public override Expression VisitNull_coalescing_expression([NotNull] calculatorParser.Null_coalescing_expressionContext context)
{
if (context.children != null)
{
foreach (IParseTree c in context.children)
{
Visit(c);
}
}
if (context.ChildCount == 0)
{
Results[context] = null;
return(null);
}
Expression lhs = Results[context.GetChild(0)];
if (context.ChildCount == 1)
{
Results[context] = lhs;
return(lhs);
}
int count = 0;
for (; count < context.ChildCount;)
{
// LHS partially computed.
// Get op.
string op = "";
if (count + 1 < context.ChildCount)
{
IParseTree op_pt = context.GetChild(count + 1);
op = op_pt.GetText();
}
// Get RHS, and update LHS.
if (count + 2 < context.ChildCount && _completeness.Results[context.GetChild(count + 2)])
{
Expression rhs = Results[context.GetChild(count + 2)];
if (op == "??")
{
lhs = rhs;
}
}
count += 2;
}
Results[context] = lhs;
return(lhs);
}
public override bool VisitNull_coalescing_expression([NotNull] calculatorParser.Null_coalescing_expressionContext context)
{
bool res = false;
Results[context] = res;
if (context.children != null)
{
foreach (IParseTree c in context.children)
{
if (!Visit(c))
{
Results[context] = false;
return(false);
}
}
}
if (context.ChildCount == 0)
{
Results[context] = res;
return(res);
}
bool lhs = Results[context.GetChild(0)];
if (context.ChildCount == 1)
{
Results[context] = lhs;
return(lhs);
}
int count = 0;
res = lhs;
for (; count < context.ChildCount && count + 2 < context.ChildCount;)
{
bool rhs = Results[context.GetChild(count + 2)];
res &= rhs;
count += 2;
}
Results[context] = res;
return(res);
}