xref: /dports/textproc/re_graph/re_graph-0.2_3/re_graph.pl

#
# re_graph.pl -- Graph a regular expression
#
=pod

=head1 NAME

re_graph.pl - Graph regular expression

=head1 SYNOPSIS

B<re_graph.pl>
[B<-d>]
[B<-o> I<out_file>]
[B<-x> I<min-x>]
[B<-y> I<min-y>]
I<regular-expression>
[I<string>]

=head1 DESCRIPTION

The I<re_graph.pl> program graphs regular expressions.  The guts of the
regular expression engine is a simple state machine.  The various states
and operations in the regular expression parser can be displayed using a
surprisingly simple diagram.

A few notes on what you are looking at:

The nodes B<Start> and B<Stop> denote the beginning and end of the regular
expression.

The solid squares denote atoms.   Lines indicate the next state.
When a line splits, the state machine will take the top line first.
If it's path is blocked it will backup and take the next lower line.
This is repeated until it finds a path to the end or all paths are exhausted.

Brown boxes indicate a grouping operation, i.e. ().

Green boxes indicate a zero with test.  The state machine will perform the
test inside the box before moving ahead.

For more information, see the tutorial below.

=head1 OPTIONS

=over 4

=item B<-d>

Turn on debugging.  The debugging output is printed on the console as regular
expressions are compiled.

=item B<-o> I<out_file>

Specify the output file for the images.  Default = I<re_graph_%02d.png>.
If only a regular expresion is specified, the output will be written
to the given file.

If the system is used in graph / execution mode, a series of files will
be written using the printf style file name specified.

=item B<-x> I<min-x>

Specify the minimum size of the image in pixels in the X direction.

=item B<-y> I<min-y>

Specify the minimum size of the image in pixels in the Y direction.

=back

=head1 TUTORIAL

This tutorial shows what happens when a set of sample regular expressions
are graphed.  This set of regular expressions closely follows the
Chapter 4 of "Perl for C Programmers" by Steve Oualline.

The set of regular expressions used for this tutorial is:

    test
    ^Test
    ^ *#
    ^[ \t]*#
    ^\s*#
    ([^#]*)(#.*)
    a|b
    ^(([^#"]*|".*")*)(#.*)
    ^((?:[^#"]*|".*?")*)(#.*)
    ^((?:[^#"]*|".*?(?<!\\)")*)(#.*)

Let's take a look at the graphs produced by these expressions.

=over 4

=begin html

<p><img src="tut_01_00.png"></p>

=end html

=item B</test/>

This is a very simple expression.  It matches "test" anywhere on the line.
If you look at the graph of this expression, it consists of three nodes "Start",
"EXACT <test>" and "END".

The "Start" node indicates the start of the regular expression.

The "EXACT <test>" node tells the engine that the text must match the
text "test" exactly.

The "END" node indicates the end of the regular expression.  If you reach
the "END" node, a successful match was found.

Flow is a straight line from "Start", through the "EXACT" check, to end.

=begin html

<p><img src="tut_02_00.png"></p>

=end html

=item B</^Test/>

A new item was added with this expression, an anchor.  It's named BOL
(Beginning of line) and shows up as an additional node.

=begin html

<p><img src="tut_03_00.png"></p>

=end html

=item B</^ *#/>

Now we start having fun.  This expression matches anything that consists
of a start of line (^), a bunch of spaces ( *), and a sharp (#).

The way the state machine works it that it starts at "Start" and works
it's way through the nodes.  You'll notice that between "BOL" and
"EXACT < >" there's a fork in the road.

The state machine will take the top branch if possible.  So if the next
character is a space, the system will take the top branch and match the
"EXACT < >" node.  If not, the bottom branch is taken and we wind up
at the "EXACT <#>" node.

If there's no path to the "END", then we don't have a match.

=begin html

<p><img src="tut_04_00.png"></p>

=end html

=item B</^[ \t]*#/>

This is the same as the previous example, except the space was replaced
by a character set.  We call the set "space and tab".  The system translates
this into "\11\40".  It's the same thing, suitable obfuscated for computer
work.

=begin html

<p><img src="tut_05_00.png"></p>

=end html

=item B</^\s*#/>

Again, the middle as been replace by another token.  In this case it's
the SPACE token which matches any whitespace.

=begin html

<p><img src="tut_06_0.png"></p>

=end html

=item B</([^#]*)(#.*)/>

This expression introduces us to the grouping operators.  They show as the
big brown boxes.

The other change is that we use the expression [^#], which matches anything
except a hash mark.  Perl changes this to a "ANYOF" clauses which matches
all characters except the single one we don't want.

Note: This ANYOF node overflows the size of the box.  This is a know bug.

The graphing program can show how the regular expression excution
process.  Let's see what happens when we run the command:

    perl re_graph.pl -o tut_06_%d.png '([^#]*)(#.*)' 'text # Comment'

=begin html

<p><img src="tut_06_1.png"></p>

=end html

The first image show a yellow arrow pointing to the first set of
(), indicating that the system is about to go into $1.

=begin html

<p><img src="tut_06_2.png"></p>

=end html

The next yellow arrow points at the B<ANYOF> operator indicating that
the regular expression engine is about to look at the C<[^#]> part
of the expression.

=begin html

<p><img src="tut_06_3.png"></p>

=end html

In the next screen, the yellow arrow has moved to the box
representing the second set of ().  That means that the first
part of matching process is done.  The string C<text> is highlighted
yellowing, indicating that that much of the string has be matched
so far.

=begin html

<p><img src="tut_06_4.png"></p>

=end html

Next the yellow arrow points to the "#" node.  The string is highlighted
up to the just before the "#".  This tells us that engine is about to
match the "#" in the string against the "#" in the regular expression.

The next few images (not shown) show the engine matching the rest of
the string.

=begin html

<p><img src="tut_07_0.png"></p>

=end html

=item B</a|b/>

Now we introduce the concept of a selection of two different atoms.  Note that
the branch arrows are drawn smaller to make them stand out.

=begin html

<p><img src="tut_08_00.png"></p>

=end html

=item B</^(([^#"]*|".*")*)(#.*)/>

See the book for what this regular expression tries to match.

This expression adds nested grouping, and some additional stuff that we've seen
before.

=begin html

<p><img src="tut_09_00.png"></p>

=end html

=item B</^((?:[^#"]*|".*?")*)(#.*)/>

This is like the previous example, except what was the $2 grouping has been
replaced by the "Group no $" operator (?:...).  Notice that the line around
the second group has disappeared and what was $3 is now $2.

(In future versions of this graphing tool we will graph the invisible group
operator.  We just did figure out how to do it yet.)

Also notice the use of the "*?" operator.  Remember when going through
the nodes, when a branch is encountered, the system will try and take
the top one first.

=begin html

<p><img src="tut_10_00.png"></p>

=end html

=item B</^((?:[^#"]*|".*?(?<!\\)")*)(#.*)/>

The grand finale.  One new type of node has been introduced: (?<!\\).  This is
the negative look-behind.  It's the red box on the screen.  When the state machine
sees this, it matches the text behind the current location marker against the
indicated text and if it fails then a match against the next node is possible.
(Boy does this not translate into English well.)

Basically the clause in question looks for a double quoted string ("xxx"), but
will ignore a double quote it's escaped ("xxx\"yyy").

=back

=head1 BUGS / LIMITATIONS

This will not graph all the regular expressions.  Some of the more advanced
features of the engine are just not handled.

We currently "graph" the "group, no $1" (?:..) operator by displaying nothing.
A box should be put around the expression.

The boxes drawn by the program are a fixed with not related to the size of
the text they contain.  Text can easily overflow the box.

The system is UNIX/Linux specific.  This is caused by only one small
section of code should anyone want to port this to a braindamaged
operating system.

