document/util/htmldiff.pl - external/github.com/WebAssembly/spec - Git at Google


            
            #!/usr/bin/perl

            
            #

            
            # htmldiff - present a diff marked version of two html documents

            
            #

            
            # Copyright (c) 1998-2006 MACS, Inc.

            
            #

            
            # Copyright (c) 2007 SiSco, Inc.

            
            #

            
            # Permission is hereby granted, free of charge, to any person obtaining

            
            # a copy of this software and associated documentation files (the

            
            # "Software"), to deal in the Software without restriction, including

            
            # without limitation the rights to use, copy, modify, merge, publish,

            
            # distribute, sublicense, and/or sell copies of the Software, and to

            
            # permit persons to whom the Software is furnished to do so, subject to

            
            # the following conditions:

            
            #

            
            # The above copyright notice and this permission notice shall be

            
            # included in all copies or substantial portions of the Software.

            
            #

            
            # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

            
            # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

            
            # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

            
            # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE

            
            # LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION

            
            # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

            
            # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

            
            #

            
            # See http://www.themacs.com for more information.

            
            #

            
            # usage: htmldiff [[-c] [-l] [-o] oldversion newversion [output]]

            
            #

            
            # -c - disable metahtml comment processing

            
            # -o - disable outputting of old text

            
            # -l - use navindex to create sequence of diffs

            
            # oldversion - the previous version of the document

            
            # newversion - the newer version of the document

            
            # output - a filename to place the output in. If omitted, the output goes to

            
            #          standard output.

            
            #

            
            # if invoked with no options or arguments, operates as a CGI script. It then

            
            # takes the following parameters:

            
            #

            
            # oldfile - the URL of the original file

            
            # newfile - the URL of the new file

            
            # mhtml - a flag to indicate whether it should be aware of MetaHTML comments.

            
            #

            
            # requires GNU diff utility

            
            # also requires the perl modules Getopt::Std

            
            #

            
            # NOTE: The markup created by htmldiff may not validate against the HTML 4.0

            
            # DTD. This is because the algorithm is relatively simple, and there are

            
            # places in the markup content model where the span element is not allowed.

            
            # Htmldiff is NOT aware of these places.

            
            #

            
            # $Source: /u/sources/public/2009/htmldiff/htmldiff.pl,v $

            
            # $Revision: 1.7 $

            
            #

            
            # $Log: htmldiff.pl,v $

            
            # Revision 1.7  2018/05/17 14:17:56  dom

            
            # Summary: take into account no </head>

            
            #

            
            # Revision 1.6  2018/05/17 13:53:51  dom

            
            # Switch from tidy to html5lib for preparing to htmldiff

            
            #

            
            # also, adapt a more robust approach to including diff style/script

            
            #

            
            # Revision 1.5  2017/03/30 09:04:03  dom

            
            # Summary: Update link to navigation script

            
            #

            
            # Revision 1.4  2017/02/10 10:48:41  dom

            
            # Remove :focus rule per Simon Pieters request

            
            #

            
            # Revision 1.3  2016/10/24 15:06:51  dom

            
            # Summary: Use nav script always

            
            #

            
            # Revision 1.2  2016/10/24 15:04:28  dom

            
            # Add navigation script

            
            #

            
            # Revision 1.1  2014-01-06 08:04:51  dom

            
            # added copy of htmldiff perl script since aptest.com repo no longer available

            
            #

            
            # Revision 1.5  2008/03/05 13:23:16  ahby

            
            # Fixed a problem with leading whitespace before markup.

            
            #

            
            # Revision 1.4  2007/12/13 13:09:16  ahby

            
            # Updated copyright and license.

            
            #

            
            # Revision 1.3  2007/12/13 12:53:34  ahby

            
            # Changed use of span to ins and del

            
            #

            
            # Revision 1.2  2002/02/13 16:27:23  ahby

            
            # Changed processing model.

            
            # Improved handling of old text and changed styles.

            
            #

            
            # Revision 1.1  2000/07/12 12:20:04  ahby

            
            # Updated to remove empty spans - this fixes validation problems under

            
            # strict.

            
            #

            
            # Revision 1.11  1999/12/08 19:46:45  ahby

            
            # Fixed validation errors introduced by placing markup where it didn't

            
            # belong.

            
            #

            
            # Revision 1.10  1999/10/18 13:42:58  ahby

            
            # Added -o to the usage message.

            
            #

            
            # Revision 1.9  1999/05/04 12:29:11  ahby

            
            # Added an option to turn off the display of old text.

            
            #

            
            # Revision 1.8  1999/04/09 14:37:27  ahby

            
            # Fixed a perl syntax error.

            
            #

            
            # Revision 1.7  1999/04/09 14:35:49  ahby

            
            # Added reference to MACS homepage.

            
            #

            
            # Revision 1.6  1999/04/09 14:35:09  ahby

            
            # Added comment about validity of generated markup.

            
            #

            
            # Revision 1.5  1999/02/22 22:17:54  ahby

            
            # Changed to use stylesheets.

            
            # Changed to rely upon span.

            
            # Changed to work around content model problems.

            
            #

            
            # Revision 1.4  1999/02/08 02:32:22  ahby

            
            # Added a copyright statement.

            
            #

            
            # Revision 1.3  1999/02/08 02:30:40  ahby

            
            # Added header processing.

            
            #

            
            # Revision 1.2  1998/12/10 17:31:31  ahby

            
            # Fixed to escape less-thans in change blocks and to not permit change

            
            # markup within specific elements (like TITLE).

            
            #

            
            # Revision 1.1  1998/11/26 00:09:22  ahby

            
            # Initial revision

            
            #

            
            #


            use Getopt::Std;


            sub usage {

            
            	print STDERR "htmldiff [-c] [-o] oldversion newversion [output]\n";

