private void VisitRestOfList(AstList ast)
{
for (var i = 1; i < ast.Length; i++)
{
Visit(ast[i]);
}
}
private void GenerateQuote(AstList ast)
{
AddInstr(new ListNewInstruction());
if (ast.Length != 2)
{
throw new InvalidOperationException("Unexpected length for quote function");
}
var datum = ast[1];
switch (datum)
{
case AstList list:
for (var i = 0; i < list.Length; i++)
{
Visit(list[i]);
AddInstr(new ListAddInstruction());
}
break;
default:
Visit(datum);
break;
}
}
void IAstVisitor.VisitList(AstList ast)
{
if (ast.Length == 0)
{
return;
}
var first = (AstSymbol)ast[0];
switch (first.Name)
{
case "def!":
DefineMethod(ast);
break;
case "add":
case "+":
VisitRestOfList(ast);
AddInstr(new AddInstruction());
break;
case "sub":
case "-":
VisitRestOfList(ast);
AddInstr(new SubtractionInstruction());
break;
case "mul":
case "*":
VisitRestOfList(ast);
AddInstr(new MultiplicationInstruction());
break;
case "div":
case "/":
VisitRestOfList(ast);
AddInstr(new DivisionInstruction());
break;
case "quote":
GenerateQuote(ast);
break;
default:
VisitRestOfList(ast);
AddInstr(new CallInstruction(first.Name));
break;
}
}
void IAstVisitor.VisitList(AstList ast)
{
if (ast.Length == 0)
{
return;
}
var first = (AstSymbol)ast[0];
switch (first.Name)
{
case "def!":
DefineMethod(ast);
break;
}
}
private void DefineMethod(AstList ast)
{
if (ast.Length < 3)
{
throw new InvalidOperationException("Too few list parameters");
}
var nameSymbol = ast[1];
if (nameSymbol is AstSymbol s)
{
this.userDefinedFunctions[s.Name] = new VMFunction(s.Name, Eval(ast[2], new ReturnInstruction()));
}
else
{
throw new InvalidOperationException($"Expected to find symbol at index 1");
}
}
private void DefineMethod(AstList ast)
{
if (ast.Length < 3)
{
throw new InvalidOperationException("Too few list parameters");
}
var nameSymbol = ast[1];
if (nameSymbol is AstSymbol s)
{
this.data.Defines[s] = Eval(ast[2]);
}
else
{
throw new InvalidOperationException($"Expected to find symbol at index 1");
}
}
private IAstNode?ParseList()
{
if (IsToken(LispTokenKind.Quote))
{
AdvanceToken(LispTokenKind.Quote);
var quotedNode = ParseList();
if (quotedNode is AstList quotedList)
{
var resultList = new AstList();
resultList.Add(new AstSymbol("quote"));
resultList.Add(quotedList);
return(resultList);
}
else
{
throw new NotImplementedException("After quotation expected to have a list");
}
}
if (!IsToken(LispTokenKind.LParen))
{
return(null);
// TODO: Maybe figure out how to not use null value as return
//throw new InvalidOperationException("Expression should start with LParen");
}
AdvanceToken(LispTokenKind.LParen);
var astList = new AstList();
while (!IsToken(LispTokenKind.RParen))
{
astList.Add(ParseAtom());
}
AdvanceToken(LispTokenKind.RParen);
return(astList);
}
