#! /usr/bin/env perl
#
# See POD documentation below or use:
#
# $ perldoc texdiff
#
# to see embedded documentation. Alternatively, you can create manual
# or HTML pages using pod2man and pod2html.  Below the POD part you
# can add your own macros to be skipped by the edit marks.
#
# $Id: texdiff 774 2009-09-28 18:33:44Z cengiz $

=pod

=head1 NAME

B<texdiff> - Compares two (La)TeX documents to create a merged version showing changes, similar to that of 'Change Tracking' in some word processors.

=head1 SYNOPSIS

texdiff [--nofloats|-n] [--debug|-d] old.tex new.tex [diff.tex]

=head1 DESCRIPTION

The first two files are compared and a new TeX file is output. When
the output file is processed with (La)TeX it marks new changes with
blue and old text with red with a strike-through line. Furthermore,
passages with changes are marked at the margin with grey bars by the
LaTeX C<changebar> package (although only after running C<dvips>, in
C<xdvi> the bars are one inch too far left to compensate the one inch
offset inserted by TeX printer drivers).

C<texdiff> uses and therefore requires the C<wdiff> command to insert
these marks. If LaTeX macros are included in those striked out or
underlined passages, the latex run will most likely fail. The source
of most problems lies in C<wdiff> tearing apart pairs of
braces. Therefore, C<texdiff> is a B<Perl> script that calls C<wdiff>
internally and fixes C<wdiff>'s output by repairing braces again and
handling some commonly used LaTeX macros. You can add your own macros
to be handled specially by manually editing the lists inside C<texdiff>.

C<texdiff> will insert the following LaTeX code in the preamble of the
output LaTeX document:

 \usepackage{xcolor} \usepackage{ulem} \usepackage{changebar}
 \newcommand\TLSins[1]{\cbstart{}\textcolor{ins}{\uline{#1}}\cbend{}}
 \newcommand\TLSdel[1]{\cbdelete{}\textcolor{del}{\sout{#1}}}

And it will define editing colors C<ins> and C<del> with existing
C<xcolor> color names:

 \colorlet{ins}{blue} \colorlet{del}{red}

These macros are automatically inserted right after a \documentclass
command, I<if it exists>. If it doesn't exist, this code is NOT
inserted because the same code should not be repeated on component
files of a multi-file document (those included by \include or \input).
You can also insert or modify these automatically inserted macros
manually to tune them as you like, i.e. change text color or position
of changebars. As an example, the following changes the insertion
color to a I<dark green>:

 \definecolor{ins}{rgb}{0, 0.5, 0}

Have a look at the documentation of the C<xcolor>, C<ulem> and
C<changebar> packages on how to do more.

Changes in the preamble of your latex file (that is, before the
\\begin{document} command), are marked as follows. Each deletion shows
up as a commented-out region and each insertion is delimited by
comments to indicate its start and end.

=head1 OPTIONS

=over

=item B<--nofloats>, B<-n>

If given, skips contents of figure environments, but does show
insertions and deletions in the caption commands. This is done to
avoid complex messups in subfloat or complex figure environments.

=item B<--debug>, B<-d>

Turns on debugging. Temporary files that contain numbered braces are
kept and a raw difference file is written as output file name appended
with '-wdiff.tex'. In addition, several regular expression diagnostics
are printed. B<Warning: produces a lot of output.>

=back

=head1 BUGS

The marking commands inserted by texdiff are somehow brittle and can
break some latex commands. Most of these commands will be skipped by
texdiff, however your document may always have ones we didn't think of
before. If you have such commands you can add them to the list of
commands to be skipped by texdiff by modifying its configuration
section at the beginning of the script.

If all else fails, you will need to manually fix the problems in the
output file. Any improvements will be welcome by the authors.

=head1 SEE ALSO

B<wdiff> documentation, using C<wdiff --help>

=head1 AUTHOR

Mark Doll <markdoll<AT>gmx.net>, Cengiz Gunay <cengique<AT>users.sf.net>.

=head1 ACKNOWLEDGMENTS

=over

=item B<*>

Version 0.5, by CG, 2009/09/25. Fixed appearing paragraphs inside
marked blocks. Added automatic insertion of the preamble.

=item B<*>

Version 0.4, by CG, 2009/09/15. Added use of GetOpt to take an optional
parameter to skip float (e.g., figure or table) contents. Added an
optional debug mode. Embedded POD documentation. Fixed problem
with insertion and deletions appearing in the middle of sectioning
commands by throwing off LaTeX.