            
            	exit;

            
            }


            sub url_encode {

            
                my $str = shift;

            
                $str =~ s/([\x00-\x1f\x7F-\xFF])/

            
                             sprintf ('%%%02x', ord ($1))/eg;

            
                return $str;

            
            }


            # markit - diff-mark the streams

            
            #

            
            # markit(file1, file2)

            
            #

            
            # markit relies upon GNUdiff to mark up the text.

            
            #

            
            # The markup is encoded using special control sequences:

            
            #

            
            #   a block wrapped in control-a is deleted text

            
            #   a block wrapped in control-b is old text

            
            #   a block wrapped in control-c is new text

            
            #

            
            # The main processing loop attempts to wrap the text blocks in appropriate

            
            # SPANs based upon the type of text that it is.

            
            #

            
            # When the loop encounters a < in the text, it stops the span. Then it outputs

            
            # the element that is defined, then it restarts the span.


            sub markit {

            
            	my $retval = "";

            
            	my($file1) = shift;

            
            	my($file2) = shift;

            
            #	my $old="<span class=\\\"diff-old-a\\\">deleted text: </span>%c'\012'%c'\001'%c'\012'%<%c'\012'%c'\001'%c'\012'";

            
            	my $old="%c'\012'%c'\001'%c'\012'%<%c'\012'%c'\001'%c'\012'";

            
            	my $new="%c'\012'%c'\003'%c'\012'%>%c'\012'%c'\003'%c'\012'";

            
            	my $unchanged="%=";

            
            	my $changed="%c'\012'%c'\001'%c'\012'%<%c'\012'%c'\001'%c'\012'%c'\004'%c'\012'%>%c'\012'%c'\004'%c'\012'";

            
            	if ($opt_o) {

            
            		$old = "";

            
            		$changed = "%c'\012'%c'\004'%c'\012'%>%c'\012'%c'\004'%c'\012'";

            
            	}

            
            #	my $old="%c'\002'<font color=\\\"purple\\\" size=\\\"-2\\\">deleted text:</font><s>%c'\012'%c'\001'%c'\012'%<%c'\012'%c'\001'%c'\012'</s>%c'\012'%c'\002'";

            
            #	my $new="%c'\002'<font color=\\\"purple\\\"><u>%c'\012'%c'\002'%>%c'\002'</u></font>%c'\002'%c'\012'";

            
            #	my $unchanged="%=";

            
            #	my $changed="%c'\002'<s>%c'\012'%c'\001'%c'\012'%<%c'\012'%c'\001'%c'\012'</s><font color=\\\"purple\\\"><u>%c'\002'%c'\012'%>%c'\012'%c'\002'</u></font>%c'\002'%c'\012'";


            	my @span;

            
            	$span[0]="</span>";

            
            	$span[1]="<del class=\"diff-old\">";

            
            	$span[2]="<del class=\"diff-old\">";

            
            	$span[3]="<ins class=\"diff-new\">";

            
            	$span[4]="<ins class=\"diff-chg\">";


            	my @diffEnd ;

            
            	$diffEnd[1] = '</del>';

            
            	$diffEnd[2] = '</del>';

            
            	$diffEnd[3] = '</ins>';

            
            	$diffEnd[4] = '</ins>';


            	my $diffcounter = 0;


            	open(FILE, qq(diff -d --old-group-format="$old" --new-group-format="$new" --changed-group-format="$changed" --unchanged-group-format="$unchanged" $file1 $file2 |)) || die("Diff failed: $!");

            
            #	system (qq(diff --old-group-format="$old" --new-group-format="$new" --changed-group-format="$changed" --unchanged-group-format="$unchanged" $file1 $file2 > /tmp/output));


            	my $state = 0;

            
            	my $inblock = 0;

            
            	my $temp = "";

            
            	my $lineCount = 0;


            # strategy:

            
            #

            
            # process the output of diff...

            
            #

            
            # a link with control A-D means the start/end of the corresponding ordinal

            
            # state (1-4). Resting state is state 0.

            
            #

            
            # While in a state, accumulate the contents for that state. When exiting the

            
            # state, determine if it is appropriate to emit the contents with markup or

            
            # not (basically, if the accumulated buffer contains only empty lines or lines

            
            # with markup, then we don't want to emit the wrappers.  We don't need them.

            
            #

            
            # Note that if there is markup in the "old" block, that markup is silently

            
            # removed.  It isn't really that interesting, and it messes up the output

            
            # something fierce.


            	while (<FILE>) {

            
            		my $anchor = $opt_l ? qq[<a tabindex="$diffcounter">] : "" ;

