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第二回 オフラインリアルタイムどう書く その2

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その1のコードを書いてからさらに30分ほど考えてみた結果。
演算を積算していくところは畳み込み関数が得意とするところなわけですが。実はC++の標準ライブラリにも畳み込み関数があります。<numeric>で定義されているaccumulate関数テンプレートです。で、第4引数に二項演算子を与えるわけですが、せっかくなので(というか外に関数を定義するのが面倒だったので)C++11のラムダ関数を引数に与えています。C++11解禁なら後半もラムダ関数にしてしまえ、というノリでfor_eachとラムダ関数を組み合わせてそろった段の削除をしています。

#include <sstream>
#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>

typedef std::vector<unsigned int> Field;

struct Data
{
    const char* input;
    const char* output;
};

const Data data[] =
{
    /* 0*/ { "ff-2f-23-f3-77-7f-3b", "1f-03-00-1c-0d-0f-06" },
    /* 1*/ { "01", "00" },
    /* 2*/ { "00", "00" },
    /* 3*/ { "7a-4e", "0c-02" },
    /* 4*/ { "56-b6", "08-14" },
    /* 5*/ { "12-12-12", "00-00-00" },
    /* 6*/ { "de-ff-7b", "0a-0f-05" },
    /* 7*/ { "95-be-d0", "05-1e-20" },
    /* 8*/ { "7c-b0-bb", "1c-20-2b" },
    /* 9*/ { "7a-b6-31-6a", "3a-56-11-2a" },
    /*10*/ { "32-0e-23-82", "18-06-11-40" },
    /*11*/ { "ff-7f-bf-df-ef", "0f-07-0b-0d-0e" },
    /*12*/ { "75-df-dc-6e-42", "35-5f-5c-2e-02" },
    /*13*/ { "62-51-ef-c7-f8", "22-11-6f-47-78" },
    /*14*/ { "0c-47-8e-dd-5d-17", "04-23-46-6d-2d-0b" },
    /*15*/ { "aa-58-5b-6d-9f-1f", "52-28-2b-35-4f-0f" },
    /*16*/ { "ff-55-d5-75-5d-57", "0f-00-08-04-02-01" },
    /*17*/ { "fe-fd-fb-f7-ef-df-bf", "7e-7d-7b-77-6f-5f-3f" },
    /*18*/ { "fd-fb-f7-ef-df-bf-7f", "7e-7d-7b-77-6f-5f-3f" },
    /*19*/ { "d9-15-b5-d7-1b-9f-de", "69-05-55-67-0b-4f-6e" },
    /*20*/ { "38-15-fd-50-10-96-ba", "18-05-7d-20-00-46-5a" },
    /*21*/ { "fe-fd-fb-f7-ef-df-bf-7f", "fe-fd-fb-f7-ef-df-bf-7f" },
           { 0, 0 }
};

std::istream& operator >> (std::istream& in, Field& field)
{
    in >> std::hex;
    unsigned int n;
    do
    {
        in >> n;
        field.push_back(n);
        char c;
        in >> c;
    } while(in.good());
    return in;
}

std::ostream& operator << (std::ostream& out, const Field& field)
{
    int fill = out.fill('0');
    out << std::hex;
    Field::const_iterator i = field.begin();
    out << std::setw(2) << *i++;
    for(; i != field.end(); ++i)
    {
        out << "-" << std::setw(2) << *i;
    }
    out << std::dec;
    out.fill(fill);
    return out;
}

int main(int, char* [])
{
    for(const Data* d = data; d->input != 0; ++d)
    {
        Field field;
        std::istringstream iss(d->input);
        iss >> field;

        Field::value_type v = std::accumulate(field.begin(), field.end(), 0xffu, [](unsigned int lhs, unsigned int rhs) { return lhs & rhs; });

        for(int i = 7; i >= 0; --i)
        {
            if(((v >> i) & 1) != 0)
            {
                std::for_each(field.begin(), field.end(), [i](unsigned int& f) { f = (f & (0xffu >> (8 - i))) | ((f >> 1) & (0xffu << i)); });
            }
        }

        std::ostringstream oss;
        oss << field;
        std::string result = oss.str();
        std::cout << result << " : " << ((result == d->output) ? "PASSED" : "FAILED") << std::endl;
    }

    return 0;
}
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