Implements issue #9951: Adds a hex() method to bytes, bytearray, & memoryview.

Also updates a few internal implementations of the same thing to use the
new built-in code.

Contributed by Arnon Yaari.

Objects/bytearrayobject.c

@@ -5,6 +5,7 @@
 #include "structmember.h"
 #include "bytes_methods.h"
 #include "bytesobject.h"
+#include "pystrhex.h"
 
 /*[clinic input]
 class bytearray "PyByteArrayObject *" "&PyByteArray_Type"
@@ -2872,6 +2873,19 @@ bytearray_fromhex_impl(PyObject*cls, PyObject *string)
     return NULL;
 }
 
+PyDoc_STRVAR(hex__doc__,
+"B.hex() -> string\n\
+\n\
+Create a string of hexadecimal numbers from a bytearray object.\n\
+Example: bytearray([0xb9, 0x01, 0xef]).hex() -> 'b901ef'.");
+
+static PyObject *
+bytearray_hex(PyBytesObject *self)
+{
+    char* argbuf = PyByteArray_AS_STRING(self);
+    Py_ssize_t arglen = PyByteArray_GET_SIZE(self);
+    return _Py_strhex(argbuf, arglen);
+}
 
 static PyObject *
 _common_reduce(PyByteArrayObject *self, int proto)
@@ -3002,6 +3016,7 @@ bytearray_methods[] = {
     BYTEARRAY_EXTEND_METHODDEF
     {"find", (PyCFunction)bytearray_find, METH_VARARGS, find__doc__},
     BYTEARRAY_FROMHEX_METHODDEF
+    {"hex", (PyCFunction)bytearray_hex, METH_NOARGS, hex__doc__},
     {"index", (PyCFunction)bytearray_index, METH_VARARGS, index__doc__},
     BYTEARRAY_INSERT_METHODDEF
     {"isalnum", (PyCFunction)stringlib_isalnum, METH_NOARGS,

Objects/bytesobject.c

@@ -5,6 +5,7 @@
 #include "Python.h"
 
 #include "bytes_methods.h"
+#include "pystrhex.h"
 #include <stddef.h>
 
 /*[clinic input]
@@ -3036,6 +3037,20 @@ bytes_fromhex_impl(PyTypeObject *type, PyObject *string)
     return NULL;
 }
 
+PyDoc_STRVAR(hex__doc__,
+"B.hex() -> string\n\
+\n\
+Create a string of hexadecimal numbers from a bytes object.\n\
+Example: b'\\xb9\\x01\\xef'.hex() -> 'b901ef'.");
+
+static PyObject *
+bytes_hex(PyBytesObject *self)
+{
+    char* argbuf = PyBytes_AS_STRING(self);
+    Py_ssize_t arglen = PyBytes_GET_SIZE(self);
+    return _Py_strhex(argbuf, arglen);
+}
+
 static PyObject *
 bytes_getnewargs(PyBytesObject *v)
 {
@@ -3057,6 +3072,7 @@ bytes_methods[] = {
      expandtabs__doc__},
     {"find", (PyCFunction)bytes_find, METH_VARARGS, find__doc__},
     BYTES_FROMHEX_METHODDEF
+    {"hex", (PyCFunction)bytes_hex, METH_NOARGS, hex__doc__},
     {"index", (PyCFunction)bytes_index, METH_VARARGS, index__doc__},
     {"isalnum", (PyCFunction)stringlib_isalnum, METH_NOARGS,
      _Py_isalnum__doc__},

Objects/memoryobject.c

@@ -1,6 +1,7 @@
 /* Memoryview object implementation */
 
 #include "Python.h"
+#include "pystrhex.h"
 #include <stddef.h>
 
 
@@ -2157,6 +2158,14 @@ memory_tobytes(PyMemoryViewObject *self, PyObject *dummy)
     return bytes;
 }
 
+static PyObject *
+memory_hex(PyMemoryViewObject *self, PyObject *dummy)
+{
+    Py_buffer *src = VIEW_ADDR(self);
+    CHECK_RELEASED(self);
+    return _Py_strhex(src->buf, src->len);
+}
+
 static PyObject *
 memory_repr(PyMemoryViewObject *self)
 {
@@ -3061,6 +3070,10 @@ PyDoc_STRVAR(memory_tobytes_doc,
 "tobytes($self, /)\n--\n\
 \n\
 Return the data in the buffer as a byte string.");
+PyDoc_STRVAR(memory_hex_doc,
+"hex($self, /)\n--\n\
+\n\
+Return the data in the buffer as a string of hexadecimal numbers.");
 PyDoc_STRVAR(memory_tolist_doc,
 "tolist($self, /)\n--\n\
 \n\
@@ -3073,6 +3086,7 @@ Cast a memoryview to a new format or shape.");
 static PyMethodDef memory_methods[] = {
     {"release",     (PyCFunction)memory_release, METH_NOARGS, memory_release_doc},
     {"tobytes",     (PyCFunction)memory_tobytes, METH_NOARGS, memory_tobytes_doc},
+    {"hex",         (PyCFunction)memory_hex, METH_NOARGS, memory_hex_doc},
     {"tolist",      (PyCFunction)memory_tolist, METH_NOARGS, memory_tolist_doc},
     {"cast",        (PyCFunction)memory_cast, METH_VARARGS|METH_KEYWORDS, memory_cast_doc},
     {"__enter__",   memory_enter, METH_NOARGS, NULL},