private object LookupUniqueField(string name)
{
INamedValues uniqueRow = null;
foreach (var row in _rows.Values)
{
if (row.Exists(name))
{
if (uniqueRow == null)
{
uniqueRow = row;
}
else
{
throw LookupError("Field name '{0}' is not unique; use a qualified name",
name);
}
}
}
if (uniqueRow == null)
{
throw LookupError("No such field or function: {0}", name);
}
return(uniqueRow.GetValue(name));
}
private static void Execute(Program program, INamedValues values, Stack <object> stack)
{
int count = program.Count;
for (int i = 0; i < count; i++)
{
object item = program[i];
if (item is Instruction instruction)
{
object value;
object other;
object result;
switch (instruction)
{
case Instruction.Nop:
break;
case Instruction.Mark:
stack.Push(Instruction.Mark);
break;
case Instruction.Dup:
value = stack.Peek();
stack.Push(value);
break;
case Instruction.Exch:
value = stack.Pop();
other = stack.Pop();
stack.Push(value);
stack.Push(other);
break;
case Instruction.Pop:
stack.Pop();
break;
case Instruction.Get:
value = stack.Pop();
Assert.True(value is string, "Bug: Get: bad type on stack");
value = values.GetValue((string)value);
stack.Push(value);
break;
case Instruction.IsNull:
value = stack.Pop();
result = IsNull(value);
stack.Push(result);
break;
case Instruction.NotNull:
value = stack.Pop();
result = !IsNull(value);
stack.Push(result);
break;
case Instruction.IsEq:
case Instruction.NotEq:
case Instruction.Gt:
case Instruction.Ge:
case Instruction.Lt:
case Instruction.Le:
value = stack.Pop();
other = stack.Pop();
// Notice the ordering of other and value!
result = Compare(other, value, instruction);
stack.Push(result);
break;
case Instruction.Neg:
value = stack.Pop();
Assert.True(value is bool, "Bug: Neg: bad type on stack");
result = !((bool)value);
stack.Push(result);
break;
case Instruction.And:
result = true;
value = stack.Pop();
while (!Equals(value, Instruction.Mark))
{
Assert.True(value is bool, "Bug: And: bad type on stack");
if (!((bool)value))
{
result = false;
}
value = stack.Pop();
}
stack.Push(result);
break;
case Instruction.Or:
result = false;
value = stack.Pop();
while (!Equals(value, Instruction.Mark))
{
Assert.True(value is bool, "Bug: Or: bad type on stack");
if ((bool)value)
{
result = true;
}
value = stack.Pop();
}
stack.Push(result);
break;
default:
throw new AssertionException(
string.Format("Bug: invalid instruction: {0}", instruction));
}
}
else
{
stack.Push(item);
}
}
}