From 9b7a5af460d5ca3c08ecc2f5668342ebd5134c5f Mon Sep 17 00:00:00 2001
From: Dong-hee Na <donghee.na@python.org>
Date: Sun, 23 Jul 2023 21:24:10 +0900
Subject: [PATCH] gh-107122: Add clear method to dbm.ndbm module

---
 Doc/library/dbm.rst                           |  5 ++++
 Lib/test/test_dbm.py                          | 15 ++++++++++
 ...-07-23-21-16-54.gh-issue-107122.VNuNcq.rst |  1 +
 Modules/_dbmmodule.c                          | 29 +++++++++++++++++++
 Modules/clinic/_dbmmodule.c.h                 | 24 ++++++++++++++-
 5 files changed, 73 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2023-07-23-21-16-54.gh-issue-107122.VNuNcq.rst

diff --git a/Doc/library/dbm.rst b/Doc/library/dbm.rst
index 2be499337a2a156..d679c050e4c400d 100644
--- a/Doc/library/dbm.rst
+++ b/Doc/library/dbm.rst
@@ -313,6 +313,11 @@ to locate the appropriate header file to simplify building this module.
 
       Close the ``ndbm`` database.
 
+   .. method:: ndbm.clear()
+      Remove all items from the ``ndbm`` database.
+
+      .. versionadded:: 3.13
+
 
 :mod:`dbm.dumb` --- Portable DBM implementation
 -----------------------------------------------
diff --git a/Lib/test/test_dbm.py b/Lib/test/test_dbm.py
index f21eebc6530c768..e3924d8ec8b5c1d 100644
--- a/Lib/test/test_dbm.py
+++ b/Lib/test/test_dbm.py
@@ -155,6 +155,21 @@ def test_keys(self):
             self.assertNotIn(b'xxx', d)
             self.assertRaises(KeyError, lambda: d[b'xxx'])
 
+    def test_clear(self):
+        with dbm.open(_fname, 'c') as d:
+            self.assertEqual(d.keys(), [])
+            a = [(b'a', b'b'), (b'12345678910', b'019237410982340912840198242')]
+            for k, v in a:
+                d[k] = v
+            for k, _ in a:
+                self.assertIn(k, d)
+            self.assertEqual(len(d), len(a))
+
+            d.clear()
+            self.assertEqual(len(d), 0)
+            for k, _ in a:
+                self.assertNotIn(k, d)
+
     def setUp(self):
         self.addCleanup(setattr, dbm, '_defaultmod', dbm._defaultmod)
         dbm._defaultmod = self.module
diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-07-23-21-16-54.gh-issue-107122.VNuNcq.rst b/Misc/NEWS.d/next/Core and Builtins/2023-07-23-21-16-54.gh-issue-107122.VNuNcq.rst
new file mode 100644
index 000000000000000..8beaf51316762c0
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2023-07-23-21-16-54.gh-issue-107122.VNuNcq.rst	
@@ -0,0 +1 @@
+Add :meth:`clear` to :mod:`dbm.ndbm`. Patch By Dong-hee Na.
diff --git a/Modules/_dbmmodule.c b/Modules/_dbmmodule.c
index 5be444d53e8da39..3cb2e55eb98c3fc 100644
--- a/Modules/_dbmmodule.c
+++ b/Modules/_dbmmodule.c
@@ -414,6 +414,34 @@ _dbm_dbm_setdefault_impl(dbmobject *self, PyTypeObject *cls, const char *key,
     return default_value;
 }
 
+/*[clinic input]
+_dbm.dbm.clear
+    cls: defining_class
+    /
+Remove all items from the database.
+
+[clinic start generated code]*/
+
+static PyObject *
+_dbm_dbm_clear_impl(dbmobject *self, PyTypeObject *cls)
+/*[clinic end generated code: output=8d126b9e1d01a434 input=43aa6ca1acb7f5f5]*/
+{
+    _dbm_state *state = PyType_GetModuleState(cls);
+    assert(state != NULL);
+    check_dbmobject_open(self, state->dbm_error);
+    for (datum key = dbm_firstkey(self->di_dbm); key.dptr; key = dbm_nextkey(self->di_dbm)) {
+        if (dbm_delete(self->di_dbm, key) < 0) {
+            dbm_clearerr(self->di_dbm);
+            PyErr_SetString(state->dbm_error, "cannot delete item from database");
+            return NULL;
+        }
+    }
+    if (self->di_size > 0) {
+        self->di_size = 0;
+    }
+    Py_RETURN_NONE;
+}
+
 static PyObject *
 dbm__enter__(PyObject *self, PyObject *args)
 {
@@ -431,6 +459,7 @@ static PyMethodDef dbm_methods[] = {
     _DBM_DBM_KEYS_METHODDEF
     _DBM_DBM_GET_METHODDEF
     _DBM_DBM_SETDEFAULT_METHODDEF
+    _DBM_DBM_CLEAR_METHODDEF
     {"__enter__", dbm__enter__, METH_NOARGS, NULL},
     {"__exit__",  dbm__exit__, METH_VARARGS, NULL},
     {NULL,  NULL}           /* sentinel */
diff --git a/Modules/clinic/_dbmmodule.c.h b/Modules/clinic/_dbmmodule.c.h
index 172dc4b9d5793e5..98aac07423c8ab1 100644
--- a/Modules/clinic/_dbmmodule.c.h
+++ b/Modules/clinic/_dbmmodule.c.h
@@ -138,6 +138,28 @@ _dbm_dbm_setdefault(dbmobject *self, PyTypeObject *cls, PyObject *const *args, P
     return return_value;
 }
 
+PyDoc_STRVAR(_dbm_dbm_clear__doc__,
+"clear($self, /)\n"
+"--\n"
+"\n"
+"Remove all items from the database.");
+
+#define _DBM_DBM_CLEAR_METHODDEF    \
+    {"clear", _PyCFunction_CAST(_dbm_dbm_clear), METH_METHOD|METH_FASTCALL|METH_KEYWORDS, _dbm_dbm_clear__doc__},
+
+static PyObject *
+_dbm_dbm_clear_impl(dbmobject *self, PyTypeObject *cls);
+
+static PyObject *
+_dbm_dbm_clear(dbmobject *self, PyTypeObject *cls, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+{
+    if (nargs) {
+        PyErr_SetString(PyExc_TypeError, "clear() takes no arguments");
+        return NULL;
+    }
+    return _dbm_dbm_clear_impl(self, cls);
+}
+
 PyDoc_STRVAR(dbmopen__doc__,
 "open($module, filename, flags=\'r\', mode=0o666, /)\n"
 "--\n"
@@ -200,4 +222,4 @@ dbmopen(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=28dcf736654137c2 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=b3053c67ecfcc29c input=a9049054013a1b77]*/