Better use of color can be made.   Specifically all the nodes do not
have to be green.  Come to think of it they call don't have to be
rectangles either.

Sometimes the lines connecting one section to another take some strange
twists.

=head1 LICENSE

Licensed under the GPL.  (See the end of the source file for a copy).

=head1 AUTHOR

Steve Oualline (oualline@www.oualline.com)

=cut
use strict;
use warnings;

use IO::Handle;
use English;
use GD;
use GD::Arrow;

#
# Constants that control th layout

# Size of a node (X Space)
use constant X_NODE_SIZE => 60;

# Size of a node (Y Space)
use constant Y_NODE_SIZE => 40;

# Space text over this far
use constant X_TEXT_OFFSET => 3;
use constant Y_TEXT_OFFSET => 3;

# Space between nodes (X)
use constant X_MARGIN => 50;

# Vertical spacing
use constant Y_MARGIN => 10;

# Offset for line 2 of a 2 line text field
use constant X_LINE2_OFFSET => 10;

# Offset for line 2 of a 2 line text field
use constant Y_LINE2_OFFSET => 15;

# Padding for PLUS style nodes (left, right)
use constant PLUS_PAD => 10;

# Space between branches (x)
use constant X_BRANCH_MARGIN => 20;

# Space between branches (y)
use constant Y_BRANCH_MARGIN => 20;

# Thickness of the lines
use constant THICKNESS => 3;

# Margin around the graph
use constant MARGIN => 100;

# Label location
use constant LABEL_LOC_X => 50;
use constant LABEL_LOC_Y => 50;

# Location of progress msg
use constant PROGRESS_X => 50;
use constant PROGRESS_Y => 70;

# Length of the yellow arrow
use constant YELLOW_ARROW_SIZE => 25;
use constant YELLOW_ARROW_WIDTH => 5;

use Getopt::Std;

use vars qw/$opt_d $opt_o $opt_x $opt_y/;

STDOUT->autoflush(1);

# Configuration items
my $x_margin = 16;	# Space between items
my $y_margin = 16;	# Space between items

#
# Fields
#       node    -- Node number
#       type    -- Node type (from re debug)
#       arg     -- Argument (optional)
#       next    -- Next node
#

# Regular expression debugging information
my @re_debug;

#
# Fields
#       x_size    - Size of the node in X
#       y_size    - Size of the node in Y
#       x_loc     - X Location of the node
#       y_loc     - Y Location of the node
#       node      - Reference to the
#			node in @re_debug
#       child     - Array of child
#			nodes for this node
#

# Formatted version of the regular expression
my @format_re;

# Re we are displaying now
my $current_re;

my $re_to_add = "";     # Re we are adding

#
# Image variables
#
my $image;		# The image
my $color_white;	# White color
my $color_black;	# The black color
my $color_green;	# The green color
my $color_blue;		# Blue color
my $color_light_green;	# Light green color

# Forward declarations
sub draw_node_array($);
sub size_array(\@);
sub layout_array($$$\@);

################################################
# filled_rectangle -- Draw a filled rectangle at
#		the given location
################################################
sub filled_rectangle($$$$$)
{
    # Corners of the rectangle
    my $x1 = shift;
    my $y1 = shift;
    my $x2 = shift;
    my $y2 = shift;

    my $color = shift;	# Color for drawing

    if ($opt_d) {
	print
	  "Rectangle($x1, $y1, $x2, $y2, $color)\n";
    }
    $image->filledRectangle(
		$x1, $y1, $x2, $y2,
		$color);
    $image->setThickness(1);
    $image->rectangle(
		$x1, $y1, $x2, $y2,
		$color_black);
}

################################################
# arrow -- Draw an arrow from x1,y1 -> x2,y2
#
# All arrows are black
################################################
sub arrow($$$$) {
    my $x1 = shift;	# Start of arrow
    my $y1 = shift;
    my $x2 = shift;	# End of arrow
    my $y2 = shift;

    if ($opt_d) {
	print "Arrow($x1, $y1, $x2, $y2)\n";
    }
    # For some reason arrows
    # tend to point backwards
    my $arrow = GD::Arrow::Full->new(
	-X1 => $x2,
	-Y1 => $y2,
	-X2 => $x1,
	-Y2 => $y1,
	-WIDTH => THICKNESS-1);
    $image->setThickness(1);
    $image->filledPolygon($arrow, $color_black);
}

############################################
# The "PLUS" node
#
#
#     0  1  2    1p 2p  3p (p = +size of child)
#     v  v  v L3 v  v   v
#     .  ---------  .   .
#     . /.   .   .\ .   .
#     ./ .   .   . \    .
# a2  <  .   .   .  > a1.
#     .\ .   .   . /.   .
#     . \+-------+/     .
#  L1--->| child |----->+ L2
#     .  +-------+  .   .
#
# Arc start, end, centers
#
#       a1 / 270  - 180 / (ap*2, y-a)
#       a2 /  90  - 180 / (a0, y-2a), (a2, y-2a)
#
#       L1 (a3, y+2a) (a3p, y+2a)
############################################

#------------------------------------------
# size_plus -- Compute the size of
#		a plus/star type node
#------------------------------------------
sub size_plus($)
{
    # Node we want layout information for
    my $node = shift;

    # Compute the size of the children
    my ($x_size, $y_size) =
    	size_array(@{$node->{children}});

    # Arc size is based on the
    # Y dimension of the children
    $node->{arc_size} =
    	int($y_size/4) + PLUS_PAD;

    $node->{child_x} = $x_size - X_MARGIN;

    $node->{x_size} =
        $node->{child_x} +
	$node->{arc_size} * 2 + X_MARGIN;

    $node->{y_size} =
        $y_size + $node->{arc_size} * 2;
}
#------------------------------------------
# Draw the plus type node
#------------------------------------------
sub draw_plus($)
{
    # The node we are drawing
    my $cur_node = shift;

    layout_array(
        $cur_node->{x_loc} +
	    $cur_node->{arc_size} * 1,
        $cur_node->{y_loc},
        $cur_node->{y_size},
        @{$cur_node->{children}});

    draw_node_array($cur_node->{children});

    # The place we start drawing from (X)
    my $from_x = $cur_node->{x_loc};

    # The current middle of the item (Y)
    my $y = $cur_node->{y_loc} +
    	int($cur_node->{y_size}/2);

    # Size of an arc
    my $arc_size = $cur_node->{arc_size};

    # Size of the child
    my $child_x = $cur_node->{child_x};

    # Debugging
    if (0) {
        for (my $debug_x = 0;
	     $debug_x < 5;
	     $debug_x++) {
            $image->line(
                    $from_x +
		        $arc_size * $debug_x,
		    $y - $arc_size*2,
                    $from_x +
			$arc_size * $debug_x,
		    $y + $arc_size*2,
		    $color_black
                    );
        }

        for (my $debug_x = 3;
	     $debug_x < 7;
	     $debug_x++) {
            $image->line(
                    $from_x + $child_x +
		    	$arc_size * $debug_x,
				$y - $arc_size*2,
                    $from_x + $child_x +
		    	$arc_size * $debug_x,
				$y + $arc_size*2,
                    $color_green
		);
        }
    }

    my $flip = 1;       # Flipping factor
    if ($cur_node->{min_flag}) {
        $flip = -1;
    }

    $image->setThickness(THICKNESS);
    # First arc (a1)
    $image->arc(
            $from_x + $child_x + $arc_size,
	    $y - $arc_size * $flip,
	    $arc_size *2, $arc_size *2,
	    270, 90,
	    $color_black);

    $image->arc(
            $from_x + $arc_size * 1,
	    	$y - $arc_size * $flip,
	    $arc_size *2, $arc_size *2,
	    90, 270,
	    $color_black);

