#!/usr/bin/perl
# wgrep.pl - windowed grep utility
#!/usr/bin/perl
# wgrep.pl - windowed grep utility
use strict;
use IO::File;
use IO::Handle;
my ($before,$after,$show_stars,$show_nums,$sep,$show_fname);
my ($show_sep,$arg,$file,$regexp,$lnum,$fhandle,$nbef,$naft);
my ($matched,$matched2,@line_buf,@temp,$fh,$ret);
$before = 3; $after = 3; # default window size
$show_stars = 0;
$show_nums = 0;
$sep = "**********\n";
$show_fname = 1;
$show_sep = 1;
# loop until an argument doesn't begin with a "-"
while ($ARGV[0] =~ /^-(\w)(.*)/) {
$arg = $1; # $arg holds the option letter
if ($arg eq "s") { $show_stars = 1; }
elsif ($arg eq "n") { $show_nums = 1; }
elsif ($arg eq "m") { $show_fname = 0; }
elsif ($arg eq "d") { $show_sep = 0; }
elsif ($arg eq "w") {
# parse 2nd matched section at colon
@temp=split(/:/,$2);
$before = $temp[0] if $temp[0] ne '';
$after = $temp[1] if $temp[1] ne '';
}
elsif ($arg eq "p") {
$before = 0;
$after = 0;
$show_sep = 0; }
elsif ($arg eq "W") {
$before = 0;
$after = 0;
}
elsif ($arg eq "h") { &usage(""); }
else { &usage("wgrep: invalid option: $ARGV[0]");
} # end of if command
shift; # go on to next argument
} # end of foreach loop
&usage("wgrep: missing regular expression") if ! $ARGV[0];
$regexp = $ARGV[0];
shift;
$regexp =~ s,/,\\/,g; # "/" --> "\/"
# if no files are specified, use standard input
if (! @ARGV[0]) { @ARGV[0] = "STDIN"; }
LOOP:
foreach $file (@ARGV) { # loop over file list
if ($file eq "STDIN") {
$fh=new IO::Handle;
$ret=$fh->fdopen(fileno(STDIN),"r");
die "Can't open STDIN." unless $ret;
}
else {
$fh = new IO::File "$file", "r";
if (! defined $fh) {
print STDERR "Can't open file $file; skipping it.\n";
next LOOP; # jump to LOOP label
}
}
$lnum = 0;
$nbef = 0; $naft = 0;
$matched = 0; $matched2 = 0;
&clear_buf(0) if $before > 0;
while (<$fh>) { # loop over the lines in the file
++$lnum; # increment line number
if ($matched) { # we're printing the match window
if ($_ =~ /$regexp/) { # if current line matches pattern:
$naft = 0; # reset the after window count,
&print_info(1); # print preliminary stuff,
print $_; # and print the line
}
else { # current line does not match
if ($after > 0 && ++$naft <= $after) {
# print line anyway if still in the after window
&print_info(0); print $_;
}
else { # after window is done
$matched = 0; # no longer in a match
$naft = 0; # reset the after window count
# save line in before buffer for future matches
push(@line_buf, $_); $nbef++;
} # end else not in after window
} # end else curr. line not a match
} # end if we're in a match
else { # we're still looking for a match
if ($_ =~ /$regexp/) { # we found one
$matched = 1; # so set match flag
# print file and/or section separator(s)
print $sep if $matched2 && $nbef > $before && $show_sep && $show_fname;
print "********** $file **********\n" if ! $matched2++ && $show_fname;
# print and clear out before buffer and reset before counter
&clear_buf(1) if $before > 0; $nbef = 0;
&print_info(1);
print $_; # print current line
}
elsif ($before > 0) {
# pop off oldest line in before buffer & add current line
shift(@line_buf) if $nbef >= $before;
push(@line_buf,$_); $nbef++;
} # end elseif before window is nonzero
} # end else not in a match
} # end while loop over lines in this file
$fh->close;
} # end foreach loop over list of files
exit; # end of script proper
# subroutines #
sub print_info {
print $_[0] ? "* " : " " if $show_stars;
printf "%4d ", $lnum if $show_nums;
} # end subroutine print_info
sub clear_buf {
# argument says whether to print before window or not
my ($i,$j,$print_flag);
$print_flag = $_[0];
$i = 0; $j = 0;
if ($print_flag) {
# if we're printing line numbers, fiddle with the
# counter to account for the before window
if ($show_nums) {
$lnum -= ($#line_buf + 1);
}
while ($j <= $#line_buf) { # print before window
&print_info(0);
print $line_buf[$j++];
$lnum++ if $show_nums;
} # end while
} # end if print_flag
@line_buf = (); # clear line_buf array
} # end subroutine clear_buf
sub usage {
# optional argument is an additional message line
print STDERR $_[0],"\n" if $_[0];
print STDERR "Usage: wgrep [-n] [-w[B][:A] | -W] ";
print STDERR "[-d] [-p] [-s] [-m] regexp file(s)\n";
print STDERR " -n = number lines\n";
print STDERR " -s = mark matched lines with asterisks\n";
print STDERR " -wB:A = display B lines before and A lines after\n";
print STDERR " each matched line [both default to 3]\n";
print STDERR " -W = suppress window; equivalent to -w0:0\n";
print STDERR " -d = suppress separation lines between sections\n";
print STDERR " -m = suppress file name header lines\n";
print STDERR " -p = plain mode: equivalent to -W -d\n";
print STDERR " -h = print this help message and exit\n";
print STDERR "Note: If present, -h prevails; otherwise, the rightmost\n";
print STDERR " option wins in the case of contradictions.\n";
exit;
} # end subroutine usage
