Re: Proposal for SentinelInputRange

[Walter Bright]

On 2/28/2013 10:52 AM, Jonathan M Davis wrote:
Notice that it has to check for empty every time that the front is popped, and
it can't avoid that,


Yes it can avoid it - that is the whole point. Notice there are no checks for 
the sentinel here - but the code is correct:

            case '>':
                p++;
                if (*p == '=')
                {   p++;
                    t->value = TOKge;                   // >=
                }
                else if (*p == '>')
                {   p++;
                    if (*p == '=')
                    {   p++;
                        t->value = TOKshrass;           // >>=
                    }
                    else if (*p == '>')
                    {   p++;
                        if (*p == '=')
                        {   p++;
                            t->value = TOKushrass;      // >>>=
                        }
                        else
                            t->value = TOKushr;         // >>>
                    }
                    else
                        t->value = TOKshr;              // >>
                }
                else
                    t->value = TOKgt;                   // >
                return;