private bool Unify(IHerbrandObject x, IHerbrandObject y)
{
x = this.findUnion.GetRepresentant(x);
y = this.findUnion.GetRepresentant(y);
if (x == y)
{
return(true);
}
if (y is TypeVariable)
{
(x, y) = (y, x);
}
if (x is TypeVariable)
{
this.findUnion.Union(x, y);
return(true);
}
if (x.GetTag() != y.GetTag() || x.GetArguments().Count() != y.GetArguments().Count())
{
return(false);
}
this.findUnion.Union(x, y);
return(x.GetArguments()
.Zip(y.GetArguments(), (first, second) => (first, second))
.All(tuple => this.Unify(tuple.first, tuple.second)));
}
private static IEnumerable <IHerbrandObject> GetAllHerbrandObjects(IHerbrandObject root)
{
yield return(root);
foreach (var obj in root.GetArguments().SelectMany(GetAllHerbrandObjects))
{
yield return(obj);
}
}
private void Dfs(
IHerbrandObject v,
ISet <IHerbrandObject> visited,
IDictionary <TypeVariable, IHerbrandObject> variableMapping)
{
if (visited.Contains(v))
{
return;
}
visited.Add(v);
if (v is TypeVariable typeVariable)
{
variableMapping.Add(typeVariable, this.findUnion.GetRepresentant(v));
}
else
{
foreach (var child in v.GetArguments())
{
this.Dfs(child, visited, variableMapping);
}
}
}