* Don't overallocate by 400% when recode is needed: only overallocate on demand
using _PyBytesWriter.
* Use _PyLong_DigitValue to convert hexadecimal digit to int
* Create _PyBytes_DecodeEscapeRecode() subfunction
Issue #25401: Optimize bytes.fromhex() and bytearray.fromhex(): they are now
between 2x and 3.5x faster. Changes:
* Use a fast-path working on a char* string for ASCII string
* Use a slow-path for non-ASCII string
* Replace slow hex_digit_to_int() function with a O(1) lookup in
_PyLong_DigitValue precomputed table
* Use _PyBytesWriter API to handle the buffer
* Add unit tests to check the error position in error messages
Issue #25399: Don't create temporary bytes objects: modify _PyBytes_Format() to
create work directly on bytearray objects.
* Rename _PyBytes_Format() to _PyBytes_FormatEx() just in case if something
outside CPython uses it
* _PyBytes_FormatEx() now uses (char*, Py_ssize_t) for the input string, so
bytearray_format() doesn't need tot create a temporary input bytes object
* Add use_bytearray parameter to _PyBytes_FormatEx() which is passed to
_PyBytesWriter, to create a bytearray buffer instead of a bytes buffer
Most formatting operations are now between 2.5 and 5 times faster.
* Add much more unit tests on PyBytes_FromFormatV()
* Remove the first loop to compute the length of the output string
* Use _PyBytesWriter to handle the bytes buffer, use overallocation
* Cleanup the code to make simpler and easier to review
Don't require _PyBytesWriter pointer to be a "char *". Same change for
_PyBytesWriter_WriteBytes() parameter.
For example, binascii uses "unsigned char*".
Optimize bytes.__mod__(args) for integere formats: %d (%i, %u), %o, %x and %X.
_PyBytesWriter is now used to format directly the integer into the writer
buffer, instead of using a temporary bytes object.
Formatting is between 30% and 50% faster on a microbenchmark.
* Thanks to the _PyBytesWriter API, output smaller than 512 bytes are allocated
on the stack and so avoid calling _PyBytes_Resize(). Because of that, change
the default buffer size to fmtcnt instead of fmtcnt+100.
* Rely on _PyBytesWriter algorithm to overallocate the buffer instead of using
a custom code. For example, _PyBytesWriter uses a different overallocation
factor (25% or 50%) depending on the platform to get best performances.
* Disable overallocation for the last write.
* Replace C loops to fill characters with memset()
* Add also many comments to _PyBytes_Format()
* Remove unused FORMATBUFLEN constant
* Avoid the creation of a temporary bytes object when formatting a floating
point number (when no custom formatting option is used)
* Fix also reference leaks on error handling
* Use Py_MEMCPY() to copy bytes between two formatters (%)
Some time ago we changed the docs to consistently use the term 'bytes-like
object' in all the contexts where bytes, bytearray, memoryview, etc are used.
This patch (by Ezio Melotti) completes that work by changing the error
messages that previously reported that certain types did "not support the
buffer interface" to instead say that a bytes-like object is required. (The
glossary entry for bytes-like object references the discussion of the buffer
protocol in the docs.)
Victor Stinner