don't negate undef in Slice/FetchFirst

[dbsrgits/Data-Query.git] / lib / Data / Query / Renderer / SQL / Slice / FetchFirst.pm

diff --git a/lib/Data/Query/Renderer/SQL/Slice/FetchFirst.pm b/lib/Data/Query/Renderer/SQL/Slice/FetchFirst.pm
index 5558074..f2741d6 100644 (file)
--- a/lib/Data/Query/Renderer/SQL/Slice/FetchFirst.pm
+++ b/lib/Data/Query/Renderer/SQL/Slice/FetchFirst.pm
@@ -1,9 +1,10 @@
 package Data::Query::Renderer::SQL::Slice::FetchFirst;
 
-use List::Util qw(reduce);
 use Data::Query::ExprHelpers;
 use Moo::Role;
 
+with 'Data::Query::Renderer::SQL::Slice::SubqueryRemap';
+
 sub _render_slice_limit {
   my ($self, $dq) = @_;
   return [
@@ -14,6 +15,10 @@ sub _render_slice_limit {
   ];
 }
 
+sub slice_stability {
+  (offset => 'requires');
+}
+
 sub _slice_type { 'FetchFirst' }
 
 sub _render_slice {
@@ -26,103 +31,67 @@ sub _render_slice {
   }
   die "Slice's inner is not a Select"
     unless is_Select my $orig_select = $dq->{from};
-  my %alias_map;
-  my $gensym_count;
-  my (@inside_select_list, @outside_select_list);
-  my $default_inside_alias;
-  SELECT: foreach my $s (@{$orig_select->{select}}) {
-    my $name;
-    if (is_Alias $s) {
-      $name = $s->{to};
-      $s = $s->{from};
-    }
-    my $key;
-    if (is_Identifier $s) {
-      if (!$name and @{$s->{elements}} == 2) {
-        $default_inside_alias ||= $s->{elements}[0];
-        if ($s->{elements}[0] eq $default_inside_alias) {
-          $alias_map{join('.',@{$s->{elements}})} = $s;
-          push @inside_select_list, $s;
-          push @outside_select_list, $s;
-          next SELECT;
-        }
-      }
-      $name ||= join('__', @{$s->{elements}});
-      $key = join('.', @{$s->{elements}});
-    } else {
-      die "XXX not implemented yet" unless $name;
-      $key = "$s";
-    }
-    $name ||= sprintf("GENSYM__%03i",++$gensym_count);
-    push @inside_select_list, Alias($name, $s);
-    push @outside_select_list, $alias_map{$key} = Identifier($name);
-  }
-  my $order = $orig_select->{from};
-  my $order_gensym_count;
   die "Slice's Select not followed by Order but order_is_stable set"
-    unless is_Order $order;
-  my (@order_nodes, %order_map);
-  while (is_Order $order) {
-    my $by = $order->{by};
-    if (is_Identifier $by) {
-      $default_inside_alias ||= $by->{elements}[0]
-        if @{$by->{elements}} == 2;
-      $order_map{$by}
-        = $alias_map{join('.', @{$by->{elements}})}
-          ||= do {
-                if (
-                  @{$by->{elements}} == 2
-                  and $by->{elements}[0] eq $default_inside_alias
-                ) {
-                  $by;
-                } else {
-                  my $name = sprintf("ORDER__BY__%03i",++$order_gensym_count);
-                  push @inside_select_list, Alias($name, $by);
-                  Identifier($name);
-                }
-              };
-    } else {
-      die "XXX not implemented yet";
-    }
-    push @order_nodes, $order;
-    $order = $order->{from};
-  }
-  my $inside_order = reduce {
-    Order($b->{by}, $b->{reverse}, $a)
-  } $order, reverse @order_nodes;
-  my $inside_select = Select(\@inside_select_list, $inside_order);
+    unless is_Order $orig_select->{from};
+
+  my %remapped = $self->_subquery_remap($orig_select);
+
+  my @inside_select_list = @{$remapped{inside_select_list}};
+  my @outside_select_list = @{$remapped{outside_select_list}};
+  my @inside_order = @{$remapped{inside_order}};
+  my @outside_order = @{$remapped{outside_order}};
+  my $default_inside_alias = $remapped{default_inside_alias};
+  my $inner_body = $remapped{inner_body};
+
   my $limit_plus_offset = +{
     %{$dq->{limit}}, value => $dq->{limit}{value} + $dq->{offset}{value}
   };
-  $default_inside_alias ||= 'me';
-  my $bridge_from = Alias(
-    $default_inside_alias,
-    Slice(undef, $limit_plus_offset, $inside_select)
-  );
-  my $outside_order = reduce {
-    Order($order_map{$b->{by}}, !$b->{reverse}, $a)
-  } $bridge_from, reverse @order_nodes;
-  my $outside_select = Select(
-    (
+
+  return $self->_render(
+    map {
       $dq->{preserve_order}
-        ? [
+        ? Select(
+          \@outside_select_list,
+          compose {
+            Order($b->{by}, $b->{reverse}, $b->{nulls}, $a)
+          } (
+            @outside_order,
+            Alias($default_inside_alias, $_)
+          )
+        )
+        : $_
+    } (
+      Slice(
+        undef, $dq->{limit},
+        Select(
+          [
             @outside_select_list,
-            grep @{$_->{elements}} == 1, @order_map{map $_->{by}, @order_nodes}
-          ]
-        : \@outside_select_list,
-    ),
-    $outside_order,
+            $dq->{preserve_order}
+              ? (grep @{$_->{elements}} == 1,
+                  map $_->{by}, @outside_order)
+              : (),
+          ],
+          compose {
+            Order($b->{by}, !$b->{reverse}, -($b->{nulls}||0), $a)
+          } (
+            @outside_order,
+            Alias(
+              $default_inside_alias,
+              Slice(
+                undef, $limit_plus_offset,
+                Select(
+                  \@inside_select_list,
+                  compose {
+                    Order($b->{by}, $b->{reverse}, $b->{nulls}, $a)
+                  } @inside_order, $inner_body
+                )
+              )
+            )
+          )
+        )
+      )
+    )
   );
-  my $final = Slice(undef, $dq->{limit}, $outside_select);
-  if ($dq->{preserve_order}) {
-    $final = Select(
-      \@outside_select_list,
-      reduce {
-        Order($order_map{$b->{by}}, $b->{reverse}, $a)
-      } Alias($default_inside_alias, $final), reverse @order_nodes
-    );
-  }
-  return $self->_render($final);
 }
 
 1;