1136 lines
33 KiB
Perl
1136 lines
33 KiB
Perl
#! @PERL@ -w
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# -*- perl -*-
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# autoupdate - modernize an Autoconf file.
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# Copyright 1994, 1999, 2000, 2001 Free Software Foundation, Inc.
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2, or (at your option)
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# any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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# 02111-1307, USA.
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# Originally written by David MacKenzie <djm@gnu.ai.mit.edu>.
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# Rewritten by Akim Demaille <akim@freefriends.org>.
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use 5.005;
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use Getopt::Long;
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use File::Basename;
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use strict;
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(my $me = $0) =~ s,.*[\\/],,;
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# Lib files.
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my $autoconf_dir = $ENV{"AC_MACRODIR"} || "@datadir@";
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my $autoconf = '';
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my $debug = 0;
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my $localdir = '.';
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# m4.
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my $m4 = $ENV{"M4"} || "@M4@";
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my $verbose = 0;
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my $SIMPLE_BACKUP_SUFFIX = $ENV{'SIMPLE_BACKUP_SUFFIX'} || '~';
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my $tmp = '';
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## ---------- ##
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## Routines. ##
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## ---------- ##
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# &mktmpdir ()
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# ------------
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sub mktmpdir ()
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{
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my $TMPDIR = $ENV{'TMPDIR'} || '/tmp';
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# If mktemp supports dirs, use it to please Marc E.
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$tmp = `(umask 077 && mktemp -d -q "$TMPDIR/auXXXXXX") 2>/dev/null`;
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chomp $tmp;
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if (!$tmp || !-d $tmp)
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{
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$tmp = "$TMPDIR/au" . int (rand 10000) . ".$$";
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mkdir $tmp, 0700
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or die "$me: cannot create $tmp: $!\n";
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}
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print STDERR "$me:$$: working in $tmp\n"
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if $debug;
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}
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# END
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# ---
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# Exit nonzero whenever closing STDOUT fails.
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sub END
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{
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use POSIX qw (_exit);
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my ($q) = ($?);
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# FIXME: Heelp! Can't find a means to properly catch system's
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# exit status (without hair I mean).
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# my $status = $? >> 8;
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if (!$debug && -d $tmp)
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{
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unlink <$tmp/*>
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or warn ("$me: cannot empty $tmp: $!\n"), _exit (1);
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rmdir $tmp
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or warn ("$me: cannot remove $tmp: $!\n"), _exit (1);
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}
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# This is required if the code might send any output to stdout
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# E.g., even --version or --help. So it's best to do it unconditionally.
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close STDOUT
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or (warn "$me: closing standard output: $!\n"), _exit (1);
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($!, $?) = (0, $q);
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}
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# print_usage ()
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# --------------
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# Display usage (--help).
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sub print_usage ()
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{
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print <<"END";
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Usage: $0 [OPTION] ... [TEMPLATE-FILE...]
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Update the TEMPLATE-FILE... if given, or \`configure.ac' if present,
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or else \`configure.in', to the syntax of the current version of
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Autoconf. The original files are backed up.
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Operation modes:
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-h, --help print this help, then exit
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-V, --version print version number, then exit
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-v, --verbose verbosely report processing
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-d, --debug don't remove temporary files
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Library directories:
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-A, --autoconf-dir=ACDIR Autoconf's macro files location (rarely needed)
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-l, --localdir=DIR location of \`aclocal.m4'
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Environment variables:
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M4 GNU M4 1.4 or above
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AUTOCONF autoconf @VERSION@
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Report bugs to <bug-autoconf\@gnu.org>.
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END
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exit 0;
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}
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# print_version ()
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# ----------------
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# Display version (--version).
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sub print_version
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{
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print <<END;
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autoupdate (@PACKAGE_NAME@) @VERSION@
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Written by David J. MacKenzie and Akim Demaille.
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Copyright 1994, 1999, 2000, 2001 Free Software Foundation, Inc.
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This is free software; see the source for copying conditions. There is NO
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warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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END
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exit 0;
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}
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# $CONFIGURE_AC
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# &find_configure_ac ()
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# ---------------------
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sub find_configure_ac ()
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{
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if (-f 'configure.ac')
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{
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if (-f 'configure.in')
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{
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warn "warning: `configure.ac' and `configure.in' both present.\n";
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warn "warning: proceeding with `configure.ac'.\n";
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}
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return 'configure.ac';
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}
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elsif (-f 'configure.in')
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{
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return 'configure.in';
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}
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return;
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}
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# parse_args ()
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# -------------
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# Process any command line arguments.
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sub parse_args ()
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{
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my $srcdir;
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# F*k. Getopt seems bogus and dies when given `-' with `bundling'.
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# If fixed some day, use this: '' => sub { push @ARGV, "-" }
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my $update_stdin = grep /^-$/, @ARGV;
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@ARGV = grep !/^-$/, @ARGV;
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Getopt::Long::config ("bundling");
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Getopt::Long::GetOptions ('A|autoconf-dir|m|macrodir=s' => \$autoconf_dir,
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'l|localdir=s' => \$localdir,
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'd|debug' => \$debug,
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'h|help' => \&print_usage,
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'V|version' => \&print_version,
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'v|verbose' => \$verbose)
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or exit 1;
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push @ARGV, '-'
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if $update_stdin;
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if (! @ARGV)
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{
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my $configure_ac = find_configure_ac;
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die 'no input file'
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unless $configure_ac;
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push @ARGV, $configure_ac;
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}
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}
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# find_slaves
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# -----------
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# Find the lib files and autoconf.
