coerce Py_UNICODE to and from single character unicode strings by default

Cython/Compiler/PyrexTypes.py

@@ -881,17 +881,60 @@ class CBIntType(CIntType):
 class CPyUnicodeIntType(CIntType):
     # Py_UNICODE
 
-    # Conversion from a unicode string to Py_UNICODE at runtime is not
-    # currently supported and may never be - we only convert from and
-    # to integers here.  The maximum value for a Py_UNICODE is
-    # 1114111, so PyInt_FromLong() will do just fine here.
+    # Py_UNICODE coerces from and to single character unicode strings,
+    # but we also allow Python integers as input.  The value range for
+    # Py_UNICODE is 0..1114111, which is checked when converting from
+    # an integer value.
 
-    to_py_function = "PyInt_FromLong"
-    from_py_function = "__Pyx_PyInt_AsPy_UNICODE"
+    to_py_function = "PyUnicode_FromOrdinal"
+    from_py_function = "__Pyx_PyObject_AsPy_UNICODE"
+
+    def create_from_py_utility_code(self, env):
+        env.use_utility_code(pyobject_as_py_unicode_utility_code)
+        return True
 
     def sign_and_name(self):
         return "Py_UNICODE"
 
+pyobject_as_py_unicode_utility_code = UtilityCode(
+proto='''
+static CYTHON_INLINE Py_UNICODE __Pyx_PyObject_AsPy_UNICODE(PyObject*);
+''',
+impl='''
+static CYTHON_INLINE Py_UNICODE __Pyx_PyObject_AsPy_UNICODE(PyObject* x) {
+   static long maxval = 0;
+   long ival;
+   if (PyUnicode_Check(x)) {
+       if (unlikely(PyUnicode_GET_SIZE(x) != 1)) {
+           PyErr_Format(PyExc_ValueError,
+               "only single character unicode strings can be converted to Py_UNICODE, got length "
+               #if PY_VERSION_HEX < 0x02050000
+               "%d",
+               #else
+               "%zd",
+               #endif
+               PyUnicode_GET_SIZE(x));
+           return (Py_UNICODE)-1;
+       }
+       return PyUnicode_AS_UNICODE(x)[0];
+   }
+   if (unlikely(!maxval))
+       maxval = (long)PyUnicode_GetMax();
+   ival = __Pyx_PyInt_AsLong(x);
+   if (unlikely(ival < 0)) {
+       if (!PyErr_Occurred())
+           PyErr_SetString(PyExc_OverflowError,
+                           "cannot convert negative value to Py_UNICODE");
+       return (Py_UNICODE)-1;
+   } else if (unlikely(ival > maxval)) {
+       PyErr_SetString(PyExc_OverflowError,
+                       "value too large to convert to Py_UNICODE");
+       return (Py_UNICODE)-1;
+   }
+   return (Py_UNICODE)ival;
+}
+''')
+
 
 class CPySSizeTType(CIntType):
 
@@ -2512,10 +2555,6 @@ type_conversion_predeclarations = """
 static CYTHON_INLINE int __Pyx_PyObject_IsTrue(PyObject*);
 static CYTHON_INLINE PyObject* __Pyx_PyNumber_Int(PyObject* x);
 
-#ifdef Py_USING_UNICODE
-static CYTHON_INLINE Py_UNICODE __Pyx_PyInt_AsPy_UNICODE(PyObject*);
-#endif
-
 static CYTHON_INLINE Py_ssize_t __Pyx_PyIndex_AsSsize_t(PyObject*);
 static CYTHON_INLINE PyObject * __Pyx_PyInt_FromSize_t(size_t);
 static CYTHON_INLINE size_t __Pyx_PyInt_AsSize_t(PyObject*);
@@ -2580,26 +2619,6 @@ static CYTHON_INLINE PyObject* __Pyx_PyNumber_Int(PyObject* x) {
   return res;
 }
 
