private SExp.SExp EatExpression(IToken startExpToken)
{
var exp = new SExp.SExp(startExpToken.Line, startExpToken.Column, new List <SExpNode>());
var token = _lexer.Eat();
do
{
switch (token.Kind)
{
case TokenKind.StartExpression:
exp.Nodes.Add(EatExpression(token));
break;
case TokenKind.EndExpression:
if (exp.Nodes.Count > 0 && exp.Nodes[0] is Atom atom && atom.Token is IdentifierToken idToken &&
_systemFunctionTable.TryGet(idToken.Value, out var function))
{
exp.Nodes.RemoveAt(0);
exp = new FunctionSExp(function, token.Line, token.Column, exp.Nodes);
}
else if (exp.Nodes.Count > 0)
{
exp = new FunctionSExp(_systemFunctionTable.Get("list"), token.Line, token.Column,
exp.Nodes);
}
return(exp);
case TokenKind.DoubleLiteral:
case TokenKind.IntegerLiteral:
case TokenKind.StringLiteral:
case TokenKind.Identifier:
exp.Nodes.Add(new Atom(token.Line, token.Column, token));
break;
private object ExecuteFunction(FunctionSExp fexp)
{
var args = new Func <object> [fexp.Nodes.Count];
if (fexp.Nodes.Count > 0)
{
for (var i = 0; i < fexp.Nodes.Count; i++)
{
var node = fexp.Nodes[i];
Func <object> nodeValueFunc;
switch (node)
{
case FunctionSExp childFExp:
nodeValueFunc = () => ExecuteFunction(childFExp);
break;
case Atom childAtom:
if (!(fexp.Function is DefFunction) && !(fexp.Function is DefFuncFunction) &&
!(fexp.Function is ParamsFunction) &&
childAtom.Token is IdentifierToken idToken)
{
nodeValueFunc = () =>
{
if (_scopeManager.Contains(idToken.Value))
{
return(_scopeManager.Get(idToken.Value));
}
if (_customFunctionTable.Contains(idToken.Value))
{
return(_customFunctionTable.GetCustomFunction(idToken.Value));
}
if (_systemFunctionTable.TryGet(idToken.Value, out var sysFunc))
{
return(sysFunc);
}
throw new InvalidOperationException($"Unknown identifier '{idToken}'");
};
}
else
{
nodeValueFunc = () => childAtom.Token.Value;
}
break;
// this will be an empty parameter list
case SExp.SExp _:
nodeValueFunc = () => new object[0];
break;
default:
throw new InvalidOperationException($"Expected a function or atom but encountered: {node}");
}
args[i] = nodeValueFunc;
}
}
CheckCallingArgs(fexp.Function, args);
return(fexp.Function.Execute(args));
}