c++ - Boost精神不检查int溢出

Question

我正在尝试用 boost spirit 解析一些整数，我必须检查数据是否溢出，spirit 文档说所有整数解析器都会检查溢出，但是如果我尝试解析有符号整数，它只适用于无符号类型spirit 将不再检查溢出。

char const* b = "6600452345243524352340";
char const* e = b + strlen("6600452345243524352340");
int32_t res = 0;
bool valid = boost::spirit::qi::parse(b, e, boost::spirit::qi::int_, res);
std::cout << valid << " " << res << std::endl;

有没有办法对签名溢出进行精神检查？我使用的是 boost 1.55、gcc 4.9。

Answer 1

两者都检查溢出就好了:

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#include <boost/spirit/include/qi.hpp>
#include <boost/multiprecision/cpp_int.hpp>

using boost::multiprecision::int128_t;
using boost::multiprecision::int256_t;
using boost::multiprecision::uint128_t;
using boost::multiprecision::uint256_t;

template <typename T>
bool try_parse(char const* s) {
    auto b = s, e = b + strlen(s);
    T res = 0;
    namespace qi = boost::spirit::qi;
    bool valid = qi::parse(b, e, qi::int_parser<T, 10>(), res);
    if (!valid)
        std::cout << "Unparsed (" << __PRETTY_FUNCTION__ << ")\n";
    else
        std::cout << "Valid: " << res << "(" << __PRETTY_FUNCTION__ << ")\n";;

    if (b!=e)
        std::cout << " --> remaining: '" << std::string(b,e) << "'\n";

    return valid;
}

int main() {
    try_parse<int8_t>    ("6600452345243524352340");
    try_parse<uint8_t>   ("6600452345243524352340");

    try_parse<int16_t>   ("6600452345243524352340");
    try_parse<uint16_t>  ("6600452345243524352340");

    try_parse<int32_t>   ("6600452345243524352340");
    try_parse<uint32_t>  ("6600452345243524352340");

    try_parse<int64_t>   ("6600452345243524352340");
    try_parse<uint64_t>  ("6600452345243524352340");

    try_parse<int128_t>  ("6600452345243524352340");
    try_parse<uint128_t> ("6600452345243524352340");
}

打印

Unparsed (bool try_parse(const char *) [T = signed char])
--> remaining: '6600452345243524352340'
Unparsed (bool try_parse(const char *) [T = unsigned char])
--> remaining: '6600452345243524352340'
Unparsed (bool try_parse(const char *) [T = short])
--> remaining: '6600452345243524352340'
Unparsed (bool try_parse(const char *) [T = unsigned short])
--> remaining: '6600452345243524352340'
Unparsed (bool try_parse(const char *) [T = int])
--> remaining: '6600452345243524352340'
Unparsed (bool try_parse(const char *) [T = unsigned int])
--> remaining: '6600452345243524352340'
Unparsed (bool try_parse(const char *) [T = long])
--> remaining: '6600452345243524352340'
Unparsed (bool try_parse(const char *) [T = unsigned long])
--> remaining: '6600452345243524352340'
Valid: 6600452345243524352340 (bool try_parse(const char *) [T = boost::multiprecision::number<boost::multiprecision::backends::cpp_int_backend<128, 128, boost::multiprecision::cpp_integer_type::signed_magnitude, boost::multiprecision::cpp_int_check_type::unchecked, void>, boost::multiprecision::expression_template_option::et_off>])
Valid: 6600452345243524352340 (bool try_parse(const char *) [T = boost::multiprecision::number<boost::multiprecision::backends::cpp_int_backend<128, 128, boost::multiprecision::cpp_integer_type::unsigned_magnitude, boost::multiprecision::cpp_int_check_type::unchecked, void>, boost::multiprecision::expression_template_option::et_off>])