    # Draw (L1)
    arrow(
            $from_x, $y,
            $from_x + $arc_size * 1, $y
    );

    # Draw (L2)
    arrow(
            $from_x + $child_x + $arc_size * 1,
	    $y,
            $from_x + $child_x + $arc_size * 2,
	    $y
    );

    # Draw (L3)
    arrow(
            $from_x + $child_x + $arc_size * 1,
	    $y - $arc_size * 2,
            $from_x + $arc_size * 1,
	    $y - $arc_size * 2
    );


    # Text to display for the current node
    my $text = $cur_node->{node}->{text_label};
    if ($cur_node->{min_flag}) {
	$text .= "?";
    }

    $image->string(
	    gdMediumBoldFont,
            $from_x + $child_x + $arc_size * 2,
	    	$y - $arc_size * 2,
            $text,
	    $color_blue);

    $cur_node->{left_x} = $from_x;
    $cur_node->{left_y} = $y;

    $cur_node->{right_x} =
    	$from_x + $cur_node->{child_x} +
		$cur_node->{arc_size} * 2;

    $cur_node->{right_y} = $y;
}
############################################
# The "STAR" node
#
#
#			(p = +size of child)
#     0  1  2    3       p3 p4  p5
#     v  v  v    v   L2  v  v   v
#     .  -----------------  .   .
#     . /.  .    .       .\ .   .
#     ./ .  .    .       . \    .
# a6  <  .  .    .    a5 .  >   .
#     .\ .  .    .       . /.   .
#     . \.  . .  +-------+/     .
#  L3----------->| child |- .   +
#     .  .\ . j  +-------+  .a4/.
#     .  . \a1   .       .  . / .
#     .  .  \    .       .  ./  .
#     .  .  |    .       .  |   .
#     .  .  .\   .       . /   .
#     .  .  a2\  .       ./a3  .
#     .  .  .  \---------
#           ^    ^    L1
#           2    3
#
# Arc / swing / center
#       a1 / 270  - 0   / (a1,  y + a)
#       a2 /  90  - 180 / (a3,  y + a)
#       a3 /   0  - 90  / (p3,  y + a)
#       a4 / 180  - 270   / (a4p, y)
#
#       a5 / 270  - 90  / (p3, y-a)
#       a6 /  90  - 270 / (a1, y-a)
#
#       L1 (a3, y+2a) (a3p, y+2a)
############################################

#-----------------------------------------
# size_star -- Compute the size of
#	a star type node
#-----------------------------------------
sub size_star($)
{
    # Node we want layout information for
    my $node = shift;

    # Compute the size of the children
    my ($x_size, $y_size) =
    	size_array(@{$node->{children}});

    # Arc size is based on the
    # Y dimension of the children
    $node->{arc_size} =
	int($y_size/4) + PLUS_PAD;

    $node->{child_x} = $x_size - X_MARGIN;

    $node->{x_size} = $node->{child_x} +
    	$node->{arc_size} * 5 + X_MARGIN;

    $node->{y_size} = $y_size +
    	$node->{arc_size} * 2 + Y_MARGIN;
}
#-----------------------------------------
# Draw the star type node
#-----------------------------------------
sub draw_star($)
{
    # The node we are drawing
    my $cur_node = shift;

    layout_array(
        $cur_node->{x_loc} +
	    $cur_node->{arc_size} * 3,
        $cur_node->{y_loc},
        $cur_node->{y_size},
        @{$cur_node->{children}});

    # The place we start drawing from (X)
    my $from_x = $cur_node->{x_loc};

    # The current middle of the item (Y)
    my $y = int($cur_node->{y_loc} +
    	$cur_node->{y_size}/2);

    # Size of an arc
    my $arc_size = $cur_node->{arc_size};

    # Size of the child
    my $child_x = $cur_node->{child_x};

    # Debugging
    if (0) {
        for (my $debug_x = 0;
		$debug_x < 5;
		$debug_x++) {
            $image->line(
                    $from_x +
		    $arc_size * $debug_x,
			$y - $arc_size*2,
                    $from_x +
		    	$arc_size * $debug_x,
		    $y + $arc_size*2,
		    $color_black
		);
        }

        for (my $debug_x = 3;
		$debug_x < 7;
		$debug_x++) {
            $image->line(
                    $from_x + $child_x +
		    	$arc_size * $debug_x,
				$y - $arc_size*2,
                    $from_x + $child_x +
		    	$arc_size * $debug_x,
				$y + $arc_size*2,
                    $color_green
		);
        }
    }

    my $flip = 1;       # Flipping factor
    if ($cur_node->{min_flag}) {
        $flip = -1;
    }

    $image->setThickness(THICKNESS);
    if ($flip == 1) {
	# First arc (a1)
	$image->arc(
		$from_x + $arc_size,
		$y + $arc_size,
		$arc_size * 2, $arc_size * 2,
		270,  0,
		$color_black);

	# Second arc (a2)
	$image->arc(
		$from_x + $arc_size * 3,
		$y + $arc_size,
		$arc_size * 2, $arc_size * 2,
		90, 180,
		$color_black);
    } else {
	# First arc (a1)
	$image->arc(
		$from_x + $arc_size,
		$y - $arc_size,
		$arc_size * 2, $arc_size * 2,
		0, 90,
		$color_black);

	# Second arc (a2)
	$image->arc(
		$from_x + $arc_size * 3,
		$y - $arc_size,
		$arc_size * 2, $arc_size * 2,
		180, 270,
		$color_black);
    }

    if ($flip > 0)  {
	# Third arc (a3)
	$image->arc(
		$from_x + $child_x +
		    $arc_size * 3,
		$y + $arc_size,
		$arc_size * 2, $arc_size * 2,
		0, 90,
		$color_black);

	# Fourth arc (a4)
	$image->arc(
		$from_x + $child_x +
		    $arc_size * 5,
		$y + $arc_size,
		$arc_size * 2, $arc_size * 2,
		180, 270,
		$color_black);
    } else {
	# Third arc (a3)
	$image->arc(
		$from_x + $child_x +
			$arc_size * 3,
		$y - $arc_size,
		$arc_size * 2, $arc_size * 2,
		270, 0,
		$color_black);

	# Fourth arc (a4)
	$image->arc(
		$from_x + $child_x +
		    $arc_size * 5,
		$y - $arc_size,
		$arc_size * 2, $arc_size * 2,
		90, 180,
		$color_black);
    }

    # Fifth arc (a5)
    $image->arc(
            $from_x + $child_x + $arc_size * 3,
	    	$y - $arc_size * $flip,
	    $arc_size * 2, $arc_size * 2,
	    270, 90,
	    $color_black);

    # Sixth arc (a6)
    $image->arc(
            $from_x + $arc_size,
	    	$y - $arc_size * $flip,
	    $arc_size * 2, $arc_size * 2,
	    90, 270,
	    $color_black);

    # L1
    arrow(
            $from_x + $arc_size * 3,
	    	$y + $arc_size * 2 * $flip,
            $from_x + $arc_size * 3 + $child_x,
		$y + $arc_size * 2 * $flip);

    # L2
    arrow(
            $from_x + $arc_size * 3 + $child_x,
	    	$y - $arc_size * 2 * $flip,
            $from_x + $arc_size * 1,
	    	$y - $arc_size * 2 * $flip);

    # Draw (L3)
    arrow(
            $from_x, $y,
            $from_x + $arc_size * 3, $y);


    $image->string(
	    gdMediumBoldFont,
            $from_x + $child_x + $arc_size * 4,
	    	$y - $arc_size * 2,
            ($cur_node->{min_flag}) ? "*?" : "*",
	    $color_black);


    draw_node_array($cur_node->{children});

    $cur_node->{left_x} = $from_x;
    $cur_node->{left_y} = $y;

    $cur_node->{right_x} =
    	$from_x + $cur_node->{child_x} +
	$cur_node->{arc_size} * 5;

