PGML Par can create bad HTML by inserting empty divs for spacing

[somiaj]

PGML Implements the Par block in HTML by inserting an empty div with a margin on it for spacing. When used inside of a list this puts these div's as children of ul or ol elements, which is considered invalid HTML.

I don't know the PGML parser that well, but can block elements look forward/backwards, so instead of Par placing the margin as a separate div, the margin is added to the previous block. For example:

BEGIN_PGML
1. First

2. Second

3. Third
END_PGML

Produces the following HTML:

<div class="PGML">
    <ol style="margin:0; padding-left:2.25em; list-style-type: decimal;">
        <li>First</li>
        <div style="margin-top:1em"></div>
        <li>Second</li>
        <div style="margin-top:1em"></div>
        <li>Third</li>
    </ol>
</div>

Instead could the Par blocks some how tag the previous block element so the style is applied there instead like (note placing margin-top on the following block element might also be a possibility):

<div class="PGML">
    <ol style="margin:0; padding-left:2.25em; list-style-type: decimal;">
        <li style="margin-bottom:1em;">First</li>
        <li style="margin-bottom:1em;">Second</li>
        <li>Third</li>
    </ol>
</div>

Tagging @dpvc as I suspect they understand the PGML parser best and if this is possible and how much work it would take to implement.

[Alex-Jordan]

Is there an alternative element like an HR that could serve the same purpose with appropriate styling? Alex Jordan Mathematics Instructor Portland Community College

…

On Mon, Dec 15, 2025, 8:50 AM Jaimos Skriletz ***@***.***> wrote: *somiaj* created an issue (openwebwork/pg#1355) <https://urldefense.com/v3/__https://github.com/openwebwork/pg/issues/1355__;!!Ka_JY85zDv0FFw!kUOOHgsT1lSe2cL5k28pmnWzZW3HwxikbrhWpmpwO22piOmfxGr74T727xDvI9K70n4mk8jYSe5lgdTvmXs4r6K5Uz4$> PGML Implements the Par block in HTML by inserting an empty div with a margin on it for spacing. When used inside of a list this puts these div's as children of ul or ol elements, which is considered invalid HTML. I don't know the PGML parser that well, but can block elements look forward/backwards, so instead of Par placing the margin as a separate div, the margin is added to the previous block. For example: BEGIN_PGML 1. First 2. Second 3. Third END_PGML Produces the following HTML: <div class="PGML"> <ol style="margin:0; padding-left:2.25em; list-style-type: decimal;"> <li>First</li> <div style="margin-top:1em"></div> <li>Second</li> <div style="margin-top:1em"></div> <li>Third</li> </ol></div> Instead could the Par blocks some how tag the previous block element so the style is applied there instead like (note placing margin-top on the following block element might also be a possibility): <div class="PGML"> <ol style="margin:0; padding-left:2.25em; list-style-type: decimal;"> <li style="margin-bottom:1em;">First</li> <li style="margin-bottom:1em;">Second</li> <li>Third</li> </ol></div> Tagging @dpvc <https://urldefense.com/v3/__https://github.com/dpvc__;!!Ka_JY85zDv0FFw!kUOOHgsT1lSe2cL5k28pmnWzZW3HwxikbrhWpmpwO22piOmfxGr74T727xDvI9K70n4mk8jYSe5lgdTvmXs4_dFT1fk$> as I suspect they understand the PGML parser best and if this is possible and how much work it would take to implement. — Reply to this email directly, view it on GitHub <https://urldefense.com/v3/__https://github.com/openwebwork/pg/issues/1355__;!!Ka_JY85zDv0FFw!kUOOHgsT1lSe2cL5k28pmnWzZW3HwxikbrhWpmpwO22piOmfxGr74T727xDvI9K70n4mk8jYSe5lgdTvmXs4r6K5Uz4$>, or unsubscribe <https://urldefense.com/v3/__https://github.com/notifications/unsubscribe-auth/ABEDOACUOL7EKMXYB4CZWYD4B3RELAVCNFSM6AAAAACPDCC3HSVHI2DSMVQWIX3LMV43ASLTON2WKOZTG4ZTCMRZGQ3DONI__;!!Ka_JY85zDv0FFw!kUOOHgsT1lSe2cL5k28pmnWzZW3HwxikbrhWpmpwO22piOmfxGr74T727xDvI9K70n4mk8jYSe5lgdTvmXs41yBRCpk$> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[Alex-Jordan]