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sub find_slaves ()
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{
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# Some non-GNU m4's don't reject the --help option, so give them /dev/null.
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# die "Autoconf requires GNU m4 1.4 or later\n"
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# if system "$m4 --help </dev/null 2>&1 | fgrep reload-state >/dev/null";
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# autoconf.
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(my $dir = $0) =~ s,[^\\/]*$,,;
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# We test "$dir/autoconf" in case we are in the build tree, in which case
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# the names are not transformed yet.
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foreach my $file ($ENV{"AUTOCONF"} || '',
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"$dir/@autoconf-name@",
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"$dir/autoconf",
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"@bindir@/@autoconf-name@")
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{
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if (-x $file)
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{
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$autoconf = $file;
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last;
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}
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}
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# This is needed because perl's '-x' isn't a smart as bash's; that
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# is, it won't find autoconf.sh.
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$autoconf = 'autoconf'
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if !$autoconf;
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}
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## -------------- ##
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## Main program. ##
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## -------------- ##
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find_slaves;
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parse_args;
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mktmpdir;
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$autoconf .= " --autoconf-dir $autoconf_dir --localdir $localdir";
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# @M4_BUILTINS -- M4 builtins and a useful comment.
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my @m4_builtins = `echo dumpdef | $m4 2>&1 >/dev/null`;
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map { s/:.*//;s/\W// } @m4_builtins;
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# m4.m4 -- enable the m4 builtins.
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# unm4.m4 -- disable the m4 builtins.
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# savem4.m4 -- save the m4 builtins.
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open M4_M4, ">$tmp/m4.m4"
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or die "$me: cannot open: $!\n";
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open UNM4_M4, ">$tmp/unm4.m4"
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or die "$me: cannot open: $!\n";
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open M4SAVE_M4, ">$tmp/m4save.m4"
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or die "$me: cannot open: $!\n";
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foreach (@m4_builtins)
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{
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print M4_M4 "_au_define([$_], _au_defn([_au_$_]))\n";
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print UNM4_M4 "_au_undefine([$_])\n";
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print M4SAVE_M4 "define([_au_$_], defn([$_]))\n";
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}
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close M4SAVE_M4
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or die "$me: cannot close: $!\n";
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close UNM4_M4
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or die "$me: cannot close: $!\n";
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close M4_M4
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or die "$me: cannot close: $!\n";
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# @AU_MACROS & AC_MACROS -- AU and AC macros and yet another useful comment.
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open MACROS, ("$autoconf "
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. "--trace AU_DEFUN:'AU:\$f:\$1' --trace define:'AC:\$f:\$1' "
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. "-i /dev/null |")
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or die "$me: cannot open: $!\n";
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my (%ac_macros, %au_macros);
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while (<MACROS>)
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{
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chomp;
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/^(AC|AU):(.*):([^:]*)$/ or next;
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my $filename = basename ($2);
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if ($1 eq "AC")
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{
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$ac_macros{$3} = $filename;
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}
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else
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{
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$au_macros{$3} = $filename;
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}
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}
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close MACROS
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or die "$me: cannot close: $!\n";
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# Don't keep AU macros in @AC_MACROS.
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delete $ac_macros{$_}
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foreach (keys %au_macros);
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if ($debug)
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{
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print STDERR "Current Autoconf macros:\n";
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print STDERR join (' ', sort keys %ac_macros) . "\n\n";
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print STDERR "Obsolete Autoconf macros:\n";
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print STDERR join (' ', sort keys %au_macros) . "\n\n";
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}
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# $au_changequote -- enable the quote `[', `]' right before any AU macro.
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my $au_changequote =
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's/\b(' . join ('|', keys %au_macros) . ')\b/_au_changequote([,])$1/g';
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# au.m4 -- definitions the AU macros.
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system ("$autoconf --trace AU_DEFUN:'_au_defun(\@<:\@\$1\@:>\@,
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\@<:\@\$2\@:>\@)' -i /dev/null "
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. ">$tmp/au.m4");
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# ac.m4 -- autoquoting definitions of the AC macros (M4sugar excluded).
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# disable.m4 -- undefine the macros of AC and m4sugar.
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open AC_M4, ">$tmp/ac.m4"
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or die "$me: cannot open: $!\n";
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open DISABLE_M4, ">$tmp/disable.m4"
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or die "$me: cannot open: $!\n";
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foreach (sort keys %ac_macros)
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{
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print AC_M4 "_au_define([$_], [[\$0(\$\@)]])\n"
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unless $ac_macros{$_} eq "m4sugar.m4";
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print DISABLE_M4 "_au_undefine([$_])\n";
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}
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close DISABLE_M4
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or die "$me: cannot close: $!\n";
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close AC_M4
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or die "$me: cannot close: $!\n";
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## ------------------- ##
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## Process the files. ##
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## ------------------- ##
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foreach my $file (@ARGV)
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{
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my $filename = $file;
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# We need an actual file.
