Refractor some of FrozenList's functions and methods

CHANGES/712.feature.rst

@@ -0,0 +1,2 @@
+Refractor methods `__len__`, `__iadd__`, `index`, `extend`, `append`, `count` and `__deecopy__` and add notes for `pop`, `append` and `extend` for contributors who are looking to
+refractor anything further -- by :user:`Vizonex`.

frozenlist/_frozenlist.pyx

@@ -2,6 +2,12 @@
 # distutils: language = c++
 
 from cpython.bool cimport PyBool_FromLong
+from cpython.list cimport PyList_GET_SIZE
+from cpython.long cimport PyLong_FromLong
+from cpython.sequence cimport (
+    PySequence_Count,
+    PySequence_InPlaceConcat,
+)
 from libcpp.atomic cimport atomic
 
 import copy
@@ -31,9 +37,6 @@ cdef class FrozenList:
         if self._frozen.load():
             raise RuntimeError("Cannot modify frozen list.")
 
-    cdef inline object _fast_len(self):
-        return len(self._items)
-
     def freeze(self):
         self._frozen.store(True)
 
@@ -49,7 +52,8 @@ cdef class FrozenList:
         del self._items[index]
 
     def __len__(self):
-        return self._fast_len()
+        # Cython does less expensive calling if PyList_GET_SIZE is utilized
+        return PyList_GET_SIZE(self._items)
 
     def __iter__(self):
         return self._items.__iter__()
@@ -71,20 +75,20 @@ cdef class FrozenList:
         if op == 5:  # =>
             return list(self) >= other
 
-    def insert(self, pos, item):
+    def insert(self, *args):
         self._check_frozen()
-        self._items.insert(pos, item)
+        self._items.insert(*args)
 
     def __contains__(self, item):
         return item in self._items
 
     def __iadd__(self, items):
         self._check_frozen()
-        self._items += list(items)
+        self._items = PySequence_InPlaceConcat(self._items, items)
         return self
 
-    def index(self, item):
-        return self._items.index(item)
+    def index(self, *args):
+        return self._items.index(*args)
 
     def remove(self, item):
         self._check_frozen()
@@ -96,22 +100,29 @@ cdef class FrozenList:
 
     def extend(self, items):
         self._check_frozen()
-        self._items += list(items)
+        # Cython will generate __Pyx_PyList_Extend
+        self._items.extend(items)
 
     def reverse(self):
         self._check_frozen()
+        # Cython will do PyList_Reverse by default...
         self._items.reverse()
 
     def pop(self, index=-1):
+        # XXX: Current pop is impossible to refactor and may
+        # require the Cython maintainers to brainstorm a new idea.
         self._check_frozen()
         return self._items.pop(index)
 
     def append(self, item):
         self._check_frozen()
-        return self._items.append(item)
+        # Cython will generate an appropriate function for append
+        self._items.append(item)
 
     def count(self, item):
-        return self._items.count(item)
+        # NOTE: doing self._items.count(item) Generates expensive call
+        # As for PyLong_FromLong it's a bit faster to call the direct C-API
+        return PyLong_FromLong(PySequence_Count(self._items, item))
 
     def __repr__(self):
         return '<FrozenList(frozen={}, {!r})>'.format(self._frozen.load(),
@@ -140,7 +151,8 @@ cdef class FrozenList:
 
         # Preserve frozen state
         if self._frozen.load():
-            new_list.freeze()
+            # faster to call .store directly rather than freeze()
+            new_list._frozen.store(True)
 
         return new_list