gh-113732: Fix support of QUOTE_NOTNULL and QUOTE_STRINGS in csv.reader

Doc/whatsnew/3.12.rst

@@ -690,7 +690,7 @@ csv
 
 * Add :const:`csv.QUOTE_NOTNULL` and :const:`csv.QUOTE_STRINGS` flags to
   provide finer grained control of ``None`` and empty strings by
-  :class:`csv.writer` objects.
+  :class:`~csv.reader` and :class:`~csv.writer` objects.
 
 dis
 ---

Lib/test/test_csv.py

@@ -392,17 +392,42 @@ def test_read_quoting(self):
         # will this fail where locale uses comma for decimals?
         self._read_test([',3,"5",7.3, 9'], [['', 3, '5', 7.3, 9]],
                         quoting=csv.QUOTE_NONNUMERIC)
+        self._read_test([',3,"5",7.3, 9'], [[None, '3', '5', '7.3', ' 9']],
+                        quoting=csv.QUOTE_NOTNULL)
+        self._read_test([',3,"5",7.3, 9'], [[None, 3, '5', 7.3, 9]],
+                        quoting=csv.QUOTE_STRINGS)
+
+        self._read_test([',,"",'], [['', '', '', '']])
+        self._read_test([',,"",'], [['', '', '', '']],
+                        quoting=csv.QUOTE_NONNUMERIC)
+        self._read_test([',,"",'], [[None, None, '', None]],
+                        quoting=csv.QUOTE_NOTNULL)
+        self._read_test([',,"",'], [[None, None, '', None]],
+                        quoting=csv.QUOTE_STRINGS)
+
         self._read_test(['"a\nb", 7'], [['a\nb', ' 7']])
         self.assertRaises(ValueError, self._read_test,
                           ['abc,3'], [[]],
                           quoting=csv.QUOTE_NONNUMERIC)
+        self.assertRaises(ValueError, self._read_test,
+                          ['abc,3'], [[]],
+                          quoting=csv.QUOTE_STRINGS)
         self._read_test(['1,@,3,@,5'], [['1', ',3,', '5']], quotechar='@')
         self._read_test(['1,\0,3,\0,5'], [['1', ',3,', '5']], quotechar='\0')
 
     def test_read_skipinitialspace(self):
         self._read_test(['no space, space,  spaces,\ttab'],
                         [['no space', 'space', 'spaces', '\ttab']],
                         skipinitialspace=True)
+        self._read_test([' , , '],
+                        [['', '', '']],
+                        skipinitialspace=True)
+        self._read_test([' , , '],
+                        [[None, None, None]],
+                        skipinitialspace=True, quoting=csv.QUOTE_NOTNULL)
+        self._read_test([' , , '],
+                        [[None, None, None]],
+                        skipinitialspace=True, quoting=csv.QUOTE_STRINGS)
 
     def test_read_bigfield(self):
         # This exercises the buffer realloc functionality and field size

Misc/NEWS.d/next/Library/2024-01-05-16-27-34.gh-issue-113732.fgDRXA.rst

@@ -0,0 +1,2 @@
+Fix support of :data:`~csv.QUOTE_NOTNULL` and :data:`~csv.QUOTE_STRINGS` in
+:func:`csv.reader`.

Modules/_csv.c

@@ -131,7 +131,7 @@ typedef struct {
     Py_UCS4 *field;             /* temporary buffer */
     Py_ssize_t field_size;      /* size of allocated buffer */
     Py_ssize_t field_len;       /* length of current field */
-    int numeric_field;          /* treat field as numeric */
+    bool unquoted_field;        /* true if no quotes around the current field */
     unsigned long line_num;     /* Source-file line number */
 } ReaderObj;
 
@@ -644,22 +644,33 @@ _call_dialect(_csvstate *module_state, PyObject *dialect_inst, PyObject *kwargs)
 static int
 parse_save_field(ReaderObj *self)
 {
+    int quoting = self->dialect->quoting;
     PyObject *field;
 
-    field = PyUnicode_FromKindAndData(PyUnicode_4BYTE_KIND,
-                                      (void *) self->field, self->field_len);
-    if (field == NULL)
-        return -1;
-    self->field_len = 0;
-    if (self->numeric_field) {
-        PyObject *tmp;
-
-        self->numeric_field = 0;
-        tmp = PyNumber_Float(field);
-        Py_DECREF(field);
-        if (tmp == NULL)
+    if (self->unquoted_field &&
+        self->field_len == 0 &&
+        (quoting == QUOTE_NOTNULL || quoting == QUOTE_STRINGS))
+    {
+        field = Py_NewRef(Py_None);
+    }
+    else {
+        field = PyUnicode_FromKindAndData(PyUnicode_4BYTE_KIND,
+                                        (void *) self->field, self->field_len);
+        if (field == NULL) {
             return -1;
-        field = tmp;
+        }
+        if (self->unquoted_field &&
+            self->field_len != 0 &&
+            (quoting == QUOTE_NONNUMERIC || quoting == QUOTE_STRINGS))
+        {
+            PyObject *tmp = PyNumber_Float(field);
+            Py_DECREF(field);
+            if (tmp == NULL) {
+                return -1;
+            }
+            field = tmp;
+        }
+        self->field_len = 0;
     }
     if (PyList_Append(self->fields, field) < 0) {
         Py_DECREF(field);
@@ -721,6 +732,7 @@ parse_process_char(ReaderObj *self, _csvstate *module_state, Py_UCS4 c)
         /* fallthru */
     case START_FIELD:
         /* expecting field */
+        self->unquoted_field = true;
         if (c == '\n' || c == '\r' || c == EOL) {
             /* save empty field - return [fields] */
             if (parse_save_field(self) < 0)
@@ -730,10 +742,12 @@ parse_process_char(ReaderObj *self, _csvstate *module_state, Py_UCS4 c)
         else if (c == dialect->quotechar &&
                  dialect->quoting != QUOTE_NONE) {
             /* start quoted field */
+            self->unquoted_field = false;
             self->state = IN_QUOTED_FIELD;
         }
         else if (c == dialect->escapechar) {
             /* possible escaped character */
+            self->unquoted_field = false;
             self->state = ESCAPED_CHAR;
         }
         else if (c == ' ' && dialect->skipinitialspace)
@@ -746,8 +760,6 @@ parse_process_char(ReaderObj *self, _csvstate *module_state, Py_UCS4 c)
         }
         else {
             /* begin new unquoted field */
-            if (dialect->quoting == QUOTE_NONNUMERIC)
-                self->numeric_field = 1;
             if (parse_add_char(self, module_state, c) < 0)
                 return -1;
             self->state = IN_FIELD;
@@ -892,7 +904,7 @@ parse_reset(ReaderObj *self)
         return -1;
     self->field_len = 0;
     self->state = START_RECORD;
-    self->numeric_field = 0;
+    self->unquoted_field = false;
     return 0;
 }