public override Term ApplySubstitution(ref Substitution s)
{
for (int i = 0; i < Arity; i++)
{
Args[i] = Args[i].Replace(s.T1.ToString(), s.T2.ToString());
}
//Regex.Replace(Args[i], ( s.T1.ToString() + "\\b"), s.T2.ToString());
return(this);
}
public override Term ApplySubstitution(ref Substitution s)
{
Content = //Regex.Replace(Content, (s.T1.ToString() + "\\b"), s.T2.ToString());
Content.Replace(s.T1.ToString(), s.T2.ToString());
return(this);
}
public virtual Term ApplySubstitution(ref Substitution s)
{
return(this);
}
private static List <Substitution> UnifyArgs(ref Term e1, ref Term e2, ref List <Substitution> subs)
{
if (subs == null)
{
subs = new List <Substitution>();
}
if (e1.Empty() && e2.Empty())
{
return(subs);
}
if (e1.Func() && e2.Func())
{
if (((Function)e1).Arity != ((Function)e2).Arity)
{
return(null);
}
}
//if (e1.Constant() && e2.Constant()) return e1.ToString().Equals(e2.ToString()) ? subs : null;
//if variable(E1) / if variable(E2)
if (e1.Var())
{
if (e2.Var())
{
if (((SimpleTerm)e1).Equals((SimpleTerm)e2))
{
return(subs);
}
else if (((SimpleTerm)e1).OccursIn(ref e2))
{
return(null);
}
}
//else {
var s = new Substitution(ref e1, ref e2);
//if (!subs.Contains(s)) {
subs.Add(s);
subs.TrimExcess();
//}
s = null;
return(subs);
//}
}
if (e2.Var())
{
if (e1.Var())
{
if (((SimpleTerm)e2).Equals((SimpleTerm)e1))
{
return(subs);
}
else if (((SimpleTerm)e2).OccursIn(ref e1))
{
return(null);
}
}
//else {
var s = new Substitution(ref e2, ref e1);
//if (!subs.Contains(s)) {
subs.Add(s);
subs.TrimExcess();
//}
s = null;
return(subs);
//}
}
else
{
var HE1 = ((Function)e1).Head();
var HE2 = ((Function)e2).Head();
var SUBS1 = UnifyArgs(ref HE1, ref HE2, ref subs);
HE1 = HE2 = null;
if (SUBS1 == null)
{
return(null);
}
var TE1 = ((Function)e1).Tail().ApplySubstitution(ref SUBS1, Performed);
var TE2 = ((Function)e2).Tail().ApplySubstitution(ref SUBS1, Performed);
SUBS1 = null;
Performed++;
var SUBS2 = UnifyArgs(ref TE1, ref TE2, ref subs);
TE1 = TE2 = null;
return(SUBS2 == null ? null : subs);
}
}