所以我们有我们的HTML转义函数，真正工作在C ++的方式，如何unescape？ [英] So we've got our HTML escape functions that really work in a C++ manner, how to do unescape?

问题描述

这里我发现一种格式化方式，对HTML编码/转义特殊字符。现在我想知道如何在C ++中解除HTML编码的文本？

Here I've found a grate way to HTML encode/escape special chars. Now I wonder how to unescape HTML encoded text in C++?

所以代码库是：

#include <algorithm>

namespace xml {

    // Helper for null-terminated ASCII strings (no end of string iterator).
    template<typename InIter, typename OutIter>
    OutIter copy_asciiz ( InIter begin, OutIter out )
    {
        while ( *begin != '\0' ) {
            *out++ = *begin++;
        }
        return (out);
    }

    // XML escaping in it's general form.  Note that 'out' is expected
    // to an "infinite" sequence.
    template<typename InIter, typename OutIter>
    OutIter escape ( InIter begin, InIter end, OutIter out )
    {
        static const char bad[] = "&<>";
        static const char* rep[] = {"&amp;", "&lt;", "&gt;"};
        static const std::size_t n = sizeof(bad)/sizeof(bad[0]);

        for ( ; (begin != end); ++begin )
        {
            // Find which replacement to use.
            const std::size_t i =
                std::distance(bad, std::find(bad, bad+n, *begin));

            // No need for escaping.
            if ( i == n ) {
                *out++ = *begin;
            }
            // Escape the character.
            else {
                out = copy_asciiz(rep[i], out);
            }
        }
        return (out);
    }

}

和

#include <iterator>
#include <string>

namespace xml {

    // Get escaped version of "content".
    std::string escape ( const std::string& content )
    {
        std::string result;
        result.reserve(content.size());
        escape(content.begin(), content.end(), std::back_inserter(result));
        return (result);
    }

    // Escape data on the fly, using "constant" memory.
    void escape ( std::istream& in, std::ostream& out )
    {
        escape(std::istreambuf_iterator<char>(in),
            std::istreambuf_iterator<char>(),
            std::ostreambuf_iterator<char>(out));
    }

}

它适用于：

#include <iostream>

int main ( int, char ** )
{
    std::cout << xml::escape("<foo>bar & qux</foo>") << std::endl;
}

$ b $ p

所以我不知道 - 如何让HTML以这种方式解析？

So I wonder - how to make HTML unescape in such manner?

推荐答案

看看我如何解决类似的问题'&＃ \\ d +）;'字符串，即数字字符引用（NCR），使用 boost :: spirit ， boost :: regex_token_iterator ， Flex ， Perl 。

Take a look at how I've solved a similar problem for '&#(\d+);' strings i.e., numeric character references (NCRs) using boost::spirit, boost::regex_token_iterator, Flex, Perl.

在您的情况下，正则表达式如果您不需要转换&（amp | lt | gt）; rel =nofollow>所有html实体。

In your case the regex is &(amp|lt|gt); if you don't need to convert all html entities.

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