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if ($file eq '-')
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{
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$file = "$tmp/stdin";
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system "cat >$file";
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}
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elsif (! -r "$file")
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{
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die "$me: $file: No such file or directory";
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}
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# input.m4 -- m4 program to produce the updated file.
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# Load the values, the dispatcher, neutralize m4, and the prepared
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# input file.
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my $input_m4 = <<EOF;
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divert(-1) -*- Autoconf -*-
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changequote([, ])
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# Move all the builtins into the \`_au_' pseudo namespace
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include([$tmp/m4save.m4])
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# _au_defun(NAME, BODY)
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# ---------------------
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# Define NAME to BODY, plus AU activation/deactivation.
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_au_define([_au_defun],
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[_au_define([\$1],
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[_au_enable()dnl
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\$2[]dnl
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_au_disable()])])
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# Import the definition of the obsolete macros.
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_au_include([$tmp/au.m4])
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## ------------------------ ##
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## _au_enable/_au_disable. ##
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## ------------------------ ##
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# They work by pair: each time an AU macro is activated, it runs
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# _au_enable, and at its end its runs _au_disable (see _au_defun
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# above). But since AU macros might use AU macros, which should
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# enable/disable only for the outter AU macros.
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#
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# \`_au_enabled' is used to this end, condionning whether we really
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# enable/disable.
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# __au_enable
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# -----------
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# Reenable the builtins, and m4sugar.
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_au_define([__au_enable],
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[_au_divert(-1)
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# Enable special characters.
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_au_changecom([#])
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# Enable the m4 builtins, m4sugar and the autoquoting AC macros.
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_au_include([$tmp/m4.m4])
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_au_include([$autoconf_dir/m4sugar.m4])
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_au_include([$tmp/ac.m4])
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_au_divert(0)])
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# _au_enable
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# ----------
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# Called at the beginning of all the obsolete macros. Reenable the
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# builtins, and m4sugar if needed.
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_au_define([_au_enable],
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[_au_ifdef([_au_enabled],
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[],
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[__au_enable()])_au_dnl
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_au_pushdef([_au_enabled])])
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# __au_disable
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# ------------
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# Disable the builtins, and m4sugar.
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_au_define([__au_disable],
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[_au_divert(-1)
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# Disable m4sugar, the AC autoquoting macros, and m4.
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_au_include([$tmp/disable.m4])
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_au_include([$tmp/unm4.m4])
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# Disable special characters.
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_au_changequote()
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_au_changecom()
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_au_divert(0)])
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# _au_disable
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# -----------
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# Called at the end of all the obsolete macros. Disable the
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# builtins, and m4sugar if needed..
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_au_define([_au_disable],
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[_au_popdef([_au_enabled])_au_dnl
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_au_ifdef([_au_enabled],
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[],
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[__au_disable()])])
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|
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## ------------------------------- ##
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## Disable, and process the file. ##
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## ------------------------------- ##
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_au_disable()_au_dnl
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EOF
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$input_m4 =~ s/^ //mg;
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# prepared input -- input, but reenables the quote before each AU macro.
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open INPUT_M4, ">$tmp/input.m4"
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or die "$me: cannot open: $!\n";
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open FILE, "<$file"
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or die "$me: cannot open: $!\n";
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print INPUT_M4 "$input_m4";
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while (<FILE>)
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{
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eval $au_changequote;
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print INPUT_M4;
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}
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close FILE
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or die "$me: cannot close: $!\n";
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close INPUT_M4
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or die "$me: cannot close: $!\n";
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# Now ask m4 to perform the update.
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print STDERR "$me: running $m4 $tmp/input.m4\n"
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if $verbose;
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if (system ("$m4 $tmp/input.m4 >$tmp/updated"))
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{
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# Exit status of system() is in the upper byte.
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|
$! >>= 8;
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die "$me: cannot update \`$filename'\n";
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};
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|
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if ("$file" eq "$tmp/stdin")
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{
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system ("cat $tmp/updated");
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}
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elsif (! system ("cmp -s $tmp/updated $file"))
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{
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# File didn't change, so don't update its mod time.
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|
print STDERR "$me: \`$file' is unchanged\n"
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|
}
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|
else
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{
|
|
# Back up and install the new one.
|
|
if (system ("mv $file $file${SIMPLE_BACKUP_SUFFIX} && "
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. "mv $tmp/updated $file") == 0)
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{
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print STDERR "$me: \`$file' is updated\n";
|
|
}
|
|
else
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{
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die "$me: cannot update \`$file'\n";
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}
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}
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|
}
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exit 0;
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|
|
|
# ## ---------------------------- ##
|
|
# ## How `autoupdate' functions. ##
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|
# ## ---------------------------- ##
|
|
#
|
|
# The task of `autoupdate' is not trivial: the biggest difficulty being
|
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# that you must limit the changes to the parts that really need to be
|
|
# updated. Finding a satisfying implementation proved to be quite hard,
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# as this is the fourth implementation of `autoupdate'.
|
|
#
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# Below, we will use a simple example of obsolete macro:
|
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#
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# AU_DEFUN([OLD], [NEW([$1, $2], m4_eval([$1 + $2]))])
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# AC_DEFUN([NEW], [echo "sum($1) = $2"])
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#
|
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# the input file contains
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#
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# dnl The Unbelievable Truth
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# OLD(1, 2)
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# NEW([0, 0], [0])
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#
|
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# Of course the expected output is
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#
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# dnl The Unbelievable Truth
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# NEW([1, 2], [3])
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# NEW([0, 0], [0])
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#
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#
|
|
# # First implementation: sed
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|
# # =========================
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#
|
|
# The first implementation was only able to change the name of obsolete
|
|
# macros.
|
|
#
|
|
# The file `acoldnames.m4' defined the old names based on the new names.
|
|
# It was simple then to produce a sed script such as:
|
|
#
|
|
# s/OLD/NEW/g
|
|
#
|
|
# Updating merely consisted in running this script on the file to
|
|
# update.
|
|
#
|
|
# This scheme suffers an obvious limitation: that `autoupdate' was
|
|
# unable to cope with new macros that just swap some of its arguments
|
|
# compared to the old macro. Fortunately, that was enough to upgrade
|
|
# from Autoconf 1 to Autoconf 2. (But I have no idea whether the
|
|
# changes in Autoconf 2 were precisely limited by this constraint.)
|
|
#
|
|
#
|
|
# # Second implementation: hooks
|
|
# # ============================
|
|
#
|
|
# The version 2.15 of Autoconf brought a vast number of changes compared
|
|
# to 2.13, so a solution was needed. One could think to extend the
|
|
# `sed' scripts with specialized code for complex macros. But this
|
|
# approach is of course full of flaws:
|
|
#
|
|
# a. the Autoconf maintainers have to write these snippets, which we
|
|
# just don't want to,
|
|
#
|
|
# b. I really don't think you'll ever manage to handle the quoting of
|
|
# m4 from sed.
|
|
#
|
|
# To satisfy a., let's remark that the code which implements the old
|
|
# features in term of the new feature is exactly the code which should
|
|
# replace the old code.
|
|
#
|
|
# To answer point b, as usual in the history of Autoconf, the answer, at
|
|
# least on the paper, is simple: m4 is the best tool to parse m4, so
|
|
# let's use m4.
|
|
#
|
|
# Therefore the specification is:
|
|
#
|
|
# I want to be able to tell Autoconf, well, m4, that the macro I
|
|
# am currently defining is an obsolete macro (so that the user is
|
|
# warned), which code is the code to use when running autoconf,
|
|
# but that the very same code has to be used when running
|
|
# autoupdate. To summarize, the interface I want is
|
|
# `AU_DEFUN(OLD-NAME, NEW-CODE)'.
|
|
#
|
|
#
|
|
# Now for the technical details.
|
|
#
|
|
# When running autoconf, except for the warning, AU_DEFUN is basically
|
|
# AC_DEFUN.
|
|
#
|
|
# When running autoupdate, we want *only* OLD-NAMEs to be expanded.
|
|
# This obviously means that acgeneral.m4 and acspecific.m4 must not be
|
|
# loaded. Nonetheless, because we want to use a rich set of m4
|
|
# features, m4sugar.m4 is needed. Please note that the fact that
|
|
# Autoconf's macros are not loaded is positive on two points:
|
|
#
|
|
# - we do get an updated `configure.ac', not a `configure'!
|
|
#
|
|
# - the old macros are replaced by *calls* to the new-macros, not the
|
|
# body of the new macros, since their body is not defined!!!
|
|
# (Whoa, that's really beautiful!).
|
|
#
|
|
# Additionally we need to disable the quotes when reading the input for
|
|
# two reasons: first because otherwise `m4' will swallow the quotes of
|
|
# other macros:
|
|
#
|
|
# NEW([1, 2], 3)
|
|
# => NEW(1, 2, 3)
|
|
#
|
|
# and second, because we want to update the macro calls which are
|
|
# quoted, i.e., we want
|
|
#
|
|
# FOO([OLD(1, 2)])
|
