Helper.h

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// ----------------------------------------------------------------------------
// -                        Open3D: www.open3d.org                            -
// ----------------------------------------------------------------------------
// Copyright (c) 2018-2023 www.open3d.org
// SPDX-License-Identifier: MIT
// ----------------------------------------------------------------------------
 
#pragma once
 
#include <cmath>
#include <cstdlib>
#include <functional>
#include <memory>
#include <random>
#include <stdexcept>
#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& hash_seed, T const& v) {
    hash_seed ^= std::hash<T>()(v) + 0x9e3779b9 + (hash_seed << 6) +
                 (hash_seed >> 2);
}
 
template <class Tuple, size_t Index = std::tuple_size<Tuple>::value - 1>
struct HashValueImpl {
    static void apply(size_t& hash_seed, Tuple const& tuple) {
        HashValueImpl<Tuple, Index - 1>::apply(hash_seed, tuple);
        hash_combine(hash_seed, std::get<Index>(tuple));
    }
};
 
template <class Tuple>
struct HashValueImpl<Tuple, 0> {
    static void apply(size_t& hash_seed, Tuple const& tuple) {
        hash_combine(hash_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 hash_seed = 0;
        HashValueImpl<std::tuple<TT...>>::apply(hash_seed, tt);
        return hash_seed;
    }
};
 
template <typename T>
struct hash_eigen {
    std::size_t operator()(T const& matrix) const {
        size_t hash_seed = 0;
        for (int i = 0; i < (int)matrix.size(); i++) {
            auto elem = *(matrix.data() + i);
            hash_seed ^= std::hash<typename T::Scalar>()(elem) + 0x9e3779b9 +
                         (hash_seed << 6) + (hash_seed >> 2);
        }
        return hash_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);
    }
};
 
std::vector<std::string> SplitString(const std::string& str,
                                     const std::string& delimiters = " ",
                                     bool trim_empty_str = true);
 
bool ContainsString(const std::string& src, const std::string& dst);
 
bool StringStartsWith(const std::string& src, const std::string& tar);
 
bool StringEndsWith(const std::string& src, const std::string& tar);
 
std::string JoinStrings(const std::vector<std::string>& strs,
                        const std::string& delimiter = ", ");
 
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);
 
template <typename... Args>
inline std::string FormatString(const std::string& format, Args... args) {
    int size_s = std::snprintf(nullptr, 0, format.c_str(), args...) +
                 1;  // Extra space for '\0'
    if (size_s <= 0) {
        throw std::runtime_error("Error during formatting.");
    }
    auto size = static_cast<size_t>(size_s);
    auto buf = std::make_unique<char[]>(size);
    std::snprintf(buf.get(), size, format.c_str(), args...);
    return std::string(buf.get(),
                       buf.get() + size - 1);  // We don't want the '\0' inside
};
 
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);
}
 
std::string GetCurrentTimeStamp();
 
}  // namespace utility
}  // namespace open3d