add but method to state

[scpubgit/DKit.git] / lib / DX / State.pm

diff --git a/lib/DX/State.pm b/lib/DX/State.pm
index f273ddb..2bf0f07 100644 (file)
--- a/lib/DX/State.pm
+++ b/lib/DX/State.pm
@@ -1,5 +1,7 @@
 package DX::State;
 
+use Return::MultiLevel qw(with_return);
+use DX::Op::FromCode;
 use Moo;
 
 has next_op => (is => 'ro', required => 1);
@@ -21,7 +23,7 @@ sub bind_stream_then {
   my ($self, $var, $stream, $then) = @_;
   warn "Binding ".$var->id." to $stream";
   my $bound = $var->with_stream($stream);
-  $self->new(%$self,
+  $self->but(
     by_id => { %{$self->by_id}, $var->id => $bound },
     next_op => $then
   )->mark_choice($bound);
@@ -29,23 +31,46 @@ sub bind_stream_then {
 
 sub mark_choice {
   my ($self, $var) = @_;
-  $self->new(%$self,
-    last_choice => [ $self, $var ]
-  );
+  $self->but(last_choice => [ $self, $var ]);
 }
 
 sub backtrack {
   my ($self) = @_;
-  while (my ($state, $var) = @{$self->last_choice}) {
+  my ($state, $var) = ($self);
+  while (($state, $var) = @{$state->last_choice}) {
     $var->bound_value; $var->clear_bound_value;
-    return $state unless $var->bound_stream->is_exhausted;
+    return $state->mark_choice($var) unless $var->bound_stream->is_exhausted;
+  }
+  if (our $No_Options_Handler) {
+    $No_Options_Handler->(undef);
   }
   die "Out of options";
 }
 
 sub then {
   my ($self, $then) = @_;
-  $self->new(%$self, next_op => $then);
+  $self->but(next_op => $then);
+}
+
+sub run {
+  my ($state) = @_;
+  with_return {
+    my ($return) = @_;
+    local our $No_Options_Handler = $return;
+    while (my $op = $state->next_op) {
+      $state = $op->run($state);
+    }
+    return $state;
+  }
+}
+
+sub push_backtrack {
+  $_[0]->then(DX::Op::FromCode->new(code => sub { $_[1]->backtrack }));
+}
+
+sub but {
+  my ($self, @but) = @_;
+  $self->new(%$self, @but);
 }
 
 1;