C++でRubyみたいに書きたい病。print文の出来には満足している

2013-05-17-e.cc

#include <sstream>
#include <iostream>
#include <cctype>
#include <list>
#include <vector>
#include <string>
#include <iterator>
#include <algorithm>

using namespace std;

// vector や list で Ruby の Array みたいなことをするクラス
template <typename Container>
class Array {
 public:
  Array() : data_() { }
  template <typename Iterator>
  Array(Iterator first, Iterator last) : data_() {
    std::copy(first, last, back_inserter(data_));
  }
  template <typename Functor>
  Array map(Functor function) const {
    Array<Container> tmp;
    std::transform(data_.begin(), data_.end(), back_inserter(tmp.data_), function);
    return tmp;
  }
  template <typename Functor>
  Array each(Functor function) const {
    std::for_each(data_.begin(), data_.end(), function);
    return *this;
  }
  template <typename Functor>
  typename Container::value_type inject(Functor binary_function, typename Container::value_type initial_value) {
    return accumulate(data_.begin(), data_.end(), initial_value, binary_function);
  }
  template <typename Functor>
  typename Container::value_type inject(Functor binary_function) {
    typename Container::value_type initial_value = data_.front();
    auto begin = ++data_.begin();
    return accumulate(begin, data_.end(), initial_value, binary_function);
  }
  string join(const string &separator) {
    string buf;
    int i = 0;
    each([&buf, &i](typename Container::value_type val) {
      ostringstream os;
      if (i++ != 0) buf += ' ';
      os  << val;
      buf += os.str();
    });
    return buf;
  }
  const Container& data() const { return data_; }
 private:
  Container data_;
};

string upcase(const string &src)
{
  string ret(src);
  int (*f)(int) = toupper; // to resolve function overload
  transform(ret.begin(), ret.end(), ret.begin(), f);
  return ret;
}

// 活目せよ。コンマ演算子！
template <typename T>
ostream& operator,(ostream& out, T val)
{
  return out << val;
}
#define print cout ,

#define do(x) ([](x) {
#define end })

int main()
{
  int    _ai[3] = {1, 2, 3};
  string _as[2] = {"hello", "world"};

  Array<vector<int>>  a  (&_ai[0], &_ai[3]);
  Array<list<string>> a2 (&_as[0], &_as[2]);

  auto b = a.map do (int n)
               return n*n*n;
             end;                        // 個々の要素を３乗
  b.each do (int n)
      print n, '\n';
    end;                                        // ３乗した要素を表示
  int sum     = b.inject(plus<int>());        // 計
  int product = b.inject(multiplies<int>()); // 積

  print "sum = ", sum, '\n';
  print "product = ", product, '\n';

  print a2.map do (string s)
    return upcase(s);
  end.join(" ") + '\n'; // 単語を大文字に
  print a2.inject(plus<string>(), ">>>") + '\n'; // ">>>" + "hello" + "world"
}