public static bool Declare(Symbol name)
{
if (!gsl.ContainsKey(name))
{
gsl[name] = new SpecialVariable(name);
return(true);
}
return(false);
}
public IVariable FindLeft(Symbol s)
{
if (ContainsParam(s))
{
return(Env.Find(s));
}
IVariable ret = SpecialVariable.Find(s);
if (ret is null)
{
return(Env.Find(s));
}
return(ret);
}
public object FindRight(Symbol s)
{
if (ContainsParam(s))
{
return(Env.Find(s));
}
IVariable ret = SpecialVariable.Find(s);
if (ret is null)
{
return(Env.FindOrExtern(s));
}
return(ret);
}
public static void CompileSpecial(IType body, Environment e, Function p)
{
if (e != Global.env)
{
throw new SyntaxError("SPECIAL: can only be declared in the outmost environment");
}
var name = Util.RequireExactly(body, 1, "SPECIAL")[0];
if (!(name is Symbol s))
{
throw new SyntaxError("SPECIAL: illegal name");
}
if (SpecialVariable.Declare(s))
{
SpecialVariable.Find(s).Push(p, Global.nil);
}
}
public static void CompileLet(IType body, Environment e, Function p)
{
if (!(body is Cons b))
{
throw new SyntaxError("LET: insufficient argument");
}
var bindings = b.car;
Environment cure = new Environment(e);
List <IL.IEntity> lvalues = new List <IL.IEntity>();
List <SpecialVariable> specials = new List <SpecialVariable>();
List <IL.IEntity> svalues = new List <IL.IEntity>();
Function fn = new Function(cure);
while (bindings is Cons l)
{
var cur = l.car;
bindings = l.cdr;
if (cur is Cons c)
{
var temp = Util.RequireExactly(cur, 2, "LET");
IType name = temp[0], value = temp[1];
if (!(name is Symbol s))
{
throw new SyntaxError("LET: illegal name");
}
var sv = SpecialVariable.Find(s);
var v = e.AddUnnamedVariable();
Core.CompileSingleExpr(value, e, p);
p.Load(v);
if (sv is null)
{
fn.AddParam(s);
lvalues.Add(v);
}
else
{
specials.Add(sv);
svalues.Add(v);
}
}
else if (cur is Symbol s)
{
var sv = SpecialVariable.Find(s);
if (sv is null)
{
fn.AddParam(s);
lvalues.Add(Global.nil);
}
else
{
specials.Add(sv);
svalues.Add(Global.nil);
}
}
else
{
throw new SyntaxError("LET: illegal binding");
}
}
LocalVariable f = e.AddUnnamedVariable(), retp = e.AddUnnamedVariable();
CompileProgn(b.cdr, cure, fn);
fn.Return();
p.Store(fn);
p.Load(f);
for (int i = 0; i < specials.Count; ++i)
{
specials[i].Push(p, svalues[i]);
}
p.Call(f, lvalues.ToArray());
p.Load(retp);
foreach (var i in specials)
{
i.Pop(p);
}
p.Store(retp);
}