=item B<*>

Version 0.3, modified by Cengiz Gunay <cengique@users.sf.net>,
2009/06/30. Added some Latex commands that should be excluded and
fixed handling of '\%' characters.

=item B<*>

Version 0.2, is a perl implementation of TeXdiff by Mark Doll
<markdoll@gmx.net>, 2006/08/09. It was derived from the original bash
and perl scripts created by Robert Maron <robmar@mimuw.edu.pl>,
available at http://www.robmar.net/TexDiff/. This version of texdiff
is available at http://mark.doll.name/texdiff/.

=back

=head1 COPYRIGHT AND LICENSE

Copyleft 2006-2009, Mark Doll and Cengiz Gunay

This library is free software; you may redistribute it and/or modify
it under the same terms as Perl itself.

=cut

# TODO:
#
# - after removing excluded commands, unify deletions and insertions
# if there're no other differences
# - investigate causes of missing brace pairs
# - put option to flatten first?
# - mark preamble changes with latex comment-outs

use Getopt::Long qw(GetOptions);
use Pod::Usage;
use POSIX qw(strftime);

use strict;
use re 'eval';			# CG: for RE code for skipping float contents

###################### START CONFIGURATION OPTIONS ####################

## Problematic commands, that will be removed from deletions and moved
## out of insertions. The array index equals the number of mandatory
## command parameters.

## INSERT YOUR HOMEBREW MACROS HERE!!!
# Omit leading backslash and separate by '|', since this will be
# interpreted as a regular expression.
my @mycommands = (
  'RCS\$[^\$]*\$',
  'cite\w*p|citet|svnid|citep',
  'if\w+',
  '',
  '',
  'Abb(?:ildung)?(?:p[psw])?',
);

## standard LaTeX macros
#FIXME: add more macros here!
my @stdcommands = (
  '\\\\|item|\%',   # will match one backslash inside regex
  'includegraphics|begin|end|input|fancyfoot|subfig|subfloat',
  '', #newcommand REMOVED FOR TESTING ONLY
);

# preamble to be inserted right after the \documentclass command
my $docpreamble = << "END";
 \\usepackage{xcolor} \\usepackage{ulem} \\usepackage{changebar}
 \\newcommand\\TLSins[1]{\\cbstart{}\\textcolor{ins}{\\uline{#1}}\\cbend{}}
 \\newcommand\\TLSdel[1]{\\cbdelete{}\\textcolor{del}{\\sout{#1}}}
 \\colorlet{ins}{blue} \\colorlet{del}{red}
END

###################### END CONFIGURATION OPTIONS ####################

# GetOpt::Long::
my $nofloats = 0;
my $help;
my $DEBUG=0;

my $result = GetOptions ("nofloats|n" => \$nofloats,
			 "debug|d" => \$DEBUG,
			 "help|?" => \$help );

#print "Figs= $nofloats\n";

pod2usage( -section => "SYNOPSIS") if ($#ARGV < 1 || $help);

## allow nesting of braces (aka curly brackets) up to 10**$w-1 levels
my $w = 2;

## wdiff marker
my $delstart = "TLSdel";
my $delend   = "TLEdel";
my $insstart = "TLSins";
my $insend   = "TLEins";

## LaTeX macros used to mark deletions/insertions in the output
my $texdelstart = "\\protect\\TLSdel\{";
my $texdelend   = "\}";
my $texinsstart = "\\protect\\TLSins\{";
my $texinsend   = "\}";


## parse command line
my ($in1,$in2,$out) = @ARGV;

## create temp files from input files with all comments removed and
## all braces numbered
write_temp($w,$in1,'tmp1.'.$$);
write_temp($w,$in2,'tmp2.'.$$);
sub write_temp {
    my ($w,$file,$tmp) = @_;

    $_ = `cat $file`;

    ## mark pairs of braces with the same $w digits.
    # i. e. convert "{ { {} } {}}" to "{01 {02 {03}03 }02 {02}02}01" ($w=2).
    #
    # FIXME: marking braces before comparison makes them appear
    # as changes if depth of nesting changes.

    my $max=10**$w-1;
    $::cnt = 0;
    s/
      (?<!\\)
      (?:
        \{ (?{ die "Fatal: Braces nested deeper than $max!\n" if ($::cnt >= $max);
               sprintf("\{%0${w}d",++$::cnt) }) |
        \} (?{ sprintf("\}%0${w}d",$::cnt--) })
      )
    /$^R/gx;

    print STDERR "Warning: ".abs($::cnt)." unmatched ".($::cnt > 0 ? "opening" : "closing")
         ." brace".(abs($::cnt) == 1 ? "" : "s")."\n" if ($::cnt != 0);

