The class template istreambuf_iterator defines an input iterator ([iterators.input]) that reads successive characters from the streambuf for which it was constructed. operator* provides access to the current input character, if any. Each time operator++ is evaluated, the iterator advances to the next input character. If the end of stream is reached (streambuf_type::sgetc() returns traits::eof()), the iterator becomes equal to the end-of-stream iterator value. The default constructor istreambuf_iterator() and the constructor istreambuf_iterator(nullptr) both construct an end-of-stream iterator object suitable for use as an end-of-range. All specializations of istreambuf_iterator shall have a trivial copy constructor, a constexpr default constructor, and a trivial destructor.
The result of operator*() on an end-of-stream iterator is undefined. For any other iterator value a char_type value is returned. It is impossible to assign a character via an input iterator.
namespace std { namespace experimental { namespace ranges { inline namespace v1 {
template <class charT, class traits = char_traits<charT>>
class istreambuf_iterator {
public:
typedef input_iterator_tag iterator_category;
typedef charT value_type;
typedef typename traits::off_type difference_type;
typedef charT reference;
typedef unspecified pointer;
typedef charT char_type;
typedef traits traits_type;
typedef typename traits::int_type int_type;
typedef basic_streambuf<charT, traits> streambuf_type;
typedef basic_istream<charT, traits> istream_type;
class proxy; // exposition only
constexpr istreambuf_iterator() noexcept;
constexpr istreambuf_iterator(default_sentinel) noexcept;
istreambuf_iterator(const istreambuf_iterator&) noexcept = default;
~istreambuf_iterator() = default;
istreambuf_iterator(istream_type& s) noexcept;
istreambuf_iterator(streambuf_type* s) noexcept;
istreambuf_iterator(const proxy& p) noexcept;
charT operator*() const;
istreambuf_iterator& operator++();
proxy operator++(int);
bool equal(const istreambuf_iterator& b) const;
private:
streambuf_type* sbuf_; // exposition only
};
template <class charT, class traits>
bool operator==(const istreambuf_iterator<charT, traits>& a,
const istreambuf_iterator<charT, traits>& b);
template <class charT, class traits>
bool operator==(default_sentinel a,
const istreambuf_iterator<charT, traits>& b);
template <class charT, class traits>
bool operator==(const istreambuf_iterator<charT, traits>& a,
default_sentinel b);
template <class charT, class traits>
bool operator!=(const istreambuf_iterator<charT, traits>& a,
const istreambuf_iterator<charT, traits>& b);
template <class charT, class traits>
bool operator!=(default_sentinel a,
const istreambuf_iterator<charT, traits>& b);
template <class charT, class traits>
bool operator!=(const istreambuf_iterator<charT, traits>& a,
default_sentinel b);
}}}}
namespace std { namespace experimental { namespace ranges { inline namespace v1 {
template <class charT, class traits = char_traits<charT>>
class istreambuf_iterator<charT, traits>::proxy { // exposition only
charT keep_;
basic_streambuf<charT, traits>* sbuf_;
proxy(charT c, basic_streambuf<charT, traits>* sbuf)
: keep_(c), sbuf_(sbuf) { }
public:
charT operator*() { return keep_; }
};
}}}}
Class istreambuf_iterator<charT, traits>::proxy is for exposition only. An implementation is permitted to provide equivalent functionality without providing a class with this name. Class istreambuf_iterator<charT, traits>::proxy provides a temporary placeholder as the return value of the post-increment operator (operator++). It keeps the character pointed to by the previous value of the iterator for some possible future access to get the character.
constexpr istreambuf_iterator() noexcept;
constexpr istreambuf_iterator(default_sentinel) noexcept;
Effects: Constructs the end-of-stream iterator.
istreambuf_iterator(basic_istream<charT, traits>& s) noexcept;
istreambuf_iterator(basic_streambuf<charT, traits>* s) noexcept;
Effects: Constructs an istreambuf_iterator that uses the basic_streambuf object *(s.rdbuf()), or *s, respectively. Constructs an end-of-stream iterator if s.rdbuf() is null.
istreambuf_iterator(const proxy& p) noexcept;
Effects: Constructs a istreambuf_iterator that uses the basic_streambuf object pointed to by the proxy object's constructor argument p.
Returns: The character obtained via the streambuf member sbuf_->sgetc().
istreambuf_iterator&
istreambuf_iterator<charT, traits>::operator++();
Effects: Equivalent to sbuf_->sbumpc().
Returns: *this.
proxy istreambuf_iterator<charT, traits>::operator++(int);
Effects: Equivalent to: return proxy(sbuf_->sbumpc(), sbuf_);
bool equal(const istreambuf_iterator& b) const;
Returns: true if and only if both iterators are at end-of-stream, or neither is at end-of-stream, regardless of what streambuf object they use.
template <class charT, class traits>
bool operator==(const istreambuf_iterator<charT, traits>& a,
const istreambuf_iterator<charT, traits>& b);
Effects: Equivalent to: return a.equal(b);
template <class charT, class traits>
bool operator==(default_sentinel a,
const istreambuf_iterator<charT, traits>& b);
Effects: Equivalent to: return istreambuf_iterator<charT, traits>{}.equal(b);
template <class charT, class traits>
bool operator==(const istreambuf_iterator<charT, traits>& a,
default_sentinel b);
Effects: Equivalent to: return a.equal(istreambuf_iterator<charT, traits>{});
template <class charT, class traits>
bool operator!=(const istreambuf_iterator<charT, traits>& a,
const istreambuf_iterator<charT, traits>& b);
template <class charT, class traits>
bool operator!=(default_sentinel a,
const istreambuf_iterator<charT, traits>& b);
template <class charT, class traits>
bool operator!=(const istreambuf_iterator<charT, traits>& a,
default_sentinel b);
Effects: Equivalent to: return !(a == b);