bpo-22385: Support output separators in hex methods. (#13578)

* bpo-22385: Support output separators in hex methods.

Also in binascii.hexlify aka b2a_hex.

The underlying implementation behind all hex generation in CPython uses the
same pystrhex.c implementation.  This adds support to bytes, bytearray,
and memoryview objects.

The binascii module functions exist rather than being slated for deprecation
because they return bytes rather than requiring an intermediate step through a
str object.

This change was inspired by MicroPython which supports sep in its binascii
implementation (and does not yet support the .hex methods).

https://bugs.python.org/issue22385

1 files changed, 26 insertions, 8 deletions

diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 6f34037..bf7c7da 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -2416,18 +2416,36 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)
     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'.");
+/*[clinic input]
+bytes.hex
+
+    sep: object = NULL
+        An optional single character or byte to separate hex bytes.
+    bytes_per_sep: int = 1
+        How many bytes between separators.  Positive values count from the
+        right, negative values count from the left.
+
+Create a str of hexadecimal numbers from a bytes object.
+
+Example:
+>>> value = b'\xb9\x01\xef'
+>>> value.hex()
+'b901ef'
+>>> value.hex(':')
+'b9:01:ef'
+>>> value.hex(':', 2)
+'b9:01ef'
+>>> value.hex(':', -2)
+'b901:ef'
+[clinic start generated code]*/
 
 static PyObject *
-bytes_hex(PyBytesObject *self, PyObject *Py_UNUSED(ignored))
+bytes_hex_impl(PyBytesObject *self, PyObject *sep, int bytes_per_sep)
+/*[clinic end generated code: output=1f134da504064139 input=f1238d3455990218]*/
 {
     char* argbuf = PyBytes_AS_STRING(self);
     Py_ssize_t arglen = PyBytes_GET_SIZE(self);
-    return _Py_strhex(argbuf, arglen);
+    return _Py_strhex_with_sep(argbuf, arglen, sep, bytes_per_sep);
 }
 
 static PyObject *
@@ -2452,7 +2470,7 @@ bytes_methods[] = {
     {"find", (PyCFunction)bytes_find, METH_VARARGS,
      _Py_find__doc__},
     BYTES_FROMHEX_METHODDEF
-    {"hex", (PyCFunction)bytes_hex, METH_NOARGS, hex__doc__},
+    BYTES_HEX_METHODDEF
     {"index", (PyCFunction)bytes_index, METH_VARARGS, _Py_index__doc__},
     {"isalnum", stringlib_isalnum, METH_NOARGS,
      _Py_isalnum__doc__},