internal override List Drop(int n)
{
if (Elements == null || Elements.Count <= n)
{
return(new List());
}
if (n < 0)
{
n = 0;
}
List.Node first = new List.Node()
{
car = Elements[n], cdr = null
};
List.Node last = first;
int cnt = Elements.Count;
for (int i = n + 1; i < cnt; i++)
{
last.cdr = new List.Node()
{
car = Elements[i], cdr = null
};
last = last.cdr;
}
return(new List(first));
}
internal override List Take(int n)
{
if (n <= 0 || Elements == null || Elements.Count == 0)
{
return(new List());
}
List.Node first = new List.Node()
{
car = Elements[0], cdr = null
};
List.Node last = first;
int cnt = Math.Min(n, Elements.Count);
for (int i = 1; i < cnt; i++)
{
last.cdr = new List.Node()
{
car = Elements[i], cdr = null
};
last = last.cdr;
}
return(new List(first));
}
internal override List Rest()
{
if (Elements == null || Elements.Count < 2)
{
return(new List(null as List.Node));
}
List.Node first = new List.Node()
{
car = Elements[1],
cdr = null
};
List.Node last = first;
for (int i = 2; i < Elements.Count; i++)
{
last.cdr = new List.Node()
{
car = Elements[i],
cdr = null
};
last = last.cdr;
}
return(new List(first));
}
internal Vector(List elms)
{
if (elms == null || elms.IsEmpty())
{
Elements = new List <Value>();
}
else
{
int cnt = elms.Count();
Elements = new List <Value>(cnt + 1);
for (List.Node elm = elms.Elements; elm != null; elm = elm.cdr)
{
Elements.Add(elm.car);
}
}
}
static Value Eval_ast(Value arg, Env env)
{
if (env == null)
{
return(arg);
}
if (arg == null)
{
return(arg);
}
if (arg is Symbol sym)
{
Value val = env.Get(sym);
if (val == null)
{
throw new MalException(string.Format("'{0}' not found", sym.Name));
}
return(val);
}
else if (arg is List lst)
{
if (lst.Elements == null)
{
return(arg);
}
List <Value> elms = new List <Value>();
for (List.Node elm = lst.Elements; elm != null; elm = elm.cdr)
{
elms.Add(EVAL(elm.car, env));
}
return(new List(elms));
}
else if (arg is Vector vec)
{
List <Value> elms = new List <Value>();
foreach (Value v in vec.Elements)
{
elms.Add(EVAL(v, env));
}
return(new Vector(elms));
}
else if (arg is HashMap map)
{
HashMap hm = new HashMap();
Dictionary <Value, Value> elms = hm.Elements;
foreach (var kv in map.Elements)
{
elms[kv.Key] = EVAL(kv.Value, env);
}
return(hm);
}
return(arg);
}