    $cur_node->{right_y} = $y;
}

############################################
# Branch nodes
############################################
#-------------------------------------------
# layout a branch node
#-------------------------------------------
sub size_branch($)
{
    # Node we want layout information for
    my $node = shift;

    my $x_size = 0;     # Current X size
    my $y_size = 0;     # Current Y size

    foreach my $cur_choice (
		@{$node->{choices}}) {

        # The size of the current choice
        my ($x_choice, $y_choice) =
		size_array(@{$cur_choice});

        if ($x_size < $x_choice) {
            $x_size = $x_choice;
        }
        if ($y_size != 0) {
            $y_size += Y_BRANCH_MARGIN;
        }
        $cur_choice->[0]->{row_y_size} =
		$y_choice;

        $y_size += $y_choice;
    }
    $x_size += 2 * X_BRANCH_MARGIN + X_MARGIN;
    $node->{x_size} = $x_size;
    $node->{y_size} = $y_size;
}
#-------------------------------------------
# draw_branch -- Draw a branch structure
#-------------------------------------------
sub draw_branch($)
{
    # Node we want layout information for
    my $cur_node = shift;

    # Location where we draw the branches
    my $x_loc = $cur_node->{x_loc} +
    	X_BRANCH_MARGIN;

    my $y_loc = $cur_node->{y_loc};

    foreach my $cur_child (
	    @{$cur_node->{choices}}
	) {
        layout_array(
            $x_loc + X_BRANCH_MARGIN,
            $y_loc,
            $cur_child->[0]->{row_y_size},
            @{$cur_child});

        $y_loc += $cur_child->[0]->{row_y_size} +
		Y_BRANCH_MARGIN;
        draw_node_array($cur_child);
    }

    # Largest right x of any node
    my $max_x = 0;

    foreach my $cur_child (
		@{$cur_node->{choices}}) {

        # Last node on the string of children
        my $last_node =
	    $cur_child->[$#{$cur_child}];

        if ($last_node->{right_x} > $max_x) {
            $max_x = $last_node->{right_x};
        }
    }
    foreach my $cur_child (
		@{$cur_node->{choices}}
	    ) {
        # Last node on the
	# string of children
        my $last_node =
	     $cur_child->[$#{$cur_child}];

        if ($last_node->{right_x} < $max_x) {
            $image->line(
                    $last_node->{right_x},
		    $last_node->{right_y},
                    $max_x,
		    $last_node->{right_y},
		    $color_black);
        }
    }

    my $left_x = $cur_node->{x_loc};
    my $right_x = $cur_node->{x_loc} +
    	$cur_node->{x_size} - X_MARGIN;

    my $y = $cur_node->{y_loc} +
    	($cur_node->{y_size} / 2);

    foreach my $cur_child (
		@{$cur_node->{choices}}
	) {
        # Create a branch line to the item
	# in the list of nodes
        $image->line(
                $left_x, $y,
                $cur_child->[0]->{left_x},
		$cur_child->[0]->{left_y},
		$color_black);

        # The last node on the list
        my $last_child =
	    $cur_child->[$#$cur_child];

        # Line from the last node
	# to the collection point
        $image->line(
                $max_x, $last_child->{right_y},
                $right_x, $y,
		$color_black);
    }

    $cur_node->{left_x} = $left_x;
    $cur_node->{left_y} = $y;

    $cur_node->{right_x} = $right_x;
    $cur_node->{right_y} = $y;
}
############################################
# Functions to compute the size of various nodes
############################################
#-------------------------------------------
# layout the start node
#-------------------------------------------
sub size_start($)
{
    # Node we want layout information for
    my $node = shift;

    $node->{x_size} = X_NODE_SIZE + X_MARGIN;
    $node->{y_size} = Y_NODE_SIZE;
}
#-------------------------------------------
# layout the end node
#-------------------------------------------
sub size_end($)
{
    # Node we want layout information for
    my $node = shift;

    $node->{x_size} = X_NODE_SIZE;
    $node->{y_size} = Y_NODE_SIZE;
}
#-------------------------------------------
# layout the "EXACT" node  (EXACT + text)
#-------------------------------------------
sub size_exact($)
{
    # Node we want layout information for
    my $node = shift;

    $node->{x_size} = X_NODE_SIZE + X_MARGIN;
    $node->{y_size} = Y_NODE_SIZE;
}
#-------------------------------------------
# layout the "ANYOF" node  (ANYOF + text)
#-------------------------------------------
# Size of a character in X dimensions
use constant X_CHAR_SIZE => 7;

sub size_text($)
{
    # Node we want layout information for
    my $node = shift;

    # Get the size of the string argument
    my $length = length($node->{node}->{arg});
    if ($length < 10) {
	$length = 10;
    }
    $node->{x_size} =
    	$length * X_CHAR_SIZE + X_MARGIN;

    $node->{y_size} = Y_NODE_SIZE;
}
#-------------------------------------------
# OPEN  the open (
#-------------------------------------------
# Size of the box around a group
use constant BOX_MARGIN => 50;

# Height of the font used to label boxes
use constant BOX_FONT_SIZE => 15;

sub size_open($)
{
    # The node we want to size
    my $node = shift;

    # Compute the size of the children
    my ($x_size, $y_size) =
    	size_array(@{$node->{children}});

    # We add X_MARGIN because we
    # must for all nodes
    #
    # We subtract X_MARGIN because one too many
    # is added in our children
    #
    # Result is nothing

    $node->{x_size} = $x_size + BOX_MARGIN;

    $node->{y_size} =
        $y_size + BOX_MARGIN + BOX_FONT_SIZE;
}


# Functions used to compute the sizes
# of various elements
my %compute_size = (
    "ANYOF" => \&size_text,
    "BOL" => \&size_exact,
    "SPACE" => \&size_exact,
    "NSPACE" => \&size_exact,
    "DIGIT" => \&size_exact,
    "BRANCH"=> \&size_branch,
    "END"   => \&size_end,
    "EOL" => \&size_exact,
    "EXACT" => \&size_exact,
    "IFMATCH"  => \&size_open,
    "OPEN"  => \&size_open,
    "PLUS"  => \&size_plus,
    "REF"   => \&size_exact,
    "REG_ANY" => \&size_exact,
    "STAR"  => \&size_star,
    "Start" => \&size_start,
    "UNLESSM"  => \&size_open
);

############################################
# draw functions
############################################
sub draw_start_end($)
{
    my $cur_node = shift;
    my $node_number = $cur_node->{node}->{node};

    filled_rectangle(
            $cur_node->{x_loc},
	    $cur_node->{y_loc},
            $cur_node->{x_loc} + X_NODE_SIZE,
            $cur_node->{y_loc} + Y_NODE_SIZE,
            $color_green);

    $cur_node->{text} = $image->string(
	    gdSmallFont,
            $cur_node->{x_loc} + X_TEXT_OFFSET,
            $cur_node->{y_loc} + Y_TEXT_OFFSET,

            $cur_node->{node}->{type},
	    $color_black);

    $cur_node->{left_x} = $cur_node->{x_loc};

    $cur_node->{left_y} =
    	$cur_node->{y_loc} + Y_NODE_SIZE / 2;

    $cur_node->{right_x} =
    	$cur_node->{x_loc} + X_NODE_SIZE;

    $cur_node->{right_y} =
    	$cur_node->{y_loc} + Y_NODE_SIZE / 2;
}

#-------------------------------------------
# draw_exact($node) -- Draw a "EXACT" re node
#-------------------------------------------
sub draw_exact($)
{
    my $cur_node = shift;       # The node
    my $node_number = $cur_node->{node}->{node};

    filled_rectangle(
            $cur_node->{x_loc},
	    $cur_node->{y_loc},
            $cur_node->{x_loc} +
	    	$cur_node->{x_size} -
	    	X_MARGIN,
            $cur_node->{y_loc} + Y_NODE_SIZE,
            $color_green);

