/// <summary>
/// Returns the possible ways that a query term can unify with a program term
/// </summary>
public static IBindings Unify(this ILiteral query, ILiteral program, IBindings bindings = null)
{
var simpleUnifier = new SimpleUnifier();
var freeVariables = new HashSet<ILiteral>();
// Run the unifier
var queryFreeVars = simpleUnifier.QueryUnifier.Compile(query, bindings);
if (queryFreeVars == null) return null;
simpleUnifier.PrepareToRunProgram();
var programFreeVars = simpleUnifier.ProgramUnifier.Compile(program, bindings);
if (programFreeVars == null) return null;
freeVariables.UnionWith(queryFreeVars);
// Retrieve the unified value for the program
var result = simpleUnifier.UnifiedValue(query.UnificationKey ?? query);
// If the result was valid, return as the one value from this function
if (result != null)
{
var variableBindings = freeVariables.ToDictionary(variable => variable,
variable => simpleUnifier.UnifiedValue(variable));
return new BasicBinding(result, variableBindings);
}
else
{
return null;
}
}
public void ManualUnification()
{
var simpleUnifier = new SimpleUnifier();
var unifier = new TraceUnifier(simpleUnifier);
var X = new[] { new Variable(), new Variable(), new Variable(), new Variable(), new Variable(), new Variable(), new Variable(), new Variable() };
var h2 = new UnboundFunctor(2);
var f1 = new UnboundFunctor(1);
var p3 = new UnboundFunctor(3);
var a0 = new UnboundFunctor(0);
unifier.BindVariable(0, X[1]);
unifier.BindVariable(1, X[2]);
unifier.BindVariable(2, X[3]);
unifier.BindVariable(3, X[4]);
unifier.BindVariable(4, X[5]);
unifier.BindVariable(5, X[6]);
unifier.BindVariable(6, X[7]);
unifier.PutStructure(h2, 2, X[3]);
unifier.SetVariable(X[2]);
unifier.SetVariable(X[5]);
unifier.PutStructure(f1, 1, X[4]);
unifier.SetValue(X[5]);
unifier.PutStructure(p3, 3, X[1]);
unifier.SetValue(X[2]);
unifier.SetValue(X[3]);
unifier.SetValue(X[4]);
unifier.GetStructure(p3, 3, X[1]);
unifier.UnifyVariable(X[2]);
unifier.UnifyVariable(X[3]);
unifier.UnifyVariable(X[4]);
unifier.GetStructure(f1, 1, X[2]);
unifier.UnifyVariable(X[5]);
unifier.GetStructure(h2, 2, X[3]);
unifier.UnifyValue(X[4]);
unifier.UnifyVariable(X[6]);
unifier.GetStructure(f1, 1, X[6]);
unifier.UnifyVariable(X[7]);
unifier.GetStructure(a0, 0, X[7]);
var result = simpleUnifier.UnifiedValue(X[1]);
Assert.IsNotNull(result);
}