    ## remove comments
    # also remove trailing newline and all whitespace at the
    # beginning of the following line like TeX does it
    s/(?<!\\)%.*?\n[ \t]*//g;

    ## output
    open(O,">$tmp") or return("Can't open $tmp: $!\n");
    print O;
    close O;
}

my $wdiff_cmd = ( "wdiff --avoid-wraps"
                . " --start-delete=\'$delstart\' --end-delete=\'$delend\'"
                . " --start-insert=\'$insstart\' --end-insert=\'$insend\'"
                . " tmp1.$$ tmp2.$$");
$_ = `$wdiff_cmd`;

# Save wdiff output to file if in debug mode
if ($DEBUG) {
  ## save wdiff output
  if (open(O,">$out-wdiff.tex")) {
    print O;
    close O;
  } else {
    print STDERR "Failed to write wdiff output file $out-wdiff.tex.\n";;
  }
}

###
### Phase I: generic processing
###

## remove paragraph boundaries (two newlines) that wdiff falsely inserted
# FIXME: Does wdiff always insert same spacing before deletion and the
# following insertion?!
s/(
    ([ \t]*\n[ \t]*\n[ \t]*)
    $delstart (?!$delend)
    (?: . (?!$delend) )* .
    $delend
  )
  \2
  $insstart
 /$1\n$insstart/gsx;

## keep paragraph boundaries (two newlines) outside of marked blocks
## because it breaks textcoloring (FIXME: this block is unnecessary
## because wdiff never outputs this. Also see merging of empty marks
## below which may result in new paragraph boundaries. -CG 2009/09/25)
if (0) {
while (
  s/( $insstart|$delstart )	# $1: insert or delete block start
    (?{ $::endtoken = ($1 eq $insstart) ? $insend : $delend;
        print "Removing par boundaries.\n" .
              "====Found $1.\n" if $DEBUG;})
    ( (?: (?! $::endtoken | \n ) . )*? ) # $2: followed by some text
    (?{ print "====Some text: '$2' before newline '$3'.\n" if $DEBUG;})
    ([ \t]*\n[ \t]*\n[ \t]*)    # $3: and 2 newlines
    ( (?: (?! $::endtoken ) . )* ) # $4: followed by more text
    $::endtoken 		# and an ending token
 /$1$2$::endtoken$3$1$4$::endtoken/gsx) {}
}

## Restore backslashed Spaces (prevents falsely escaped right braces)
# Escaped spaces '\ ' at the end of an insertion/deletion will result in the
# backslash before the end marker and the space after it. Therefore swap
# whitespace and end marker. (This might falsely make the insertion/deletion
# span the following paragraph boundary, but this will be fixed by the next
# step below).  When the end markers finally get replaced by $tex(ins|del)end,
# which typically is a '}', without this swapping, this would result in escaped
# right braces and LaTeX complaining about a missing right brace.
s/(?<!\\)\\($delend|$insend)(\s+)/\\$2$1/g;


## split up insertions and deletions that span multiple paragraphs
while (
  s/(
      $delstart (?!$delend)
      (?: . (?! [ \t]*\n[ \t]*\n[ \t]* | $delend ) )*? .?
    )
    ([ \t]*\n[ \t]*\n[ \t]*)
   /$1$delend$2$delstart/gsx ) {}

while (
  s/(
      $insstart (?!$insend)
      (?: . (?! [ \t]*\n[ \t]*\n[ \t]* | $insend ) )*? .?
    )
    ([ \t]*\n[ \t]*\n[ \t]*)
   /$1$insend$2$insstart/gsx ) {}


## Handle unpaired braces
# Search for all unpaired braces, meaning, they are inside a text
# deletion or insertion passage, but their counterpart is not within
# that passage. If they are located inside a deletion passage, simply
# delete them.  If there a inside a insertion passage, move them out
# by placing an insertion end marker before and an insertion start
# marker after the brace. In case that a left brace belongs to a
# preceding LaTeX command (plus and any more zero-parameter commands
# directly preceding that command; that's matched by a non-whitespace
# character sequence started by a backslash), also delete resp. move
# that/these command(s) together with the left brace.
#
# FIXME: why is while loop necessary here, but not for handling right braces?
#
# FIXME: If there's not at least one character before the character
# sequence specified in the look-ahead negative assertion, the match
# would stop at the second occurence of that sequence instead of the
# first. This leads to the effect, that the following regular
# expressions may skip $(del|ins)end if it follows directly the left
# brace (+number). The use of *? instead of * mitigates this effect,
# but it's not perfect.

