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BigOh neato

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struct BigO
{
    double exp = 0, logExp = 0;
    bool opEqual(BigO rhs) const
    {
        return exp == rhs.exp && logExp == rhs.logExp;
    }

int opCmp(BigO rhs) const
    {
        if (exp == rhs.exp)
            return logExp < rhs.logExp ? -1 : (logExp > rhs.logExp);
        return exp > rhs.exp ? 1 : -1;
    }

BigO opMul(BigO rhs) const
    {
        return BigO(exp + rhs.exp, logExp + rhs.logExp);
    }

static immutable
        constant = BigO(),
        logarithmic = BigO(0, 1),
        sqrt = BigO(0.5),
        linear = BigO(1),
        linearithmic = BigO(1, 1),
        quadratic = BigO(2),
        cubic = BigO(3),
        fastGrowing = BigO(double.infinity);
}

BigO complexity(alias fun)()
{
    enum traits = __traits(getAttributes, fun);
    foreach (i, trait; traits)
    {
        static if (is(typeof(trait) : const BigO)) return trait;
    }
    return BigO();
}

struct List(T)
{
    void insertFront(T x) @(BigO.constant);
}

void main()
{
    List!int lst;
    static assert(complexity!(List!int.insertFront) == BigO.constant);
    static assert(complexity!(List!int.insertFront) < BigO.quadratic);
    assert(BigO.constant * BigO.linear == BigO.linear);
}

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Author: Guest

Views: 492

Private: no

Expires: Never

Uploaded: 05.12.15 19:58

Votes: 0

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Compiler: DMD 2.079.1 ( 2.079.1 )

Pointer size: m64

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