[streambuf.virtuals] - C++17 → C++20

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tmp/tmps7icqqxf/{from.md → to.md} +18 -18

tmp/tmps7icqqxf/{from.md → to.md} RENAMED Viewed

@@ -1,6 +1,6 @@
-#### `basic_streambuf` virtual functions <a id="streambuf.virtuals">[[streambuf.virtuals]]</a>
 ##### Locales <a id="streambuf.virt.locales">[[streambuf.virt.locales]]</a>
 ``` cpp
 void imbue(const locale&);
@@ -61,11 +61,11 @@ int sync();
 is, if `pbase()` is non-null the characters between `pbase()` and
 `pptr()` are written to the controlled sequence. The pointers may then
 be reset as appropriate.
 *Returns:* `-1` on failure. What constitutes failure is determined by
-each derived class ([[filebuf.virtuals]]).
 *Default behavior:* Returns zero.
 ##### Get area <a id="streambuf.virt.get">[[streambuf.virt.get]]</a>
@@ -102,11 +102,11 @@ to `sbumpc()` would return `traits::eof()`.
 ``` cpp
 int_type underflow();
 ```
 *Remarks:* The public members of `basic_streambuf` call this virtual
-function only if `gptr()` is null or `gptr() >= egptr()`
 *Returns:* `traits::to_int_type(c)`, where `c` is the first *character*
 of the *pending sequence*, without moving the input sequence position
 past it. If the pending sequence is null then the function returns
 `traits::eof()` to indicate failure.
@@ -144,13 +144,13 @@ that either
 ``` cpp
 int_type uflow();
 ```
-*Requires:* The constraints are the same as for `underflow()`, except
-that the result character shall be transferred from the pending sequence
-to the backup sequence, and the pending sequence shall not be empty
 before the transfer.
 *Default behavior:* Calls `underflow()`. If `underflow()` returns
 `traits::eof()`, returns `traits::eof()`. Otherwise, returns the value
 of `traits::to_int_type(*gptr())` and increment the value of the next
@@ -177,11 +177,11 @@ modifications that
   is determined.
 - If `traits::eq_int_type(c, traits::eof())` returns `false`, then `c`
   is prepended. Whether the input sequence is backed up or modified in
   any other way is unspecified.
-*Postconditions:* On return, the constraints of `gptr()`, `eback()`, and
 `pptr()` are the same as for `underflow()`.
 *Returns:* `traits::eof()` to indicate failure. Failure may occur
 because the input sequence could not be backed up, or if for some other
 reason the pointers could not be set consistent with the constraints.
@@ -213,32 +213,32 @@ int_type overflow(int_type c = traits::eof());
 *Effects:* Consumes some initial subsequence of the characters of the
 *pending sequence*. The pending sequence is defined as the concatenation
 of
-- the empty sequence if `pbase()` is not null, otherwise the
   `pptr() - pbase()` characters beginning at `pbase()`, followed by
 - the empty sequence if `traits::eq_int_type(c, traits::eof())` returns
   `true`, otherwise the sequence consisting of `c`.
 *Remarks:* The member functions `sputc()` and `sputn()` call this
 function in case that no room can be found in the put buffer enough to
 accommodate the argument character sequence.
-*Requires:* Every overriding definition of this virtual function shall
-obey the following constraints:
-1.  The effect of consuming a character on the associated output
-    sequence is specified[^16]
-2.  Let `r` be the number of characters in the pending sequence not
- consumed. If `r` is nonzero then `pbase()` and `pptr()` shall be set
-    so that: `pptr() - pbase() == r` and the `r` characters starting at
   `pbase()` are the associated output stream. In case `r` is zero (all
   characters of the pending sequence have been consumed) then either
- `pbase()` is set to `nullptr`, or `pbase()` and `pptr()` are both
-    set to the same non-null value.
-3.  The function may fail if either appending some character to the
   associated output stream fails or if it is unable to establish
   `pbase()` and `pptr()` according to the above rules.
 *Returns:* `traits::eof()` or throws an exception if the function fails.

+#### Virtual functions <a id="streambuf.virtuals">[[streambuf.virtuals]]</a>
 ##### Locales <a id="streambuf.virt.locales">[[streambuf.virt.locales]]</a>
 ``` cpp
 void imbue(const locale&);
 is, if `pbase()` is non-null the characters between `pbase()` and
 `pptr()` are written to the controlled sequence. The pointers may then
 be reset as appropriate.
 *Returns:* `-1` on failure. What constitutes failure is determined by
+each derived class [[filebuf.virtuals]].
 *Default behavior:* Returns zero.
 ##### Get area <a id="streambuf.virt.get">[[streambuf.virt.get]]</a>
 ``` cpp
 int_type underflow();
 ```
 *Remarks:* The public members of `basic_streambuf` call this virtual
+function only if `gptr()` is null or `gptr() >= egptr()`.
 *Returns:* `traits::to_int_type(c)`, where `c` is the first *character*
 of the *pending sequence*, without moving the input sequence position
 past it. If the pending sequence is null then the function returns
 `traits::eof()` to indicate failure.
 ``` cpp
 int_type uflow();
 ```
+*Preconditions:* The constraints are the same as for `underflow()`,
+except that the result character is transferred from the pending
+sequence to the backup sequence, and the pending sequence is not empty
 before the transfer.
 *Default behavior:* Calls `underflow()`. If `underflow()` returns
 `traits::eof()`, returns `traits::eof()`. Otherwise, returns the value
 of `traits::to_int_type(*gptr())` and increment the value of the next
   is determined.
 - If `traits::eq_int_type(c, traits::eof())` returns `false`, then `c`
   is prepended. Whether the input sequence is backed up or modified in
   any other way is unspecified.
+*Ensures:* On return, the constraints of `gptr()`, `eback()`, and
 `pptr()` are the same as for `underflow()`.
 *Returns:* `traits::eof()` to indicate failure. Failure may occur
 because the input sequence could not be backed up, or if for some other
 reason the pointers could not be set consistent with the constraints.
 *Effects:* Consumes some initial subsequence of the characters of the
 *pending sequence*. The pending sequence is defined as the concatenation
 of
+- the empty sequence if `pbase()` is null, otherwise the
   `pptr() - pbase()` characters beginning at `pbase()`, followed by
 - the empty sequence if `traits::eq_int_type(c, traits::eof())` returns
   `true`, otherwise the sequence consisting of `c`.
 *Remarks:* The member functions `sputc()` and `sputn()` call this
 function in case that no room can be found in the put buffer enough to
 accommodate the argument character sequence.
+*Preconditions:* Every overriding definition of this virtual function
+obeys the following constraints:
+- The effect of consuming a character on the associated output sequence
+ is specified.[^16]
+- Let `r` be the number of characters in the pending sequence not
+ consumed. If `r` is nonzero then `pbase()` and `pptr()` are set so
+ that: `pptr() - pbase() == r` and the `r` characters starting at
   `pbase()` are the associated output stream. In case `r` is zero (all
   characters of the pending sequence have been consumed) then either
+ `pbase()` is set to `nullptr`, or `pbase()` and `pptr()` are both set
+ to the same non-null value.
+- The function may fail if either appending some character to the
   associated output stream fails or if it is unable to establish
   `pbase()` and `pptr()` according to the above rules.
 *Returns:* `traits::eof()` or throws an exception if the function fails.

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