vectorscan/src/nfagraph/ng_expr_info.cpp

/*
 * 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 Code for discovering properties of an NGWrapper used by
 * hs_expression_info.
 */
#include "ng_expr_info.h"

#include "hs_internal.h"
#include "ng.h"
#include "ng_asserts.h"
#include "ng_depth.h"
#include "ng_edge_redundancy.h"
#include "ng_holder.h"
#include "ng_reports.h"
#include "ng_util.h"
#include "ue2common.h"
#include "parser/position.h" // for POS flags
#include "util/boundary_reports.h"
#include "util/compile_context.h"
#include "util/depth.h"
#include "util/graph.h"
#include "util/graph_range.h"
#include "util/report_manager.h"

#include <limits.h>
#include <set>

using namespace std;

namespace ue2 {

/* get rid of leading \b and multiline ^ vertices */
static
void removeLeadingVirtualVerticesFromRoot(NGWrapper &w, NFAVertex root) {
    vector<NFAVertex> victims;

    for (auto v : adjacent_vertices_range(root, w)) {
        if (w[v].assert_flags & POS_FLAG_VIRTUAL_START) {
            DEBUG_PRINTF("(?m)^ vertex or leading \\[bB] vertex\n");
            victims.push_back(v);
        }
    }

    for (auto u : victims) {
        for (auto v : adjacent_vertices_range(u, w)) {
            add_edge_if_not_present(root, v, w);
        }
    }

    remove_vertices(victims, w);
}

static
void checkVertex(const ReportManager &rm, const NGWrapper &w, NFAVertex v,
                 const vector<DepthMinMax> &depths, DepthMinMax &info) {
    if (is_any_accept(v, w)) {
        return;
    }
    if (is_any_start(v, w)) {
        info.min = 0;
        info.max = max(info.max, depth(0));
        return;
    }

    u32 idx = w[v].index;
    assert(idx < depths.size());
    const DepthMinMax &d = depths.at(idx);

    for (ReportID report_id : w[v].reports) {
        const Report &report = rm.getReport(report_id);
        assert(report.type == EXTERNAL_CALLBACK);

        DepthMinMax rd = d;

        // Compute graph width to this report, taking any offset adjustment
        // into account.
        rd.min += report.offsetAdjust;
        rd.max += report.offsetAdjust;

        // A min_length param is a lower bound for match width.
        if (report.minLength && report.minLength <= depth::max_value()) {
            depth min_len((u32)report.minLength);
            rd.min = max(rd.min, min_len);
            rd.max = max(rd.max, min_len);
        }

        // A max_offset param is an upper bound for match width.
        if (report.maxOffset && report.maxOffset <= depth::max_value()) {
            depth max_offset((u32)report.maxOffset);
            rd.min = min(rd.min, max_offset);
            rd.max = min(rd.max, max_offset);
        }

        DEBUG_PRINTF("vertex %u report %u: %s\n", w[v].index, report_id,
                      rd.str().c_str());

        info = unionDepthMinMax(info, rd);
    }
}

static
bool hasOffsetAdjust(const ReportManager &rm, const NGWrapper &w) {
    for (const auto &report_id : all_reports(w)) {
        if (rm.getReport(report_id).offsetAdjust) {
            return true;
        }
    }
    return false;
}

void fillExpressionInfo(ReportManager &rm, NGWrapper &w, hs_expr_info *info) {
    assert(info);

    /* ensure utf8 starts at cp boundary */
    ensureCodePointStart(rm, w);
    resolveAsserts(rm, w);
    optimiseVirtualStarts(w);

    removeLeadingVirtualVerticesFromRoot(w, w.start);
    removeLeadingVirtualVerticesFromRoot(w, w.startDs);

    vector<DepthMinMax> depths;
    calcDepthsFrom(w, w.start, depths);

    DepthMinMax d;

    for (auto u : inv_adjacent_vertices_range(w.accept, w)) {
        checkVertex(rm, w, u, depths, d);
    }

    for (auto u : inv_adjacent_vertices_range(w.acceptEod, w)) {
        checkVertex(rm, w, u, depths, d);
    }

    if (d.max.is_finite()) {
        info->max_width = d.max;
    } else {
        info->max_width = UINT_MAX;
    }
    if (d.min.is_finite()) {
        info->min_width = d.min;
    } else {
        info->min_width = UINT_MAX;
    }

    info->unordered_matches = hasOffsetAdjust(rm, w);
    info->matches_at_eod = can_match_at_eod(w);
    info->matches_only_at_eod = can_only_match_at_eod(w);
}

} // namespace ue2