ExecutionResults OnLibraryCallBacktrackingPredicate(WamInstruction instruction, BacktrackingPredicate predicate)
{
var arguments = new WamReferenceTarget[instruction.Functor.Arity];
for (var index = 0; index < instruction.Functor.Arity; ++index)
{
arguments[index] = ArgumentRegisters[index];
}
IEnumerable <bool> enumerable;
try
{
enumerable = predicate.BacktrackingPredicateDelegate(this, arguments);
}
catch
{
// Backtrack on exception.
//
return(ExecutionResults.Backtrack);
}
var enumerator = enumerable.GetEnumerator();
ChoicePoint = new WamChoicePoint(ChoicePoint, Environment, StackIndex, ReturnInstructionPointer, ArgumentRegisters, CutChoicePoint)
{
BacktrackInstructionPointer = InstructionPointer.GetNext(),
PredicateEnumerator = enumerator
};
InstructionPointer = ChoicePoint.BacktrackInstructionPointer;
PredicateEnumerator = ChoicePoint.PredicateEnumerator;
return(ExecutionResults.None);
}
ExecutionResults OnTryMeElse(WamInstruction instruction)
{
var instructionPointer = GetInstructionPointer(instruction.Functor, instruction.Index);
if (instructionPointer == WamInstructionPointer.Undefined)
{
return(ExecutionResults.Failure);
}
ChoicePoint = new WamChoicePoint(ChoicePoint, Environment, StackIndex, ReturnInstructionPointer, ArgumentRegisters, CutChoicePoint)
{
BacktrackInstructionPointer = instructionPointer
};
InstructionPointer = InstructionPointer.GetNext();
return(ExecutionResults.None);
}
public WamChoicePoint(WamChoicePoint predecessor, WamEnvironment environment, int stackIndex, WamInstructionPointer returnInstructionPointer, IEnumerable <WamReferenceTarget> argumentRegisters, WamChoicePoint cutChoicePoint)
{
Generation = NextGeneration++;
Predecessor = predecessor;
Environment = environment;
StackIndex = stackIndex;
ReturnInstructionPointer = returnInstructionPointer;
ArgumentRegisters = new WamReferenceTargetList(argumentRegisters);
CutChoicePoint = cutChoicePoint;
BacktrackInstructionPointer = WamInstructionPointer.Undefined;
PredicateEnumerator = null;
Trail = new List <WamVariable>();
}
public WamChoicePoint(WamChoicePoint predecessor, WamEnvironment environment, int stackIndex, WamInstructionPointer returnInstructionPointer, IEnumerable<WamReferenceTarget> argumentRegisters, WamChoicePoint cutChoicePoint)
{
m_generation = s_nextGeneration++;
m_predecessor = predecessor;
m_environment = environment;
m_stackIndex = stackIndex;
m_returnInstructionPointer = returnInstructionPointer;
m_argumentRegisters = new WamReferenceTargetList(argumentRegisters);
m_cutChoicePoint = cutChoicePoint;
m_backtrackInstructionPointer = WamInstructionPointer.Undefined;
m_predicateEnumerator = null;
m_trail = new List<WamVariable>();
}
public WamChoicePoint(WamChoicePoint predecessor, WamEnvironment environment, int stackIndex, WamInstructionPointer returnInstructionPointer, IEnumerable<WamReferenceTarget> argumentRegisters, WamChoicePoint cutChoicePoint)
{
Generation = NextGeneration++;
Predecessor = predecessor;
Environment = environment;
StackIndex = stackIndex;
ReturnInstructionPointer = returnInstructionPointer;
ArgumentRegisters = new WamReferenceTargetList(argumentRegisters);
CutChoicePoint = cutChoicePoint;
BacktrackInstructionPointer = WamInstructionPointer.Undefined;
PredicateEnumerator = null;
Trail = new List<WamVariable>();
}
public WamChoicePoint(WamChoicePoint predecessor, WamEnvironment environment, int stackIndex, WamInstructionPointer returnInstructionPointer, IEnumerable <WamReferenceTarget> argumentRegisters, WamChoicePoint cutChoicePoint)
{
m_generation = s_nextGeneration++;
m_predecessor = predecessor;
m_environment = environment;
m_stackIndex = stackIndex;
m_returnInstructionPointer = returnInstructionPointer;
m_argumentRegisters = new WamReferenceTargetList(argumentRegisters);
m_cutChoicePoint = cutChoicePoint;
m_backtrackInstructionPointer = WamInstructionPointer.Undefined;
m_predicateEnumerator = null;
m_trail = new List <WamVariable>();
}
private ExecutionResults OnTryMeElse(WamInstruction instruction)
{
WamInstructionPointer instructionPointer = GetInstructionPointer(instruction.Functor, instruction.Index);
if (instructionPointer == WamInstructionPointer.Undefined)
{
return ExecutionResults.Failure;
}
ChoicePoint = new WamChoicePoint(ChoicePoint, Environment, StackIndex, ReturnInstructionPointer, ArgumentRegisters, CutChoicePoint);
ChoicePoint.BacktrackInstructionPointer = instructionPointer;
InstructionPointer = InstructionPointer.GetNext();
return ExecutionResults.None;
}
private ExecutionResults OnLibraryCallBacktrackingPredicate(WamInstruction instruction, BacktrackingPredicate predicate)
{
WamReferenceTarget[] arguments = new WamReferenceTarget[instruction.Functor.Arity];
for (int index = 0; index < instruction.Functor.Arity; ++index)
{
arguments[index] = ArgumentRegisters[index];
}
IEnumerable<bool> enumerable;
try
{
enumerable = predicate.BacktrackingPredicateDelegate(this, arguments);
}
catch
{
// Backtrack on exception.
//
return ExecutionResults.Backtrack;
}
IEnumerator<bool> enumerator = enumerable.GetEnumerator();
ChoicePoint = new WamChoicePoint(ChoicePoint, Environment, StackIndex, ReturnInstructionPointer, ArgumentRegisters, CutChoicePoint);
ChoicePoint.BacktrackInstructionPointer = InstructionPointer.GetNext();
ChoicePoint.PredicateEnumerator = enumerator;
InstructionPointer = ChoicePoint.BacktrackInstructionPointer;
PredicateEnumerator = ChoicePoint.PredicateEnumerator;
return ExecutionResults.None;
}