    $image->string(
	    gdSmallFont,
            $cur_node->{x_loc} + X_TEXT_OFFSET,
            $cur_node->{y_loc} + Y_TEXT_OFFSET,
	    "$cur_node->{node}->{type}",
	    $color_black);

    $image->string(
	    gdSmallFont,
            $cur_node->{x_loc} +
	    	X_TEXT_OFFSET + X_LINE2_OFFSET,
            $cur_node->{y_loc} +
	    	Y_TEXT_OFFSET + Y_LINE2_OFFSET,
	    "$cur_node->{node}->{arg}",
	    $color_black);

    $cur_node->{left_x} = $cur_node->{x_loc};

    $cur_node->{left_y} =
    	$cur_node->{y_loc} + Y_NODE_SIZE / 2;

    $cur_node->{right_x} =
        $cur_node->{x_loc} + X_NODE_SIZE;

    $cur_node->{right_y} =
    	$cur_node->{y_loc} + Y_NODE_SIZE / 2;
}
#-------------------------------------------
# draw_ref($node) -- Draw a "REF" re node
#-------------------------------------------
sub draw_ref($)
{
    my $cur_node = shift;       # The node
    my $node_number = $cur_node->{node}->{node};

    filled_rectangle(
            $cur_node->{x_loc},
	    $cur_node->{y_loc},
            $cur_node->{x_loc} + X_NODE_SIZE,
            $cur_node->{y_loc} + Y_NODE_SIZE,
            $color_light_green);

    $cur_node->{text} = $image->String(
	    gdSmallFont,
            $cur_node->{x_loc} + X_TEXT_OFFSET,
            $cur_node->{y_loc} + Y_TEXT_OFFSET,
            "Back Reference:\n".
	    "  $cur_node->{node}->{ref}",
	    $color_black);

    $cur_node->{left_x} = $cur_node->{x_loc};

    $cur_node->{left_y} =
    	$cur_node->{y_loc} + Y_NODE_SIZE / 2;

    $cur_node->{right_x} =
        $cur_node->{x_loc} + X_NODE_SIZE;

    $cur_node->{right_y} =
        $cur_node->{y_loc} + Y_NODE_SIZE;
}
#-------------------------------------------
# draw the () stuff
#-------------------------------------------
sub draw_open($$)
{
    my $cur_node = shift;       # The node

    $image->setStyle(
	$color_black, $color_black,
		$color_black, $color_black,
		$color_black,
	$color_white, $color_white,
		$color_white, $color_white,
		$color_white
    );
    $image->rectangle(
            $cur_node->{x_loc},
		$cur_node->{y_loc} +
		BOX_FONT_SIZE,
            $cur_node->{x_loc} +
	    	$cur_node->{x_size} -
		X_MARGIN,
            $cur_node->{y_loc} +
	    	$cur_node->{y_size},
            gdStyled);

    $image->string(
	    gdSmallFont,
            $cur_node->{x_loc},
	    $cur_node->{y_loc},
            $cur_node->{text},
	    $color_black);

    layout_array(
        $cur_node->{x_loc} +
		BOX_MARGIN/2,
        $cur_node->{y_loc} +
		BOX_MARGIN/2 + BOX_FONT_SIZE,
        $cur_node->{y_size} -
		BOX_MARGIN - BOX_FONT_SIZE,
        @{$cur_node->{children}});

    draw_node_array($cur_node->{children});

    $cur_node->{left_x} = $cur_node->{x_loc};
    $cur_node->{left_y} = $cur_node->{y_loc} +
    	($cur_node->{y_size} + BOX_FONT_SIZE)/2;

    $cur_node->{right_x} = $cur_node->{x_loc} +
    	$cur_node->{x_size} - X_MARGIN;

    $cur_node->{right_y} = $cur_node->{left_y};

    # Child we are drawing arrows to / from
    my $child = $cur_node->{children}->[0];
    $image->line(
            $cur_node->{left_x},
	    $cur_node->{left_y},
            $child->{left_x},
	    $child->{left_y},
	    $color_black
    );
    $child =
       $cur_node->{children}->[
	   $#{$cur_node->{children}}
       ];

    $image->line(
            $child->{right_x},
	    $child->{right_y},
            $cur_node->{right_x},
	    $cur_node->{right_y},
	    $color_black
    );
}

my %draw_node = (
    "ANYOF" => \&draw_exact,
    "BOL"   => \&draw_start_end,
    "EOL"   => \&draw_start_end,
    "SPACE"   => \&draw_start_end,
    "NSPACE"   => \&draw_start_end,
    "DIGIT"   => \&draw_start_end,
    "BRANCH"=> \&draw_branch,
    "END"   => \&draw_start_end,
    "EXACT" => \&draw_exact,
    "IFMATCH"  => \&draw_open,
    "OPEN"  => \&draw_open,
    "PLUS"  => \&draw_plus,
    "REF"   => \&draw_ref,
    "REG_ANY" => \&draw_start_end,
    "STAR"  => \&draw_star,
    "Start" => \&draw_start_end,
    "UNLESSM"  => \&draw_open
);


################################################
# usage -- Tell the user how to use us
################################################
sub usage()
{
    print STDERR <<EOF;
Usage is $0 [options] [-o <file>] <re> [<str>]
Options:
  -d -- Debug
  -o <out_file> -- Output file (%d = sequence number)
  -x <size> -- Minimum size in X
  -y <size> -- Minimum size in Y
EOF
    exit (8);
}
################################################
# parse_re -- Parse a regular expression
#    and leave the results in the array @re
################################################
sub parse_re()
{
    my $quote_re = $current_re;
    $quote_re =~ s/\\/\\\\/g;
    my $cmd = <<EOF ;
perl 2>&1 <<SHELL_EOF
use re 'debug';
/$quote_re/;
SHELL_EOF
EOF

    # The raw debug output
    my @raw_debug = `$cmd`;

    if ($opt_d) {
        print @raw_debug;
    }

    if ($CHILD_ERROR != 0) {
    my $cmd = <<EOF ;
perl 2>&1 <<SHELL_EOF
use re 'debug';
/ERROR/;
SHELL_EOF
EOF
        @raw_debug = `$cmd`;
        if ($CHILD_ERROR != 0) {
            die("Could not run perl");
        }
    }

    @re_debug = ();     # Clear out old junk
    push(@re_debug, {
            node => 0,
            type => "Start",
            next => 1
            });
    foreach my $cur_line (@raw_debug) {
        if ($cur_line =~ /^Compiling/) {
            next;
        }
        if ($cur_line =~ /^\s*size/) {
            next;
        }
        #                 +++---------------------------------- Spaces
        #                 ||| +++------------------------------ Digits
        #                 |||+|||+----------------------------- Group $1
        #                 ||||||||                              (Node)
        #                 ||||||||
        #                 ||||||||+---------------------------- Colon
        #                 |||||||||+++------------------------- Spaces
        #                 ||||||||||||
        #                 |||||||||||| +++--------------------- Word chars
        #                 ||||||||||||+|||+-------------------- Group $2
        #                 |||||||||||||||||                       (Type)
        #                 |||||||||||||||||
        #                 |||||||||||||||||+++----------------- Spaces
        #                 ||||||||||||||||||||
        #                 |||||||||||||||||||| ++--------------- Any char str
        #                 ||||||||||||||||||||+||+-------------- Group $3
        #                 ||||||||||||||||||||||||               (arg)
        #                 ||||||||||||||||||||||||------------- Lit <>
        #                 ||||||||||||||||||||||||
        #                 ||||||||||||||||||||||||+++---------- Spaces
        #                 |||||||||||||||||||||||||||
        #                 |||||||||||||||||||||||||||   ++----- Any char str
        #                 |||||||||||||||||||||||||||++ || ++-- Lit ()
        #                 ||||||||||||||||||||||||||||| || ||   (next state)
        #                 |||||||||||||||||||||||||||||+||+||-- Group $4
        if ($cur_line =~ /\s*(\d+):\s*(\w+)\s*(.*)\s*\((.*)\)/) {
            push(@re_debug, {
                    node => $1,
                    type => $2,
                    raw_type => $2,
                    arg => $3,
                    next => $4
                    });
            next;
        }
        if ($cur_line =~ /^anchored/) {
            next;
        }
        if ($cur_line =~ /^Freeing/) {
            last;
        }
    }
}
################################################
# $new_index = parse_node($index,
#		$array, $next, $close)
#
#       -- Parse a single regular expression node
#       -- Stop when next (or end) is found
#       -- Or when a close ")" is found
################################################
sub parse_node($$$$);
sub parse_node($$$$)
{
    # Index into the array
    my $index = shift;

