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  1. #include <iostream>
  2. #include <functional>
  3. #include <algorithm>
  4. #include <utility>
  5. #include <memory>
  6. #include <cstddef>
  7. #include <cassert>
  8.  
  9.  
  10. template<typename T>
  11. struct matrix {
  12.  
  13.    template<typename V>
  14.    struct index_proxy {
  15.  
  16.    	  V & operator [](std::size_t const j) const {
  17.    	  	 assert(index < ref.height());
  18.    	  	 assert(j < ref.width());
  19.  
  20.    	     return ref.data()[ref.width() * index + j];
  21.    	  }
  22.  
  23.    	  operator V &() const {
  24.    	  	assert(index < ref.size());
  25.  
  26.    	  	return ref.data()[index];
  27.    	  }
  28.  
  29.    	  template<typename S>
  30.    	  void operator =(S && value) {
  31.    	     assert(index < ref.size());
  32.  
  33.    	     ref.data()[index] = std::forward<S>(value);
  34.    	  }
  35.  
  36.    private:
  37.       friend class matrix;
  38.  
  39.       index_proxy(matrix & ref, std::size_t const index) : ref(ref), index(index) {}
  40.  
  41.       index_proxy(index_proxy const&) = delete;
  42.       index_proxy(index_proxy &&) = delete;
  43.  
  44.       matrix &          ref;
  45.       std::size_t const index;
  46.    };
  47.  
  48.  
  49.    matrix(std::size_t const height_, std::size_t const width_)
  50.        : data_(new T[height_ * width_])
  51.        , height_(height_)
  52.        , width_(width_)
  53.        {}
  54.  
  55.    matrix(matrix const& other) : matrix(other.height(), other.width()) {
  56.       std::copy_n(other.data(), size(), data());
  57.    }
  58.  
  59.    matrix(matrix && other)
  60.        : data_(std::move(other.data_))
  61.        , height_(other.height_)
  62.        , width_(other.width_)
  63.        {}
  64.  
  65.   matrix & operator =(matrix const& other) {
  66.       height_ = other.height();
  67.       width_  = other.width();
  68.  
  69.       if (size() != other.size()) {
  70.          data().reset(new T[height() * width()]);
  71.       }
  72.  
  73.       std::copy_n(other.data(), size(), data());
  74.  
  75.       return *this;
  76.    }
  77.  
  78.     matrix & operator =(matrix && other) {
  79.       data_   = std::move(other.data_);
  80.       height_ = other.height_;
  81.       width_  = other.width_;
  82.  
  83.       return *this;
  84.    }
  85.  
  86.  
  87.    index_proxy<T> operator [](std::size_t const index) {
  88.       return {*this, index};
  89.    }
  90.    index_proxy<T const> operator [](std::size_t const index) const {
  91.       return {*this, index};
  92.    }
  93.  
  94.  
  95.    std::size_t height() const {
  96.       return height_;
  97.    }
  98.  
  99.    std::size_t width() const {
  100.       return width_;
  101.    }
  102.  
  103.    std::size_t size() const {
  104.       return height() * width();
  105.    }
  106.  
  107.    T * data() {
  108.       return data_.get();
  109.    }
  110.    T const* data() const {
  111.       return data_.get();
  112.    }
  113.  
  114.  
  115. private:
  116.    std::unique_ptr<T[]> data_;
  117.    std::size_t          height_;
  118.    std::size_t          width_;
  119. };
  120.  
  121.  
  122. int main() {
  123.    matrix<int> m(3, 4);
  124.  
  125.    for (std::size_t i = 0; i != m.size(); ++i) {
  126.       m[i] = static_cast<int>(i);
  127.    }
  128.  
  129.    for (std::size_t i = 0; i != m.size(); ++i) {
  130.       std::cout << m[i] << ' ';
  131.    }
  132.    std::cout << std::endl;
  133.  
  134.    for (std::size_t i = 0; i != m.height(); ++i) {
  135.       for (std::size_t j = 0; j != m.width(); ++j) {
  136.          std::cout << m[i][j] << ' ';
  137.       }
  138.       std::cout << std::endl;
  139.    }
  140. }
Success #stdin #stdout 0s 3472KB
comments (?)
stdin
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Standard input is empty
stdout
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0 1 2 3 4 5 6 7 8 9 10 11 
0 1 2 3 
4 5 6 7 
8 9 10 11
https://ideone.com/LxIDrE
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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