ENH: datetime-autounit: Make 'now' and 'today' only parse with appropriate units

In particular, 'now' needs time-like units, and 'today' needs
date-like units.

3 files changed, 34 insertions, 7 deletions

diff --git a/numpy/core/src/multiarray/_datetime.h b/numpy/core/src/multiarray/_datetime.h
index b07fe2f51..643c9b106 100644
--- a/numpy/core/src/multiarray/_datetime.h
+++ b/numpy/core/src/multiarray/_datetime.h
@@ -192,6 +192,8 @@ get_datetime_iso_8601_strlen(int local, NPY_DATETIMEUNIT base);
  *   day according to local time) and "Now" (current time in UTC).
  *
  * 'str' must be a NULL-terminated string, and 'len' must be its length.
+ * 'unit' should contain -1 if the unit is unknown, or the unit
+ *      which will be used if it is.
  *
  * 'out' gets filled with the parsed date-time.
  * 'out_local' gets set to 1 if the parsed time was in local time,
@@ -210,12 +212,12 @@ get_datetime_iso_8601_strlen(int local, NPY_DATETIMEUNIT base);
  */
 NPY_NO_EXPORT int
 parse_iso_8601_date(char *str, int len,
+                    NPY_DATETIMEUNIT unit,
                     npy_datetimestruct *out,
                     npy_bool *out_local,
                     NPY_DATETIMEUNIT *out_bestunit,
                     npy_bool *out_special);
 
-
 /*
  * Converts an npy_datetimestruct to an (almost) ISO 8601
  * NULL-terminated string.
diff --git a/numpy/core/src/multiarray/datetime.c b/numpy/core/src/multiarray/datetime.c
index 8e57961eb..642341570 100644
--- a/numpy/core/src/multiarray/datetime.c
+++ b/numpy/core/src/multiarray/datetime.c
@@ -2278,6 +2278,8 @@ add_minutes_to_datetimestruct(npy_datetimestruct *dts, int minutes)
  *   day according to local time) and "Now" (current time in UTC).
  *
  * 'str' must be a NULL-terminated string, and 'len' must be its length.
+ * 'unit' should contain -1 if the unit is unknown, or the unit
+ *      which will be used if it is.
  *
  * 'out' gets filled with the parsed date-time.
  * 'out_local' gets set to 1 if the parsed time was in local time,
@@ -2296,6 +2298,7 @@ add_minutes_to_datetimestruct(npy_datetimestruct *dts, int minutes)
  */
 NPY_NO_EXPORT int
 parse_iso_8601_date(char *str, int len,
+                    NPY_DATETIMEUNIT unit,
                     npy_datetimestruct *out,
                     npy_bool *out_local,
                     NPY_DATETIMEUNIT *out_bestunit,
@@ -2350,6 +2353,14 @@ parse_iso_8601_date(char *str, int len,
         time_t rawtime = 0;
         struct tm tm_;
 
+        /* 'today' only works for units of days or larger */
+        if (unit != -1 && unit > NPY_FR_D) {
+            PyErr_SetString(PyExc_ValueError,
+                        "Special value 'today' can only be converted "
+                        "to a NumPy datetime with 'D' or larger units");
+            return -1;
+        }
+
         time(&rawtime);
 #if defined(_WIN32)
         if (localtime_s(&tm_, &rawtime) != 0) {
@@ -2392,6 +2403,15 @@ parse_iso_8601_date(char *str, int len,
                     tolower(str[2]) == 'w') {
         time_t rawtime = 0;
         PyArray_DatetimeMetaData meta;
+
+        /* 'now' only works for units of hours or smaller */
+        if (unit != -1 && unit < NPY_FR_h) {
+            PyErr_SetString(PyExc_ValueError,
+                        "Special value 'now' can only be converted "
+                        "to a NumPy datetime with 'h' or smaller units");
+            return -1;
+        }
+
         time(&rawtime);
 
         /* Set up a dummy metadata for the conversion */
@@ -3658,7 +3678,8 @@ convert_pyobject_to_datetime(PyArray_DatetimeMetaData *meta, PyObject *obj,
         }
 
         /* Parse the ISO date */
-        if (parse_iso_8601_date(str, len, &dts, NULL, &bestunit, NULL) < 0) {
+        if (parse_iso_8601_date(str, len, meta->base, &dts,
+                                NULL, &bestunit, NULL) < 0) {
             Py_DECREF(bytes);
             return -1;
         }
diff --git a/numpy/core/tests/test_datetime.py b/numpy/core/tests/test_datetime.py
index 9fb249340..316d03ecc 100644
--- a/numpy/core/tests/test_datetime.py
+++ b/numpy/core/tests/test_datetime.py
@@ -239,10 +239,18 @@ class TestDateTime(TestCase):
         assert_equal(np.datetime64('today').dtype,
                      np.dtype('M8[D]'))
 
+        assert_raises(ValueError, np.datetime64, 'today', 'h')
+        assert_raises(ValueError, np.datetime64, 'today', 's')
+        assert_raises(ValueError, np.datetime64, 'today', 'as')
+
         # 'now' special value
         assert_equal(np.datetime64('now').dtype,
                      np.dtype('M8[s]'))
 
+        assert_raises(ValueError, np.datetime64, 'now', 'Y')
+        assert_raises(ValueError, np.datetime64, 'now', 'M')
+        assert_raises(ValueError, np.datetime64, 'now', 'D')
+
     def test_datetime_nat_casting(self):
         a = np.array('NaT', dtype='M8[D]')
         b = np.datetime64('NaT', '[D]')
@@ -352,7 +360,7 @@ class TestDateTime(TestCase):
         a = np.array(['2000-01-01', datetime.date(2000, 1, 1)], dtype='M8[s]')
         assert_equal(a[0], a[1])
         # Will fail if the date changes during the exact right moment
-        a = np.array(['today', datetime.date.today()], dtype='M8[s]')
+        a = np.array(['today', datetime.date.today()], dtype='M8[D]')
         assert_equal(a[0], a[1])
         # datetime.datetime.now() returns local time, not UTC
         #a = np.array(['now', datetime.datetime.now()], dtype='M8[s]')
@@ -470,14 +478,10 @@ class TestDateTime(TestCase):
                              np.array('1932-02-17T00:00:00Z', dtype=dt2))
                 assert_equal(np.array('10000-04-27', dtype=dt1),
                              np.array('10000-04-27T00:00:00Z', dtype=dt2))
-                assert_equal(np.array('today', dtype=dt1),
-                             np.array('today', dtype=dt2))
                 assert_equal(np.datetime64('1932-02-17', unit1),
                              np.datetime64('1932-02-17T00:00:00Z', unit2))
                 assert_equal(np.datetime64('10000-04-27', unit1),
                              np.datetime64('10000-04-27T00:00:00Z', unit2))
-                assert_equal(np.datetime64('today', unit1),
-                             np.datetime64('today', unit2))
 
         # Shouldn't be able to compare datetime and timedelta
         # TODO: Changing to 'same_kind' or 'safe' casting in the ufuncs by