From: Bonita.Montero@gmail.com   
      
   I made a little benchmark that compares the table code against the   
   convention   
   &&-cascaded code. On my Zen4-PC the table code is about 25% faster with   
   clang.   
   I'm doing a AVX2 and AVX-512 version now. I guess it's about 20 - 30 times   
   faster.   
      
   #include    
      
   #include    
   #include    
   #include    
   #include    
      
   using namespace std;   
   using namespace filesystem;   
   using namespace chrono;   
      
   template   
   bool binary( string const &buf );   
      
   int main()   
   {   
        ifstream ifs;   
        ifs.exceptions( ios_base::failbit | ios_base::badbit );   
        ifs.open( "main.cpp", ios_base::binary | ios_base::ate );   
        streampos pos = ifs.tellg();   
        if( pos > (size_t)-1 )   
            throw ios_base::failure( "file too large", error_code(   
   (int)errc::file_too_large, generic_category() ) );   
        string buf( (size_t)pos, 0 );   
        ifs.seekg( 0 );   
        ifs.read( buf.data(), buf.size() );   
        binary( buf );   
        auto bench = [&]( bool_constant ) -> int   
        {   
            int ret = 0;   
            auto start = high_resolution_clock::now();   
            for( size_t r = 1'000'000; r; --r )   
                ret += binary( buf );   
            double secs = (double)duration_cast(   
   high_resolution_clock::now() - start ).count() / 1.0e9;   
            cout << (Table ? "table" : "check") << ": " << secs << endl;   
            return ret;   
        };   
        int ret = bench( false_type() );   
        ret += bench( true_type() );   
        return ret;   
   }   
      
   template   
   bool binary( string const &buf )   
   {   
        static auto invalid = []( unsigned char c ) static { return c <   
   0x20 && c != '\r' && c != '\n' && c != '\t'; };   
        if constexpr( Table )   
        {   
            static vector invalidTbl = Table ? []()   
                {   
                    vector ret( numeric_limits::max() );   
                    for( size_t c = ret.size(); c--; )   
                        ret[c] = invalid( (unsigned char)c );   
                    return ret;   
                }() : vector();   
            return find_if( buf.begin(), buf.end(), [&]( unsigned char c )   
   { return invalidTbl[c]; } ) == buf.end();   
        }   
        else   
            return find_if( buf.begin(), buf.end(), invalid ) == buf.end();   
   }   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   



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