extract backtrack decisions out into steps

[scpubgit/DX.git] / lib / DX / SearchState.pm

diff --git a/lib/DX/SearchState.pm b/lib/DX/SearchState.pm
index 9c831df..18979e7 100644 (file)
--- a/lib/DX/SearchState.pm
+++ b/lib/DX/SearchState.pm
@@ -1,6 +1,7 @@
 package DX::SearchState;
 
 use Types::Standard qw(Maybe);
+use DX::Step::Backtrack;
 use DX::Step::InvokeNextPredicate;
 use DX::Class;
 
@@ -13,9 +14,10 @@ has propositions => (is => 'ro', isa => PropositionSequence, required => 1);
 has alternatives => (is => 'ro', isa => AlternativeList, required => 1);
 
 sub next_proposition {
-  my ($self) = @_;
+  my ($self, $hyp) = @_;
+  $hyp ||= $self->current_hypothesis;
   $self->propositions->members->[
-    $self->current_hypothesis->resolved_propositions->resolved_count
+    $hyp->resolved_propositions->resolved_count
   ];
 }
 
@@ -33,43 +35,8 @@ sub new_for {
 
 sub with_one_step {
   my ($self) = @_;
-  my $hyp = $self->current_hypothesis;
   return undef unless my $step = $self->next_step;
-  my ($first_alt, @rest_alt) = my @alt = @{$self->alternatives};
-  my ($new_hyp, $alt_step) = $step->apply_to($hyp);
-  if ($new_hyp) {
-    return $self->but(
-      current_hypothesis => $new_hyp,
-      alternatives => [
-        ($alt_step
-          ? [ $hyp, $alt_step ]
-          : ()),
-        @alt
-      ],
-      next_step => DX::Step::InvokeNextPredicate->new(
-        proposition => $self->next_proposition,
-      ),
-    );
-  }
-  if ($alt_step) {
-    return $self->but(next_step => $alt_step);
-  }
-  return undef unless $first_alt;
-  trace 'search.backtrack.rewind_to' => $first_alt->[1];
-  return $self->but(
-    current_hypothesis => $first_alt->[0],
-    alternatives => \@rest_alt,
-    next_step => $first_alt->[1],
-  );
-}
-
-sub find_solution {
-  my $state = $_[0];
-  while ($state and $state->next_proposition) {
-    $state = $state->with_one_step;
-  }
-  trace 'search.solution.hyp' => $state->current_hypothesis if $state;
-  return $state;
+  return $step->apply_to($self);
 }
 
 sub force_backtrack {
@@ -85,10 +52,4 @@ sub force_backtrack {
   );
 }
 
-sub find_next_solution {
-  my ($self) = @_;
-  return undef unless my $bt = $self->force_backtrack;
-  return $bt->find_solution;
-}
-
 1;