            
            		my $anchorEnd = $opt_l ? q[</a>] : "" ;

            
            		$lineCount ++;

            
            		if ($state == 0) {	# if we are resting and we find a marker,

            
            							# then we must be entering a block

            
            			if (m/^([\001-\004])/) {

            
            				$state = ord($1);

            
            				$_ = "";

            
            			}

            
            #			if (m/^\001/) {

            
            #				$state = 1;

            
            #				s/^/$span[1]/;

            
            #			} elsif (m/^\002/) {

            
            #				$state = 2;

            
            #				s/^/$span[2]/;

            
            #			} elsif (m/^\003/) {

            
            #				$state = 3;

            
            #				s/^/$span[3]/;

            
            #			} elsif (m/^\004/) {

            
            #				$state = 4;

            
            #				s/^/$span[4]/;

            
            #			}

            
            		} else {

            
            			# if we are in "old" state, remove markup

            
            			if (($state == 1) || ($state == 2)) {

            
            				s/\<.*\>//;	# get rid of any old markup

            
            				s/\</&lt;/g; # escape any remaining STAG or ETAGs

            
            				s/\>/&gt;/g;

            
            			}

            
            			# if we found another marker, we must be exiting the state

            
            			if (m/^([\001-\004])/) {

            
            				if ($temp ne "") {

            
            					$_ = $span[$state] . $anchor . $temp . $anchorEnd . $diffEnd[$state] . "\n";

            
            					$temp = "";

            
            				} else {

            
            					$_ = "" ;

            
            				}

            
            				$state = 0;

            
            			} elsif (m/^\s*\</) { # otherwise, is this line markup?

            
            				# if it is markup AND we haven't seen anything else yet,

            
            				# then we will emit the markup

            
            				if ($temp eq "") {

            
            					$retval .= $_;

            
            					$_ = "";

            
            				} else {	# we wrap it with the state switches and hold it

            
            					s/^/$anchorEnd$diffEnd[$state]/;

            
            					s/$/$span[$state]$anchor/;

            
            					$temp .= $_;

            
            					$_ = "";

            
            				}

            
            			} else {

            
            				if (m/.+/) {

            
            					$temp .= $_;

            
            					$_ = "";

            
            				}

            
            			}

            
            		}


            		s/\001//g;

            
            		s/\002//g;

            
            		s/\003//g;

            
            		s/\004//g;

            
            		if ($_ !~ m/^$/) {

            
            			$retval .= $_;

            
            		}

            
            		$diffcounter++;

            
            	}

            
            	close FILE;

            
            	$retval =~ s/$span[1]\n+$diffEnd[1]//g;

            
            	$retval =~ s/$span[2]\n+$diffEnd[2]//g;

            
            	$retval =~ s/$span[3]\n+$diffEnd[3]//g;

            
            	$retval =~ s/$span[4]\n+$diffEnd[4]//g;

            
            	$retval =~ s/$span[1]\n*$//g;

            
            	$retval =~ s/$span[2]\n*$//g;

            
            	$retval =~ s/$span[3]\n*$//g;

            
            	$retval =~ s/$span[4]\n*$//g;

            
            	return $retval;

            
            }


            sub splitit {

            
            	my $filename = shift;

            
            	my $headertmp = shift;

            
            	my $inheader=0;

            
            	my $preformatted=0;

            
            	my $inelement=0;

            
            	my $retval = "";

            
            	my $styles = q(<style type='text/css'>

            
            .diff-old-a {

            
              font-size: smaller;

            
              color: red;

            
            }


            .diff-new { background-color: yellow; }

            
            .diff-chg { background-color: lime; }

            
            .diff-new:before,

            
            .diff-new:after

            
                { content: "\2191" }

            
            .diff-chg:before, .diff-chg:after

            
                { content: "\2195" }

            
            .diff-old { text-decoration: line-through; background-color: #FBB; }

            
            .diff-old:before,

            
            .diff-old:after

            
                { content: "\2193" }

            
            </style>

            
            <script src="https://w3c.github.io/htmldiff-nav/index.js"></script>);

            
            	if ($opt_t) {

            
            		$styles .= q(

            
            <script type="text/javascript">

            
            <!--

            
            function setOldDisplay() {

            
            	for ( var s = 0; s < document.styleSheets.length; s++ ) {

            
            		var css = document.styleSheets[s];

            
            		var mydata ;

            
            		try { mydata = css.cssRules ;

            
            		if ( ! mydata ) mydata = css.rules;

            
            		for ( var r = 0; r < mydata.length; r++ ) {

            
            			if ( mydata[r].selectorText == '.diff-old' ) {

            
            				mydata[r].style.display = ( mydata[r].style.display == '' ) ? 'none'

            
            : '';

            
            				return;

            
            			}

            
            		}

            
            		} catch(e) {} ;

            
            	}

            
            }

            
            -->

            
            </script>

            
            );


            	}


            	if ($stripheader) {

            
            		open(HEADER, ">$headertmp");

            
            	}


            	my $incomment = 0;

            
                    my $styleprinted = 0;

            
            	my $inhead = 1;

            
            	open(FILE, $filename) || die("File $filename cannot be opened: $!");