-#ifdef Py_USING_UNICODE
-static CYTHON_INLINE Py_UNICODE __Pyx_PyInt_AsPy_UNICODE(PyObject* x) {
-   long ival = __Pyx_PyInt_AsLong(x);
-   static long maxval = 0;
-   if (unlikely(!maxval))
-       maxval = (long)PyUnicode_GetMax();
-   if (unlikely(ival < 0)) {
-       if (!PyErr_Occurred())
-           PyErr_SetString(PyExc_OverflowError,
-                           "can't convert negative value to Py_UNICODE");
-       return (Py_UNICODE)-1;
-   } else if (unlikely(ival > maxval)) {
-       PyErr_SetString(PyExc_OverflowError,
-                       "value too large to convert to Py_UNICODE");
-       return (Py_UNICODE)-1;
-   }
-   return (Py_UNICODE)ival;
-}
-#endif
-
 static CYTHON_INLINE Py_ssize_t __Pyx_PyIndex_AsSsize_t(PyObject* b) {
   Py_ssize_t ival;
   PyObject* x = PyNumber_Index(b);

tests/run/py_unicode_type.pyx

@@ -3,7 +3,6 @@
 cdef Py_UNICODE char_ASCII = u'A'
 cdef Py_UNICODE char_KLINGON = u'\uF8D2'
 
-
 def compare_ASCII():
     """
     >>> compare_ASCII()
@@ -39,31 +38,68 @@ def index_literal(int i):
     >>> index_literal(4) == '5'
     True
     """
-    # runtime casts are not currently supported
-    #return <Py_UNICODE>(u"12345"[i])
     return u"12345"[i]
 
 
-def unicode_cardinal(Py_UNICODE i):
+def index_literal_pyunicode(int i):
+    """
+    >>> index_literal_pyunicode(0) == '1'
+    True
+    >>> index_literal_pyunicode(-5) == '1'
+    True
+    >>> index_literal_pyunicode(2) == '3'
+    True
+    >>> index_literal_pyunicode(4) == '5'
+    True
     """
-    >>> import sys
+    return <Py_UNICODE>(u"12345"[i])
 
-    >>> unicode_cardinal(0)
-    0
-    >>> unicode_cardinal(1)
-    1
-    >>> unicode_cardinal(sys.maxunicode) == sys.maxunicode
+
+from cpython.unicode cimport PyUnicode_FromOrdinal
+import sys
+
+u0 = u'\x00'
+u1 = u'\x01'
+umax = PyUnicode_FromOrdinal(sys.maxunicode)
+
+def unicode_ordinal(Py_UNICODE i):
+    """
+    >>> ord(unicode_ordinal(0)) == 0
+    True
+    >>> ord(unicode_ordinal(1)) == 1
+    True
+    >>> ord(unicode_ordinal(sys.maxunicode)) == sys.maxunicode
     True
 
+    >>> ord(unicode_ordinal(u0)) == 0
+    True
+    >>> ord(unicode_ordinal(u1)) == 1
+    True
+    >>> ord(unicode_ordinal(umax)) == sys.maxunicode
+    True
 
-    >>> unicode_cardinal(-1) #doctest: +ELLIPSIS
+    Value too small:
+    >>> unicode_ordinal(-1) #doctest: +ELLIPSIS
     Traceback (most recent call last):
     ...
     OverflowError: ...
 
-    >>> unicode_cardinal(sys.maxunicode+1) #doctest: +ELLIPSIS
+    Value too large:
+    >>> unicode_ordinal(sys.maxunicode+1) #doctest: +ELLIPSIS
     Traceback (most recent call last):
     ...
     OverflowError: ...
+
+    Less than one character:
+    >>> unicode_ordinal(u0[:0])
+    Traceback (most recent call last):
+    ...
+    ValueError: only single character unicode strings can be converted to Py_UNICODE, got length 0
+
+    More than one character:
+    >>> unicode_ordinal(u0+u1)
+    Traceback (most recent call last):
+    ...
+    ValueError: only single character unicode strings can be converted to Py_UNICODE, got length 2
     """
     return i