private AstNode UndefineSymbol()
{
var line = Match(TokenType.Undef);
var variable = Variable();
var node = new UndefNode(variable)
{
Line = line
};
return(node);
}
public override DynValue Visit(UndefNode undefNode)
{
var variable = undefNode.Variable as VariableNode;
if (variable == null)
{
throw new RuntimeException("Expected a variable.", undefNode.Line);
}
Environment.LocalScope.UnSetInChain(variable.Identifier);
return(DynValue.Zero);
}
public override DynValue Visit(UndefNode undefNode)
{
switch (undefNode.Type)
{
case UndefineType.Local:
if (CallStack.Count == 0)
{
throw new RuntimeException($"Attempt to undefine a local variable outside a function '{undefNode.Name}'.", undefNode.Line);
}
var callStackItem = CallStack.Peek();
if (!callStackItem.LocalVariableScope.ContainsKey(undefNode.Name))
{
throw new RuntimeException($"Attempt to undefine a non-existent local variable '{undefNode.Name}'.", undefNode.Line);
}
callStackItem.LocalVariableScope.Remove(undefNode.Name);
break;
case UndefineType.Function:
if (Environment.BuiltIns.ContainsKey(undefNode.Name))
{
throw new RuntimeException($"Attempt to undefine a built-in function '{undefNode.Name}'.", undefNode.Line);
}
if (!Environment.Functions.ContainsKey(undefNode.Name))
{
throw new RuntimeException($"Attempt to undefine a non-existent function '{undefNode.Name}'", undefNode.Line);
}
Environment.Functions.Remove(undefNode.Name);
break;
case UndefineType.Global:
if (!Environment.Globals.ContainsKey(undefNode.Name))
{
throw new RuntimeException($"Attempt to undefine a non-existent global variable '{undefNode.Name}'.", undefNode.Line);
}
Environment.Globals.Remove(undefNode.Name);
break;
default:
throw new RuntimeException("Internal interpreter error: unexpected UndefType value.", undefNode.Line);
}
return(DynValue.Zero);
}
private AstNode UndefineSymbol()
{
var line = Match(TokenType.Undef);
var node = new UndefNode {
Type = UndefineType.Global, Line = line
};
if (Scanner.State.CurrentToken.Type == TokenType.Fn)
{
Match(TokenType.Fn);
node.Type = UndefineType.Function;
}
else if (Scanner.State.CurrentToken.Type == TokenType.LocalVar)
{
Match(TokenType.LocalVar);
node.Type = UndefineType.Local;
}
node.Name = (string)Scanner.State.CurrentToken.Value;
Match(TokenType.Identifier);
return(node);
}
public abstract DynValue Visit(UndefNode undefNode);