|
# => FOO([NEW([1, 2], [3])])
|
|
#
|
|
# If we don't disable the quotes, only the macros called at the top
|
|
# level would be updated.
|
|
#
|
|
# So, let's disable the quotes.
|
|
#
|
|
# Well, not quite: m4sugar.m4 still needs to use quotes for some macros.
|
|
# Well, in this case, when running in autoupdate code, each macro first
|
|
# reestablishes the quotes, expands itself, and disables the quotes.
|
|
#
|
|
# Thinking a bit more, you realize that in fact, people may use `define'
|
|
# `ifelse' etc. in their files, and you certainly don't want to process
|
|
# them. Another example is `dnl': you don't want to remove the
|
|
# comments. You then realize you don't want exactly to import m4sugar:
|
|
# you want to specify when it is enabled (macros active), and disabled.
|
|
# m4sugar provides m4_disable/m4_enable to this end.
|
|
#
|
|
# You're getting close to it. Now remains one task: how to handle
|
|
# twofold definitions?
|
|
#
|
|
# Remember that the same AU_DEFUN must be understood in two different
|
|
# ways, the AC way, and the AU way.
|
|
#
|
|
# One first solution is to check whether acgeneral.m4 was loaded. But
|
|
# that's definitely not cute. Another is simply to install `hooks',
|
|
# that is to say, to keep in some place m4 knows, late `define' to be
|
|
# triggered *only* in AU mode.
|
|
#
|
|
# You first think to design AU_DEFUN like this:
|
|
#
|
|
# 1. AC_DEFUN(OLD-NAME,
|
|
# [Warn the user OLD-NAME is obsolete.
|
|
# NEW-CODE])
|
|
#
|
|
# 2. Store for late AU binding([define(OLD_NAME,
|
|
# [Reestablish the quotes.
|
|
# NEW-CODE
|
|
# Disable the quotes.])])
|
|
#
|
|
# but this will not work: NEW-CODE has probably $1, $2 etc. and these
|
|
# guys will be replaced with the argument of `Store for late AU binding'
|
|
# when you call it.
|
|
#
|
|
# I don't think there is a means to avoid this using this technology
|
|
# (remember that $1 etc. are *always* expanded in m4). You may also try
|
|
# to replace them with $[1] to preserve them for a later evaluation, but
|
|
# if `Store for late AU binding' is properly written, it will remain
|
|
# quoted till the end...
|
|
#
|
|
# You have to change technology. Since the problem is that `$1'
|
|
# etc. should be `consumed' right away, one solution is to define now a
|
|
# second macro, `AU_OLD-NAME', and to install a hook than binds OLD-NAME
|
|
# to AU_OLD-NAME. Then, autoupdate.m4 just need to run the hooks. By
|
|
# the way, the same method was used in autoheader.
|
|
#
|
|
#
|
|
# # Third implementation: m4 namespaces by m4sugar
|
|
# # ==============================================
|
|
#
|
|
# Actually, this implementation was just a clean up of the previous
|
|
# implementation: instead of defining hooks by hand, m4sugar was equipped
|
|
# with `namespaces'. What are they?
|
|
#
|
|
# Sometimes we want to disable some *set* of macros, and restore them
|
|
# later. We provide support for this via namespaces.
|
|
#
|
|
# There are basically three characters playing this scene: defining a
|
|
# macro in a namespace, disabling a namespace, and restoring a namespace
|
|
# (i.e., all the definitions it holds).
|
|
#
|
|
# Technically, to define a MACRO in NAMESPACE means to define the macro
|
|
# named `NAMESPACE::MACRO' to the VALUE. At the same time, we append
|
|
# `undefine(NAME)' in the macro named `m4_disable(NAMESPACE)', and
|
|
# similarly a binding of NAME to the value of `NAMESPACE::MACRO' in
|
|
# `m4_enable(NAMESPACE)'. These mechanisms allow to bind the macro of
|
|
# NAMESPACE and to unbind them at will.
|
|
#
|
|
# Of course this implementation is really inefficient: m4 has to grow
|
|
# strings which can become quickly huge, which slows it significantly.
|
|
#
|
|
# In particular one should avoid as much as possible to use `define' for
|
|
# temporaries. Now that `define' as quite a complex meaning, it is an
|
|
# expensive operations that should be limited to macros. Use
|
|
# `m4_define' for temporaries.
|
|
#
|
|
# Private copies of the macros we used in entering / exiting the m4sugar
|
|
# namespace. It is much more convenient than fighting with the renamed
|
|
# version of define etc.
|
|
#
|
|
#
|
|
#
|
|
# Those two implementations suffered from serious problems:
|
|
#
|
|
# - namespaces were really expensive, and incurred a major performance
|
|
# loss on `autoconf' itself, not only `autoupdate'. One solution
|
|
# would have been the limit the use of namespaces to `autoupdate', but
|
|
# that's again some complications on m4sugar, which really doesn't need
|
|
# this. So we wanted to get rid of the namespaces.
|
|
#
|
|
# - since the quotes were disabled, autoupdate was sometimes making
|
