Helper.h

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// -                        Open3D: www.open3d.org                            -
// ----------------------------------------------------------------------------
// The MIT License (MIT)
//
// Copyright (c) 2018 www.open3d.org
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// furnished to do so, subject to the following conditions:
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#pragma once

#include <cmath>
#include <cstdlib>
#include <functional>
#include <string>
#include <tuple>
#include <vector>

namespace open3d {
namespace utility {


template <typename TT>
struct hash_tuple {
    size_t operator()(TT const& tt) const { return std::hash<TT>()(tt); }
};

namespace {

template <class T>
inline void hash_combine(std::size_t& seed, T const& v) {
    seed ^= hash_tuple<T>()(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
}

template <class Tuple, size_t Index = std::tuple_size<Tuple>::value - 1>
struct HashValueImpl {
    static void apply(size_t& seed, Tuple const& tuple) {
        HashValueImpl<Tuple, Index - 1>::apply(seed, tuple);
        hash_combine(seed, std::get<Index>(tuple));
    }
};

template <class Tuple>
struct HashValueImpl<Tuple, 0> {
    static void apply(size_t& seed, Tuple const& tuple) {
        hash_combine(seed, std::get<0>(tuple));
    }
};

}  // unnamed namespace

template <typename... TT>
struct hash_tuple<std::tuple<TT...>> {
    size_t operator()(std::tuple<TT...> const& tt) const {
        size_t seed = 0;
        HashValueImpl<std::tuple<TT...>>::apply(seed, tt);
        return seed;
    }
};

template <typename T>
struct hash_eigen {
    std::size_t operator()(T const& matrix) const {
        size_t seed = 0;
        for (int i = 0; i < (int)matrix.size(); i++) {
            auto elem = *(matrix.data() + i);
            seed ^= std::hash<typename T::Scalar>()(elem) + 0x9e3779b9 +
                    (seed << 6) + (seed >> 2);
        }
        return seed;
    }
};

// Hash function for enum class for C++ standard less than C++14
// https://stackoverflow.com/a/24847480/1255535
struct hash_enum_class {
    template <typename T>
    std::size_t operator()(T t) const {
        return static_cast<std::size_t>(t);
    }
};

void SplitString(std::vector<std::string>& tokens,
                 const std::string& str,
                 const std::string& delimiters = " ",
                 bool trim_empty_str = true);

size_t WordLength(const std::string& doc,
                  size_t start_pos,
                  const std::string& valid_chars = "_");

std::string& LeftStripString(std::string& str,
                             const std::string& chars = "\t\n\v\f\r ");

std::string& RightStripString(std::string& str,
                              const std::string& chars = "\t\n\v\f\r ");

std::string& StripString(std::string& str,
                         const std::string& chars = "\t\n\v\f\r ");

std::string ToLower(const std::string& s);

std::string ToUpper(const std::string& s);

void Sleep(int milliseconds);

inline int DivUp(int x, int y) {
    div_t tmp = std::div(x, y);
    return tmp.quot + (tmp.rem != 0 ? 1 : 0);
}

int UniformRandInt(const int min, const int max);

template <typename T>
T UniformRandFloatBinaryFriendly(unsigned int power = 5) {
    double p = std::pow(2, power);
    int n = UniformRandInt(0, p - 1);
    return static_cast<T>(1. / p * n);
}

}  // namespace utility
}  // namespace open3d