            
            	while (<FILE>) {

            
            		if ($inhead == 1) {

            
            			if (m/\<\/head/i) {

            
                                            s/\<\/head/$styles\<\/head/i;

            
                                            $styleprinted = 1;

            
            			}

            
            			if (m/\<body/i) {

            
                                            if (!$styleprinted) {

            
                                                  s/\<body/$styles\<body/i;

            
                                            }

            
            				$inhead = 0;

            
            				print HEADER;

            
            				if ($opt_t) {

            
            					print HEADER q(

            
            <form action=""><input type="button" onclick="setOldDisplay()" value="Show/Hide Old Content" /></form>

            
            );

            
            				}

            
            				close HEADER;

            
            			} else {

            
            				print HEADER;

            
            			}

            
            		} else {

            
            			if ($incomment) {

            
            				if (m;-->;) {

            
            					$incomment = 0;

            
            					s/.*-->//;

            
            				} else {

            
            					next;

            
            				}

            
            			}

            
            			if (m;<!--;) {

            
            				while (m;<!--.*-->;) {

            
            					s/<!--.*?-->//;

            
            				}

            
            				if (m;<!--; ) {

            
            					$incomment = 1;

            
            					s/<!--.*//;

            
            				}

            
            			}

            
            			if (m/\<pre/i) {

            
            				$preformatted = 1;

            
            			}

            
            			if (m/\<\/pre\>/i) {

            
            				$preformatted = 0;

            
            			}

            
            			if ($preformatted) {

            
            				$retval .= $_;

            
            			} elsif ($mhtmlcomments && /^;;;/) {

            
            				$retval .= $_;

            
            			} else {

            
            				my @list = split(' ');

            
            				foreach $element (@list) {

            
            					if ($element =~ m/\<H[1-6]/i) {

            
            #						$inheader = 1;

            
            					}

            
            					if ($inheader == 0) {

            
            						$element =~ s/</\n</g;

            
            						$element =~ s/^\n//;

            
            						$element =~ s/>/>\n/g;

            
            						$element =~ s/\n$//;

            
            						$element =~ s/>\n([.,:!]+)/>$1/g;

            
            					}

            
            					if ($element =~ m/\<\/H[1-6]\>/i) {

            
            						$inheader = 0;

            
            					}

            
            					$retval .= "$element";

            
            					$inelement += ($element =~ s/</&lt;/g);

            
            					$inelement -= ($element =~ s/>/&gt;/g);

            
            					if ($inelement < 0) {

            
            						$inelement = 0;

            
            					}

            
            					if (($inelement == 0) && ($inheader == 0)) {

            
            						$retval .= "\n";

            
            					} else {

            
            						$retval .= " ";

            
            					}

            
            				}

            
            			undef @list;

            
            			}

            
            		}

            
            	}

            
            	$retval .= "\n";

            
            	close FILE;

            
            	return $retval;

            
            }


            $mhtmlcomments = 1;


            sub cli {

            
            	getopts("clto") || usage();


            	if ($opt_c) {$mhtmlcomments = 0;}


            	if (@ARGV < 2) { usage(); }


            	$file1 = $ARGV[0];

            
            	$file2 = $ARGV[1];

            
            	$file3 = $ARGV[2];


            	$tmp = splitit($file1, $headertmp1);

            
            	open (FILE, ">$tmp1");

            
            	print FILE $tmp;

            
            	close FILE;


            	$tmp = splitit($file2, $headertmp2);

            
            	open (FILE, ">$tmp2");

            
            	print FILE $tmp;

            
            	close FILE;


            	$output = "";


            	if ($stripheader) {

            
            		open(FILE, $headertmp2);

            
            		while (<FILE>) {

            
            			$output .= $_;

            
            		}

            
            		close(FILE);

            
            	}


            	$output .= markit($tmp1, $tmp2);


            	if ($file3) {

            
            		open(FILE, ">$file3");

            
            		print FILE $output;

            
            		close FILE;

            
            	} else {

            
            		print $output;

            
            	}

            
            }


            sub cgi {

            
            #	use LWP::UserAgent;

            
            #	use CGI;


            	my $query = new CGI;

            
            	my $url1 = $query->param("oldfile");

            
            	my $url2 = $query->param("newfile");

            
            	my $mhtml = $query->param("mhtml");


            	my $file1 = "/tmp/htdcgi1.$$";

            
            	my $file2 = "/tmp/htdcgi2.$$";


            	my $ua = new LWP::UserAgent;

            
            	$ua->agent("MACS, Inc. HTMLdiff/0.9 " . $ua->agent);


            	# Create a request


            	my $req1 = new HTTP::Request GET => $url1;


            	my $res1 = $ua->request($req1, $file1);

            
            	if ($res1->is_error) {

            
            		print $res1->error_as_HTML();

            
            		print "<p>The URL $url1 could not be found.  Please check it and try again.</p>";

            
            		return;

            
            	}


            	my $req2 = new HTTP::Request GET => $url2;


            	my $res2 = $ua->request($req2, $file2);

            
            	if ($res2->is_error) {

            
            		print $res2->error_as_HTML();

            
            		print "<p>The URL $url2 could not be found.  Please check it and try again.</p>";

            
            		return;

            
            	}


            	$split1 = splitit($file1, $headertmp1);

