+++ /dev/null
-/** @file match_bug.cpp
- *
- * Check for bug in GiNaC::ex::match() described here:
- * http://www.ginac.de/pipermail/ginac-devel/2006-April/000942.html */
-
-/*
- * GiNaC Copyright (C) 1999-2014 Johannes Gutenberg University Mainz, Germany
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include "ginac.h"
-#include "error_report.h"
-
-#include <iostream>
-using namespace GiNaC;
-
-/*
- * basic::match(lst&) used to have an obscure side effect: repl_lst
- * could be modified even if the match failed! Although this "feature"
- * was documented it happend to be very confusing *even for GiNaC
- * developers*, see
- * http://www.ginac.de/pipermail/ginac-devel/2006-April/000942.html
- *
- * It was fixed in 192ed7390b7b2b705ad100e3db0a92eedd2b20ad. Let's make
- * sure it will be never re-added:
- */
-static void failed_match_have_side_effects()
-{
- symbol x("x");
- ex e = pow(x, 5);
- ex pattern = pow(wild(0), -1);
- // obviously e does NOT match the pattern
- exmap repls;
- bool match_p = e.match(pattern, repls);
- cbug_on(match_p, "match(" << e << ", " << pattern << ") says \"Yes\"");
- cbug_on(repls.size() != 0,
- "failed match have side effects: repls = " << repls);
-}
-
-/*
- * As a consequence of the bug described above pattern matching can wrongly
- * fail. In particular, x^5*y^(-1) fails to match ($0)^(-1)*x^($2).
- *
- * The first thing that is attempted to match is x^5 with $0^(-1). This match
- * will fail. However repl_lst will contain $0 == x as a side effect. This
- * repl_lst will prevent the match of y^(-1) to ($0)^(-1) to succeed.
- *
- * This issue was worked around by 73f0ce4cf8d91f073f35a45443f5fbe886921c5c.
- * Now we have a real fix (192ed7390b7b2b705ad100e3db0a92eedd2b20ad), but
- * let's add a check.
- */
-static void match_false_negative()
-{
- symbol x("x"), y("y");
- ex e = pow(x, 5)*pow(y, -1);
- ex pattern = pow(wild(0), -1)*pow(x, wild(2));
- exmap repls;
- bool match_p = e.match(pattern, repls);
- cbug_on(!match_p, "false negative: " << e << " did not match "
- << 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;
-}