"the substring from pointer in input"

[GPHemsley]

#343 introduced the phrasing "the substring from pointer in input" to essentially check c and the first one or two characters in remaining.

I sort of raised this in a comment at the time, but I'm actually attempting to implement it now, and it's a little tedious, so I wanted to revisit: Is there a better way to phrase this, perhaps in a way that makes better use of the definitions in §1.2. Parsers?

[GPHemsley]

Relatedly, #343 claims to solve the remaining problem outlined in #308, but I'm not convinced that it does.

[annevk]

We could make it "c concatenated with remaining".

[rmisev]

We could make it "c concatenated with remaining".

Before using remaining we need to checkc is not EOF. While "the substring from pointer in input" is just empty when c is EOF.

[annevk]

Since substring is now defined I think this is clear enough.