Simplify and rename _resolve_prefetch

No functional changes, just logic and arglist cleanup - a couple of them were
no longer used: $order was forgotten in d4d8e97, and the alias-prefix went
unused somewhere around that time as well

lib/DBIx/Class/ResultSet.pm

@@ -3725,7 +3725,7 @@ sub _resolved_attrs {
     # this is a separate structure (we don't look in {from} directly)
     # as the resolver needs to shift things off the lists to work
     # properly (identical-prefetches on different branches)
-    my $join_map = {};
+    my $joined_node_aliases_map = {};
     if (ref $attrs->{from} eq 'ARRAY') {
 
       my $start_depth = $attrs->{seen_join}{-relation_chain_depth} || 0;
@@ -3737,14 +3737,14 @@ sub _resolved_attrs {
 
         my @jpath = map { keys %$_ } @{$j->[0]{-join_path}};
 
-        my $p = $join_map;
+        my $p = $joined_node_aliases_map;
         $p = $p->{$_} ||= {} for @jpath[ ($start_depth/2) .. $#jpath]; #only even depths are actual jpath boundaries
         push @{$p->{-join_aliases} }, $j->[0]{-alias};
       }
     }
 
     ( push @{$attrs->{select}}, $_->[0] ) and ( push @{$attrs->{as}}, $_->[1] )
-      for $source->_resolve_prefetch( $prefetch, $alias, $join_map );
+      for $source->_resolve_selection_from_prefetch( $prefetch, $joined_node_aliases_map );
   }
 
 

lib/DBIx/Class/ResultSource/RowParser.pm

@@ -14,59 +14,73 @@ use DBIx::Class::ResultSource::RowParser::Util qw(
   assemble_collapsing_parser
 );
 
+use DBIx::Class::Carp;
+
 use namespace::clean;
 
-# Accepts one or more relationships for the current source and returns an
-# array of column names for each of those relationships. Column names are
-# prefixed relative to the current source, in accordance with where they appear
-# in the supplied relationships.
-sub _resolve_prefetch {
-  my ($self, $pre, $alias, $alias_map, $order, $pref_path) = @_;
+# Accepts a prefetch map (one or more relationships for the current source),
+# returns a set of select/as pairs for each of those relationships. Columns
+# are fully qualified inflation_slot names
+sub _resolve_selection_from_prefetch {
+  my ($self, $pre, $alias_map, $pref_path) = @_;
+
+  # internal recursion marker
   $pref_path ||= [];
 
   if (not defined $pre or not length $pre) {
     return ();
   }
   elsif( ref $pre eq 'ARRAY' ) {
-    return
-      map { $self->_resolve_prefetch( $_, $alias, $alias_map, $order, [ @$pref_path ] ) }
-        @$pre;
+    map { $self->_resolve_selection_from_prefetch( $_, $alias_map, [ @$pref_path ] ) }
+      @$pre;
   }
   elsif( ref $pre eq 'HASH' ) {
-    my @ret =
     map {
-      $self->_resolve_prefetch($_, $alias, $alias_map, $order, [ @$pref_path ] ),
-      $self->related_source($_)->_resolve_prefetch(
-         $pre->{$_}, "${alias}.$_", $alias_map, $order, [ @$pref_path, $_] )
+      $self->_resolve_selection_from_prefetch($_, $alias_map, [ @$pref_path ] ),
+      $self->related_source($_)->_resolve_selection_from_prefetch(
+         $pre->{$_}, $alias_map, [ @$pref_path, $_] )
     } keys %$pre;
-    return @ret;
   }
   elsif( ref $pre ) {
     $self->throw_exception(
       "don't know how to resolve prefetch reftype ".ref($pre));
   }
   else {
     my $p = $alias_map;
-    $p = $p->{$_} for (@$pref_path, $pre);
+    $p = $p->{$_} for @$pref_path, $pre;
 
     $self->throw_exception (
       "Unable to resolve prefetch '$pre' - join alias map does not contain an entry for path: "
       . join (' -> ', @$pref_path, $pre)
     ) if (ref $p->{-join_aliases} ne 'ARRAY' or not @{$p->{-join_aliases}} );
 
-    my $as = shift @{$p->{-join_aliases}};
-
-    my $rel_info = $self->relationship_info( $pre );
-    $self->throw_exception( $self->source_name . " has no such relationship '$pre'" )
-      unless $rel_info;
+    # this shift() is critical - it is what allows prefetch => [ (foo) x 2 ] to work
+    my $src_alias = shift @{$p->{-join_aliases}};
+
+    # ordered [select => as] pairs
+    map { [
+      "${src_alias}.$_" => join ( '.',
+        @$pref_path,
+        $pre,
+        $_,
+      )
+    ] } $self->related_source($pre)->columns;
+  }
+}
 
-    my $as_prefix = ($alias =~ /^.*?\.(.+)$/ ? $1.'.' : '');
+sub _resolve_prefetch {
+  carp_unique(
+    'There is no good reason to call this internal deprecated method - '
+  . 'please open a ticket detailing your usage, so that a better plan can '
+  . 'be devised for your case. In either case _resolve_prefetch() is '
+  . 'deprecated in favor of _resolve_selection_from_prefetch(), which has '
+  . 'a greatly simplified arglist.'
+  );
 
-    return map { [ "${as}.$_", "${as_prefix}${pre}.$_", ] }
-      $self->related_source($pre)->columns;
-  }
+  $_[0]->_resolve_selection_from_prefetch( $_[1], $_[3] );
 }
 
+
 # Takes an arrayref of {as} dbic column aliases and the collapse and select
 # attributes from the same $rs (the selector requirement is a temporary
 # workaround... I hope), and returns a coderef capable of: