I was playing a bit with rapidjson and came up with t

provide a sample handler calculating a SHA1 hash for a document about rapidjson HOT 3 CLOSED

tencent commented on May 18, 2024

provide a sample handler calculating a SHA1 hash for a document

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Comments (3)

miloyip commented on May 18, 2024

Thank you for your contribution.

Besides, you can also use Reader, if you only need to compute hash for a JSON but not do anything more on it. Then there will be no overhead of creating a DOM.

A good thing is that, without any modification, your code can do that perfectly.

HashCalculator hasher;
Reader reader;
StringStream ss(json);
reader.Parse(ss,hasher);
std::string hash = hasher.get_hash();

~~Besides, I think your calculate_hash() function should be a static or global function.~~

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Kosta-Github commented on May 18, 2024

calculate_hash() is in global scope outside of the HashCalculator...

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Kosta-Github commented on May 18, 2024

BTW, your example of the CapitalizeFilter could be shortened if you inherit the template parameter OutputHandler like this:

template<typename OutputHandler>
struct CapitalizeFilter : public OutputHandler {

    template<typename... ARGS>
    inline CapitalizeFilter(ARGS&&... args) : OutputHandler(std::forward<ARGS>(args)...) { }

    inline bool String(const char* str, rapidjson::SizeType len, bool) {
        buffer_.assign(str, str + len);
        std::transform(buffer_.begin(), buffer_.end(), buffer_.begin(), [](char c) { return std::toupper(c); });
        return OutputHandler::String(buffer_.data(), len, true); // true = output handler need to copy the string
    }

    std::string buffer_;
};

std::string calculate_hash(document const& doc_) {
    CapitalizeFilter<HashCalculator> cap_hasher;
    doc_.Accept(cap_hasher);
    return cap_hasher.get_hash();
}