    # Array to put things on
    my $array = shift;

    my $next = shift;           # Next node

    # Looking for a close?
    my $close = shift;

    my $min_flag = 0;           # Minimize flag
    while (1) {
        if (not defined($re_debug[$index])) {
            return ($index);
        }
        if (defined($next)) {
            if ($next <=
	    	$re_debug[$index]->{node}) {

                return ($index);
            }
        }
        if ($re_debug[$index]->{type} =~
		/CLOSE(\d+)/) {
            if (defined($close)) {
                if ($1 == $close) {
                    return ($index + 1);
                }
            }
        }
        if ($re_debug[$index]->{type} eq
		"MINMOD") {
            $min_flag = 1;
            $index++;
            next;
        }
#--------------------------------------------
        if (($re_debug[$index]->{type} eq
		"IFMATCH") ||
            ($re_debug[$index]->{type} eq
	    	"UNLESSM")) {
            if ($re_debug[$index]->{arg} !~
	    	/\[(.*?)\]/) {
                die("IFMATCH/UNLESSM funny ".
		     "argument ".
		     "$re_debug[$index]->{arg}");
            }
	    # Ending text (= or !=)
            my $equal = "!=";

            if ($re_debug[$index]->{type} eq
		    "IFMATCH") {
                $equal = "=";
            }
            # Flag indicating the next look ahead
            my $flag = $1;

	    # Text to label this box
            my $text;

            if ($flag eq "-0") {
                $text = "$equal ahead";
            } elsif ($flag eq "-0") {
                $text = "$equal behind";
            } elsif ($flag eq "-1") {
                $text = "$equal behind";
            } else {
                die("Unknown IFMATCH/UNLESSM ".
		    	"flag text $flag");
                exit;
            }
            push(@{$array}, {
		node => $re_debug[$index],
		text => $text,
	        children => []
	    });

            $index = parse_node($index+1,
		$$array[$#$array]->{children},
		$re_debug[$index]->{next},
		undef);
            next;
        }
#-----------------------------------------
        if ($re_debug[$index]->{type} =~
		/OPEN(\d+)/) {

            my $paren_count = $1;
            $re_debug[$index]->{type} = "OPEN";
            push(@{$array}, {
		node => $re_debug[$index],
		paren_count => $paren_count,
		text => "( ) => \$$paren_count",
	       children => []
	   });

            $index = parse_node($index+1,
		$$array[$#$array]->{children},
		undef, $paren_count);
            next;
        }
#-----------------------------------------
        if ($re_debug[$index]->{type} =~
		/REF(\d+)/) {

            my $ref_number = $1;
            $re_debug[$index]->{type} = "REF";
            push(@{$array}, {
		node => $re_debug[$index],
		ref => $ref_number,
	       children => []
	   });

            ++$index;
            next;
        }
#-----------------------------------------
        if ($re_debug[$index]->{type} eq
	        "BRANCH") {

            push(@{$array}, {
		node => $re_debug[$index],
	       choices => []
	    });

            my $choice_index = 0;
            while (1) {
                # Next node in this series
                my $next =
		    $re_debug[$index]->{next};

                $$array[$#$array]->
		   {choices}[$choice_index] = [];

                $index = parse_node($index+1,
		    $$array[$#$array]->
		    	{choices}[$choice_index],
		    $next, undef);

                if (not defined(
			  $re_debug[$index])) {
                    last;
                }

                if ($re_debug[$index]->{type} ne
			"BRANCH") {
                    last;
                }
                $choice_index++;
            }
            next;
        }
#--------------------------------------------
        if (($re_debug[$index]->{type} eq
	        "CURLYX") |
	    ($re_debug[$index]->{type} eq
	        "CURLY")) {

	    # Min number of matches
            my $min_number;

	    # Max number of matches
            my $max_number;

            if ($re_debug[$index]->{arg} =~
			/{(\d+),(\d+)}/) {
                $min_number = $1;
                $max_number = $2;
            } else {
                die("Funny CURLYX args ".
		    "$re_debug[$index]->{arg}");
                exit;
            }

	    my $star_flag = ($min_number == 0);

	    my $text = "+";
	    if ($min_number == 0) {
		$text = "*";
	    }
	    if (($max_number != 32767) ||
			($min_number > 1)) {

		$text =
		    "{$min_number, $max_number}";
		if ($max_number == 32767) {
		    $text = "min($min_number)";
		}
	    }
	    # Node that's enclosed
	    # inside this one
	    my $child = {
		node => {
		    type =>
		       ($star_flag) ?
		       	 "STAR" : "PLUS",
		    raw_type =>
		       $re_debug[$index]->{type},
		    arg =>
		        $re_debug[$index]->{arg},
		    next =>
		       $re_debug[$index]->{next},
		    text_label =>
		        $text
		},
		min_flag => $min_flag,
		children => [],
	    };

	    push(@{$array}, $child);

	    $index = parse_node($index+1,
		    $child->{children},
		    $re_debug[$index]->{next},
		    undef);
	    next;
        }
#-----------------------------------------
        if ($re_debug[$index]->{type} eq
		"CURLYM") {

            my $paren_count;    # () number

	    # Min number of matches
            my $min_number;

	    # Max number of matches
            my $max_number;

            if ($re_debug[$index]->{arg} =~
		  /\[(\d+)\]\s*{(\d+),(\d+)}/) {
                $paren_count = $1;
                $min_number = $2;
                $max_number = $3;
            } else {
                die("Funny CURLYM args ".
		    "$re_debug[$index]->{arg}");
                exit;
            }
	    # Are we doing a * or +
	    # (anything else is just too hard_

	    my $star_flag = ($min_number == 0);

	    # The text for labeling this node
	    my $text = "+";
	    if ($min_number == 0) {
		$text = "*";
	    }
	    if (($max_number != 32767) ||
			($min_number > 1)) {

		$text =
		   "{$min_number, $max_number}";

		if ($max_number == 32767) {
		    $text = "min($min_number)";
		}
	    }

	    # Node that's enclosed
	    # inside this one
	    my $child = {
		node => {
		    type =>
		        ($star_flag) ?
			    "STAR" : "PLUS",
		    raw_type =>
		       $re_debug[$index]->{type},
		    arg =>
		        $re_debug[$index]->{arg},
		    next =>
		       $re_debug[$index]->{next},
		    text_label =>
		        $text
		},
		min_flag => $min_flag,
		children => [],
	    };
	    $min_flag = 0;

	    # The text for labeling this node
	    $text = "( ) => \$$paren_count";
	    if ($paren_count == 0) {
		$text = '( ) [no $x]';
	    }
	    push(@{$array},
	    {
		node => {
		    type =>
		        "OPEN",
		    raw_type =>
		       $re_debug[$index]->{type},
		    arg =>
		        $re_debug[$index]->{arg},
		    next =>
		        $re_debug[$index]->{next}
		},
		paren_count => $paren_count,
		text => $text,
		children => [$child]
	    });

