+sub modify_xml_document {
+ my($xc, $fieldsByKey, $data) = @_;
+
+ my $nchanges = 0;
+ foreach my $key (keys %$data) {
+ my $value = $data->{$key};
+ my $ref = $fieldsByKey->{$key} or die "no field '$key'";
+ my($name, $nlines, $caption, $xpath, @addAfter) = @$ref;
+ #print "Considering $key='$value' ($xpath)<br/>\n";
+ my @nodes = $xc->findnodes($xpath);
+ if (@nodes) {
+ warn scalar(@nodes), " nodes match '$xpath'" if @nodes > 1;
+ my $node = $nodes[0];
+
+ if ($node->isa("XML::LibXML::Attr")) {
+ if ($value ne $node->getValue()) {
+ $node->setValue($value);
+ $nchanges++;
+ print "Attr $key: '", $node->getValue(), "' -> '$value' ($xpath)<br/>\n";
+ }
+ } elsif ($node->isa("XML::LibXML::Element")) {
+ # The contents could be any mixture of text and
+ # comments and maybe even other crud such as processing
+ # instructions. The simplest thing is just to throw it all
+ # away and start again, making a single Text node the
+ # canonical representation. But before we do that,
+ # we'll check whether the element is already
+ # canonical, to determine whether our change is a
+ # no-op.
+ my $old = "???";
+ my @children = $node->childNodes();
+ if (@children == 1) {
+ my $child = $node->firstChild();
+ if (ref $child && ref $child eq "XML::LibXML::Text") {
+ $old = $child->getData();
+ next if $value eq $old;
+ }
+ }
+
+ $node->removeChildNodes();
+ my $child = new XML::LibXML::Text($value);
+ $node->appendChild($child);
+ $nchanges++;
+ print "Elem $key: '$old' -> '$value' ($xpath)<br/>\n";
+ } else {
+ warn "unexpected node type $node";
+ }
+
+ } else {
+ next if !$value; # No need to create a new empty node
+ my($ppath, $element) = $xpath =~ /(.*)\/(.*)/;
+ dom_add_element($xc, $ppath, $element, $value, @addAfter);
+ print "Add $key ($xpath) = '$value'<br/>\n";
+ $nchanges++;
+ }
+ }
+
+ return $nchanges;
+}
+
+