1 files changed, 37 insertions, 0 deletions
diff --git a/alot/completion/completer.py b/alot/completion/completer.py
new file mode 100644
index 00000000..de15d312
--- /dev/null
+++ b/alot/completion/completer.py
@@ -0,0 +1,37 @@
+# Copyright (C) 2011-2019  Patrick Totzke <patricktotzke@gmail.com>
+# This file is released under the GNU GPL, version 3 or a later revision.
+# For further details see the COPYING file
+import abc
+
+
+class Completer:
+    """base class for completers"""
+
+    __metaclass__ = abc.ABCMeta
+
+    @abc.abstractmethod
+    def complete(self, original, pos):
+        """returns a list of completions and cursor positions for the
+        string original from position pos on.
+
+        :param original: the string to complete
+        :type original: str
+        :param pos: starting position to complete from
+        :type pos: int
+        :returns: pairs of completed string and cursor position in the
+                  new string
+        :rtype: list of (str, int)
+        :raises: :exc:`CompletionError`
+        """
+        pass
+
+    def relevant_part(self, original, pos, sep=' '):
+        """
+        calculates the subword in a `sep`-splitted list of substrings of
+        `original` that `pos` is ia.n
+        """
+        start = original.rfind(sep, 0, pos) + 1
+        end = original.find(sep, pos - 1)
+        if end == -1:
+            end = len(original)
+        return original[start:end], start, end, pos - start