	    $index = parse_node($index+1,
		    $child->{children},
		    $re_debug[$index]->{next},
		    undef);
	    next;
        }
#-----------------------------------------
        if ($re_debug[$index]->{type} eq
		"STAR") {
            push(@{$array},
		{
		    node => {
			%{$re_debug[$index]},
			-text_label => "+"
		   },
		   min_flag => $min_flag,
		   children => []
	       });
            $min_flag = 0;

	    # Where we go for the next state
            my $star_next;

            if (defined($next)) {
                $star_next = $next;
            } else {
                $star_next =
		    $re_debug[$index]->{next};
            }

            $index = parse_node($index+1,
		$$array[$#$array]->{children},
		$star_next, undef);
            next;
        }
#-----------------------------------------
        if ($re_debug[$index]->{type} eq
		"PLUS") {
            push(@{$array},
		{
		    node => {
			%{$re_debug[$index]},
			text_label => "+"
		    },
		    min_flag => $min_flag,
		    children => []
	       });
            $min_flag = 0;
            $index = parse_node($index+1,
		$$array[$#$array]->{children},
		$re_debug[$index]->{next},
		undef);
            next;
        }
#-----------------------------------------
        # Ignore a couple of nodes
        if ($re_debug[$index]->{type} eq
		"WHILEM") {
            ++$index;
            next;
        }
        if ($re_debug[$index]->{type} eq
		"SUCCEED") {
            ++$index;
            next;
        }
        if ($re_debug[$index]->{type} eq
		"NOTHING") {
            ++$index;
            next;
        }
        if ($re_debug[$index]->{type} eq
		"TAIL") {
            ++$index;
            next;
        }
        push(@$array, {
	    node => $re_debug[$index]});

        if ($re_debug[$index]->{type} eq "END") {
            return ($index+1);
        }
        $index++;

    }
}
################################################
# do_size($cur_node) --
#	Compute the size of a given node
################################################
sub do_size($);
sub do_size($)
{
    my $cur_node = shift;

    if (not defined(
	    $compute_size{
		$cur_node->{node}->{type}})) {

        die("No compute function for ".
	    	"$cur_node->{node}->{type}");
        exit;
    }
    $compute_size{
	$cur_node->{node}->{type}}($cur_node);
}
################################################
# size_array(\@array) -- Compute the size of
#			an array of nodes
#
# Returns
#       (x_size, y_size) -- Size of the elements
#
#       x_size -- Size of all the elements in X
#               (We assume they are
#			laid out in a line)
#       y_size -- Biggest Y size
#			(side by side layout)
#################################################
sub size_array(\@)
{
    # The array
    my $re_array = shift;

    # Size of the array in X
    my $x_size = 0;

    # Size of the elements in Y
    my $y_size = 0;

    foreach my $cur_node(@$re_array) {
        do_size($cur_node);
        $x_size += $cur_node->{x_size};
        if ($y_size < $cur_node->{y_size}) {
            $y_size = $cur_node->{y_size};
        }
    }
    return ($x_size, $y_size);
}
################################################
# layout_array($x_start, $y_start,
#	$y_max, \@array)
#
# Layout an array of nodes
################################################
sub layout_array($$$\@)
{
    # Starting point in X
    my $x_start = shift;

    # Starting point in Y
    my $y_start = shift;

    # largest Y value
    my $y_max = shift;

    # The data
    my $re_array = shift;

    foreach my $cur_node(@$re_array) {
        $cur_node->{x_loc} = $x_start;
        $cur_node->{y_loc} = $y_start +
	    int(($y_max -
	         $cur_node->{y_size})/2);
        $x_start += $cur_node->{x_size};
    }
}
################################################
# convert_re -- Convert @re_debug -> @format_re
#
# The formatted re node contains layout
# information as
# well as information on nodes contained
# inside the current one.
################################################
sub convert_re()
{
    # Clear out old data
    @format_re = ();

    parse_node(0, \@format_re, undef, undef);
    #
    # Compute sizes of each node
    #
    my ($x_size, $y_size) =
    	size_array(@format_re);

    #
    # Compute the location of each node
    #
    layout_array(MARGIN,
	MARGIN, $y_size,
	@format_re
    );
    return (MARGIN + $x_size, MARGIN + $y_size);
}

##############################################
# draw_node_array -- draw an array of nodes
##############################################
sub draw_node_array($)
{
    my $array = shift;
    #
    # Draw Nodes
    #
    foreach my $cur_node (@$array) {
        if (not defined(
	    $draw_node{
		$cur_node->{node}->{type}})) {

            die("No draw function for ".
		    "$cur_node->{node}->{type}");
        }
        $draw_node{
	    $cur_node->{node}->{type}}(
		$cur_node
	    );
    }
    #
    # Loop through all the things
    # (except the last) and
    # draw arrows between them
    #
    for (my $index = 0;
         $index < $#$array;
	 ++$index) {

        my $from_x = $array->[$index]->{right_x};
        my $from_y = $array->[$index]->{right_y};

        my $to_x = $array->[$index+1]->{left_x};
        my $to_y = $array->[$index+1]->{left_y};

        arrow(
	    $from_x, $from_y,
	    $to_x, $to_y
        );
    }
}
##############################################
# draw_re -- Draw the image
##############################################
sub draw_re()
{
    # Draw the top level array
    #	(Which recursively draws
    #    all the enclosed elements)
    draw_node_array(\@format_re);
    # Make all the canvas visible
}

##############################################
# find_node($state, $node_array) -- Find a node
#	the parsed node tree
#
# Returns the location of the node
##############################################
sub find_node($$);
sub find_node($$)
{
    # State (node number) to find
    my $state = shift;

    my $array = shift;	# The array to search

    foreach my $cur_node (@$array) {
	if ($cur_node->{node}->{node} ==
		$state) {

	    return ($cur_node->{x_loc},
	            $cur_node->{y_loc});

	}
	if (defined($cur_node->{children})) {
	    # Get the x,y to return from
	    # 	the children
	    my ($ret_x, $ret_y) =
	        find_node(
		    $state,
		    $cur_node->{children});

	    if (defined($ret_x)) {
		return ($ret_x, $ret_y);
	    }
	}
	if (defined($cur_node->{choices})) {
	    my $choices = $cur_node->{choices};
	    foreach my $cur_choice (@$choices) {
		# Get the x,y to return from the
		# 	choice list
		my ($ret_x, $ret_y) =
		    find_node(
			$state, $cur_choice);

		if (defined($ret_x)) {
		    return ($ret_x, $ret_y);
		}
	    }
	}
    }
    return (undef, undef);
}
##############################################
# draw_progress($cur_line, $page)
#
# Draw a progress page
#
# Returns true if the page was drawn
##############################################
sub draw_progress($$$)
{
    my $value = shift;	 # Value to check
    my $cur_line = shift;# Line we are processing
    my $page = shift;    # Page number

    # Check to see if this
    # is one of the progress lines
    if (substr($cur_line, 26, 1) ne '|') {
	return (0);	# Not a good line
    }
    # Line containing the progress number
    # from the debug output
    my $progress_line = substr($cur_line, 0, 24);

    # Location of the current state information
    my $state_line = substr($cur_line, 27);

    # Extract progress number
    $progress_line =~ /^\s*(\d+)/;
    my $progress = $1;

    # Extract state number
    $state_line =~ /^\s*(\d+)/;
    my $state = $1;

    # Find the location of this node
    # on the graph
    my ($x_location, $y_location) =
	find_node($state, \@format_re);

    if ($opt_d) {
	if (defined($x_location)) {
	    print
		"node $state ".
		"($x_location, $y_location)\n";
	} else {
	    print "node $state not found\n";
	}
    }
    # If the node is not graphable,
    # skip this step
    if (not defined($x_location)) {
	return (0);
    }
    # Create a new image with arrow
    my $new_image =
	GD::Image->newFromPngData(
	    $image->png(0));

