public void Unify(XPredicate src, XPredicate dest, IXExpression expression)
{
for (int i = 0; i < src.Signature.Arity; ++i)
{
var sArg = src.Vars[i];
var dArg = dest.Vars[i];
if (sArg.Type == XType.Var && dArg.Type == XType.Const)
{
expression.Bind(sArg, dArg);
}
}
}
public bool Resolve(XPredicate target, IXExpression expression, out List <XPredicate> facts, out List <XPredicate> localFacts)
{
if (expression == null)
{
facts = new List <XPredicate>();
localFacts = new List <XPredicate>();
return(true);
}
switch (expression.Type)
{
case XOperand.Predicate:
var predicateExp = expression as XExpression;
facts = new List <XPredicate>();
if (Run(predicateExp.Predicate, out localFacts))
{
foreach (var f in localFacts)
{
var clone = target.Clone();
for (int i = 0; i < f.Vars.Length; ++i)
{
var sArg = predicateExp.Predicate.Vars[i];
var dArg = f.Vars[i];
if (sArg.Type == XType.Var && dArg.Type == XType.Const)
{
clone.Bind(sArg, dArg);
}
}
facts.Add(clone);
}
return(true);
}
return(false);
case XOperand.Not:
var notExp = expression as XNot;
return(!Resolve(target, notExp.Expression.Clone(), out facts, out localFacts));
default:
var andExp = expression as XAnd;
return(Resolve2(target, andExp, out facts, out localFacts));
}
}
public bool Resolve2(XPredicate target, XAnd expression, out List <XPredicate> facts, out List <XPredicate> localFacts)
{
if (expression.Childs.Count > 0)
{
var exp = expression.Childs[0];
facts = new List <XPredicate>();
if (!Resolve(target, exp, out List <XPredicate> partialSolutions, out localFacts))
{
return(false);
}
if (exp.Type == XOperand.Predicate)
{
var src = exp as XExpression;
expression.Childs.RemoveAt(0);
bool hasSolutions = false;
for (int i = 0; i < localFacts.Count; ++i)
{
var dest = localFacts[i];
var expCopy = expression.Clone();
Unify(src.Predicate, dest, expCopy);
++logger.Indent;
if (Resolve2(partialSolutions[i], expCopy, out List <XPredicate> partialSolutions2, out _))
{
facts.AddRange(partialSolutions2);
hasSolutions = true;
}
--logger.Indent;
}
return(hasSolutions);
}
return(false);
}
facts = new List <XPredicate>()
{
target
};
localFacts = new List <XPredicate>();
return(true);
}
public bool Run(XPredicate target, out List <XPredicate> solutions)
{
logger.LogD("Target: {0}", target);
solutions = new List <XPredicate>();
if (!VerifySignature(target.Signature))
{
logger.LogD("FAILED");
return(false);
}
foreach (var c in Database.Clauses)
{
var clause = c.Bind(target.Clone());
if (clause != null)
{
logger.LogD("Suitable clause: {0}", clause);
++logger.Indent;
var newTarget = clause.Predicate;
if (Resolve(newTarget, clause.Body, out List <XPredicate> partialSolutions, out _))
{
if (clause.Body == null && !solutions.Contains(newTarget))
{
solutions.Add(newTarget);
}
else
{
solutions.AddRange(partialSolutions);
}
}
--logger.Indent;
}
}
if (solutions.Count != 0)
{
logger.LogD("SUCCESS");
return(true);
}
logger.LogD("FAILED");
return(false);
}
public XClause Bind(XPredicate predicate)
{
if (predicate.Signature != Predicate.Signature)
{
return(null);
}
var copy = this.Clone();
for (int i = 0; i < predicate.Signature.Arity; ++i)
{
var sArg = predicate.Vars[i];
var dArg = copy.Predicate.Vars[i];
if (sArg.Type == XType.Const && dArg.Type == XType.Const && sArg.Value != dArg.Value)
{
return(null);
}
if (sArg != dArg)
{
if (dArg.Type != XType.Const)
{
for (int j = 0; j < copy.Predicate.Signature.Arity; ++j)
{
if (copy.Predicate.Vars[j] == dArg)
{
copy.Predicate.Vars[j] = sArg;
if (copy.Body != null)
{
copy.Body.Bind(dArg, sArg);
}
}
}
}
else if (sArg.Type != XType.Const)
{
predicate.Bind(sArg, dArg);
}
}
}
return(copy);
}
public XExpression(XPredicate predicate)
{
Predicate = predicate;
}
public XClause(IXExpression body, XPredicate predicate)
{
Body = body;
Predicate = predicate;
}