private CatVarScopes ComputeVarScopes()
{
CatVarScopes scopes = new CatVarScopes();
ComputeVarScopes(scopes, new Stack <CatFxnType>());
return(scopes);
}
private void ComputeFreeVars()
{
CatVarScopes scopes = ComputeVarScopes();
SetFreeVars(scopes, new Stack <CatFxnType>());
// TODO:
// Use the scopes to find out if a function type is well-formed or not.
// i.e. CheckIsWellFormed(scopes);
}
private void SetFreeVars(CatVarScopes scopes, Stack <CatFxnType> visited)
{
if (visited.Contains(this))
{
return;
}
foreach (CatKind k in GetDescendantKinds())
{
// iterate over the values
if (IsFreeVar(k, scopes))
{
mpFreeVars.Add(k);
}
else if (k is CatFxnType)
{
visited.Push(this);
(k as CatFxnType).SetFreeVars(scopes, visited);
visited.Pop();
}
}
}
/* TODO: LOWPRI: remove
* private CatTypeVarList GetVarsExcept(CatFxnType except)
* {
* CatTypeVarList ret = new CatTypeVarList();
* GetVarsExcept(except, ret);
* return ret;
* }
*
* private void GetVarsExcept(CatFxnType except, CatTypeVarList vars)
* {
* foreach (CatKind k in GetChildKinds())
* {
* if (k is CatFxnType)
* {
* CatFxnType ft = k as CatFxnType;
* if (ft != except)
* ft.GetVarsExcept(except, vars);
* }
* else
* {
* if (k.IsKindVar())
* vars.Add(k);
* }
* }
* }
*/
/// <summary>
/// Every kind variable has a scope in which it is free.
/// This allows us to compute whether a variable is free or bound.
/// The purpose of figuring whether a variable is free or bound, is so
/// that when we copy a function, we can make sure that any free variables
/// are given new unique names. Basically we want to make new names,
/// but we can't always do that.
/// </summary>
/// <param name="scopes"></param>
private void ComputeVarScopes(CatVarScopes scopes, Stack <CatFxnType> visited)
{
if (visited.Contains(this))
{
return;
}
foreach (CatKind k in GetChildKinds())
{
if (k.IsKindVar())
{
scopes.Add(k, this);
}
else if (k is CatFxnType)
{
CatFxnType ft = k as CatFxnType;
visited.Push(ft);
ft.ComputeVarScopes(scopes, visited);
visited.Pop();
}
}
}
private bool IsFreeVar(CatKind k, CatVarScopes scopes)
{
return(scopes.IsFreeVar(this, k));
}