## 1. unpaired left brace inside a deletion: delete brace and any preceding LaTeX command(s)
while (
  s/(						# $1: everything till unpaired '{'
      $delstart (?!$delend)			# would otherwise not detect end marker of empty deletions!
      (?: . (?!$delend))*?
    )
    ( (?<!\\) \\\S* )?				# $2: optional command(s) preceding the '{'
    (?<!\\) \{([0-9]{$w}) (?!\}\3)		# '{' and $3: number
    (						# $4: everything what's remaining
      (?: . (?! (?<!\\)\}\3 | $delend) )*? .?	# will stop at a matching '}', too
      $delend					# won't match if preceeding line found a matching '}'
    )
   /$1$4/sgx ) {}				# remove the '{' with number and any preceeding command(s)

## 2. unpaired left brace inside an insertion: move brace out including any preceding LaTeX command(s)
while (
  s/(
      $insstart (?!$insend)
      (?: . (?!$insend))*?
           )
           ( \s* (?: (?<!\\) \\\S* )? )		# also move preceeding whitespace preceding out
    (?<!\\) \{([0-9]{$w}) (?!\}\3)
    (
      (?: . (?! (?<!\\)\}\3 | $insend) )*? .?
      $insend
    )
   /$1$insend$2\{$3$insstart$4/sgx ) {}		# move the '{' with number and any preceeding command(s) out

## 3. unpaired right brace inside a deletion: delete brace
s/(							# $1: everything till unpaired '}'
    $delstart (?!$delend)				# would otherwise not detect end marker of empty deletions!
    (?> (?:						## grab all paired braces (prevent backtracking):
      (?: . (?! (?<!\\)\{[0-9]{$w} | $delend) )*? .?	# any text till next (unescaped) '{'
      \{([0-9]{$w})					# '{' with $2: number
      (?: . (?! (?<!\\)\}\2        | $delend) )*? .?	#any text till matching '}'
      \}\2						# '}' with same number $2
    )* )						## end of disabled backtracking
    (?: . (?!$delend))*?				# any text
  )
  ( \}[0-9]{$w} )					# $3: the (first) unpaired '}' with number
  (							# $4: everything what's remaining
    (?: . (?!$delend))*? .?
    $delend
  )
 /$1$4/sgx;						# remove the unpaired '}' with number

## 4. unpaired right brace inside an insertion: move brace out
s/(
    $insstart (?! $insend)
    (?> (?:
      (?: . (?! (?<!\\)\{[0-9]{$w} | $insend ) )*? .?
      \{([0-9]{$w})
      (?: . (?! (?<!\\)\}\2        | $insend ) )*? .?
      \}\2
    )* )
    (?: . (?!$insend))*?
  )
  ( \}[0-9]{$w} \s* )				# also move whitespace following the '}' out
  (
    (?: . (?!$insend))*? .?
    $insend
  )
 /$1$insend$3$insstart$4/sgx;				# move the unpaired '}' with number out


## concatenate consecutive insertions and consecutive deletions
# Don't concatenate over paragraph (two newlines) boundaries, since
# the LaTeX macros used to mark changed passages can't span multiple
# paragraphs. Run this before handling LaTeX-commands specifically to
# allow as much of a command inside a single passage as possible.
# FIXME: in below, [^\n] works but not (?<!\n)
s/([^\n])$delend([ \t]*\n?[ \t]*)$delstart/$1$2/g;
s/([^\n])$insend([ \t]*\n?[ \t]*)$insstart/$1$2/g;



