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, 74 insertions, 0 deletions

diff --git a/Objects/clinic/memoryobject.c.h b/Objects/clinic/memoryobject.c.h
new file mode 100644
index 0000000000..64fce10acb
--- /dev/null
+++ b/Objects/clinic/memoryobject.c.h
@@ -0,0 +1,74 @@
+/*[clinic input]
+preserve
+[clinic start generated code]*/
+
+PyDoc_STRVAR(memoryview_hex__doc__,
+"hex($self, /, sep=None, bytes_per_sep=1)\n"
+"--\n"
+"\n"
+"Return the data in the buffer as a str of hexadecimal numbers.\n"
+"\n"
+"  sep\n"
+"    An optional single character or byte to separate hex bytes.\n"
+"  bytes_per_sep\n"
+"    How many bytes between separators.  Positive values count from the\n"
+"    right, negative values count from the left.\n"
+"\n"
+"Example:\n"
+">>> value = memoryview(b\'\\xb9\\x01\\xef\')\n"
+">>> value.hex()\n"
+"\'b901ef\'\n"
+">>> value.hex(\':\')\n"
+"\'b9:01:ef\'\n"
+">>> value.hex(\':\', 2)\n"
+"\'b9:01ef\'\n"
+">>> value.hex(\':\', -2)\n"
+"\'b901:ef\'");
+
+#define MEMORYVIEW_HEX_METHODDEF    \
+    {"hex", (PyCFunction)(void(*)(void))memoryview_hex, METH_FASTCALL|METH_KEYWORDS, memoryview_hex__doc__},
+
+static PyObject *
+memoryview_hex_impl(PyMemoryViewObject *self, PyObject *sep,
+                    int bytes_per_sep);
+
+static PyObject *
+memoryview_hex(PyMemoryViewObject *self, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+{
+    PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"sep", "bytes_per_sep", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "hex", 0};
+    PyObject *argsbuf[2];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
+    PyObject *sep = NULL;
+    int bytes_per_sep = 1;
+
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 2, 0, argsbuf);
+    if (!args) {
+        goto exit;
+    }
+    if (!noptargs) {
+        goto skip_optional_pos;
+    }
+    if (args[0]) {
+        sep = args[0];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    if (PyFloat_Check(args[1])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    bytes_per_sep = _PyLong_AsInt(args[1]);
+    if (bytes_per_sep == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+skip_optional_pos:
+    return_value = memoryview_hex_impl(self, sep, bytes_per_sep);
+
+exit:
+    return return_value;
+}
+/*[clinic end generated code: output=5e44e2bcf01057b5 input=a9049054013a1b77]*/