bool matcher::matches_r(expression * e, matchable * item) {
if (e) {
switch (e->op) {
/* the operator "and" and "or" simply connect two different subexpressions */
case LOGOP_AND:
return matches_r(e->l, item) && matches_r(e->r, item); // short-circuit evaulation in C -> short circuit evaluation in the filter language
case LOGOP_OR:
return matches_r(e->l, item) || matches_r(e->r, item); // same here
/* while the other operator connect an attribute with a value */
case MATCHOP_EQ:
return matchop_eq(e, item);
case MATCHOP_NE:
return !matchop_eq(e, item);
case MATCHOP_LT:
return matchop_lt(e, item);
case MATCHOP_BETWEEN:
return matchop_between(e, item);
case MATCHOP_GT:
return matchop_gt(e, item);
case MATCHOP_LE:
return !matchop_gt(e, item);
case MATCHOP_GE:
return !matchop_lt(e, item);
case MATCHOP_RXEQ:
return matchop_rxeq(e, item);
case MATCHOP_RXNE:
return !matchop_rxeq(e, item);
case MATCHOP_CONTAINS:
return matchop_cont(e, item);
case MATCHOP_CONTAINSNOT:
return !matchop_cont(e, item);
default:
LOG(LOG_ERROR, "matcher::matches_r: invalid operator %d", e->op);
assert(false); // that's an error condition
}
return false;
} else {
return true; // shouldn't happen
}
}
bool matcher::matches(matchable* item) {
/*
* with this method, every class that is derived from matchable can be
* matched against a filter expression that was previously passed to the
* class with the parse() method.
*
* This makes it easy to use the matcher virtually everywhere, since C++
* allows multiple inheritance (i.e. deriving from matchable can even be
* used in class hierarchies), and deriving from matchable means that you
* only have to implement two methods has_attribute() and get_attribute().
*
* The whole matching code is speed-critical, as the matching happens on a
* lot of different occassions, and slow matching can be easily measured
* (and felt by the user) on slow computers with a lot of items to match.
*/
bool retval = false;
if (item) {
scope_measure m1("matcher::matches");
retval = matches_r(p.get_root(), item);
}
return retval;
}
