AOP C # in Action (cont. 2)

Today began to write Paser, but borrowed from SharpDevelop (do not want to reinvent the wheel, ^_^). However, there are some changes to the original code, even if the RC2, the SharpDevelop code is still a problem. Looking at the code today is the discovery of two places. For example, the following code:
static public int Compare (IList A, IList B, IComparer comparer)
{
if (a = = NULL | | | b = NULL) {
return 1;
}
if (A.count!= b.count) {
Return Math.sign (A.count-b.count);
}
int limit = (A.count < B.count)? A.count:b.count;
for (int i=0 i < limit; i++) {
if (A[i] is IComparable && b[i] is IComparable) {
int cmp = Comparer.compare (A[i], b[i]);
if (CMP!= 0) {
return CMP;
}
}
}
return a.count-b.count;
}
The second if block puzzled me for a while. Look at the mono has been corrected, doubt that paragraph is not drinking only write.