Provide Context About Vetting Expression in Failure

[brodieG]

Ideally would return full vetting expression, and the token that triggered the failure, potentially as an attribute for vet, and as part of the error message for vetr?

For example, in:

a <- quote(integer() && . > 0)
b <- quote(logical(1L) && !is.na(.))
c <- quote(a || b)

vet(c, -1)

The returned attribute might be structured as:

list(
  vet.exp=quote((integer() && . > 0) || (logical(1L) && !is.na(.))),
  fail.tokens=list(vet.exp[[2]][[2]][[3]], vet.exp[[3]][[2]][[2]])
)

although the vet.exp part in fail.tokens may need to be expanded.