|
# wrong guesses, for instance on:
|
|
#
|
|
# foo([1, 2])
|
|
#
|
|
# m4 saw 2 arguments: `[1'and `2]'. A simple solution, somewhat
|
|
# fragile, is to reestablish the quotes right before all the obsolete
|
|
# macros, i.e., to use sed so that the previous text becomes
|
|
#
|
|
# changequote([, ])foo([1, 2])
|
|
#
|
|
# To this end, one wants to trace the definition of obsolete macros.
|
|
#
|
|
# It was there that the limitations of the namespace approach became
|
|
# painful: because it was a complex machinery playing a lot with the
|
|
# builtins of m4 (hence, quite fragile), tracing was almost impossible.
|
|
#
|
|
#
|
|
# So this approach was dropped.
|
|
#
|
|
#
|
|
# # The fourth implementation: two steps
|
|
# # ====================================
|
|
#
|
|
# If you drop the uses of namespaces, you no longer can compute the
|
|
# updated value, and replace the old call with it simultaneously.
|
|
#
|
|
# Obviously you will use m4 to compute the updated values, but you may
|
|
# use some other tool to achieve the replacement. Personally, I trust
|
|
# nobody but m4 to parse m4, so below, m4 will perform the two tasks.
|
|
#
|
|
# How can m4 be used to replace *some* macros calls with newer values.
|
|
# Well, that's dead simple: m4 should learn the definitions of obsolete
|
|
# macros, forget its builtins, disable the quotes, and then run on the
|
|
# input file, which amounts to doing this:
|
|
#
|
|
# divert(-1)dnl
|
|
# changequote([, ])
|
|
# define([OLD], [NEW([$1, $2], m4_eval([$1 + $2]))changequote()])
|
|
# undefine([dnl])
|
|
# undefine([m4_eval])
|
|
# # Some more undefines...
|
|
# changequote()
|
|
# divert(0)dnl
|
|
# dnl The Unbelievable Truth
|
|
# changequote([, ])OLD(1, 2)
|
|
# NEW([0, 0],
|
|
# 0)
|
|
#
|
|
# which will result in
|
|
#
|
|
# dnl The Unbelievable Truth
|
|
# NEW(1, 2, m4_eval(1 + 2))
|
|
# NEW([0, 0],
|
|
# 0)
|
|
#
|
|
# Grpmh. Two problems. A minor problem: it would have been much better
|
|
# to have the `m4_eval' computed, and a major problem: you lost the
|
|
# quotation in the result.
|
|
#
|
|
# Let's address the big problem first. One solution is to define any
|
|
# modern macro to rewrite its calls with the proper quotation, thanks to
|
|
# `$@'. Again, tracing the `define's makes it possible to know which
|
|
# are these macros, so you input is:
|
|
#
|
|
# divert(-1)dnl
|
|
# changequote([, ])
|
|
# define([OLD], [NEW([$1, $2], m4_eval([$1 + $2]))changequote()])
|
|
# define([NEW], [[NEW($@)]changequote()])
|
|
# undefine([dnl])
|
|
# undefine([m4_eval])
|
|
# # Some more undefines...
|
|
# changequote()
|
|
# divert(0)dnl
|
|
# dnl The Unbelievable Truth
|
|
# changequote([, ])OLD(1, 2)
|
|
# changequote([, ])NEW([0, 0],
|
|
# 0)
|
|
#
|
|
# which results in
|
|
#
|
|
# dnl The Unbelievable Truth
|
|
# NEW([1, 2],[m4_eval(1 + 2)])
|
|
# NEW([0, 0],[0])
|
|
#
|
|
# Our problem is solved, i.e., the first call to `NEW' is properly
|
|
# quoted, but introduced another problem: we changed the layout of the
|
|
# second calls, which can be a drama in the case of huge macro calls
|
|
# (think of `AC_TRY_RUN' for instance). This example didn't show it,
|
|
# but we also introduced parens to macros which did not have some:
|
|
#
|
|
# AC_INIT
|
|
# => AC_INIT()
|
|
#
|
|
# No big deal for the semantics (unless the macro depends upon $#, which
|
|
# is bad), but the users would not be happy.
|
|
#
|
|
# Additionally, we introduced quotes that we not there before, which is
|
|
# OK in most cases, but could change the semantics of the file.
|
|
#
|
|
# Cruel dilemma: we do want the auto-quoting definition of `NEW' when
|
|
# evaluating `OLD', but we don't when we evaluate the second `NEW'.
|
|
# Back to namespaces?
|
|
#
|
|
# No.
|
|
#
|
|
#
|
|
# # Second step: replacement
|
|
# # ------------------------
|
|
#
|
|
# No, as announced above, we will work in two steps: in a first step we
|
|
# compute the updated values, and in a second step we replace them. Our
|
|
# goal is something like this:
|
|
#
|
|
# divert(-1)dnl
|
|
# changequote([, ])
|
|
# define([OLD], [NEW([1, 2], [3])changequote()])
|
|
# undefine([dnl])
|
|
# undefine([m4_eval])
|
|
# # Some more undefines...
|
|
# changequote()
|
|
# divert(0)dnl
|
|
# dnl The Unbelievable Truth
|
|
# changequote([, ])OLD(1, 2)
|
|
# NEW([0, 0],
|
|
# 0)
|
|
#
|
|
# i.e., the new value of `OLD' is precomputed using the auto-quoting
|
|
# definition of `NEW' and the m4 builtins. We'll see how afterwards,
|
|
# let's finish with the replacement.
|
|
#
|
|
# Of course the solution above is wrong: if there were other calls to
|
|
