Proposal for SentinelInputRange

[Walter Bright]

On 2/28/2013 9:18 AM, Steven Schveighoffer wrote:
> The point is, if the lexer simply requires an input range, and not a sentinel
> input range, it is more flexible for its input.  But when it does get called
> with a sentinel input range, the optimizer can reap the benefits.

I suggest you compile lexer.c with various compilers, add in a !empty() call 
before every front(), and verify your assumption about this.