH BUGS
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.PP
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.I Tabgen
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assumes that characters are 8 bits wide.
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