Annex D (normative) Compatibility features [depr]

D.13 char* streams [depr.str.strstreams]

D.13.2 Class strstreambuf [depr.strstreambuf]

D.13.2.1 General [depr.strstreambuf.general]

namespace std { class strstreambuf : public basic_streambuf<char> { public: strstreambuf() : strstreambuf(0) {} explicit strstreambuf(streamsize alsize_arg); strstreambuf(void* (*palloc_arg)(size_t), void (*pfree_arg)(void*)); strstreambuf(char* gnext_arg, streamsize n, char* pbeg_arg = nullptr); strstreambuf(const char* gnext_arg, streamsize n); strstreambuf(signed char* gnext_arg, streamsize n, signed char* pbeg_arg = nullptr); strstreambuf(const signed char* gnext_arg, streamsize n); strstreambuf(unsigned char* gnext_arg, streamsize n, unsigned char* pbeg_arg = nullptr); strstreambuf(const unsigned char* gnext_arg, streamsize n); virtual ~strstreambuf(); void freeze(bool freezefl = true); char* str(); int pcount(); protected: int_type overflow (int_type c = EOF) override; int_type pbackfail(int_type c = EOF) override; int_type underflow() override; pos_type seekoff(off_type off, ios_base::seekdir way, ios_base::openmode which = ios_base::in | ios_base::out) override; pos_type seekpos(pos_type sp, ios_base::openmode which = ios_base::in | ios_base::out) override; streambuf* setbuf(char* s, streamsize n) override; private: using strstate = T1; // exposition only static const strstate allocated; // exposition only static const strstate constant; // exposition only static const strstate dynamic; // exposition only static const strstate frozen; // exposition only strstate strmode; // exposition only streamsize alsize; // exposition only void* (*palloc)(size_t); // exposition only void (*pfree)(void*); // exposition only }; }

The class strstreambuf associates the input sequence, and possibly the output sequence, with an object of some character array type, whose elements store arbitrary values.

The array object has several attributes.

[Note 1:

For the sake of exposition, these are represented as elements of a bitmask type (indicated here as T1) called strstate.

The elements are:

(2.1)
allocated, set when a dynamic array object has been allocated, and hence will be freed by the destructor for the strstreambuf object;
(2.2)
constant, set when the array object has const elements, so the output sequence cannot be written;
(2.3)
dynamic, set when the array object is allocated (or reallocated) as necessary to hold a character sequence that can change in length;
(2.4)
frozen, set when the program has requested that the array object not be altered, reallocated, or freed.

— end note]

[Note 2:

For the sake of exposition, the maintained data is presented here as:

(3.1)
strstate strmode, the attributes of the array object associated with the strstreambuf object;
(3.2)
int alsize, the suggested minimum size for a dynamic array object;
(3.3)
void* (*palloc)(size_t), points to the function to call to allocate a dynamic array object;
(3.4)
void (*pfree)(void*), points to the function to call to free a dynamic array object.

— end note]

Each object of class strstreambuf has a seekable area, delimited by the pointers seeklow and seekhigh.

If gnext is a null pointer, the seekable area is undefined.

Otherwise, seeklow equals gbeg and seekhigh is either pend, if pend is not a null pointer, or gend.