Initial commit of Hyperscan

src/nfagraph/ng_restructuring.h

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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 State numbering and late graph restructuring code.
+
+ */
+#ifndef NG_RESTRUCTURING_H
+#define NG_RESTRUCTURING_H
+
+#include "ng_holder.h"
+#include "ue2common.h"
+#include "util/ue2_containers.h"
+
+#include <map>
+#include <vector>
+
+namespace ue2 {
+
+class NGHolder;
+
+/** Construct a reversed copy of an arbitrary NGHolder, mapping starts to
+ * accepts. */
+void reverseHolder(const NGHolder &g, NGHolder &out);
+
+/** Connect the start vertex to each of the vertices in \p tops. This is useful
+ * temporarily for when we need to run a graph algorithm that expects a single
+ * source vertex. */
+void wireStartToTops(NGHolder &g, const std::map<u32, NFAVertex> &tops,
+                     std::vector<NFAEdge> &topEdges);
+
+/**
+ * \brief Special state index value meaning that the vertex will not
+ * participate in an (NFA/DFA/etc) implementation.
+ */
+static constexpr u32 NO_STATE = ~0;
+
+/**
+ * \brief Gives each participating vertex in the graph a unique state index.
+ */
+ue2::unordered_map<NFAVertex, u32>
+numberStates(NGHolder &h,
+             const std::map<u32, NFAVertex> &tops = std::map<u32, NFAVertex>{});
+
+/**
+ * \brief Counts the number of states (vertices with state indices) in the
+ * graph.
+ *
+ * If addTops is true, also accounts for states that will be constructed for
+ * each unique top.
+ */
+u32 countStates(const NGHolder &g,
+                const ue2::unordered_map<NFAVertex, u32> &state_ids,
+                bool addTops = true);
+
+/** Optimisation: drop unnecessary start states. */
+void dropUnusedStarts(NGHolder &g, ue2::unordered_map<NFAVertex, u32> &states);
+
+} // namespace ue2
+
+#endif