Indices: simplify dependencies for RW turnover

No need to calculate calc_abc for the phylo
variant.

This has the knock-on effect of needing to handle
arrays and hashes for the element_list[12] args.
The intent is to clean that up as part of issue #919.

lib/Biodiverse/Indices/RWTurnover.pm

@@ -9,6 +9,7 @@ no warnings 'experimental::refaliasing';
 
 use Carp;
 use List::Util qw /sum reduce/;
+use Ref::Util qw /is_hashref/;
 
 our $VERSION = '4.99_002';
 
@@ -65,12 +66,20 @@ sub calc_rw_turnover {
         #  or inverse of ranges
         my $cache
             = $self->get_cached_value_dor_set_default_href ('_calc_phylo_rwt_pairwise_branch_sum_cache');
+        #  use postfix idiom?
+        #  ideally we would only be passed arrays, but see issue #919
+        my $key1 = is_hashref ($args{element_list1})
+            ? ((keys %{$args{element_list1}})[0])
+            : (${$args{element_list1}}[0]);
+        my $key2 = is_hashref ($args{element_list2})
+            ? ((keys %{$args{element_list2}})[0])
+            : (${$args{element_list2} //[]}[0]);
         #  Could use a reduce call to collapse the "sum map {} @list" idiom,
         #  thus avoiding a list generation.  These are only run once per group,
         #  though, so it might not matter.
-        my $sum_i = $cache->{(keys %{$args{element_list1}})[0]}  # use postfix deref?
+        my $sum_i = $cache->{$key1}
             //= (sum map {1 / $_} @ranges{keys %list1}) // 0;
-        my $sum_j = $cache->{(keys %{$args{element_list2}})[0]}
+        my $sum_j = $cache->{$key2}
             //= (sum map {1 / $_} @ranges{keys %list2}) // 0;
         #  save some looping, mainly when there are large differences in key counts
         if (keys %list1 <= keys %list2) {
@@ -121,7 +130,7 @@ sub get_metadata_calc_phylo_rw_turnover {
         name            => 'Phylo Range weighted Turnover',
         reference       => 'Laffan et al. (2016) https://doi.org/10.1111/2041-210X.12513',
         type            => 'Phylogenetic Turnover',
-        pre_calc        => [qw /calc_abc _calc_pe_lists_per_element_set/],
+        pre_calc        => [qw /_calc_pe_lists_per_element_set/],
         # pre_calc_global => [qw /
         #     get_node_range_hash_as_lists
         #     get_trimmed_tree_parent_name_hash
@@ -164,9 +173,20 @@ sub calc_phylo_rw_turnover {
         #  simplify the calcs as we only need to find $aa
         my $cache
             = $self->get_cached_value_dor_set_default_href ('_calc_phylo_rwt_pairwise_branch_sum_cache');
-        my $sum_i = $cache->{(keys %{$args{element_list1}})[0]}  # use postfix deref?
+        #  use postfix idiom?
+        #  ideally we would only be passed arrays, but see issue #919
+        my $key1 = is_hashref ($args{element_list1})
+            ? ((keys %{$args{element_list1}})[0])
+            : (${$args{element_list1}}[0]);
+        my $key2 = is_hashref ($args{element_list2})
+            ? ((keys %{$args{element_list2}})[0])
+            : (${$args{element_list2} //[]}[0]);
+        #  Could use a reduce call to collapse the "sum map {} @list" idiom,
+        #  thus avoiding a list generation.  These are only run once per group,
+        #  though, so it might not matter.
+        my $sum_i = $cache->{$key1}
             //= (sum values %list1) // 0;
-        my $sum_j = $cache->{(keys %{$args{element_list2}})[0]}
+        my $sum_j = $cache->{$key2}
             //= (sum values %list2) // 0;
         #  save some looping, mainly when there are large differences in key counts
         if (keys %list1 <= keys %list2) {