Indices: reuse whole and central endemism results when appropriate

If the second neighbour set is empty then the
whole and central variants return the same results.
So short circuit in these cases.

lib/Biodiverse/Indices/Endemism.pm

@@ -298,11 +298,24 @@ sub get_metadata_calc_endemism_central_hier_part {
 }
 
 sub calc_endemism_central_hier_part {
-    my $self = shift;
+    my ($self, %args) = @_;
+
+    #  If we have no nbrs in set 2 then we are the same as the "whole" variant.
+    #  So just grab its values if it has already been calculated.
+    if (!keys %{$args{label_hash2}}) {
+        my $cache_hash = $self->get_cached_value('AS_RESULTS_FROM_LOCAL');
+        my $cached = $cache_hash->{calc_endemism_whole_hier_part};
+        if ($cached) {
+            my %remapped;
+            @remapped{map {$_ =~ s/ENDW/ENDC/r} keys %$cached}
+                = values %$cached;
+            return wantarray ? %remapped : \%remapped;
+        }
+    }
 
     return $self->_calc_endemism_hier_part (
-        @_,
-        prefix        => 'ENDC_HPART_',
+        %args,
+        prefix => 'ENDC_HPART_',
     );
 }
 
@@ -317,11 +330,25 @@ sub get_metadata_calc_endemism_whole_hier_part {
 }
 
 sub calc_endemism_whole_hier_part {
-    my $self = shift;
+    my ($self, %args) = @_;
+
+    #  If we have no nbrs in set 2 then we are the same as the "central" variant.
+    #  So just grab its values if it has already been calculated.
+    if (!keys %{$args{label_hash2}}) {
+        my $cache_hash = $self->get_cached_value('AS_RESULTS_FROM_LOCAL');
+        my $cached = $cache_hash->{calc_endemism_central_hier_part};
+        if ($cached) {
+            # say STDERR join ' ', sort keys %$cached;
+            my %remapped;
+            @remapped{map {$_ =~ s/ENDC/ENDW/r} keys %$cached}
+                = values %$cached;
+            return wantarray ? %remapped : \%remapped;
+        }
+    }
 
     return $self->_calc_endemism_hier_part (
-        @_,
-        prefix        => 'ENDW_HPART_',
+        %args,
+        prefix => 'ENDW_HPART_',
     );
 }
 
@@ -407,6 +434,7 @@ sub metadata_for_calc_endemism_hier_part {
         formula         => $formula,
         pre_calc        => [
             "_calc_endemism_$endemism_type",
+            'calc_abc2',
         ],
         pre_calc_global => 'get_basedata_labels_as_tree',
         uses_nbr_lists  => 1,  #  how many sets of lists it must have
@@ -555,6 +583,15 @@ sub _calc_endemism_central {
     my $self = shift;
     my %args = @_;
 
+    #  If we have no nbrs in set 2 then we are the same as the "whole" variant.
+    #  So just grab its values if it has already been calculated.
+    if (!keys %{$args{label_hash2}}) {
+        my $cache_hash = $self->get_cached_value('AS_RESULTS_FROM_LOCAL');
+        my $cached = $cache_hash->{_calc_endemism_whole};
+        return wantarray ? %$cached : $cached
+            if $cached;
+    }
+
     return $self->_calc_endemism(%args, end_central => 1);
 }
 
@@ -694,8 +731,18 @@ sub get_metadata__calc_endemism_whole {
 
 #  wrapper sub
 sub _calc_endemism_whole {
-    my $self = shift;
-    return $self->_calc_endemism(@_, end_central => 0);
+    my ($self, %args) = @_;
+
+    #  If we have no nbrs in set 2 then we are the same as the "central" variant.
+    #  So just grab its values if it has already been calculated.
+    if (!keys %{$args{label_hash2}}) {
+        my $cache_hash = $self->get_cached_value('AS_RESULTS_FROM_LOCAL');
+        my $cached = $cache_hash->{_calc_endemism_central};
+        return wantarray ? %$cached : $cached
+          if $cached;
+    }
+
+    return $self->_calc_endemism(%args, end_central => 0);
 }
 
 #  Calculate endemism.  Private method called by others
@@ -707,8 +754,7 @@ sub _calc_endemism {
     my $bd = $self->get_basedata_ref;
 
     #  if element_list2 is specified and end_central == 1,
-    #  then it will consider those elements in the local range calculations,
-    #  but only use those labels that occur in the element_list1
+    #  then it will use the local ranges across sets 1 and 2
 
     my $local_ranges = $args{label_hash_all};
     my $label_list   = $args{end_central}