public static Symbol For(string value)
{
Symbol result;
if (Symbol.table.TryGetValue(value, out result))
return result;
result = new Symbol(value);
Symbol.table.Add(value, result);
return result;
}
public SchemeObject GetValue(Symbol key)
{
for (SchemeEnvironment env = this; env != null; env = env.parent)
{
SchemeObject value;
if (env.dictionary.TryGetValue(key, out value))
return value;
}
throw new InvalidSyntaxException();
}
public void SetValue(Symbol key, SchemeObject value, bool isDefinition)
{
SchemeEnvironment env = this;
if (!isDefinition)
{
for (; env != null; env = env.parent)
if (env.dictionary.ContainsKey(key))
break;
if (env == null)
throw new InvalidSyntaxException();
}
env.dictionary[key] = value;
}
public void Add(Symbol key, SchemeObject value)
{
this.dictionary[key] = value;
}
internal AssignmentContinuation(Symbol destination, bool isDefinition, SchemeEnvironment environment)
: base(environment, ContinuationKind.Assignment)
{
this.Destination = destination;
this.IsDefinition = isDefinition;
}