diff --git a/jedi/parser/utils.py b/jedi/parser/utils.py
new file mode 100644
index 00000000..a854aa40
--- /dev/null
+++ b/jedi/parser/utils.py
@@ -0,0 +1,201 @@
+import inspect
+import time
+import os
+import sys
+import json
+import hashlib
+import gc
+import shutil
+try:
+    import cPickle as pickle
+except ImportError:
+    import pickle
+
+from jedi import settings
+from jedi import debug
+
+
+def underscore_memoization(func):
+    """
+    Decorator for methods::
+
+        class A(object):
+            def x(self):
+                if self._x:
+                    self._x = 10
+                return self._x
+
+    Becomes::
+
+        class A(object):
+            @underscore_memoization
+            def x(self):
+                return 10
+
+    A now has an attribute ``_x`` written by this decorator.
+    """
+    name = '_' + func.__name__
+
+    def wrapper(self):
+        try:
+            return getattr(self, name)
+        except AttributeError:
+            result = func(self)
+            if inspect.isgenerator(result):
+                result = list(result)
+            setattr(self, name, result)
+            return result
+
+    return wrapper
+
+
+# for fast_parser, should not be deleted
+parser_cache = {}
+
+
+class ParserCacheItem(object):
+    def __init__(self, parser, change_time=None):
+        self.parser = parser
+        if change_time is None:
+            change_time = time.time()
+        self.change_time = change_time
+
+
+def load_parser(path):
+    """
+    Returns the module or None, if it fails.
+    """
+    p_time = os.path.getmtime(path) if path else None
+    try:
+        parser_cache_item = parser_cache[path]
+        if not path or p_time <= parser_cache_item.change_time:
+            return parser_cache_item.parser
+    except KeyError:
+        if settings.use_filesystem_cache:
+            return ParserPickling.load_parser(path, p_time)
+
+
+def save_parser(path, parser, pickling=True):
+    try:
+        p_time = None if path is None else os.path.getmtime(path)
+    except OSError:
+        p_time = None
+        pickling = False
+
+    item = ParserCacheItem(parser, p_time)
+    parser_cache[path] = item
+    if settings.use_filesystem_cache and pickling:
+        ParserPickling.save_parser(path, item)
+
+
+class ParserPickling(object):
+
+    version = 24
+    """
+    Version number (integer) for file system cache.
+
+    Increment this number when there are any incompatible changes in
+    parser representation classes.  For example, the following changes
+    are regarded as incompatible.
+
+    - Class name is changed.
+    - Class is moved to another module.
+    - Defined slot of the class is changed.
+    """
+
+    def __init__(self):
+        self.__index = None
+        self.py_tag = 'cpython-%s%s' % sys.version_info[:2]
+        """
+        Short name for distinguish Python implementations and versions.
+
+        It's like `sys.implementation.cache_tag` but for Python < 3.3
+        we generate something similar.  See:
+        http://docs.python.org/3/library/sys.html#sys.implementation
+
+        .. todo:: Detect interpreter (e.g., PyPy).
+        """
+
+    def load_parser(self, path, original_changed_time):
+        try:
+            pickle_changed_time = self._index[path]
+        except KeyError:
+            return None
+        if original_changed_time is not None \
+                and pickle_changed_time < original_changed_time:
+            # the pickle file is outdated
+            return None
+
+        with open(self._get_hashed_path(path), 'rb') as f:
+            try:
+                gc.disable()
+                parser_cache_item = pickle.load(f)
+            finally:
+                gc.enable()
+
+        debug.dbg('pickle loaded: %s', path)
+        parser_cache[path] = parser_cache_item
+        return parser_cache_item.parser
+
+    def save_parser(self, path, parser_cache_item):
+        self.__index = None
+        try:
+            files = self._index
+        except KeyError:
+            files = {}
+            self._index = files
+
+        with open(self._get_hashed_path(path), 'wb') as f:
+            pickle.dump(parser_cache_item, f, pickle.HIGHEST_PROTOCOL)
+            files[path] = parser_cache_item.change_time
+
+        self._flush_index()
+
+    @property
+    def _index(self):
+        if self.__index is None:
+            try:
+                with open(self._get_path('index.json')) as f:
+                    data = json.load(f)
+            except (IOError, ValueError):
+                self.__index = {}
+            else:
+                # 0 means version is not defined (= always delete cache):
+                if data.get('version', 0) != self.version:
+                    self.clear_cache()
+                    self.__index = {}
+                else:
+                    self.__index = data['index']
+        return self.__index
+
+    def _remove_old_modules(self):
+        # TODO use
+        change = False
+        if change:
+            self._flush_index(self)
+            self._index  # reload index
+
+    def _flush_index(self):
+        data = {'version': self.version, 'index': self._index}
+        with open(self._get_path('index.json'), 'w') as f:
+            json.dump(data, f)
+        self.__index = None
+
+    def clear_cache(self):
+        shutil.rmtree(self._cache_directory())
+
+    def _get_hashed_path(self, path):
+        return self._get_path('%s.pkl' % hashlib.md5(path.encode("utf-8")).hexdigest())
+
+    def _get_path(self, file):
+        dir = self._cache_directory()
+        if not os.path.exists(dir):
+            os.makedirs(dir)
+        return os.path.join(dir, file)
+
+    def _cache_directory(self):
+        return os.path.join(settings.cache_directory, self.py_tag)
+
+
+# is a singleton
+ParserPickling = ParserPickling()