/// <summary>
/// Return the unique symbol associated with a
/// string. Repeated calls to CreateSymbol will return the
/// same Symbol.
/// </summary>
internal static Symbol CreateSymbol (string n)
{
n = LateBinding.MapToInternalName (n);
string u = String.Intern (n);
Symbol s = (Symbol) dict [u];
if (s == null) {
s = new Symbol (u);
dict [u] = s;
}
return s;
}
internal bool InCurrentScope (string ns, Symbol id)
{
IdentificationTable symbols = (IdentificationTable) namespaces [ns];
if (symbols == null)
throw new Exception (ns + " does not exist");
return symbols.InCurrentScope (id);
}
internal void Enter (string ns, Symbol key, object value)
{
IdentificationTable symbols = (IdentificationTable) namespaces [ns];
if (symbols == null)
throw new Exception (ns + " does not exist");
symbols.Enter (key, value);
}
internal void Remove (string ns, Symbol key)
{
IdentificationTable symbols = (IdentificationTable) namespaces [ns];
if (symbols == null)
throw new Exception (ns + " does not exist");
symbols.Remove (key);
}
internal bool Contains (string ns, Symbol key)
{
IdentificationTable symbols = (IdentificationTable) namespaces [ns];
if (symbols == null)
return false;
return symbols.Contains (key);
}
internal object Get (string ns, Symbol key)
{
IdentificationTable symbols = (IdentificationTable) namespaces [ns];
if (symbols == null)
return null;
return symbols.Get (key);
}
/// <summary>
/// Restores the table to what it was at the most recent BeginScope
/// that has not already been ended
/// </summary>
internal void EndScope ()
{
//
// Delete all the elements until we find
// that top is null, that occurs when we find
// the scope marker.
//
while (top != null) {
Binder e = (Binder) dict [top];
//
// If there's a chain we delete the first
// element of it, otherwise remove the symbol
// from the table.
//
if (e.Tail != null)
dict [top] = e.Tail;
else
dict.Remove (top);
top = e.PrevTop;
}
//
// marks.PrevTop always contains the latest symbol
// which was bound before the new scope was created.
//
top = marks.PrevTop;
//
// delete the latest scope mark
//
marks = marks.Tail;
locals.Pop ();
depth--;
catch_scope = previous_scope;
}
internal bool InCurrentScope (Symbol id)
{
Hashtable hash = (Hashtable) locals.Peek ();
return hash.ContainsKey (id.Value) && hash [id.Value] != null;
}
/// <summary>
/// Delete symbol from the table
/// </summary>
internal void Remove (Symbol key)
{
Binder e = (Binder) dict [key];
if (e != null)
if (e.Tail != null)
dict [key] = e.Tail;
else
dict.Remove (key);
}
/// <summary>
/// Remembers the current state of the table
/// </summary>
internal void BeginScope (bool catchScope)
{
previous_scope = catch_scope;
catch_scope = catchScope;
marks = new Binder (null, top, marks);
top = null;
locals.Push (new Hashtable ());
depth++;
}
/// <summary>
/// Bind a key
/// </summary>
internal void Enter (Symbol key, object value)
{
Binder e = (Binder) dict [key];
/// <remarks>
/// If a Binder's Value is null means that it
/// represents a in-transit binding, we must
/// set its value to something useful.
/// </remarks>
if (e != null && e.Value == null)
e.Value = value;
else {
//
// If 'key' is already on the table we form a
// Binder's chain, otherwise we include the new key
// represented with its association object.
//
dict [key] = new Binder (value, top, (Binder) dict [key]);
//
// make 'key' the most recent symbol bound
//
top = key;
}
Hashtable top_ht = (Hashtable) locals.Peek ();
string val = key.Value;
top_ht[val] = value;
}
/// <summary>
/// Gets the object associated to the symbol in the table
/// </summary>
internal object Get (Symbol key)
{
Binder e = (Binder) dict [key];
if (e == null)
return null;
else
return e.Value;
}
internal bool Contains (Symbol key)
{
Binder e = (Binder) dict [key];
return e != null;
}
internal Binder (object value, Symbol prev_top, Binder tail)
{
this.value = value;
this.prev_top = prev_top;
this.tail = tail;
}
internal Identifier(AST parent, string id, Location location)
: base(parent, location)
{
this.name = Symbol.CreateSymbol (id);
}