public DefaultBasicHost(IBasicInputOutput io = null)
{
this.io = io ?? new TextWriterIO(Console.Out);
}
public override BasicNode Eval(BasicEnvironment env)
{
env.InstructionCount++;
runtime = env;
printer = env.printer;
bool suppressNL = false;
for (int i = 0; i < items.Count; i++)
{
suppressNL = false;
var item = items[i];
var node = item as BasicNode;
if (node != null)
{
node = node.Eval(env);
if (node.IsAbort())
{
return(node);
}
var sNode = node as StringConstantNode;
if (sNode != null)
{
WriteString(sNode.Text);
continue;
}
var nNode = node as NumericConstantNode;
if (nNode != null)
{
WriteNumericConstant(nNode);
continue;
}
var cNode = node as ControlNode;
if (cNode.Kind == EvalResultKind.Tab)
{
var numNode = cNode.Target as NumericConstantNode;
int amount = numNode.IntValue;
if (amount <= 0)
{
env.RuntimeError(ERuntimeErrors.InvalidTab, amount);
amount = 1;
}
amount--;
if (runtime.Column < amount)
{
WriteString(new string(' ', amount - runtime.Column));
}
else
{
printer.NewLine();
WriteString(new string(' ', amount));
}
continue;
}
return(env.RuntimeError());
}
var sval = item as string;
if (sval == ",")
{
int rem = runtime.Column % printer.PrintZoneWidth;
rem = printer.PrintZoneWidth - rem;
WriteString(new string(' ', rem));
}
if (sval == ";" || sval == ",")
{
suppressNL = true;
continue;
}
return(env.RuntimeError());
}
if (!suppressNL)
{
runtime.Column = 0;
printer.NewLine();
}
return(this);
}
