vectorscan/src/util/charreach.cpp

/*
 * Copyright (c) 2015-2016, Intel Corporation
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/** \file
 * \brief Class for representing character reachability.
 *
 * This is a simple (but hopefully fast) class for representing 8-bit character
 * reachability, along with a bunch of useful operations.
 */
#include "ue2common.h"
#include "charreach.h"
#include "charreach_util.h"
#include "compare.h"
#include "unicode_def.h"

#include <cassert>
#include <string>

namespace ue2 {

/// Switch on the bits corresponding to the characters in \a s.
void CharReach::set(const std::string &s) {
    for (const auto &c : s) {
        set(c);
    }
}

/// Do we only contain bits representing alpha characters?
bool CharReach::isAlpha() const {
    if (none()) {
        return false;
    }
    for (size_t i = find_first(); i != npos; i = find_next(i)) {
        if (!ourisalpha((char)i)) {
            return false;
        }
    }
    return true;
}

/// Do we represent an uppercase/lowercase pair?
bool CharReach::isCaselessChar() const {
    if (count() != 2) {
        return false;
    }
    size_t first = find_first();
    size_t second = find_next(first);
    assert(first != npos && second != npos);
    return (char)first == mytoupper((char)second);
}

/// Do we represent a cheapskate caseless set?
bool CharReach::isBit5Insensitive() const {
    for (size_t i = find_first(); i != npos; i = find_next(i)) {
        if (!test((char)i ^ 0x20)) {
            return false;
        }
    }
    return true;
}

/// Return a string containing the characters that are switched on.
std::string CharReach::to_string() const {
    std::string s;
    for (size_t i = find_first(); i != npos; i = find_next(i)) {
        s += (char)i;
    }
    return s;
}

/** \brief True iff there is a non-empty intersection between \a and \a b */
bool overlaps(const CharReach &a, const CharReach &b) {
    return (a & b).any();
}

/** \brief True iff \a small is a subset of \a big. */
bool isSubsetOf(const CharReach &small, const CharReach &big) {
    return small.isSubsetOf(big);
}

/// True if this character class is a subset of \a other.
bool CharReach::isSubsetOf(const CharReach &other) const {
    return (bits & other.bits) == bits;
}

void make_caseless(CharReach *cr) {
    for (char c = 'A'; c <= 'Z'; c++) {
        if (cr->test(c) || cr->test(mytolower(c))) {
            cr->set(c);
            cr->set(mytolower(c));
        }
    }
}

bool isutf8ascii(const CharReach &cr) {
    return (cr & ~CharReach(0x0, 0x7f)).none();
}

bool isutf8start(const CharReach &cr) {
    return (cr & CharReach(0x0, UTF_CONT_MAX)).none();
}

void fill_bitvector(const CharReach &cr, u8 *bits) {
    assert(bits);
    std::fill_n(bits, 32, 0);
    for (size_t i = cr.find_first(); i != cr.npos; i = cr.find_next(i)) {
        bits[i / 8U] |= (u8)1U << (i % 8U);
    }
}

void make_and_cmp_mask(const CharReach &cr, u8 *and_mask, u8 *cmp_mask) {
    u8 lo = 0xff;
    u8 hi = 0;

    for (size_t c = cr.find_first(); c != cr.npos; c = cr.find_next(c)) {
        hi |= (u8)c;
        lo &= (u8)c;
    }

    *and_mask = ~(lo ^ hi);
    *cmp_mask = lo;
}

} // namespace ue2