NAME
shtool-scpp - GNU shtool C source file pre-processor
SYNOPSIS
shtool scpp [-v|--verbose] [-p|--preserve] [-f|--filter filter]
[-o|--output ofile] [-t|--template tfile] [-M|--mark mark] [-D|--define
dname] [-C|--class cname] file [file ...]
DESCRIPTION
This command is an additional ANSI C source file pre-processor for
sharing cpp(1) code segments, internal variables and internal
functions. The intention for this comes from writing libraries in ANSI
C. Here a common shared internal header file is usually used for
sharing information between the library source files.
The operation is to parse special constructs in files, generate a few
things out of these constructs and insert them at position mark in
tfile by writing the output to ofile. Additionally the files are never
touched or modified. Instead the constructs are removed later by the
cpp(1) phase of the build process. The only prerequisite is that every
file has a ‘‘"#include ""ofile"""’’ at the top.
This command provides the following features: First it avoids namespace
pollution and reduces prototyping efforts for internal symbols by
recognizing functions and variables which are defined with the storage
class identifier ‘‘cname’’. For instance if cname is ‘‘intern’’, a
function ‘‘"intern void *foobar(int quux)"’’ in one of the files is
translated into both a ‘‘"#define foobar __foobar"’’ and a ‘‘"extern
void *foobar(int quux);"’’ in ofile. Additionally a global ‘‘"#define"
cname "/**/"’’ is also created in ofile to let the compiler silently
ignore this additional storage class identifier.
Second, the library source files usually want to share "typedef"s,
"#define"s, etc. over the source file boundaries. To achieve this one
can either place this stuff manually into tfile or use the second
feature of scpp: All code in files encapsulated with ‘‘"#if "dname ...
"#endif"’’ is automatically copied to ofile. Additionally a global
‘‘"#define" dname 0’’ is also created in ofile to let the compiler
silently skip this parts (because it was already found in the header).
OPTIONS
The following command line options are available.
-v, --verbose
Display some processing information.
-p, --preserve
Preserves ofile independent of the generated ‘‘#line’’ lines. This
is useful for Makefiles if the real contents of ofile will not
change, just line numbers. Default is to overwrite.
-f, --filter filter
Apply one or more pre-processing sed(1) filter commands (usually of
type ‘‘"s/.../.../"’’) to each input file before their input is
parsed. This option can occur multiple times.
-o, --output ofile
Output file name. Default is "lib.h".
-t, --template tfile
Template file name. Default is "lib.h.in".
-M, --mark mark
Mark to be replaced by generated constructs. Default is "%%MARK%%".
-D, --define dname
FIXME. Default is "cpp".
-C, --class cname
FIXME. Default is "intern".
EXAMPLE
# Makefile
SRCS=foo_bar.c foo_quux.c
foo_p.h: foo_p.h.in
shtool scpp -o foo_p.h -t foo_p.h.in \
-M %%MARK%% -D cpp -C intern $(SRCS)
/* foo_p.h.in */
#ifndef FOO_P_H
#define FOO_P_H
%%MARK%%
#endif /* FOO_P_H */
/* foo_bar.c */
#include "foo_p.h"
#if cpp
#define OURS_INIT 4711
#endif
intern int ours;
static int myone = 0815;
intern int bar(void)
{
ours += myone;
}
/* foo_quux.c */
#include "foo_p.h"
int main(int argc, char *argv[])
{
int i;
ours = OURS_INIT
for (i = 0; i < 10; i++) {
bar();
printf("ours now %d\n", ours);
}
return 0;
}
HISTORY
The GNU shtool scpp command was originally written by Ralf S.
Engelschall <rse@engelschall.com> in 1999 for GNU shtool. Its was
prompted by the need to have a pre-processing facility in the GNU pth
project.
SEE ALSO
shtool(1), cpp(1).