###
### Phase II: LaTeX-command specific processing
###

## For COMPLETELY removed/inserted sections, move section command out.
#
# May create empty insertions/removals, therefore execute this before
# the removal of empty (or whitespace only) insertions/removals!
#
# Partly changed section titles have been handled by the preceding
# rules. In case of removal, prevent renumbering by using asterisk
# form; in case of insertion, add a short form without markers to
# prevent problems when LaTeX'ing the diff.
my $sectionre = "chapter|section|subsection|subsubsection|paragraph";
s/
  (						# $1: text before section command
    $delstart (?!$delend)
    (?: . (?!$delend) )*?
  )
  \\($sectionre)				# '\' and $2: section command
  \{([0-9]{$w})					# '{' and $3: number
  ( (?: . (?! (?<!\\)\}\3 | $delend) )*? .? )	# $4: section command parameter (title)
  ( \}\3 \s* )				# '}' and same number plus following whitespace
  /$1$delend\\$2\*\{$3$delstart$4$delend$5$delstart/sgx;
  # move section commmand out and convert command to asterisk form

s/
  (						# $1: text before section command
    $insstart (?!$insend)
    (?: . (?!$insend) )*?
  )
  \\($sectionre)				# '\' and $2: section command
  \{([0-9]{$w})					# '{' and $3: number
  ( (?: . (?! (?<!\\)\}\3 | $insend) )*? .? )	# $4: section command parameter (title)
  ( \}\3 \s* )				# $5: '}' and same number plus following whitespace
  /$1$insend\\$2\[$4\]\{$3$insstart$4$insend$5$insstart/sgx;
  # move sections command out and add short form without markers

s/
  \\($sectionre)				# '\' and $1: section command
  (?{ $::titlecontents = ""; $::optcontents = "" }) # initialize vars
  ( (?: \[ (?: (?! \] ) . )* \]			# $2: optional argument
        (?{ print "====Found \\$1 opt arg '$^N'." if $DEBUG; })
     )? )
  \{([0-9]{$w})    				# '{' and $3: number
  (?:			# Groups text followed by ins or del block
      ( (?! \}\3) (?: (?! \}\3 ) . )*? (?= $insstart | $delstart ) )
      (?{ print "=====Found ins\|del start before section end '$^N'!\n" if $DEBUG;
          $::titlecontents .= $^N; $::optcontents .= $^N })
      (?: ( $delstart (?: (?!$delend) . )* $delend )
        (?{ print "=====Found del end!\n" if $DEBUG;
            $::titlecontents .= $^N }) )?  # dont keep deletions in opt
      (?: $insstart ( (?: (?!$insend) . )* ) $insend
        (?{ print "=====Found ins end '$^N'!\n" if $DEBUG;
            $::titlecontents .= "$insstart$^N$insend"; 
            $::optcontents .= $^N }) )?  # keep insertions in opt
  )+ #  end text + ins or del (need at least one for this to succeed)
  (?: ( (?: (?! \}\3 ) . )+ )
      (?{ print "=====Found text after ins\|del end and before section end: '$^N'!\n" if $DEBUG;
          $::titlecontents .= $^N; $::optcontents .= $^N}) )?
  (?: \}\3)				# '}' and same number
  (?{ print "=====End of \\$1.\n" if $DEBUG;
      $::optcontents = ($2 ne "" ? $2 : $::optcontents ) })
  /\\$1\[$::optcontents\]\{$3$::titlecontents\}$3/sgx;
  # Add a short form with removed insertions and deletions in section commands
  # Will not add the short form if it already exists.

## Remove problematic commands from deletions and move them out of insertions
for my $num (0 .. ($#mycommands>$#stdcommands ? $#mycommands : $#stdcommands)) {
  my $command = "";

  $command .= $mycommands[$num]	 if ($mycommands[$num]                      );
  $command .= "|"                if ($mycommands[$num] && $stdcommands[$num]);
  $command .= $stdcommands[$num] if (                     $stdcommands[$num]);

  next if(!$command);

  s/
    (						# $1: anything before the command
      $delstart (?!$delend)
      (?: . (?!$delend) )*? .?
    )
    (						# $2: the command with all its parameters
      \\(?:$command)				# the command itself (preceded by a '\')
      (?: \[ .*? (?<!\\)\] )*			# any optional parameters (enclosed in '[]')
      (?: \{([0-9]{$w}) .*? (?<!\\)\}\3 ){$num} # $num mandatory parameters
    )
   /$1/gsx;

  s/(
      $insstart (?!$insend)
      (?: . (?!$insend) )*? .?
    )
    (
      \\(?:$command)
      (?: \[ .*? (?<!\\)\] )*
      (?: \{([0-9]{$w}) .*? (?<!\\)\}\3 ){$num}
    )
   /$1$insend$2$insstart/gsx;
}

