The type Iterator must at least model Readable Iterator. The -resulting transform_iterator models the most refined of the +
The type Iterator must at least model Readable Iterator.
+The resulting transform_iterator models the most refined of the following options that is also modeled by Iterator.
@@ -104,8 +109,8 @@ concept that is modeled by Iterator result_of<UnaryFunction(iterator_traits<Iterator>::reference)>::type. The value_type is remove_cv<remove_reference<reference> >::type.
transform_iterator();
Iterator base() const;
+| Returns: | m_iterator | +
|---|
UnaryFunction functor() const;
typename transform_iterator::value_type dereference() const;
+reference operator*() const;
| Returns: | m_f(transform_iterator::dereference()); | +
|---|---|
| Returns: | m_f(*m_iterator) | +
transform_iterator& operator++();
+| Effects: | ++m_iterator | +
|---|---|
| Returns: | *this | +
+template <class UnaryFunction, class Iterator> +transform_iterator<UnaryFunction, Iterator> +make_transform_iterator(Iterator it, UnaryFunction fun); ++
| Returns: | An instance of transform_iterator<UnaryFunction, Iterator> with m_f +initialized to f and m_iterator initialized to x. | +
|---|
+template <class UnaryFunction, class Iterator> +transform_iterator<UnaryFunction, Iterator> +make_transform_iterator(Iterator it); ++
| Returns: | An instance of transform_iterator with m_f +default constructed and m_iterator initialized to x. |
|---|
This is a simple example of using the transform_iterators class to +generate iterators that multiply (or add to) the value returned by +dereferencing the iterator. It would be cooler to use lambda library +in this example.
+
+int x[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
+const int N = sizeof(x)/sizeof(int);
+
+typedef boost::binder1st< std::multiplies<int> > Function;
+typedef boost::transform_iterator<Function, int*> doubling_iterator;
+
+doubling_iterator i(x, boost::bind1st(std::multiplies<int>(), 2)),
+ i_end(x + N, boost::bind1st(std::multiplies<int>(), 2));
+
+std::cout << "multiplying the array by 2:" << std::endl;
+while (i != i_end)
+ std::cout << *i++ << " ";
+std::cout << std::endl;
+
+std::cout << "adding 4 to each element in the array:" << std::endl;
+std::copy(boost::make_transform_iterator(x, boost::bind1st(std::plus<int>(), 4)),
+ boost::make_transform_iterator(x + N, boost::bind1st(std::plus<int>(), 4)),
+ std::ostream_iterator<int>(std::cout, " "));
+std::cout << std::endl;
+
+The output is:
++multiplying the array by 2: +2 4 6 8 10 12 14 16 +adding 4 to each element in the array: +5 6 7 8 9 10 11 12 ++