            
            	open (FILE, ">$tmp1");

            
            	print FILE $split1;

            
            	close FILE;


            	$split2 = splitit($file2, $headertmp2);

            
            	open (FILE, ">$tmp2");

            
            	print FILE $split2;

            
            	close FILE;


            	$output = "";


            	if ($stripheader) {

            
            		open(FILE, $headertmp2);

            
            		while (<FILE>) {

            
            			$output .= $_;

            
            		}

            
            		close(FILE);

            
            	}


            	$output .= markit($tmp1, $tmp2);


            	my $base=$res2->base;


            	if ($base !~ /\/$/) {

            
            		$base =~ s/[^\/]*$//;

            
            	}


            	if ( $output !~ /<base/i ) {

            
            		$output =~ s/<head>/<head>\n<base href="$base">/i ||

            
            	  	$output =~ s/<html>/<html>\n<base href="$base">/i ;

            
            	}


            	print $query->header(-type=>'text/html',-nph=>1);

            
            	print $output;


            	unlink $file1;

            
            	unlink $file2;


            }


            $tmp1="/tmp/htdtmp1.$$";

            
            $headertmp1="/tmp/htdhtmp1.$$";

            
            $tmp2="/tmp/htdtmp2.$$";

            
            $headertmp2="/tmp/htdhtmp2.$$";

            
            $stripheader = 1;


            if (@ARGV == 0) {

            
            	cgi();		# if no arguments, we must be operating as a cgi script

            
            } else {

            
            	cli();		# if there are arguments, then we are operating as a CLI

            
            }


            unlink $tmp1;

            
            unlink $headertmp1;

            
            unlink $tmp2;

            
            unlink $headertmp2;
	#!/usr/bin/perl
	#
	# htmldiff - present a diff marked version of two html documents
	#
	# Copyright (c) 1998-2006 MACS, Inc.
	#
	# Copyright (c) 2007 SiSco, Inc.
	#
	# Permission is hereby granted, free of charge, to any person obtaining
	# a copy of this software and associated documentation files (the
	# "Software"), to deal in the Software without restriction, including
	# without limitation the rights to use, copy, modify, merge, publish,
	# distribute, sublicense, and/or sell copies of the Software, and to
	# permit persons to whom the Software is furnished to do so, subject to
	# the following conditions:
	#
	# The above copyright notice and this permission notice shall be
	# included in all copies or substantial portions of the Software.
	#
	# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
	# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
	# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
	# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	#
	# See http://www.themacs.com for more information.
	#
	# usage: htmldiff [[-c] [-l] [-o] oldversion newversion [output]]
	#
	# -c - disable metahtml comment processing
	# -o - disable outputting of old text
	# -l - use navindex to create sequence of diffs
	# oldversion - the previous version of the document
	# newversion - the newer version of the document
	# output - a filename to place the output in. If omitted, the output goes to
	# standard output.
	#
	# if invoked with no options or arguments, operates as a CGI script. It then
	# takes the following parameters:
	#
	# oldfile - the URL of the original file
	# newfile - the URL of the new file
	# mhtml - a flag to indicate whether it should be aware of MetaHTML comments.
	#
	# requires GNU diff utility
	# also requires the perl modules Getopt::Std
	#
	# NOTE: The markup created by htmldiff may not validate against the HTML 4.0
	# DTD. This is because the algorithm is relatively simple, and there are
	# places in the markup content model where the span element is not allowed.
	# Htmldiff is NOT aware of these places.
	#
	# $Source: /u/sources/public/2009/htmldiff/htmldiff.pl,v $
	# $Revision: 1.7 $
	#
	# $Log: htmldiff.pl,v $
	# Revision 1.7 2018/05/17 14:17:56 dom
	# Summary: take into account no </head>
	#
	# Revision 1.6 2018/05/17 13:53:51 dom
	# Switch from tidy to html5lib for preparing to htmldiff
	#
	# also, adapt a more robust approach to including diff style/script
	#
	# Revision 1.5 2017/03/30 09:04:03 dom
	# Summary: Update link to navigation script
	#
	# Revision 1.4 2017/02/10 10:48:41 dom
	# Remove :focus rule per Simon Pieters request
	#
	# Revision 1.3 2016/10/24 15:06:51 dom
	# Summary: Use nav script always
	#
	# Revision 1.2 2016/10/24 15:04:28 dom
	# Add navigation script
	#
	# Revision 1.1 2014-01-06 08:04:51 dom
	# added copy of htmldiff perl script since aptest.com repo no longer available
	#
	# Revision 1.5 2008/03/05 13:23:16 ahby
	# Fixed a problem with leading whitespace before markup.
	#
	# Revision 1.4 2007/12/13 13:09:16 ahby
	# Updated copyright and license.
	#
	# Revision 1.3 2007/12/13 12:53:34 ahby
	# Changed use of span to ins and del
	#
	# Revision 1.2 2002/02/13 16:27:23 ahby
	# Changed processing model.
	# Improved handling of old text and changed styles.
	#
	# Revision 1.1 2000/07/12 12:20:04 ahby
	# Updated to remove empty spans - this fixes validation problems under
	# strict.
	#
	# Revision 1.11 1999/12/08 19:46:45 ahby
	# Fixed validation errors introduced by placing markup where it didn't
	# belong.
	#
	# Revision 1.10 1999/10/18 13:42:58 ahby
	# Added -o to the usage message.
	#
	# Revision 1.9 1999/05/04 12:29:11 ahby
	# Added an option to turn off the display of old text.
	#
	# Revision 1.8 1999/04/09 14:37:27 ahby
	# Fixed a perl syntax error.
	#
	# Revision 1.7 1999/04/09 14:35:49 ahby
	# Added reference to MACS homepage.
	#
	# Revision 1.6 1999/04/09 14:35:09 ahby
	# Added comment about validity of generated markup.
	#
	# Revision 1.5 1999/02/22 22:17:54 ahby
	# Changed to use stylesheets.
	# Changed to rely upon span.
	# Changed to work around content model problems.
	#
	# Revision 1.4 1999/02/08 02:32:22 ahby
	# Added a copyright statement.
	#
	# Revision 1.3 1999/02/08 02:30:40 ahby
	# Added header processing.
	#
	# Revision 1.2 1998/12/10 17:31:31 ahby
	# Fixed to escape less-thans in change blocks and to not permit change
	# markup within specific elements (like TITLE).
	#
	# Revision 1.1 1998/11/26 00:09:22 ahby
	# Initial revision
	#
	#

