From 6cac9de94181189decfe67da9c7f3402ed45a4f0 Mon Sep 17 00:00:00 2001
From: Bruce Miller <nebconinc@gmail.com>
Date: Thu, 21 Dec 2023 09:52:14 -0500
Subject: [PATCH] Fixup \centering, \raggedright,... so they only start
 centering after the current node

---
 lib/LaTeXML/Package/LaTeX.pool.ltxml | 51 ++++++++++++++--------------
 1 file changed, 25 insertions(+), 26 deletions(-)

diff --git a/lib/LaTeXML/Package/LaTeX.pool.ltxml b/lib/LaTeXML/Package/LaTeX.pool.ltxml
index 94438288a..90fdc62b5 100644
--- a/lib/LaTeXML/Package/LaTeX.pool.ltxml
+++ b/lib/LaTeXML/Package/LaTeX.pool.ltxml
@@ -1364,42 +1364,41 @@ DefEnvironment('{flushright}', sub {
 
 # These add an operation to be carried out on the current node & following siblings, when the current group ends.
 # These operators will add alignment (class) attributes to each "line" in the current block.
-#DefPrimitiveI('\centering',   undef, sub { UnshiftValue(beforeAfterGroup=>T_CS('\@add@centering')); });
-# NOTE: THere's a problem here.  The current method seems to work right for these operators
-# appearing within the typical environments.  HOWEVER, it doesn't work for a simple \bgroup or \begingroup!!!
-# (they don't create a node! or even a whatsit!)
-DefConstructorI('\centering', undef,
-  sub { AssignValue(ALIGNING_NODE => $_[0]->getElement); return; },
+sub setupAligningContext {
+  my ($document) = @_;
+  my $node = $document->getElement;
+  AssignValue(ALIGNING_NODE => [$node, $node->lastChild]);
+  return; }
+
+sub applyAligningContext {
+  my ($document, $align, $class) = @_;
+  if (my $container = LookupValue('ALIGNING_NODE')) {
+    my ($node, $previous) = @$container;
+    my @children = $node->childNodes($node);
+    while (my $skip = shift(@children)) {
+      last if !$previous || $previous->isSameNode($skip); }
+    while (my $child = shift(@children)) {
+      setAlignOrClass($document, $child, $align, $class); } }
+  return; }
+
+DefConstructorI('\centering', undef, \&setupAligningContext,
   beforeDigest => sub { UnshiftValue(beforeAfterGroup => T_CS('\@add@centering')); });
-DefConstructorI('\raggedright', undef,
-  sub { AssignValue(ALIGNING_NODE => $_[0]->getElement); return; },
+DefConstructorI('\raggedright', undef, \&setupAligningContext,
   beforeDigest => sub { UnshiftValue(beforeAfterGroup => T_CS('\@add@raggedright')); });
-DefConstructorI('\raggedleft', undef,
-  sub { AssignValue(ALIGNING_NODE => $_[0]->getElement); return; },
+DefConstructorI('\raggedleft', undef, \&setupAligningContext,
   beforeDigest => sub { UnshiftValue(beforeAfterGroup => T_CS('\@add@raggedleft')); });
 
 DefConstructorI('\@add@centering', undef,
-  sub { if (my $node = LookupValue('ALIGNING_NODE')) {
-      map { setAlignOrClass($_[0], $_, 'center', 'ltx_centering') }
-        $_[0]->getChildElements($node); } });
+  sub { applyAligningContext($_[0], 'center', 'ltx_centering'); });
 # Note that \raggedright is essentially align left
 DefConstructorI('\@add@raggedright', undef,
-  sub { if (my $node = LookupValue('ALIGNING_NODE')) {
-      map { setAlignOrClass($_[0], $_, undef, 'ltx_align_left') }
-        $_[0]->getChildElements($node); } });
+  sub { applyAligningContext($_[0], undef, 'ltx_align_left'); });
 DefConstructorI('\@add@raggedleft', undef,
-  sub { if (my $node = LookupValue('ALIGNING_NODE')) {
-      map { setAlignOrClass($_[0], $_, undef, 'ltx_align_right') }
-        $_[0]->getChildElements($node); } });
-
+  sub { applyAligningContext($_[0], undef, 'ltx_align_right'); });
 DefConstructorI('\@add@flushright', undef,
-  sub { if (my $node = LookupValue('ALIGNING_NODE')) {
-      map { setAlignOrClass($_[0], $_, 'right', 'ltx_align_right') }
-        $_[0]->getChildElements($node); } });
+  sub { applyAligningContext($_[0], 'right', 'ltx_align_right'); });
 DefConstructorI('\@add@flushleft', undef,
-  sub { if (my $node = LookupValue('ALIGNING_NODE')) {
-      map { setAlignOrClass($_[0], $_, 'left', 'ltx_align_left') }
-        $_[0]->getChildElements($node); } });
+  sub { applyAligningContext($_[0], 'left', 'ltx_align_left'); });
 
 #======================================================================-
 # C.6.1 Quotations and Verse