private static TermFunction SubstituteFunction(TermFunction function, Substitution theta)
{
if (!function.HasVariables)
return function;
var body = new List<Term>();
for (int i = 0; i < function.Arity; i++)
body.Add(SubstituteTerm(function.GetTerm(i), theta));
return new TermFunction(function.FunctionName, body.ToArray());
}
private TermFunction RenameFunction(TermFunction function, Dictionary<TermVariable, TermVariable> renamings)
{
if (!function.HasVariables)
return function;
var body = new List<Term>();
for (int i = 0; i < function.Arity; i++)
body.Add(RenameTerm(function.GetTerm(i), renamings));
return new TermFunction(function.FunctionName, body.ToArray());
}
private static void VisitFunction(TermFunction function, GdlVisitor visitor)
{
visitor.VisitFunction(function);
VisitTerms(function.Arguments, visitor);
}
protected override int CompareTo(TermFunction t)
{
int comp = FunctionName - t.FunctionName;
if (comp != 0)
return Math.Sign(comp);
// At this point, function names are equal
comp = Arguments.Length - t.Arguments.Length;
if (comp != 0)
return Math.Sign(comp);
// At this point, both term-functions have same number of arguments
for (int i = 0; i < Arguments.Length; i++)
{
comp = Arguments[i].CompareTo(t.Arguments[i]);
if (comp != 0)
return comp;
}
return 0;
}
protected override int CompareTo(TermFunction t)
{
// Obj < Func < Var
return -1;
}
private SimpleSentenceForm(TermFunction function)
: this(function.FunctionName, function.Arity, function.Arguments)
{
}
private bool Matches(TermFunction function)
{
if (function.FunctionName != Name || function.Arity != _arity)
return false;
for (int i = 0; i < function.Arity; i++)
{
var term = function.GetTerm(i) as TermFunction;
if (_functions.ContainsKey(i) && term == null)
return false;
if (term != null)
if (!_functions.ContainsKey(i) || !_functions[i].Matches(term))
return false;
}
return true;
}
/**
* Gets the mapping for a function.
* Iterates over all the Term of the functions and recursively tries to map them.
*
* @param func The function whose mappings to compute.
* @return The function after all substitutions have been made.
*/
public virtual TermFunction GetMapping(TermFunction func)
{
var result = new TermFunction(true, func.FunctionName, func.Arguments);
for (int i = 0; i < result.Arity; i++)
{
if (result.Arguments[i] is TermVariable)
{
Term replacement = GetMapping((TermVariable)result.Arguments[i]);
if (replacement != null)
result.Arguments[i] = replacement;
}
else if (result.Arguments[i] is TermFunction)
{
Term replacement = GetMapping((TermFunction)result.Arguments[i]);
if (replacement != null)
result.Arguments[i] = replacement;
}
}
return result;
}