	use Getopt::Std;

	sub usage {
	print STDERR "htmldiff [-c] [-o] oldversion newversion [output]\n";
	exit;
	}

	sub url_encode {
	my $str = shift;
	$str =~ s/([\x00-\x1f\x7F-\xFF])/
	sprintf ('%%%02x', ord ($1))/eg;
	return $str;
	}

	# markit - diff-mark the streams
	#
	# markit(file1, file2)
	#
	# markit relies upon GNUdiff to mark up the text.
	#
	# The markup is encoded using special control sequences:
	#
	# a block wrapped in control-a is deleted text
	# a block wrapped in control-b is old text
	# a block wrapped in control-c is new text
	#
	# The main processing loop attempts to wrap the text blocks in appropriate
	# SPANs based upon the type of text that it is.
	#
	# When the loop encounters a < in the text, it stops the span. Then it outputs
	# the element that is defined, then it restarts the span.

	sub markit {
	my $retval = "";
	my($file1) = shift;
	my($file2) = shift;
	# my $old="<span class=\\\"diff-old-a\\\">deleted text: </span>%c'\012'%c'\001'%c'\012'%<%c'\012'%c'\001'%c'\012'";
	my $old="%c'\012'%c'\001'%c'\012'%<%c'\012'%c'\001'%c'\012'";
	my $new="%c'\012'%c'\003'%c'\012'%>%c'\012'%c'\003'%c'\012'";
	my $unchanged="%=";
	my $changed="%c'\012'%c'\001'%c'\012'%<%c'\012'%c'\001'%c'\012'%c'\004'%c'\012'%>%c'\012'%c'\004'%c'\012'";
	if ($opt_o) {
	$old = "";
	$changed = "%c'\012'%c'\004'%c'\012'%>%c'\012'%c'\004'%c'\012'";
	}
	# my $old="%c'\002'<font color=\\\"purple\\\" size=\\\"-2\\\">deleted text:</font><s>%c'\012'%c'\001'%c'\012'%<%c'\012'%c'\001'%c'\012'</s>%c'\012'%c'\002'";
	# my $new="%c'\002'<font color=\\\"purple\\\"><u>%c'\012'%c'\002'%>%c'\002'</u></font>%c'\002'%c'\012'";
	# my $unchanged="%=";
	# my $changed="%c'\002'<s>%c'\012'%c'\001'%c'\012'%<%c'\012'%c'\001'%c'\012'</s><font color=\\\"purple\\\"><u>%c'\002'%c'\012'%>%c'\012'%c'\002'</u></font>%c'\002'%c'\012'";

	my @span;
	$span[0]="</span>";
	$span[1]="<del class=\"diff-old\">";
	$span[2]="<del class=\"diff-old\">";
	$span[3]="<ins class=\"diff-new\">";
	$span[4]="<ins class=\"diff-chg\">";

	my @diffEnd ;
	$diffEnd[1] = '</del>';
	$diffEnd[2] = '</del>';
	$diffEnd[3] = '</ins>';
	$diffEnd[4] = '</ins>';

	my $diffcounter = 0;

	open(FILE, qq(diff -d --old-group-format="$old" --new-group-format="$new" --changed-group-format="$changed" --unchanged-group-format="$unchanged" $file1 $file2 \|)) \|\| die("Diff failed: $!");
	# system (qq(diff --old-group-format="$old" --new-group-format="$new" --changed-group-format="$changed" --unchanged-group-format="$unchanged" $file1 $file2 > /tmp/output));

	my $state = 0;
	my $inblock = 0;
	my $temp = "";
	my $lineCount = 0;

	# strategy:
	#
	# process the output of diff...
	#
	# a link with control A-D means the start/end of the corresponding ordinal
	# state (1-4). Resting state is state 0.
	#
	# While in a state, accumulate the contents for that state. When exiting the
	# state, determine if it is appropriate to emit the contents with markup or
	# not (basically, if the accumulated buffer contains only empty lines or lines
	# with markup, then we don't want to emit the wrappers. We don't need them.
	#
	# Note that if there is markup in the "old" block, that markup is silently
	# removed. It isn't really that interesting, and it messes up the output
	# something fierce.