# `OLD' with different values, we would smash them to the same value.
|
|
# But it is quite easy to generalize the scheme above:
|
|
#
|
|
# divert(-1)dnl
|
|
# changequote([, ])
|
|
# define([OLD([1],[2])], [NEW([1, 2], [3])])
|
|
# define([OLD], [defn([OLD($@)])changequote()])
|
|
# undefine([dnl])
|
|
# undefine([m4_eval])
|
|
# # Some more undefines...
|
|
# changequote()
|
|
# divert(0)dnl
|
|
# dnl The Unbelievable Truth
|
|
# changequote([, ])OLD(1, 2)
|
|
# NEW([0, 0],
|
|
# 0)
|
|
#
|
|
# i.e., for each call to obsolete macros, we build an array `call =>
|
|
# value', and use a macro to dispatch these values. This results in:
|
|
#
|
|
# dnl The Unbelievable Truth
|
|
# NEW([1, 2], [3])
|
|
# NEW([0, 0],
|
|
# 0)
|
|
#
|
|
# In French, we say `Youpi !', which you might roughly translate as
|
|
# `yipeee!'.
|
|
#
|
|
#
|
|
# # First step: computation
|
|
# # -----------------------
|
|
#
|
|
# Let's study the anatomy of the file, and name its sections:
|
|
#
|
|
# prologue
|
|
# divert(-1)dnl
|
|
# changequote([, ])
|
|
# values
|
|
# define([OLD([1],[2])], [NEW([1, 2], [3])])
|
|
# dispatcher
|
|
# define([OLD], [defn([OLD($@)])changequote()])
|
|
# disabler
|
|
# undefine([dnl])
|
|
# undefine([m4_eval])
|
|
# # Some more undefines...
|
|
# changequote()
|
|
# divert(0)dnl
|
|
# input
|
|
# dnl The Unbelievable Truth
|
|
# changequote([, ])OLD(1, 2)
|
|
# NEW([0, 0],
|
|
# 0)
|
|
#
|
|
#
|
|
# # Computing the `values' section
|
|
# # ..............................
|
|
#
|
|
# First we need to get the list of all the AU macro uses. To this end,
|
|
# first get the list of all the AU macros names by tracing `AU_DEFUN' in
|
|
# the initialization of autoconf. This list is computed in the file
|
|
# `au.txt' below.
|
|
#
|
|
# Then use this list to trace all the AU macro uses in the input. The
|
|
# goal is obtain in the case of our example:
|
|
#
|
|
# [define([OLD([1],[2])],]@<<@OLD([1],[2])@>>@[)]
|
|
#
|
|
# This is the file `values.in' below.
|
|
#
|
|
# We want to evaluate this with only the builtins (in fact m4sugar), the
|
|
# auto-quoting definitions of the new macros (`new.m4'), and the
|
|
# definition of the old macros (`old.m4'). Computing these last two
|
|
# files is easy: it's just a matter of using the right `--trace' option.
|
|
#
|
|
# So the content of `values.in' is:
|
|
#
|
|
# include($autoconf_dir/m4sugar.m4)
|
|
# m4_include(new.m4)
|
|
# m4_include(old.m4)
|
|
# divert(0)dnl
|
|
# [define([OLD([1],[2])],]@<<@OLD([1],[2])@>>@[)]
|
|
#
|
|
# We run m4 on it, which yields:
|
|
#
|
|
# define([OLD([1],[2])],@<<@NEW([1, 2], [3])@>>@)
|
|
#
|
|
# Transform `@<<@' and `@>>@' into quotes and we get
|
|
#
|
|
# define([OLD([1],[2])],[NEW([1, 2], [3])])
|
|
#
|
|
# This is `values.m4'.
|
|
#
|
|
#
|
|
# # Computing the `dispatcher' section
|
|
# # ..................................
|
|
#
|
|
# The `prologue', and the `disabler' are simple and need no commenting.
|
|
#
|
|
# To compute the `dispatcher' (`dispatch.m4'), again, it is a simple
|
|
# matter of using the right `--trace'.
|
|
#
|
|
# Finally, the input is not exactly the input file, rather it is the
|
|
# input file with the added `changequote'. To this end, we build
|
|
# `quote.sed'.
|
|
#
|
|
#
|
|
# # Putting it all together
|
|
# # .......................
|
|
#
|
|
# We build the file `input.m4' which contains:
|
|
#
|
|
# divert(-1)dnl
|
|
# changequote([, ])
|
|
# include(values.m4)
|
|
# include(dispatch.m4)
|
|
# undefine([dnl])
|
|
# undefine([eval])
|
|
# # Some more undefines...
|
|
# changequote()
|
|
# divert(0)dnl
|
|
# dnl The Unbelievable Truth
|
|
# changequote([, ])OLD(1, 2)
|
|
# NEW([0, 0],
|
|
# 0)
|
|
#
|
|
# And we just run m4 on it. Et voila`, Monsieur ! Mais oui, mais oui.
|
|
#
|
|
# Well, there are a few additional technicalities. For instance, we
|
|
# rely on `changequote', `ifelse' and `defn', but we don't want to
|
|
# interpret the changequotes of the user, so we simply use another name:
|
|
# `_au_changequote' etc.
|
|
#
|
|
#
|
|
# # Failure of the fourth approach
|
|
# # ------------------------------
|
|
#
|
|
# This approach is heavily based on traces, but then there is an obvious
|
|
# problem: non expanded code will never be seen/ In particular, the body
|
|
# of a `define' definition is not seen, so on the input
|
|
#
|
|
# define([idem], [OLD(0, [$1])])
|
|
#
|
|
# autoupdate would never see the `OLD', and wouldn't have updated it.
|
|
# Worse yet, if `idem(0)' was used later, then autoupdate sees that
|
|
# `OLD' is used, computes the result for `OLD(0, 0)' and sets up a
|
|
# dispatcher for `OLD'. Since there was no computed value for `OLD(0,
|
