/// <summary>
/// Unifies a value on the heap
/// </summary>
public static bool Unify(this IReferenceLiteral address1, IReferenceLiteral address2, ITrail trail)
{
var unifyStack = new Stack <IReferenceLiteral>();
// Push the addresses that we're going to unify
unifyStack.Push(address1);
unifyStack.Push(address2);
// Iterate until the stack is empty
while (unifyStack.Count > 0)
{
// Deref the values on the stack
var value1 = unifyStack.Pop().Dereference();
var value2 = unifyStack.Pop().Dereference();
if (!ReferenceEquals(value1, value2))
{
if (value1.IsReference())
{
// Bind references
trail.Record(value1);
value1.SetTo(value2);
}
else if (value2.IsReference())
{
trail.Record(value2);
value2.SetTo(value1);
}
else
{
if (Equals(value1.Term, value2.Term))
{
// Process the rest of the structure
var structurePos1 = value1.Reference;
var structurePos2 = value2.Reference;
while (structurePos1 != null)
{
unifyStack.Push(structurePos1);
unifyStack.Push(structurePos2);
structurePos1 = structurePos1.NextArgument;
structurePos2 = structurePos2.NextArgument;
}
}
else
{
// Structures do not match: fail
return(false);
}
}
}
}
return(true);
}
/// <summary>
/// Unifies a value on the heap
/// </summary>
public static bool Unify(this IReferenceLiteral address1, IReferenceLiteral address2, ITrail trail)
{
var unifyStack = new Stack<IReferenceLiteral>();
// Push the addresses that we're going to unify
unifyStack.Push(address1);
unifyStack.Push(address2);
// Iterate until the stack is empty
while (unifyStack.Count > 0)
{
// Deref the values on the stack
var value1 = unifyStack.Pop().Dereference();
var value2 = unifyStack.Pop().Dereference();
if (!ReferenceEquals(value1, value2))
{
if (value1.IsReference())
{
// Bind references
trail.Record(value1);
value1.SetTo(value2);
}
else if (value2.IsReference())
{
trail.Record(value2);
value2.SetTo(value1);
}
else
{
if (Equals(value1.Term, value2.Term))
{
// Process the rest of the structure
var structurePos1 = value1.Reference;
var structurePos2 = value2.Reference;
while (structurePos1 != null)
{
unifyStack.Push(structurePos1);
unifyStack.Push(structurePos2);
structurePos1 = structurePos1.NextArgument;
structurePos2 = structurePos2.NextArgument;
}
}
else
{
// Structures do not match: fail
return false;
}
}
}
}
return true;
}
/// <summary>
/// Binds one value to anoteher
/// </summary>
private void Bind(IReferenceLiteral target, IReferenceLiteral value)
{
_trail.Record(target);
target.SetTo(value);
}