	while (<FILE>) {
	my $anchor = $opt_l ? qq[<a tabindex="$diffcounter">] : "" ;
	my $anchorEnd = $opt_l ? q[</a>] : "" ;
	$lineCount ++;
	if ($state == 0) { # if we are resting and we find a marker,
	# then we must be entering a block
	if (m/^([\001-\004])/) {
	$state = ord($1);
	$_ = "";
	}
	# if (m/^\001/) {
	# $state = 1;
	# s/^/$span[1]/;
	# } elsif (m/^\002/) {
	# $state = 2;
	# s/^/$span[2]/;
	# } elsif (m/^\003/) {
	# $state = 3;
	# s/^/$span[3]/;
	# } elsif (m/^\004/) {
	# $state = 4;
	# s/^/$span[4]/;
	# }
	} else {
	# if we are in "old" state, remove markup
	if (($state == 1) \|\| ($state == 2)) {
	s/\<.*\>//; # get rid of any old markup
	s/\</</g; # escape any remaining STAG or ETAGs
	s/\>/>/g;
	}
	# if we found another marker, we must be exiting the state
	if (m/^([\001-\004])/) {
	if ($temp ne "") {
	$_ = $span[$state] . $anchor . $temp . $anchorEnd . $diffEnd[$state] . "\n";
	$temp = "";
	} else {
	$_ = "" ;
	}
	$state = 0;
	} elsif (m/^\s*\</) { # otherwise, is this line markup?
	# if it is markup AND we haven't seen anything else yet,
	# then we will emit the markup
	if ($temp eq "") {
	$retval .= $_;
	$_ = "";
	} else { # we wrap it with the state switches and hold it
	s/^/$anchorEnd$diffEnd[$state]/;
	s/$/$span[$state]$anchor/;
	$temp .= $_;
	$_ = "";
	}
	} else {
	if (m/.+/) {
	$temp .= $_;
	$_ = "";
	}
	}
	}

	s/\001//g;
	s/\002//g;
	s/\003//g;
	s/\004//g;
	if ($_ !~ m/^$/) {
	$retval .= $_;
	}
	$diffcounter++;
	}
	close FILE;
	$retval =~ s/$span[1]\n+$diffEnd[1]//g;
	$retval =~ s/$span[2]\n+$diffEnd[2]//g;
	$retval =~ s/$span[3]\n+$diffEnd[3]//g;
	$retval =~ s/$span[4]\n+$diffEnd[4]//g;
	$retval =~ s/$span[1]\n*$//g;
	$retval =~ s/$span[2]\n*$//g;
	$retval =~ s/$span[3]\n*$//g;
	$retval =~ s/$span[4]\n*$//g;
	return $retval;
	}

	sub splitit {
	my $filename = shift;
	my $headertmp = shift;
	my $inheader=0;
	my $preformatted=0;
	my $inelement=0;
	my $retval = "";
	my $styles = q(<style type='text/css'>
	.diff-old-a {
	font-size: smaller;
	color: red;
	}

	.diff-new { background-color: yellow; }
	.diff-chg { background-color: lime; }
	.diff-new:before,
	.diff-new:after
	{ content: "\2191" }
	.diff-chg:before, .diff-chg:after
	{ content: "\2195" }
	.diff-old { text-decoration: line-through; background-color: #FBB; }
	.diff-old:before,
	.diff-old:after
	{ content: "\2193" }
	</style>
	<script src="https://w3c.github.io/htmldiff-nav/index.js"></script>);
	if ($opt_t) {
	$styles .= q(
	<script type="text/javascript">
	<!--
	function setOldDisplay() {
	for ( var s = 0; s < document.styleSheets.length; s++ ) {
	var css = document.styleSheets[s];
	var mydata ;
	try { mydata = css.cssRules ;
	if ( ! mydata ) mydata = css.rules;
	for ( var r = 0; r < mydata.length; r++ ) {
	if ( mydata[r].selectorText == '.diff-old' ) {
	mydata[r].style.display = ( mydata[r].style.display == '' ) ? 'none'
	: '';
	return;
	}
	}
	} catch(e) {} ;
	}
	}
	-->
	</script>
	);

