Fix parsing not raising an error for week 53 for ordinary years

Author: sdispater

CHANGELOG.md

@@ -7,7 +7,8 @@
 - Fixed the `weeks` property for negative `Period` instances.
 - Fixed `start_of()` methods not setting microseconds to 0.
 - Fixed errors on some systems when retrieving timezone from clock files.
-- Fix parsing of partial time.
+- Fixed parsing of partial time.
+- Fixed parsing not raising an error for week 53 for ordinary years.
 
 
 ## [2.0.1] - 2018-05-10

pendulum/_extensions/_helpers.c

@@ -93,17 +93,25 @@ const int DAY_OF_WEEK_TABLE[12] = {
 
 /* ------------------------------------------------------------------------- */
 
+int _p(int y) {
+    return y + y/4 - y/100 + y /400;
+}
+
 int _is_leap(int year) {
     return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
 }
 
+int _is_long_year(int year) {
+    return (p(year) % 7 == 4) || (p(year - 1) % 7 == 3);
+}
+
 int _week_day(int year, int month, int day) {
     int y;
     int w;
 
     y = year - (month < 3);
 
-    w = (y + y/4 - y/100 + y /400 + DAY_OF_WEEK_TABLE[month - 1] + day) % 7;
+    w = (_p(y) + DAY_OF_WEEK_TABLE[month - 1] + day) % 7;
 
     if (!w) {
         w = 7;
@@ -329,6 +337,22 @@ PyObject* is_leap(PyObject *self, PyObject *args) {
     return leap;
 }
 
+PyObject* is_long_year(PyObject *self, PyObject *args) {
+    PyObject *is_long;
+    int year;
+
+    if (!PyArg_ParseTuple(args, "i", &year)) {
+        PyErr_SetString(
+            PyExc_ValueError, "Invalid parameters"
+        );
+        return NULL;
+    }
+
+    is_long = PyBool_FromLong(_is_long_year(year));
+
+    return is_long;
+}
+
 PyObject* week_day(PyObject *self, PyObject *args) {
     PyObject *wd;
     int year;
@@ -820,6 +844,12 @@ static PyMethodDef helpers_methods[] = {
         METH_VARARGS,
         PyDoc_STR("Checks if a year is a leap year.")
     },
+    {
+        "is_long_year",
+        (PyCFunction) is_long_year,
+        METH_VARARGS,
+        PyDoc_STR("Checks if a year is a long year.")
+    },
     {
         "week_day",
         (PyCFunction) week_day,

pendulum/_extensions/helpers.py

@@ -51,6 +51,13 @@ def is_leap(year):
     return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)
 
 
+def is_long_year(year):
+    def p(y):
+        return y + y//4 - y//100 + y//400
+
+    return p(year) % 7 == 4 or p(year - 1) % 7 == 3
+
+
 def week_day(year, month, day):
     if month < 3:
         year -= 1

pendulum/helpers.py

@@ -11,13 +11,13 @@
 try:
     from ._extensions._helpers import (
         local_time, precise_diff,
-        is_leap, week_day, days_in_year,
+        is_leap, is_long_year, week_day, days_in_year,
         timestamp
     )
 except ImportError:
     from ._extensions.helpers import (
         local_time, precise_diff,
-        is_leap, week_day, days_in_year,
+        is_leap, is_long_year, week_day, days_in_year,
         timestamp
     )
 

pendulum/parsing/_iso8601.c

@@ -132,6 +132,11 @@ const char PARSER_ERRORS[17][80] = {
 
 /* ------------------------------------------------------------------------- */
 
+
+int p(int y) {
+    return y + y/4 - y/100 + y/400;
+}
+
 int is_leap(int year) {
     return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
 }
@@ -142,7 +147,7 @@ int week_day(int year, int month, int day) {
 
     y = year - (month < 3);
 
-    w = (y + y/4 - y/100 + y /400 + DAY_OF_WEEK_TABLE[month - 1] + day) % 7;
+    w = (p(y) + DAY_OF_WEEK_TABLE[month - 1] + day) % 7;
 
     if (!w) {
         w = 7;
@@ -159,6 +164,10 @@ int days_in_year(int year) {
     return DAYS_PER_N_YEAR;
 }
 
+int is_long_year(int year) {
+    return (p(year) % 7 == 4) || (p(year - 1) % 7 == 3);
+}
+
 
 /* ------------------------ Custom Types ------------------------------- */
 
@@ -576,7 +585,7 @@ Parsed* _parse_iso8601_datetime(char *str, Parsed *parsed) {
         }
 
         // Checks
-        if (week > 53) {
+        if (week > 53 || week > 52 && !is_long_year(parsed->year)) {
             parsed->error = PARSER_INVALID_WEEK_NUMBER;
 
             return NULL;

pendulum/parsing/iso8601.py

@@ -7,7 +7,7 @@
     HOURS_PER_DAY, MINUTES_PER_HOUR, SECONDS_PER_MINUTE,
     MONTHS_OFFSETS
 )
-from ..helpers import week_day, days_in_year, is_leap
+from ..helpers import week_day, days_in_year, is_leap, is_long_year
 from ..tz.timezone import FixedTimezone
 from ..duration import Duration
 from .exceptions import ParserError
@@ -409,7 +409,7 @@ def _get_iso_8601_week(year, week, weekday):
     year = int(year)
     week = int(week)
 
-    if week > 53:
+    if week > 53 or week > 52 and not is_long_year(year):
         raise ParserError('Invalid week for week date')
 
     if weekday > 7:

tests/parsing/test_parsing.py

@@ -315,6 +315,20 @@ def test_iso8601_week_number():
     assert 0 == parsed.microsecond
     assert parsed.tzinfo is None
 
+    # Long Year
+    text = '2015W53'
+
+    parsed = parse(text)
+
+    assert 2015 == parsed.year
+    assert 12 == parsed.month
+    assert 28 == parsed.day
+    assert 0 == parsed.hour
+    assert 0 == parsed.minute
+    assert 0 == parsed.second
+    assert 0 == parsed.microsecond
+    assert parsed.tzinfo is None
+
     text = '2012-W05-5'
 
     parsed = parse(text)
@@ -632,6 +646,12 @@ def test_invalid():
     with pytest.raises(ParserError):
         parse(text)
 
+    # W53 in normal year (not long)
+    text = '2017W53'
+
+    with pytest.raises(ParserError):
+        parse(text)
+
 
 def test_exif_edge_case():
     text = '2016:12:26 15:45:28'