Question

在运行时确定匹配参数的数量时，我无法使用RE2 :: FullMatchN。

const RE2::Arg* args[10];
int n;
bool match = RE2::FullMatchN("abcd@abcd.com", "([^ @]+)@([^ @]+)", args, n);

最后，我想在上面的示例中获得2个字符串 - abcd和abcd.com

Answer 1

您可以使用RE2作为对象。如果RE2对象已成功解析正则表达式，则可以调用NumberOfCapturingGroups()方法。知道有多少捕获组，您可以动态地分配指向RE2::Arg的指针数组。

这是一个示例函数：

我还建议你将正则表达式包装在＆＃39;（＆＃39; - ＆＃39;）＆＃39;因为re2默认情况下不会返回0th参数，因为许多其他API会完全匹配。

bool re2_full_match(const std::string & pattern, const std::string & str, std::vector<std::string> & results)
{
    std::string wrapped_pattern = "(" + pattern + ")";
    RE2::Options opt;
    opt.set_log_errors(false);
    opt.set_case_sensitive(false);
    opt.set_utf8(false);
    RE2 re2(wrapped_pattern, opt);
    if (!re2.ok()) {
        /// Failed to compile regular expression.
        return false;
    }

    /// Argument vector.
    std::vector<RE2::Arg> arguments;
    /// Vercor of pointers to arguments.
    std::vector<RE2::Arg *> arguments_ptrs;

    /// Get number of arguments.
    std::size_t args_count = re2.NumberOfCapturingGroups();

    /// Adjust vectors sizes.
    arguments.resize(args_count);
    arguments_ptrs.resize(args_count);
    results.resize(args_count);
    /// Capture pointers to stack objects and result object in vector..
    for (std::size_t i = 0; i < args_count; ++i) {
        /// Bind argument to string from vector.
        arguments[i] = &results[i];
        /// Save pointer to argument.
        arguments_ptrs[i] = &arguments[i];
    }

    return RE2::FullMatchN(StringPiece(str), re2, arguments_ptrs.data(), args_count);
}

但本着正则表达式的精神，我建议您使用^....$代替full_match，并将full_match重命名为find：

bool re2_find(const std::string & pattern, const std::string & str, std::vector<std::string> & results)
{
    std::string wrapped_pattern = "(" + pattern + ")";
    RE2::Options opt;
    opt.set_log_errors(false);
    opt.set_case_sensitive(false);
    opt.set_utf8(false);
    RE2 re2(wrapped_pattern, opt);
    if (!re2.ok()) {
        /// Failed to compile regular expression.
        return false;
    }

    /// Argument vector.
    std::vector<RE2::Arg> arguments;
    /// Vercor of pointers to arguments.
    std::vector<RE2::Arg *> arguments_ptrs;

    /// Get number of arguments.
    std::size_t args_count = re2.NumberOfCapturingGroups();

    /// Adjust vectors sizes.
    arguments.resize(args_count);
    arguments_ptrs.resize(args_count);
    results.resize(args_count);
    /// Capture pointers to stack objects and result object in vector..
    for (std::size_t i = 0; i < args_count; ++i) {
        /// Bind argument to string from vector.
        arguments[i] = &results[i];
        /// Save pointer to argument.
        arguments_ptrs[i] = &arguments[i];
    }

    StringPiece piece(str);
    return RE2::FindAndConsumeN(&piece, re2, arguments_ptrs.data(), args_count);
}

匹配参数未知时如何使用RE2库

1 个答案: