malign.pl - align code blocks in context (called from vim)

malign.pl

# /usr/bin/perl
#-----------------------------------------------------------------------
# $Id: malign,v 1.2 2018/06/16 22:25:40 root Exp root $
# Created: 2010-02-08

# Description: Determine the narrowest left margin in passed text,
#   then pad the output of align with this pad (less 1, align's left margin).
#-----------------------------------------------------------------------
use strict;
use warnings;
use File::Temp;
use Fcntl qw(:DEFAULT :flock LOCK_EX);  # built-in for file control and I/O

my $debug = 0;

my $tabstop = '';

#-----------------------------------------------------------------------
# STUB - respect tabstop.

if (exists($ENV{'TABSTOP'})) {
    if ( $debug > 1) { print "Tabstop: $ENV{'TABSTOP'}\n"; }
} else {
    if ( $debug > 1) { print "No TABSTOP found."; }
}

#-----------------------------------------------------------------------
# MAIN

#------------------------------
# Slurp stdin to tempfile.

my $tmpfile;
my $tmpfile2;

do { $tmpfile = tmpnam() }
    until sysopen(TMPFILE, $tmpfile, O_RDWR|O_CREAT|O_EXCL);

do { $tmpfile2 = tmpnam() }
    until sysopen(TMPFILE2, $tmpfile2, O_RDWR|O_CREAT|O_EXCL);

# As stdin comes in, write it to first tempfile.
while (<>) {
    print TMPFILE $_;
}

# Go back to top of tempfile for reading
seek (TMPFILE,0,0); 

#------------------------------

# Determine the left margin of the first tempfile.
my $min_margin = 0;
my $marginpad = '';

while (<TMPFILE>) {

    # If there are leading spaces ...
    if (m/^([ ]+)/) {
        # Get their length.
        my $margin_text = $1;
        my $my_margin = length($margin_text);

        # If the minimum margin isn't set yet, set it.
        if ($min_margin eq 0) { 
            $min_margin = $my_margin; 
            $marginpad = $margin_text;
        }

        # If our current margin is less than the minimum, save it.
        if ($my_margin < $min_margin) { 
            $min_margin = $my_margin;
        }

        if ( $debug > 1) { print "\nDEBUG: Minimum margin is now " . $min_margin . "\n";}
    }
    if ( $debug > 1) { print; }

}

if ( $debug > 1) { print "Minimum margin is " . $min_margin . "\n"; }

# Go back to top of tempfile for reading.
seek (TMPFILE,0,0); 

# Run align against the output, writing it to a second tempfile.
open(CMD, "| /usr/local/scripts/align -s s+ -j _> $tmpfile2 ");
while (<TMPFILE>) {
    chomp;
    print CMD "$_\n";
}
close CMD || warn "cmd exited $?";

if ($debug > 1) {
    print "tmp 1: $tmpfile\n";
    system('cat',$tmpfile);
    print "tmp 2: $tmpfile2\n";
    system('cat',$tmpfile2);
}

# Calculate one less than the margin.
# FIXME: "negative repeat count does nothing"
my $alignpad;
if ($min_margin > 0) {
	$alignpad = ' ' x ($min_margin - 1);
} else {
	$alignpad = '';
}

# Pad the left margin of the align output with the pad.
while (<TMPFILE2>) {
    chomp;
    print $alignpad . $_ . "\n";
}

# Remove tempfiles.
unlink($tmpfile) or warn "Couldn't unlink $tmpfile : $!";
unlink($tmpfile2) or warn "Couldn't unlink $tmpfile : $!";

#-----------------------------------------------------------------------