I should have looked it up. No, nothing but li is a valid child of ol or ul. Alex Jordan Mathematics Instructor Portland Community College

…

On Mon, Dec 15, 2025, 10:40 AM Alex Jordan ***@***.***> wrote: Is there an alternative element like an HR that could serve the same purpose with appropriate styling? Alex Jordan Mathematics Instructor Portland Community College On Mon, Dec 15, 2025, 8:50 AM Jaimos Skriletz ***@***.***> wrote: > *somiaj* created an issue (openwebwork/pg#1355) > <https://urldefense.com/v3/__https://github.com/openwebwork/pg/issues/1355__;!!Ka_JY85zDv0FFw!kUOOHgsT1lSe2cL5k28pmnWzZW3HwxikbrhWpmpwO22piOmfxGr74T727xDvI9K70n4mk8jYSe5lgdTvmXs4r6K5Uz4$> > > PGML Implements the Par block in HTML by inserting an empty div with a > margin on it for spacing. When used inside of a list this puts these div's > as children of ul or ol elements, which is considered invalid HTML. > > I don't know the PGML parser that well, but can block elements look > forward/backwards, so instead of Par placing the margin as a separate div, > the margin is added to the previous block. For example: > > BEGIN_PGML > 1. First > > 2. Second > > 3. Third > END_PGML > > Produces the following HTML: > > <div class="PGML"> > <ol style="margin:0; padding-left:2.25em; list-style-type: decimal;"> > <li>First</li> > <div style="margin-top:1em"></div> > <li>Second</li> > <div style="margin-top:1em"></div> > <li>Third</li> > </ol></div> > > Instead could the Par blocks some how tag the previous block element so > the style is applied there instead like (note placing margin-top on the > following block element might also be a possibility): > > <div class="PGML"> > <ol style="margin:0; padding-left:2.25em; list-style-type: decimal;"> > <li style="margin-bottom:1em;">First</li> > <li style="margin-bottom:1em;">Second</li> > <li>Third</li> > </ol></div> > > Tagging @dpvc > <https://urldefense.com/v3/__https://github.com/dpvc__;!!Ka_JY85zDv0FFw!kUOOHgsT1lSe2cL5k28pmnWzZW3HwxikbrhWpmpwO22piOmfxGr74T727xDvI9K70n4mk8jYSe5lgdTvmXs4_dFT1fk$> > as I suspect they understand the PGML parser best and if this is possible > and how much work it would take to implement. > > — > Reply to this email directly, view it on GitHub > <https://urldefense.com/v3/__https://github.com/openwebwork/pg/issues/1355__;!!Ka_JY85zDv0FFw!kUOOHgsT1lSe2cL5k28pmnWzZW3HwxikbrhWpmpwO22piOmfxGr74T727xDvI9K70n4mk8jYSe5lgdTvmXs4r6K5Uz4$>, > or unsubscribe > <https://urldefense.com/v3/__https://github.com/notifications/unsubscribe-auth/ABEDOACUOL7EKMXYB4CZWYD4B3RELAVCNFSM6AAAAACPDCC3HSVHI2DSMVQWIX3LMV43ASLTON2WKOZTG4ZTCMRZGQ3DONI__;!!Ka_JY85zDv0FFw!kUOOHgsT1lSe2cL5k28pmnWzZW3HwxikbrhWpmpwO22piOmfxGr74T727xDvI9K70n4mk8jYSe5lgdTvmXs41yBRCpk$> > . > You are receiving this because you are subscribed to this thread.Message > ID: ***@***.***> >

[dpvc]

This might do what you are looking for:

