1 files changed, 117 insertions, 0 deletions
diff --git a/src/cachetools/cache.py b/src/cachetools/cache.py
new file mode 100644
index 0000000..973d50b
--- /dev/null
+++ b/src/cachetools/cache.py
@@ -0,0 +1,117 @@
+from collections.abc import MutableMapping
+
+
+class _DefaultSize:
+
+    __slots__ = ()
+
+    def __getitem__(self, _):
+        return 1
+
+    def __setitem__(self, _, value):
+        assert value == 1
+
+    def pop(self, _):
+        return 1
+
+
+class Cache(MutableMapping):
+    """Mutable mapping to serve as a simple cache or cache base class."""
+
+    __marker = object()
+
+    __size = _DefaultSize()
+
+    def __init__(self, maxsize, getsizeof=None):
+        if getsizeof:
+            self.getsizeof = getsizeof
+        if self.getsizeof is not Cache.getsizeof:
+            self.__size = dict()
+        self.__data = dict()
+        self.__currsize = 0
+        self.__maxsize = maxsize
+
+    def __repr__(self):
+        return "%s(%r, maxsize=%r, currsize=%r)" % (
+            self.__class__.__name__,
+            list(self.__data.items()),
+            self.__maxsize,
+            self.__currsize,
+        )
+
+    def __getitem__(self, key):
+        try:
+            return self.__data[key]
+        except KeyError:
+            return self.__missing__(key)
+
+    def __setitem__(self, key, value):
+        maxsize = self.__maxsize
+        size = self.getsizeof(value)
+        if size > maxsize:
+            raise ValueError("value too large")
+        if key not in self.__data or self.__size[key] < size:
+            while self.__currsize + size > maxsize:
+                self.popitem()
+        if key in self.__data:
+            diffsize = size - self.__size[key]
+        else:
+            diffsize = size
+        self.__data[key] = value
+        self.__size[key] = size
+        self.__currsize += diffsize
+
+    def __delitem__(self, key):
+        size = self.__size.pop(key)
+        del self.__data[key]
+        self.__currsize -= size
+
+    def __contains__(self, key):
+        return key in self.__data
+
+    def __missing__(self, key):
+        raise KeyError(key)
+
+    def __iter__(self):
+        return iter(self.__data)
+
+    def __len__(self):
+        return len(self.__data)
+
+    def get(self, key, default=None):
+        if key in self:
+            return self[key]
+        else:
+            return default
+
+    def pop(self, key, default=__marker):
+        if key in self:
+            value = self[key]
+            del self[key]
+        elif default is self.__marker:
+            raise KeyError(key)
+        else:
+            value = default
+        return value
+
+    def setdefault(self, key, default=None):
+        if key in self:
+            value = self[key]
+        else:
+            self[key] = value = default
+        return value
+
+    @property
+    def maxsize(self):
+        """The maximum size of the cache."""
+        return self.__maxsize
+
+    @property
+    def currsize(self):
+        """The current size of the cache."""
+        return self.__currsize
+
+    @staticmethod
+    def getsizeof(value):
+        """Return the size of a cache element's value."""
+        return 1