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authorDevtools Arcadia <arcadia-devtools@yandex-team.ru>2022-02-07 18:08:42 +0300
committerDevtools Arcadia <arcadia-devtools@mous.vla.yp-c.yandex.net>2022-02-07 18:08:42 +0300
commit1110808a9d39d4b808aef724c861a2e1a38d2a69 (patch)
treee26c9fed0de5d9873cce7e00bc214573dc2195b7 /contrib/libs/hyperscan/src/nfagraph/ng_sep.cpp
downloadydb-1110808a9d39d4b808aef724c861a2e1a38d2a69.tar.gz
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ref:cde9a383711a11544ce7e107a78147fb96cc4029
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+/*
+ * Copyright (c) 2015, Intel Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * * Neither the name of Intel Corporation nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** \file
+ * \brief Short Exhaustible Passthroughs.
+ *
+ * Analysis code for determining whether a graph should be treated specially
+ * because it is short and contains exhaustible reports; typically we turn
+ * these into outfixes rather than risk them becoming Rose literals.
+ *
+ * For example, the pattern:
+ *
+ * /[a-f]/H
+ *
+ * ... is far better suited to becoming a small outfix that generates one match
+ * and goes dead than being split into six one-byte Rose literals that end up
+ * in the literal matcher.
+ */
+#include "ng_sep.h"
+
+#include "grey.h"
+#include "ng_holder.h"
+#include "ng_reports.h"
+#include "ng_util.h"
+#include "ue2common.h"
+#include "util/graph_range.h"
+
+using namespace std;
+
+namespace ue2 {
+
+static
+bool checkFromVertex(const NGHolder &g, NFAVertex start) {
+ for (auto v : adjacent_vertices_range(start, g)) {
+ if (v == g.startDs) {
+ continue;
+ }
+
+ assert(!is_special(v, g)); /* should not be vacuous */
+
+ if (!edge(g.startDs, v, g).second) { /* only floating starts */
+ return false;
+ } else if (out_degree(v, g) == 1
+ && edge(v, g.accept, g).second) { /* only floating end */
+ ; /* possible sep */
+ } else {
+ return false;
+ }
+ }
+ return true;
+}
+
+bool isSEP(const NGHolder &g, const ReportManager &rm, const Grey &grey) {
+ if (!grey.mergeSEP || !can_exhaust(g, rm)) {
+ return false;
+ }
+
+ if (!checkFromVertex(g, g.start) || !checkFromVertex(g, g.startDs)) {
+ return false;
+ }
+
+ assert(out_degree(g.start, g) || proper_out_degree(g.startDs, g));
+
+ DEBUG_PRINTF("graph is an SEP\n");
+ return true;
+}
+
+} // namespace ue2