/*
 * Copyright (c) 2015, Intel Corporation
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 * modification, are permitted provided that the following conditions are met:
 *
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 *    this list of conditions and the following disclaimer.
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 *    may be used to endorse or promote products derived from this software
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 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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/** \file
 * \brief Rose compile-time analysis for lookaround masks.
 */
#ifndef ROSE_ROSE_BUILD_LOOKAROUND_H
#define ROSE_ROSE_BUILD_LOOKAROUND_H

#include "rose_graph.h"

#include <vector>

namespace ue2 {

class CharReach;
class RoseBuildImpl;

/** \brief Lookaround entry prototype, describing the reachability at a given
 * distance from the end of a role match. */
struct LookEntry {
    LookEntry(s8 offset_in, const CharReach &reach_in)
        : offset(offset_in), reach(reach_in) {}
    s8 offset; //!< offset from role match location.
    CharReach reach; //!< reachability at given offset.

    bool operator==(const LookEntry &other) const {
        return offset == other.offset && reach == other.reach;
    }
};

static inline
size_t hash_value(const LookEntry &l) {
    size_t val = 0;
    boost::hash_combine(val, l.offset);
    boost::hash_combine(val, l.reach);
    return val;
}

void findLookaroundMasks(const RoseBuildImpl &tbi, const RoseVertex v,
                         std::vector<LookEntry> &lookaround);

/**
 * \brief If possible, render the prefix of the given vertex as a lookaround.
 *
 * Given a prefix, returns true (and fills the lookaround vector) if
 * it can be satisfied with a lookaround alone.
 */
bool makeLeftfixLookaround(const RoseBuildImpl &build, const RoseVertex v,
                           std::vector<LookEntry> &lookaround);

void mergeLookaround(std::vector<LookEntry> &lookaround,
                     const std::vector<LookEntry> &more_lookaround);

} // namespace ue2

#endif // ROSE_ROSE_BUILD_LOOKAROUND_H