	}

	if ($stripheader) {
	open(HEADER, ">$headertmp");
	}

	my $incomment = 0;
	my $styleprinted = 0;
	my $inhead = 1;
	open(FILE, $filename) \|\| die("File $filename cannot be opened: $!");
	while (<FILE>) {
	if ($inhead == 1) {
	if (m/\<\/head/i) {
	s/\<\/head/$styles\<\/head/i;
	$styleprinted = 1;
	}
	if (m/\<body/i) {
	if (!$styleprinted) {
	s/\<body/$styles\<body/i;
	}
	$inhead = 0;
	print HEADER;
	if ($opt_t) {
	print HEADER q(
	<form action=""><input type="button" onclick="setOldDisplay()" value="Show/Hide Old Content" /></form>
	);
	}
	close HEADER;
	} else {
	print HEADER;
	}
	} else {
	if ($incomment) {
	if (m;-->;) {
	$incomment = 0;
	s/.*-->//;
	} else {
	next;
	}
	}
	if (m;<!--;) {
	while (m;<!--.*-->;) {
	s/<!--.*?-->//;
	}
	if (m;<!--; ) {
	$incomment = 1;
	s/<!--.*//;
	}
	}
	if (m/\<pre/i) {
	$preformatted = 1;
	}
	if (m/\<\/pre\>/i) {
	$preformatted = 0;
	}
	if ($preformatted) {
	$retval .= $_;
	} elsif ($mhtmlcomments && /^;;;/) {
	$retval .= $_;
	} else {
	my @list = split(' ');
	foreach $element (@list) {
	if ($element =~ m/\<H[1-6]/i) {
	# $inheader = 1;
	}
	if ($inheader == 0) {
	$element =~ s/</\n</g;
	$element =~ s/^\n//;
	$element =~ s/>/>\n/g;
	$element =~ s/\n$//;
	$element =~ s/>\n([.,:!]+)/>$1/g;
	}
	if ($element =~ m/\<\/H[1-6]\>/i) {
	$inheader = 0;
	}
	$retval .= "$element";
	$inelement += ($element =~ s/</</g);
	$inelement -= ($element =~ s/>/>/g);
	if ($inelement < 0) {
	$inelement = 0;
	}
	if (($inelement == 0) && ($inheader == 0)) {
	$retval .= "\n";
	} else {
	$retval .= " ";
	}
	}
	undef @list;
	}
	}
	}
	$retval .= "\n";
	close FILE;
	return $retval;
	}

	$mhtmlcomments = 1;

	sub cli {
	getopts("clto") \|\| usage();

	if ($opt_c) {$mhtmlcomments = 0;}

	if (@ARGV < 2) { usage(); }

	$file1 = $ARGV[0];
	$file2 = $ARGV[1];
	$file3 = $ARGV[2];

	$tmp = splitit($file1, $headertmp1);
	open (FILE, ">$tmp1");
	print FILE $tmp;
	close FILE;

	$tmp = splitit($file2, $headertmp2);
	open (FILE, ">$tmp2");
	print FILE $tmp;
	close FILE;

	$output = "";

	if ($stripheader) {
	open(FILE, $headertmp2);
	while (<FILE>) {
	$output .= $_;
	}
	close(FILE);
	}

	$output .= markit($tmp1, $tmp2);

	if ($file3) {
	open(FILE, ">$file3");
	print FILE $output;
	close FILE;
	} else {
	print $output;
	}
	}

	sub cgi {
	# use LWP::UserAgent;
	# use CGI;

	my $query = new CGI;
	my $url1 = $query->param("oldfile");
	my $url2 = $query->param("newfile");
	my $mhtml = $query->param("mhtml");

	my $file1 = "/tmp/htdcgi1.$$";
	my $file2 = "/tmp/htdcgi2.$$";

	my $ua = new LWP::UserAgent;
	$ua->agent("MACS, Inc. HTMLdiff/0.9 " . $ua->agent);

	# Create a request

	my $req1 = new HTTP::Request GET => $url1;

	my $res1 = $ua->request($req1, $file1);
	if ($res1->is_error) {
	print $res1->error_as_HTML();
	print "<p>The URL $url1 could not be found. Please check it and try again.</p>";
	return;
	}

	my $req2 = new HTTP::Request GET => $url2;

	my $res2 = $ua->request($req2, $file2);
	if ($res2->is_error) {
	print $res2->error_as_HTML();
	print "<p>The URL $url2 could not be found. Please check it and try again.</p>";
	return;
	}

	$split1 = splitit($file1, $headertmp1);
	open (FILE, ">$tmp1");
	print FILE $split1;
	close FILE;

	$split2 = splitit($file2, $headertmp2);
	open (FILE, ">$tmp2");
	print FILE $split2;
	close FILE;

	$output = "";

	if ($stripheader) {
	open(FILE, $headertmp2);
	while (<FILE>) {
	$output .= $_;
	}
	close(FILE);
	}

	$output .= markit($tmp1, $tmp2);

	my $base=$res2->base;

	if ($base !~ /\/$/) {
	$base =~ s/[^\/]*$//;
	}

	if ( $output !~ /<base/i ) {
	$output =~ s/<head>/<head>\n<base href="$base">/i \|\|
	$output =~ s/<html>/<html>\n<base href="$base">/i ;
	}

	print $query->header(-type=>'text/html',-nph=>1);
	print $output;

	unlink $file1;
	unlink $file2;

	}

	$tmp1="/tmp/htdtmp1.$$";
	$headertmp1="/tmp/htdhtmp1.$$";
	$tmp2="/tmp/htdtmp2.$$";
	$headertmp2="/tmp/htdhtmp2.$$";
	$stripheader = 1;

	if (@ARGV == 0) {
	cgi(); # if no arguments, we must be operating as a cgi script
	} else {
	cli(); # if there are arguments, then we are operating as a CLI
	}

	unlink $tmp1;
	unlink $headertmp1;
	unlink $tmp2;
	unlink $headertmp2;