From: Matt S Trout <mst@shadowcat.co.uk>
Date: Sat, 23 Jul 2016 21:19:50 +0000 (+0000)
Subject: tug firmly, and recursion pops out into iteration
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=7af7ed1e813a1fb1ee1818637ad92ce5d93453bc;p=scpubgit%2FDX.git

tug firmly, and recursion pops out into iteration
---

diff --git a/lib/DX/SearchState.pm b/lib/DX/SearchState.pm
index 553b304..4715606 100644
--- a/lib/DX/SearchState.pm
+++ b/lib/DX/SearchState.pm
@@ -21,10 +21,10 @@ has on_exhaustion_step => (is => 'ro', isa => Maybe[Step], required => 1);
 has on_solution_step => (is => 'ro', isa => Maybe[Step], required => 1);
 
 sub next_proposition {
-  my ($self, $hyp) = @_;
-  $hyp ||= $self->current_hypothesis;
+  my ($self) = @_;
+  my $hyp = $self->current_hypothesis;
   $self->propositions->members->[
-    $hyp->resolved_propositions->resolved_count
+    $hyp->resolved_propositions->resolved_count + 1
   ];
 }
 
diff --git a/lib/DX/Step/EnterRecheck.pm b/lib/DX/Step/EnterRecheck.pm
index 7134462..4d48553 100644
--- a/lib/DX/Step/EnterRecheck.pm
+++ b/lib/DX/Step/EnterRecheck.pm
@@ -1,6 +1,7 @@
 package DX::Step::EnterRecheck;
 
 use DX::Step::CompleteRecheck;
+use DX::Step::FailRecheck;
 
 use DX::Class;
 
@@ -10,6 +11,8 @@ has proposition_list => (is => 'ro', required => 1);
 
 has on_completion_step => (is => 'ro', required => 1);
 
+has on_failure_step => (is => 'ro', required => 1);
+
 sub apply_to {
   my ($self, $old_ss) = @_;
 
@@ -54,11 +57,13 @@ sub apply_to {
                    proposition => $prop,
                  ),
     is_solution_state => 0,
-    on_exhaustion_step => undef,
     on_solution_step => DX::Step::CompleteRecheck->new(
       resume_search_state => $old_ss->but(next_step => $next_step),
       was_recheck_for => $prop,
     ),
+    on_exhaustion_step => DX::Step::FailRecheck->new(
+      resume_search_state => $old_ss->but(next_step => $self->on_failure_step),
+    ),
   );
 
   return $ss;
diff --git a/lib/DX/Step/FailRecheck.pm b/lib/DX/Step/FailRecheck.pm
new file mode 100644
index 0000000..f120f04
--- /dev/null
+++ b/lib/DX/Step/FailRecheck.pm
@@ -0,0 +1,14 @@
+package DX::Step::FailRecheck;
+
+use DX::Class;
+
+with 'DX::Role::Step';
+
+has resume_search_state => (is => 'ro', required => 1);
+
+sub apply_to {
+  my ($self, $old_ss) = @_;
+  return $self->resume_search_state;
+}
+
+1;
diff --git a/lib/DX/Step/ResolveProposition.pm b/lib/DX/Step/ResolveProposition.pm
index 95ed10d..cb236d8 100644
--- a/lib/DX/Step/ResolveProposition.pm
+++ b/lib/DX/Step/ResolveProposition.pm
@@ -1,6 +1,7 @@
 package DX::Step::ResolveProposition;
 
 use DX::Step::EnterRecheck;
+use DX::Step::Backtrack;
 
 use Types::Standard qw(ArrayRef);
 use DX::Utils qw(deparse);
@@ -28,34 +29,30 @@ sub but_with_dependencies_on {
 }
 
 sub apply_to {
-  my ($self, $ss) = @_;
-  trace 'step.apply.old_hyp '.$self => $ss->current_hypothesis;
-  trace 'step.apply.actions '.$self => $self->actions;
-  my $new_ss = $self->_apply_to_ss($ss);
-  return $ss->but(next_step => DX::Step::Backtrack->new) unless $new_ss;
-  trace 'step.apply.new_hyp '.$self => $new_ss->current_hypothesis;
+  my ($self, $old_ss) = @_;
   my $ns = do {
-    if (my $prop = $new_ss->next_proposition) {
+    if (my $prop = $old_ss->next_proposition) {
       DX::Step::ConsiderProposition->new(
         proposition => $prop
       )
     } else {
-      $new_ss->on_solution_step
+      $old_ss->on_solution_step
     }
   };
   my $alt_step = $self->alternative_step;
-  return (
-    $new_ss->but(
-      next_step => $ns,
-      ($alt_step
-        ? (alternatives => [
-            [ $ss->current_hypothesis, $alt_step ],
-            @{$ss->alternatives}
-          ])
-        : ()
-      ),
+  my $ss = $old_ss->but(
+    next_step => $ns,
+    ($alt_step
+      ? (alternatives => [
+          [ $old_ss->current_hypothesis, $alt_step ],
+          @{$old_ss->alternatives}
+        ])
+      : ()
     ),
   );
+  my $new_ss = $self->_apply_to_ss($ss);
+  return $ss->but(next_step => DX::Step::Backtrack->new) unless $new_ss;
+  return $new_ss;
 }
 
 sub _apply_to_ss {
@@ -79,22 +76,12 @@ sub _recheck_for {
   my $ss = $old_ss->but(
     next_step => DX::Step::EnterRecheck->new(
       proposition_list => \@recheck,
-      on_completion_step => DX::Step::MarkAsSolution->new,
+      on_completion_step => $old_ss->next_step,
+      on_failure_step => DX::Step::Backtrack->new,
     ),
   );
 
-  my $sp = DX::SearchProcess->new(
-    current_search_state => $ss,
-  );
-
-  my $sol_sp = $sp->find_solution;
-
-  unless ($sol_sp) {
-    trace 'step.recheck.fail' => 'argh';
-    return undef;
-  }
-
-  return $sol_sp->current_search_state->but(is_solution_state => 0);
+  return $ss;
 }
 
 1;