Use Mapping interface

Author: asottile

pysass.cpp

@@ -139,6 +139,8 @@ static union Sass_Value* _to_sass_value(PyObject* value) {
     PyObject* sass_error_t = PyObject_GetAttrString(types_mod, "SassError");
     PyObject* sass_comma = PyObject_GetAttrString(types_mod, "SASS_SEPARATOR_COMMA");
     PyObject* sass_space = PyObject_GetAttrString(types_mod, "SASS_SEPARATOR_SPACE");
+    PyObject* collections_mod = PyImport_ImportModule("collections");
+    PyObject* mapping_t = PyObject_GetAttrString(collections_mod, "Mapping");
 
     if (value == Py_None) {
         retv = sass_make_null();
@@ -150,17 +152,21 @@ static union Sass_Value* _to_sass_value(PyObject* value) {
         Py_DECREF(bytes);
     } else if (PySass_Bytes_Check(value)) {
         retv = sass_make_string(PySass_Bytes_AS_STRING(value));
-    } else if (PyDict_Check(value)) {
+    /* XXX: PyMapping_Check returns true for lists and tuples in python3 :( */
+    } else if (PyObject_IsInstance(value, mapping_t)) {
         size_t i = 0;
         Py_ssize_t pos = 0;
         PyObject* d_key = NULL;
         PyObject* d_value = NULL;
-        retv = sass_make_map(PyDict_Size(value));
-        while (PyDict_Next(value, &pos, &d_key, &d_value)) {
+        PyObject* dct = PyDict_New();
+        PyDict_Update(dct, value);
+        retv = sass_make_map(PyDict_Size(dct));
+        while (PyDict_Next(dct, &pos, &d_key, &d_value)) {
             sass_map_set_key(retv, i, _to_sass_value(d_key));
             sass_map_set_value(retv, i, _to_sass_value(d_value));
             i += 1;
         }
+        Py_DECREF(dct);
     } else if (PyObject_IsInstance(value, sass_number_t)) {
         PyObject* d_value = PyObject_GetAttrString(value, "value");
         PyObject* unit = PyObject_GetAttrString(value, "unit");
@@ -190,7 +196,6 @@ static union Sass_Value* _to_sass_value(PyObject* value) {
         Py_ssize_t i = 0;
         PyObject* items = PyObject_GetAttrString(value, "items");
         PyObject* separator = PyObject_GetAttrString(value, "separator");
-        /* TODO: I don't really like this, maybe move types to C */
         Sass_Separator sep = SASS_COMMA;
         if (separator == sass_comma) {
             sep = SASS_COMMA;
@@ -260,6 +265,8 @@ static union Sass_Value* _to_sass_value(PyObject* value) {
     Py_DECREF(sass_error_t);
     Py_DECREF(sass_comma);
     Py_DECREF(sass_space);
+    Py_DECREF(collections_mod);
+    Py_DECREF(mapping_t);
     return retv;
 }
 

sass.py

@@ -457,17 +457,29 @@ def __new__(cls, msg):
         return super(SassWarning, cls).__new__(cls, msg)
 
 
-class SassMap(dict):
+class SassMap(collections.Mapping):
     """Because sass maps can have mapping types as keys, we need an immutable
     hashable mapping type.
     """
-    __slots__ = ('_hash',)
+    __slots__ = ('_dict', '_hash',)
 
-    def __new__(cls, *args, **kwargs):
-        value = super(SassMap, cls).__new__(cls, *args, **kwargs)
+    def __init__(self, *args, **kwargs):
+        self._dict = dict(*args, **kwargs)
         # An assertion that all things are hashable
-        value._hash = hash(frozenset(value.items()))
-        return value
+        self._hash = hash(frozenset(self._dict.items()))
+
+    # Mapping interface
+
+    def __getitem__(self, key):
+        return self._dict[key]
+
+    def __iter__(self):
+        return iter(self._dict)
+
+    def __len__(self):
+        return len(self._dict)
+
+    # Our interface
 
     def __repr__(self):
         return '{0}({1})'.format(type(self).__name__, frozenset(self.items()))
@@ -476,6 +488,6 @@ def __hash__(self):
         return self._hash
 
     def _immutable(self, *_):
-        raise AssertionError('SassMaps are immutable')
+        raise TypeError('SassMaps are immutable.')
 
     __setitem__ = __delitem__ = _immutable