diff --git a/macros/core/PGML.pl b/macros/core/PGML.pl
index cbeb92fa..fcb1b3b8 100644
--- a/macros/core/PGML.pl
+++ b/macros/core/PGML.pl
@@ -1270,15 +1270,16 @@ sub string {
        my $block   = shift;
        my @strings = ();
        my $string;
+       my $i = 0;
        foreach my $item (@{ $block->{stack} }) {
                $self->{item} = $item;
                $self->{nl}   = (!defined($strings[-1]) || $strings[-1] =~ m/\n$/ ? "" : "\n");
                for ($item->{type}) {
                        /indent/   && do { $string = $self->Indent($item);                    last };
                        /align/    && do { $string = $self->Align($item);                     last };
-                       /par/      && do { $string = $self->Par($item);                       last };
+                       /par/      && do { $string = $self->Par($item, $block, $i);           last };
                        /list/     && do { $string = $self->List($item);                      last };
-                       /bullet/   && do { $string = $self->Bullet($item);                    last };
+                       /bullet/   && do { $string = $self->Bullet($item, $block, $i);        last };
                        /text/     && do { $string = $self->Text($item);                      last };
                        /variable/ && do { $string = $self->Variable($item, $block);          last };
                        /command/  && do { $string = $self->Command($item);                   last };
@@ -1301,6 +1302,7 @@ sub string {
                        PGML::Warning "Warning: unknown block type '$item->{type}' in " . ref($self) . "::format\n";
                }
                push(@strings, $string) unless (!defined $string || $string eq '');
+               $i++;
        }
        $self->{nl} = (!defined($strings[-1]) || $strings[-1] =~ m/\n$/ ? "" : "\n");
        return join('', @strings);
@@ -1577,7 +1579,11 @@ sub List {
 sub Bullet {
        my $self = shift;
        my $item = shift;
-       return $self->nl . '<li>' . $self->string($item) . "</li>\n";
+       my $block = shift;
+       my $i = shift;
+       my $stack = $block->{stack};
+       my $style = $i + 1 < scalar(@$stack) && $stack->[$i+1]{type} eq 'par' ? ' style="margin-bottom: 1em"' : '';
+       return $self->nl . "<li${style}>" . $self->string($item) . "</li>\n";
 }
 
 sub Code {
@@ -1606,6 +1612,9 @@ sub Heading {
 sub Par {
        my $self = shift;
        my $item = shift;
+       my $block = shift;
+       my $i = shift;
+       return '' if $block->{stack}[$i-1]{type} eq 'bullet';
        return $self->nl . '<div style="margin-top:1em"></div>' . "\n";
 }

[somiaj]

@dpvc Thanks, that seems to work. I was envisioning something a little more general so the margin could be added to other block elements besides just bullets. I reworked what you wrote as follows, any thoughts on this? Currently it only works for bullets, but this could be extended to other block items to put less empty divs in the html for spacing.

diff --git a/macros/core/PGML.pl b/macros/core/PGML.pl
index 34cba7fc..4e8bab5d 100644
--- a/macros/core/PGML.pl
+++ b/macros/core/PGML.pl
@@ -1266,11 +1266,14 @@ sub format {
 }
 
 sub string {
-       my $self    = shift;
-       my $block   = shift;
+       my ($self, $block) = @_;
+       my $stack   = $block->{stack};
+       my $n       = scalar(@$stack);
        my @strings = ();
        my $string;
-       foreach my $item (@{ $block->{stack} }) {
+       for my $i (0 .. $n - 1) {
+               my $item     = $stack->[$i];
+               my $next_par = $i + 1 < $n && $stack->[ $i + 1 ]{type} eq 'par' ? $stack->[ $i + 1 ] : undef;
                $self->{item} = $item;
                $self->{nl}   = (!defined($strings[-1]) || $strings[-1] =~ m/\n$/ ? "" : "\n");
                for ($item->{type}) {
@@ -1278,7 +1281,7 @@ sub string {
                        /align/    && do { $string = $self->Align($item);                     last };
                        /par/      && do { $string = $self->Par($item);                       last };
                        /list/     && do { $string = $self->List($item);                      last };
-                       /bullet/   && do { $string = $self->Bullet($item);                    last };
+                       /bullet/   && do { $string = $self->Bullet($item, $next_par);         last };
                        /text/     && do { $string = $self->Text($item);                      last };
                        /variable/ && do { $string = $self->Variable($item, $block);          last };
                        /command/  && do { $string = $self->Command($item);                   last };
@@ -1574,8 +1577,11 @@ sub List {
 }
 
 sub Bullet {
-       my $self = shift;
-       my $item = shift;
+       my ($self, $item, $next_par) = @_;
+       if ($next_par) {
+               $next_par->{used_on_prev_item} = 1;
+               return $self->nl . '<li style="margin-bottom: 1em;">' . $self->string($item) . "</li>\n";
+       }
        return $self->nl . '<li>' . $self->string($item) . "</li>\n";
 }

@@ -1603,9 +1609,8 @@ sub Heading {
 }
 
 sub Par {
-       my $self = shift;
-       my $item = shift;
-       return $self->nl . '<div style="margin-top:1em"></div>' . "\n";
+       my ($self, $item) = @_;
+       return $item->{used_on_prev_item} ? '' : $self->nl . '<div style="margin-top:1em"></div>' . "\n";
 }
 
 sub Break {"<br />\n"}