Configure - Allow CODErefs and ARRAYrefs in configuration setting arrays

This provides for more powerful lazy evaluation and buildup of the
setting contents.  For example, something like this becomes possible:

    defines => [ sub { $config{thisorthat} ? "FOO" : () } ]

Any undefined result of such functions (such as 'undef' or the empty
list) will be ignored.

Reviewed-by: Andy Polyakov <appro@openssl.org>

diff --git a/Configure b/Configure
index 96be54171849bb402273e31c074574ddf096faeb..ce8fac77be4d08ba1e8aa46e97a24cce935e90dc 100755 (executable)
--- a/Configure
+++ b/Configure
@@ -1949,18 +1949,26 @@ sub _add {
 
     my @values =
        map {
-           if (ref($_) eq "ARRAY") {
-               $found_array = 1;
-               @$_;
+           my $res = $_;
+           while (ref($res) eq "CODE") {
+               $res = $res->();
+           }
+           if (defined($res)) {
+               if (ref($res) eq "ARRAY") {
+                   $found_array = 1;
+                   @$res;
+               } else {
+                   $res;
+               }
            } else {
-               $_;
+               ();
            }
     } (@_);
 
     if ($found_array) {
        [ @values ];
     } else {
-       join($separator, @values);
+       join($separator, grep { defined($_) && $_ ne "" } @values);
     }
 }
 sub add_before {
@@ -2080,6 +2088,30 @@ sub resolve_config {
     my %all_keys =
        map { $_ => 1 } (keys %combined_inheritance,
                         keys %{$table{$target}});
+
+    sub process_values {
+       my $object    = shift;
+       my $inherited = shift;  # Always a [ list ]
+       my $target    = shift;
+       my $entry     = shift;
+
+        while(ref($object) eq "CODE") {
+            $object = $object->(@$inherited);
+        }
+        if (!defined($object)) {
+            return ();
+        }
+        elsif (ref($object) eq "ARRAY") {
+            return [ map { process_values($_, $inherited, $target, $entry) }
+                     @$object ];
+        } elsif (ref($object) eq "") {
+            return $object;
+        } else {
+            die "cannot handle reference type ",ref($object)
+                ," found in target ",$target," -> ",$entry,"\n";
+        }
+    }
+
     foreach (sort keys %all_keys) {
 
        # Current target doesn't have a value for the current key?
@@ -2089,20 +2121,12 @@ sub resolve_config {
            $table{$target}->{$_} = $default_combiner;
        }
 
-       my $valuetype = ref($table{$target}->{$_});
-       if ($valuetype eq "CODE") {
-           # CODE reference, execute it with the inherited values as
-           # arguments.
-           $table{$target}->{$_} =
-               $table{$target}->{$_}->(@{$combined_inheritance{$_}});
-       } elsif ($valuetype eq "ARRAY" || $valuetype eq "") {
-           # ARRAY or Scalar, just leave it as is.
-       } else {
-           # Some other type of reference that we don't handle.
-           # Better to abort at this point.
-           die "cannot handle reference type $valuetype,"
-               ," found in target $target -> $_\n";
-       }
+       $table{$target}->{$_} = process_values($table{$target}->{$_},
+                                              $combined_inheritance{$_},
+                                              $target, $_);
+        unless(defined($table{$target}->{$_})) {
+            delete $table{$target}->{$_};
+        }
     }
 
     # Finally done, return the result.