  NPATH is a metric introduced by Brian A. Nejmeh in [13] that is aimed at
overcoming some important limitations of McCabe's cyclomatic complexity.
Despite the fact that the declared NPATH objective is to count the number of
acyclic execution paths through a function, the definition given for the C
language in [13] fails to do so even for very simple programs. We show that
counting the number of acyclic paths in CFG is unfeasible in general. Then we
define a new metric for C-like languages, called ACPATH, that allows to quickly
compute a very good estimation of the number of acyclic execution paths through
the given function. We show that, if the function body does not contain
backward gotos and does not contain jumps into a loop from outside the loop,
then such estimation is actually exact.
