--- trunk/webwork-modperl/lib/WeBWorK/ContentGenerator.pm	2002/08/22 22:02:39	505
+++ trunk/webwork-modperl/lib/WeBWorK/ContentGenerator.pm	2002/08/29 19:45:18	525
@@ -89,6 +89,8 @@
 	my ($self, $templateFile) = (shift, shift);
 	my $r = $self->{r};
 	my $courseEnvironment = $self->{courseEnvironment};
+	my @ifstack = (1); # Start off in printing mode
+		# say $ifstack[-1] to get the result of the last <#!--if-->
 	
 	# so even though the variable $/ APPEARS to contain a newline,
 	# <TEMPLATE> is slurping the whole file into the first element of
@@ -99,7 +101,6 @@
 	#close TEMPLATE;
 	#
 	# Let's try something else instead:
-	
 	my @template = split /\n/, readFile($templateFile);
 	
 	foreach my $line (@template) {
@@ -109,38 +110,47 @@
 		while ($line =~ m/\G(.*?)<!--#(\w*)((?:\s+.*?)?)-->/gc) {
 			my ($before, $function, $raw_args) = ($1, $2, $3);
 			# $args here will be a hashref
-			my $args = $raw_args =~ /\S/ ? cook_args($raw_args) : {};
-			print $before;
-			
+			my @args = $raw_args =~ /\S/ ? cook_args($raw_args) : {};
+			if ($ifstack[-1]) {
+				print $before;
+			}
+
 			if ($self->can($function)) {
-				print $self->$function(@_, $args);
+				if ($function eq "if") {
+					push @ifstack, $self->$function(@_, [@args]);
+				} elsif ($function eq "else" and @ifstack > 1) {
+					$ifstack[-1] = not $ifstack[-1];
+				} elsif ($function eq "endif" and @ifstack > 1) {
+					pop @ifstack;
+				} elsif ($ifstack[-1]) {
+					print $self->$function(@_, {@args});
+				}
 			}
 		}
 		
-		print substr $line, (defined(pos($line)) ? pos($line) : 0);
+		if ($ifstack[-1]) {
+			print substr $line, (defined pos $line) ? pos $line : 0;
+		}
 	}
 }
 
 # cook_args(STRING) - parses a string of the form ARG1="FOO" ARG2="BAR". Returns
-# a reference to a hash containing the parsed arguments.
+# a list which pairs into key/values and fits nicely in {}s.
 # 
 sub cook_args($) {
-	# There are a bunch of commented-out lines that I am using to remind myself
-	# That I want to write a better regex sometime.
 	my ($raw_args) = @_;
-	my $args = {};
-	#my $quotable_string = qr/(?:".*?(?<![^\\](?:\\\\)*\\)"|\W*)/;
-	#my $quotable_string = qr/(?:".*?(?<!\\)"|\W*)/;
-	#my $test_string = '"hel \" lo" hello';
-	
-	#warn $test_string =~ m/($quotable_string)/ ? $1 : "false";
+	my @args = ();
 	
-	while ($raw_args =~ m/\G\s*(\w*)="(.*?)"/g) {
-	#while ($raw_args =~ m/\G\s*($quotable_string)=($quotable_string)/g) {
-		$args->{$1} = $2;
+	# Boy I love m//g in scalar context!  Go read the camel book, heathen.
+	# First, get the whole token with the quotes on both ends...
+	while ($raw_args =~ m/\G\s*(\w*)="((?:[^"\\]|\\.)*)"/g) {
+		my ($key, $value) = ($1, $2);
+		# ... then, rip out all the protecty backspaces
+		$value =~ s/\\(.)/$1/g;
+		push @args, $key => $value;
 	}
 	
-	return $args;
+	return @args;
 }
 
 ################################################################################
@@ -335,12 +345,55 @@
 	;
 }
 
-sub title {
-	return "WeBWorK";
+# This is different.  It probably should print anything (except in debugging cases)
+# and it should return a boolean, not a string.  &if is called in a nonstandard way
+# by &template, with $args as an arrayref instead of a hashref.  this is a hack!  yay!
+
+# OK, this is a pluggin architecture.  it iterates through attributes of the "if" tag,
+# and for each predicate $p, it calls &if_$p in an object-oriented way, continuing the
+# grand templating theme of an object-oriented pluggable architecture using ->can($).
+sub if {
+	my ($self, $args) = @_[0,-1];
+	# A single if "or"s it's components.  Nesting produces "and".
+	
+	my @args = @$args; # Hahahahaha, get it?!
+	
+	if (@args % 2 != 0) {
+		# flip out and kill people, but do not commit seppuku
+		print '<!--&if recieved an uneven number of arguments.  This shouldn\'t happen, but I\'ll let it slide.-->\n';
+	}
+	
+	while (@args > 1) {
+		my ($key, $value) = (shift @args, shift @args);
+		
+		# a non-existent &if_$key is the same as a false result, but we're ORing, so it's OK
+		my $sub = "if_$key"; # perl doesn't like it when you try to construct a string right in a method invocation
+		if ($self->can("if_$key") and $self->$sub("$value")) {
+			return 1;
+		}
+	}
+	
+	return 0;
 }
 
-sub body {
-	return "Generated content";
+# &if_can will return 1 if the current object->can("do $_[1]")
+sub if_can ($$) {
+	my ($self, $arg) = (@_);
+	
+	if ($self->can("$arg")) {
+		return 1;
+	} else {
+		return 0;
+	}
 }
 
 1;
+
+__END__
+
+=head1 AUTHOR
+
+Written by Dennis Lambe Jr., malsyned (at) math.rochester.edu
+and Sam Hathaway, sh002i (at) math.rochester.edu.
+
+=cut