|
# [$1])', the dispatcher would have replaced with... nothinhg, leading
|
|
# to
|
|
#
|
|
# define([idem], [])
|
|
#
|
|
# With some more thinking, you see that the two step approach is wrong,
|
|
# the namespace approach was much saner.
|
|
#
|
|
# But you learned a lot, in particular you realized that using traces
|
|
# can make it possible to simulate namespaces!
|
|
#
|
|
#
|
|
#
|
|
# # The fifth implementation: m4 namespaces by files
|
|
# # ================================================
|
|
#
|
|
# The fourth implementation demonstrated something unsurprising: you
|
|
# cannot precompute, i.e., the namespace approach was the right one.
|
|
# Still, we no longer want them, they're too expensive. Let's have a
|
|
# look at the way it worked.
|
|
#
|
|
# When updating
|
|
#
|
|
# dnl The Unbelievable Truth
|
|
# OLD(1, 2)
|
|
# NEW([0, 0], [0])
|
|
#
|
|
# you evaluate `input.m4':
|
|
#
|
|
# divert(-1)
|
|
# changequote([, ])
|
|
# define([OLD],
|
|
# [m4_enable()NEW([$1, $2], m4_eval([$1 + $2]))m4_disable()])
|
|
# ...
|
|
# m4_disable()
|
|
# dnl The Unbelievable Truth
|
|
# OLD(1, 2)
|
|
# NEW([0, 0], [0])
|
|
#
|
|
# where `m4_disable' undefines the m4 and m4sugar, and disables the quotes
|
|
# and comments:
|
|
#
|
|
# define([m4_disable],
|
|
# [undefine([__file__])
|
|
# ...
|
|
# changecom(#)
|
|
# changequote()])
|
|
#
|
|
# `m4_enable' does the converse: reestablish quotes and comments
|
|
# --easy--, reestablish m4sugar --easy: just load `m4sugar.m4' again-- and
|
|
# reenable the builtins. This later task requires that you first save
|
|
# the builtins. And BTW, the definition above of `m4_disable' cannot
|
|
# work: you undefined `changequote' before using it! So you need to use
|
|
# your privates copies of the builtins. Let's introduce three files for
|
|
# this:
|
|
#
|
|
# `m4save.m4'
|
|
# moves the m4 builtins into the `_au_' pseudo namespace
|
|
# `unm4.m4'
|
|
# undefines the builtins
|
|
# `m4.m4'
|
|
# restores them
|
|
#
|
|
# So `input.m4' is:
|
|
#
|
|
# divert(-1)
|
|
# changequote([, ])
|
|
#
|
|
# include([m4save.m4])
|
|
#
|
|
# # Import AU.
|
|
# define([OLD],
|
|
# [m4_enable()NEW([$1, $2], m4_eval([$1 + $2]))m4_disable()])
|
|
#
|
|
# define([_au_enable],
|
|
# [_au_changecom([#])
|
|
# _au_include([m4.m4])
|
|
# _au_include(m4sugar.m4)])
|
|
#
|
|
# define([_au_disable],
|
|
# [# Disable m4sugar.
|
|
# # Disable the m4 builtins.
|
|
# _au_include([unm4.m4])
|
|
# # 1. Disable special characters.
|
|
# _au_changequote()
|
|
# _au_changecom()])
|
|
#
|
|
# m4_disable()
|
|
# dnl The Unbelievable Truth
|
|
# OLD(1, 2)
|
|
# NEW([0, 0], [0])
|
|
#
|
|
# Based on what we learned in the fourth implementation we know that we
|
|
# have to enable the quotes *before* any AU macro, and we know we need
|
|
# to build autoquoting versions of the AC macros. But the autoquoting
|
|
# AC definitions must be disabled in the rest of the file, and enabled
|
|
# inside AU macros.
|
|
#
|
|
# Using `autoconf --trace' it is easy to build the files
|
|
#
|
|
# `ac.m4'
|
|
# define the autoquoting AC fake macros
|
|
# `disable.m4'
|
|
# undefine the m4sugar and AC autoquoting macros.
|
|
# `au.m4'
|
|
# definitions of the AU macros (such as `OLD' above).
|
|
#
|
|
# Now, `input.m4' is:
|
|
#
|
|
# divert(-1)
|
|
# changequote([, ])
|
|
#
|
|
# include([m4save.m4])
|
|
# # Import AU.
|
|
# include([au.m4])
|
|
#
|
|
# define([_au_enable],
|
|
# [_au_changecom([#])
|
|
# _au_include([m4.m4])
|
|
# _au_include(m4sugar.m4)
|
|
# _au_include(ac.m4)])
|
|
#
|
|
# define([_au_disable],
|
|
# [_au_include([disable.m4])
|
|
# _au_include([unm4.m4])
|
|
# # 1. Disable special characters.
|
|
# _au_changequote()
|
|
# _au_changecom()])
|
|
#
|
|
# m4_disable()
|
|
# dnl The Unbelievable Truth
|
|
# _au_changequote([, ])OLD(1, 2)
|
|
# NEW([0, 0], [0])
|
|
#
|
|
# Finally, version V is ready.
|
|
#
|
|
# Well... almost.
|
|
#
|
|
# There is a slight problem that remains: if an AU macro OUTTER includes
|
|
# an AU macro INNER, then _au_enable will be run when entering OUTTER
|
|
# and when entering INNER (not good, but not too bad yet). But when
|
|
# getting out of INNER, _au_disable will disable everything while we
|
|
# were still in OUTTER. Badaboom.
|
|
#
|
|
# Therefore _au_enable and _au_disable have to be written to work by
|
|
# pairs: each _au_enable pushdef's _au_enabled, and each _au_disable
|
|
# popdef's _au_enabled. And of course _au_enable and _au_disable are
|
|
# effective when _au_enabled is *not* defined.
|
|
#
|
|
# Finally, version V' is ready. And there is much rejoicing. (And I
|
|
# have free time again. I think. Yeah, right.)
|