<< pattern);
}
+/*
+ * expairseq::match() should not have any side effects if the match failed.
+ */
+static void expairseq_failed_match_no_side_effect(int count)
+{
+ for (int i = 0; i < count; ++i) {
+ exmap repls;
+ symbol t("t"), A("A");
+ ex e = pow(t, 2)*exp(t*A);
+ ex pattern = pow(t, wild(0))*exp(wild(1))*A;
+ bool matched = e.match(pattern, repls);
+ cbug_on(matched, "unexpected match: " << e << " vs " << pattern);
+ cbug_on(repls.size(), "failed match has side effects");
+ }
+}
+
+/*
+ * exp(a)*sin(x) + exp(b)*sin(y) used to fail to match
+ * exp(a)*sin($0) + exp(b)*sin($1). The failure was not deterministic.
+ *
+ * The first attempted submatch is sin(y)*exp(b) with sin($0)*exp(a).
+ * It fails but $0 == y gets assigned due to a spurious side effect.
+ * Next submatch is sin(x)*exp(a) with sin($0)*exp(a) (the same pattern
+ * as in the first submatch). This one fails because of (incorrect)
+ * $0 == y assignment.
+ *
+ * Note: due to the unstable term ordering the sequence of submatches
+ * might be different and the match might succeed (as it should), hence
+ * we repeat the test several times.
+ */
+static void expairseq_match_false_negative(int count)
+{
+ for (int i = 0; i < count; ++i) {
+ symbol a("a"), b("b"), x("x"), y("y");
+ ex e = exp(a)*sin(x) + exp(b)*sin(y);
+ ex pattern = exp(a)*sin(wild(0)) + exp(b)*sin(wild(1));
+ cbug_on(!e.match(pattern), "match failed: " << e << "did not"
+ "match " << pattern);
+ }
+}
+
int main(int argc, char** argv)
{
+ const int repetitions = 100;
std::cout << "checking for historical bugs in match()... " << std::flush;
failed_match_have_side_effects();
match_false_negative();
+ expairseq_failed_match_no_side_effect(repetitions);
+ expairseq_match_false_negative(repetitions);
std::cout << "not found. ";
return 0;
}
}
}
+ // Even if the expression does not match the pattern, some of
+ // its subexpressions could match it. For example, x^5*y^(-1)
+ // does not match the pattern $0^5, but its subexpression x^5
+ // does. So, save repl_lst in order to not add bogus entries.
+ exmap tmp_repl = repl_lst;
+
// Unfortunately, this is an O(N^2) operation because we can't
// sort the pattern in a useful way...
continue;
exvector::iterator it = ops.begin(), itend = ops.end();
while (it != itend) {
- if (it->match(p, repl_lst)) {
+ if (it->match(p, tmp_repl)) {
ops.erase(it);
goto found;
}
for (size_t i=0; i<num; i++)
vp->push_back(split_ex_to_pair(ops[i]));
ex rest = thisexpairseq(vp, default_overall_coeff());
- for (exmap::const_iterator it = repl_lst.begin(); it != repl_lst.end(); ++it) {
- if (it->first.is_equal(global_wildcard))
- return rest.is_equal(it->second);
+ for (exmap::const_iterator it = tmp_repl.begin(); it != tmp_repl.end(); ++it) {
+ if (it->first.is_equal(global_wildcard)) {
+ if (rest.is_equal(it->second)) {
+ repl_lst = tmp_repl;
+ return true;
+ }
+ return false;
+ }
}
+ repl_lst = tmp_repl;
repl_lst[global_wildcard] = rest;
return true;
// No global wildcard, then the match fails if there are any
// unmatched terms left
- return ops.empty();
+ if (ops.empty()) {
+ repl_lst = tmp_repl;
+ return true;
+ }
+ return false;
}
}
return inherited::match(pattern, repl_lst);