## CG: optionally leave figure contents intact: remove deletions and keep
## insertions. do not touch the caption command
## => tested with multiple figures
## => tested with multi-captions and no captions. should work with subfig and subfloat

s/( \\begin\{[0-9]{$w}\s*((?:figure|table)\*?)(?{ $::floatname = $^N })\s*\}[0-9]{$w} )	 # begin figure or table line
  (?{ print "=====Found figure!\n" if $DEBUG;
      $::figcontents=$^N })            # Save into variable
  (?: 			# Groups BLOCK + caption command
    (?:			# BLOCK of insert and delete commands until caption
      ( (?! \\caption) (?: (?! $insstart | $delstart | \\caption | \\end\{[0-9]{$w}\s*figure ) . )* )
      (?{ print "=====Found ins\|del start or caption '$^N'!\n" if $DEBUG;
          $::figcontents .= $^N })
      (?: $delstart (?: (?!$delend) . )* $delend
        (?{ print "=====Found del end!\n" if $DEBUG;  }) )?  # dont keep deletions
      (?: $insstart ( (?: (?!$insend) . )* ) $insend
        (?{ print "=====Found ins end '$^N'!\n" if $DEBUG; $::figcontents .= $^N }) )?  # keep insertions
    )*?			#  end BLOCK
    (?: (\\caption (?: \[ (?: (?! (?<!\\) \]) . )* \])? \s* 
      \{ ([0-9]{$w}) (?{ $::captiondepth=$^N })
      (?: (?! \}(??{ $::captiondepth })) . )* \}(??{$::captiondepth}) )
      (?{ print "=====" . pos() . ": Found caption ($::captiondepth) '$^N'!\n" if $DEBUG; $::figcontents .= $^N }) )?  	 # caption
  )*?			# end BLOCK + caption
  ( \\end\{[0-9]{$w}\s*figure\*?\s*\}[0-9]{$w} )
  (?{ print "=====Found figure end '$^N'!\n" if $DEBUG; $::figcontents .= $^N })
  /$::figcontents/gsx;

###
### Phase III: cleaup, conversion, output
###

## remove insertions and removals that are empty or only mark whitespace
s/$delstart(\s*)$delend/$1/g;
s/$insstart(\s*)$insend/$1/g;

## remove brace numbers (REGEXPS BELOW HERE SHOULD NOT NEED TO MATCH BRACES)
s/(?<!\\)(?:(\{|\})[0-9]{$w})/$1/g;

## replace edit marks with actual LaTeX code in the body of the
## document
sub placeFinalLatexCodeBody() {
  local $_ = shift;

  ## substitute final LaTeX macro code
  s/$delstart/$texdelstart/g;
  s/$delend/$texdelend/g;
  s/$insstart/$texinsstart/g;
  s/$insend/$texinsend/g;

  return $_;
}

my $date = strftime "%a %b %e %H:%M:%S %Y", localtime;
## replace edit marks with special LaTeX code in the preamble
sub placeFinalLatexCodePreamble() {
  local $_ = shift;

  ## replace old preamble contents with commented out latex code
  s/$delstart (?{ $::delcontents = "" })
    (?: ( (?: (?! $delend | \n) . )* )
      (?{ $::delcontents .= "%% $^N\n" }) \n? )* $delend
    (?{ print "=====Found del end!\n" if $DEBUG;  })
    /%% DELETE START from texdiff on $date\n$::delcontents%% DELETE END from texdiff on $date\n/sxg;

  ## add text indicating insertion marks and keep them
  s/$insstart/%% INSERT START from texdiff on $date\n/g;
  s/$insend/\n%% INSERT END from texdiff on $date\n/g;

  return $_;
}

if (/\\begin{document}/) {
  print "Found \\begin{document}\n" if ( $DEBUG );
  s/^ ( (?: (?! \\begin{document}) . )* ) # $1: everything before
   ( \\begin{document} )	          # $2: begin statement
   ( (?: (?! \\end{document}) . )* )      # $3: everything after
   /&placeFinalLatexCodePreamble($1) . "$2" .
    &placeFinalLatexCodeBody($3)/esgx;
} else {
  $_ = &placeFinalLatexCodeBody($_);
}

## Insert preamble if the document contains the \documentclass command
s/( \\documentclass(?: \[ (?: (?! (?<!\\) \]) . )* \])?
        { (?: (?! (?<!\\) \}) . )* } ) # $1: documentclass command
 /$1\n$docpreamble/sx;


## output
if ($out ne "") {
  if (open(O,">$out")) {
    print O;
    close O;
  } else {
    print STDERR "Failed to write output file $out.\n";
  }
} else {
  print ;
}

## remove temp files
if (!$DEBUG) {
  unlink('tmp1.'.$$);
  unlink('tmp2.'.$$);
}