Initial commit of Hyperscan

src/nfagraph/ng_sep.cpp

@@ -0,0 +1,93 @@
+/*
+ * 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