[istreambuf.iterator] (original) (raw)

24.6.4.1 General [istreambuf.iterator.general]

The class templateistreambuf_iteratordefines an input iterator that reads successive_characters_from the streambuf for which it was constructed.

operator*provides access to the current input character, if any.

Each timeoperator++is evaluated, the iterator advances to the next input character.

If the end of stream is reached (streambuf_type​::​sgetc() returnstraits​::​eof()), the iterator becomes equal to theend-of-streamiterator value.

The default constructoristreambuf_iterator()and the constructoristreambuf_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 ofoperator*()on an end-of-stream iterator is undefined.

For any other iterator value achar_typevalue is returned.

It is impossible to assign a character via an input iterator.

namespace std { template<class charT, class traits = char_traits<charT>> class istreambuf_iterator { public: using iterator_category = input_iterator_tag;using value_type = charT;using difference_type = typename traits::off_type;using pointer = unspecified;using reference = charT;using char_type = charT;using traits_type = traits;using int_type = typename traits::int_type;using streambuf_type = basic_streambuf<charT,traits>;using istream_type = basic_istream<charT,traits>;class proxy; constexpr istreambuf_iterator() noexcept;constexpr istreambuf_iterator(default_sentinel_t) 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; istreambuf_iterator& operator=(const istreambuf_iterator&) noexcept = default; charT operator*() const; istreambuf_iterator& operator++();proxy operator++(int);bool equal(const istreambuf_iterator& b) const;friend bool operator==(const istreambuf_iterator& i, default_sentinel_t s);private: streambuf_type* sbuf_; };}

24.6.4.2 Class istreambuf_iterator​::​proxy [istreambuf.iterator.proxy]

Classistreambuf_iterator<charT,traits>​::​_proxy_is for exposition only.

An implementation is permitted to provide equivalent functionality without providing a class with this name.

Classistreambuf_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.

namespace std { template<class charT, class traits> class istreambuf_iterator<charT, traits>::proxy { charT keep_; basic_streambuf<charT,traits>* sbuf_;proxy(charT c, basic_streambuf<charT,traits>* sbuf) : keep_(c), sbuf_(sbuf) { } public: charT operator*() { return keep_; } };}

24.6.4.3 Constructors [istreambuf.iterator.cons]

For each istreambuf_iterator constructor in this subclause, an end-of-stream iterator is constructed if and only if the exposition-only member sbuf_ is initialized with a null pointer value.

constexpr istreambuf_iterator() noexcept;constexpr istreambuf_iterator(default_sentinel_t) noexcept;

Effects: Initializes sbuf_ with nullptr.

istreambuf_iterator(istream_type& s) noexcept;

Effects: Initializes sbuf_ with s.rdbuf().

istreambuf_iterator(streambuf_type* s) noexcept;

Effects: Initializes sbuf_ with s.

istreambuf_iterator(const _proxy_& p) noexcept;

Effects: Initializes sbuf_ with p.sbuf_.

24.6.4.4 Operations [istreambuf.iterator.ops]

Returns: The character obtained via thestreambufmembersbuf_->sgetc().

istreambuf_iterator& operator++();

Effects: As if by sbuf_->sbumpc().

Returns: proxy(sbuf_->sbumpc(), sbuf_).

bool equal(const istreambuf_iterator& b) const;

Returns: trueif and only if both iterators are at end-of-stream, or neither is at end-of-stream, regardless of whatstreambufobject they use.

template<class charT, class traits> bool operator==(const istreambuf_iterator<charT,traits>& a,const istreambuf_iterator<charT,traits>& b);

friend bool operator==(const istreambuf_iterator& i, default_sentinel_t s);