    # Create the arrow
    my $arrow = GD::Arrow::Full->new(
	-X1 => $x_location,
	-Y1 => $y_location,
	-X2 => $x_location - YELLOW_ARROW_SIZE,
	-Y2 => $y_location - YELLOW_ARROW_SIZE,
	-WIDTH => YELLOW_ARROW_WIDTH
    );

    $new_image->setThickness(1);

    # Create some colors for
    # the new image
    my $new_color_yellow =
	$new_image->colorAllocate(255, 255, 0);

    my $new_color_black =
	$new_image->colorAllocate(0,0,0);

    # Make the arrow point
    # to the current step
    $new_image->filledPolygon(
	$arrow, $new_color_yellow);

    $new_image->polygon(
	$arrow, $new_color_black);

    # Get the size of the font we are using
    my $char_width = gdGiantFont->width;
    my $char_height = gdGiantFont->height;

    $new_image->filledRectangle(
	PROGRESS_X, PROGRESS_Y,
	PROGRESS_X +
	$progress * $char_width,
	PROGRESS_Y + $char_height,
	$new_color_yellow
    );

    $new_image->string(gdGiantFont,
	PROGRESS_X, PROGRESS_Y,
	$value, $new_color_black);

    # Generate the output file name
    my $out_file =
    sprintf($opt_o, $page);

    open OUT_FILE, ">$out_file" or
    die("Could not open output".
    "file: $out_file");

    binmode OUT_FILE;
    print OUT_FILE $new_image->png(0);
    close OUT_FILE;
    return (1);
}
##############################################
# chart_progress -- Chart the progress of the
#	execution of the RE
##############################################
sub chart_progress()
{
    my $value = $ARGV[0];	# Value to check

    # Value with ' quoted
    my $quote_value = $value;
    $quote_value =~ s/'/\\'/g;

    # Regular expression
    my $quote_re = $current_re;
    $quote_re =~ s/\\/\\\\/g;

    my $cmd = <<EOF ;
perl 2>&1 <<SHELL_EOF
use re 'debug';
'$quote_value' =~ /$quote_re/;
SHELL_EOF
EOF

    # The raw debug output
    my @raw_debug = `$cmd`;

    # Go do to the part when the matching starts
    while (($#raw_debug > 0) and
	($raw_debug[0] !~ /^Matching/)) {
	shift(@raw_debug);
    }
    shift(@raw_debug);

    my $page = 1;	# Current output page

    foreach my $cur_line (@raw_debug) {
	# Skip other lines
	if (length($cur_line) < 27) {
	    next;
	}
	if (draw_progress($value,
		$cur_line, $page)) {
	    ++$page;
	}
    }
}


# -d	-- Print RE debug output and draw output
# -o file -- specify output file (template)
# -x <min-x>
# -y <min-y>
my $status = getopts("do:x:y:");
if ($status == 0)
{
    usage();
}

if (not defined($opt_o)) {
    $opt_o = "re_graph_%02d.png";
}

if ($#ARGV == -1) {
    usage();
}
$current_re = shift(@ARGV);

parse_re();
my ($x_size, $y_size) = convert_re();
$x_size += MARGIN;
$y_size += MARGIN;
if (defined($opt_x)) {
    if ($opt_x > $x_size) {
	$x_size = $opt_x;
    }
}
if (defined($opt_y)) {
    if ($opt_y > $y_size) {
	$y_size = $opt_y;
    }
}

$image = GD::Image->new($x_size, $y_size);
# Background color
$color_white =
    $image->colorAllocate(255,255,255);
$color_black = $image->colorAllocate(0,0,0);
$color_green = $image->colorAllocate(0, 255, 0);
$color_blue = $image->colorAllocate(0, 0, 255);
$color_light_green =
	$image->colorAllocate(0, 128, 0);

draw_re();

$image->string(gdGiantFont,
    LABEL_LOC_X, LABEL_LOC_Y,
    "Regular Expression: /$current_re/",
    $color_black);

my $out_file = sprintf($opt_o, 0);
open OUT_FILE, ">$out_file" or
    die("Could not open output file: $out_file");

binmode OUT_FILE;
print OUT_FILE $image->png(0);
close OUT_FILE;

if ($#ARGV != -1) {
    chart_progress();
}

__END__

		    GNU GENERAL PUBLIC LICENSE
		       Version 2, June 1991

 Copyright (C) 1989, 1991 Free Software Foundation, Inc.
     59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

			    Preamble

  The licenses for most software are designed to take away your
freedom to share and change it.  By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users.  This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it.  (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.)  You can apply it to
your programs, too.

  When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.

  To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.

  For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have.  You must make sure that they, too, receive or can get the
source code.  And you must show them these terms so they know their
rights.

  We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.

  Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software.  If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
authors' reputations.

  Finally, any free program is threatened constantly by software
patents.  We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary.  To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.

  The precise terms and conditions for copying, distribution and
modification follow.

		    GNU GENERAL PUBLIC LICENSE
   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License.  The "Program", below,
refers to any such program or work, and a "work based on the Program"
means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it,
either verbatim or with modifications and/or translated into another
language.  (Hereinafter, translation is included without limitation in
the term "modification".)  Each licensee is addressed as "you".

Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope.  The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.

  1. You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.

You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.

  2. You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:

    a) You must cause the modified files to carry prominent notices
    stating that you changed the files and the date of any change.

    b) You must cause any work that you distribute or publish, that in
    whole or in part contains or is derived from the Program or any
    part thereof, to be licensed as a whole at no charge to all third
    parties under the terms of this License.

    c) If the modified program normally reads commands interactively
    when run, you must cause it, when started running for such
    interactive use in the most ordinary way, to print or display an
    announcement including an appropriate copyright notice and a
    notice that there is no warranty (or else, saying that you provide
    a warranty) and that users may redistribute the program under
    these conditions, and telling the user how to view a copy of this
    License.  (Exception: if the Program itself is interactive but
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    the Program is not required to print an announcement.)

These requirements apply to the modified work as a whole.  If
identifiable sections of that work are not derived from the Program,
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Thus, it is not the intent of this section to claim rights or contest
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In addition, mere aggregation of another work not based on the Program
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  3. You may copy and distribute the Program (or a work based on it,
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  4. You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
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  5. You are not required to accept this License, since you have not
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all its terms and conditions for copying, distributing or modifying
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  6. Each time you redistribute the Program (or any work based on the
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  7. If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent issues),
conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License.  If you cannot
distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you
may not distribute the Program at all.  For example, if a patent
license would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you, then
the only way you could satisfy both it and this License would be to
refrain entirely from distribution of the Program.

If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
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It is not the purpose of this section to induce you to infringe any
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This section is intended to make thoroughly clear what is believed to
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  8. If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
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may add an explicit geographical distribution limitation excluding
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  9. The Free Software Foundation may publish revised and/or new versions
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Foundation.

  10. If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the author
to ask for permission.  For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes
make exceptions for this.  Our decision will be guided by the two goals
of preserving the free status of all derivatives of our free software and
of promoting the sharing and reuse of software generally.

			    NO WARRANTY

  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
REPAIR OR CORRECTION.

  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.

		     END OF TERMS AND CONDITIONS

	    How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

    <one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:

    Gnomovision version 69, Copyright (C) year  name of author
    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License.  Of course, the commands you use may
be called something other than `show w' and `show c'; they could even be
mouse-clicks or menu items--whatever suits your program.

You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the program, if
necessary.  Here is a sample; alter the names:

  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
  `Gnomovision' (which makes passes at compilers) written by James Hacker.

  <signature of Ty Coon>, 1 April 1989
  Ty Coon, President of Vice

This General Public License does not permit incorporating your program into
proprietary programs.  If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library.  If this is what you want to do, use the GNU Library General
Public License instead of this License.