1 files changed, 92 insertions, 0 deletions
diff --git a/nikola/state.py b/nikola/state.py
new file mode 100644
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+++ b/nikola/state.py
@@ -0,0 +1,92 @@
+# -*- coding: utf-8 -*-
+
+# Copyright © 2012-2016 Roberto Alsina and others.
+
+# Permission is hereby granted, free of charge, to any
+# person obtaining a copy of this software and associated
+# documentation files (the "Software"), to deal in the
+# Software without restriction, including without limitation
+# the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the
+# Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice
+# shall be included in all copies or substantial portions of
+# the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+# PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
+# OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+"""Persistent state implementation."""
+
+import json
+import os
+import shutil
+import tempfile
+import threading
+
+from . import utils
+
+
+class Persistor():
+    """Persist stuff in a place.
+
+    This is an intentionally dumb implementation. It is *not* meant to be
+    fast, or useful for arbitrarily large data. Use lightly.
+
+    Intentionally it has no namespaces, sections, etc. Use as a
+    responsible adult.
+    """
+
+    def __init__(self, path):
+        """Where do you want it persisted."""
+        self._path = path
+        self._local = threading.local()
+        self._local.data = {}
+
+    def _set_site(self, site):
+        """Set site and create path directory."""
+        self._site = site
+        utils.makedirs(os.path.dirname(self._path))
+
+    def get(self, key):
+        """Get data stored in key."""
+        self._read()
+        return self._local.data.get(key)
+
+    def set(self, key, value):
+        """Store value in key."""
+        self._read()
+        self._local.data[key] = value
+        self._save()
+
+    def delete(self, key):
+        """Delete key and the value it contains."""
+        self._read()
+        if key in self._local.data:
+            self._local.data.pop(key)
+        self._save()
+
+    def _read(self):
+        if os.path.isfile(self._path):
+            with open(self._path) as inf:
+                self._local.data = json.load(inf)
+
+    def _save(self):
+        dname = os.path.dirname(self._path)
+        with tempfile.NamedTemporaryFile(dir=dname, delete=False) as outf:
+            # TODO replace with encoding='utf-8' and mode 'w+' in v8
+            tname = outf.name
+            data = json.dumps(self._local.data, sort_keys=True, indent=2)
+            try:
+                outf.write(data)
+            except TypeError:
+                outf.write(data.encode('utf-8'))
+        shutil.move(tname, self._path)