Implement simple completion into the Column UI

Currently it works only with single completion candidate and works for:
contexts, projects, subcommands.

topydo/lib/Completer.py

+# Topydo - A todo.txt client written in Python.
+# Copyright (C) 2017 Bram Schoenmakers <bram@topydo.org>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from topydo.Commands import _SUBCOMMAND_MAP
+from topydo.lib.Config import config
+
+
+def _get_subcmds():
+    subcmd_map = config().aliases()
+    subcmd_map.update(_SUBCOMMAND_MAP)
+
+    return sorted(subcmd_map.keys())
+
+
+class CompleterBase(object):
+    def __init__(self, p_todolist):
+        self.todolist = p_todolist
+        self._subcmds = _get_subcmds()
+
+    def _complete_context(self, p_word):
+        completions = ['@' + context for context in self.todolist.contexts() if
+                       context.startswith(p_word[1:])]
+        return completions
+
+    def _complete_project(self, p_word):
+        completions = ['+' + project for project in self.todolist.projects() if
+                       project.startswith(p_word[1:])]
+        return completions
+
+    def _complete_subcmd(self, p_word):
+        completions = [cmd for cmd in self._subcmds if
+                       cmd.startswith(p_word)]
+        return completions
+
+    def get_completions(self, p_word, p_is_first_word=False):
+        completions = []
+
+        if p_word.startswith('+'):
+            completions = self._complete_project(p_word)
+        elif p_word.startswith('@'):
+            completions = self._complete_context(p_word)
+        elif p_is_first_word:
+            completions = self._complete_subcmd(p_word)
+
+        return completions

topydo/ui/columns/CommandLineWidget.py

@@ -16,13 +16,27 @@
 
 import urwid
 
+
+def _get_word_before_pos(p_text, p_pos):
+    is_first_word = False
+    text = p_text
+    pos = p_pos
+    start = text.rfind(' ', 0, pos) + 1
+
+    if pos == 0 or text.lstrip().rfind(' ', 0, pos) == -1:
+        is_first_word = True
+
+    return (text[start:pos], is_first_word)
+
+
 class CommandLineWidget(urwid.Edit):
-    def __init__(self, *args, **kwargs):
+    def __init__(self, p_completer, *args, **kwargs):
 
         self.history = []
         self.history_pos = None
         # temporary history storage for edits before cmd execution
         self.history_tmp = []
+        self.completer = p_completer
 
         super().__init__(*args, **kwargs)
         urwid.register_signal(CommandLineWidget, ['blur', 'execute_command'])
@@ -71,12 +85,35 @@ class CommandLineWidget(urwid.Edit):
         if self.history_pos != 0:
             self._history_move(-1)
 
+    def _complete(self):
+        pos = self.edit_pos
+        text = self.edit_text
+
+        word_before_cursor, is_first = _get_word_before_pos(text, pos)
+        completions = self.completer.get_completions(word_before_cursor,
+                                                     is_first)
+
+        if not completions:
+            return
+        elif len(completions) > 1:  # TODO multiple completions
+            return
+        else:
+            replacement = completions[0]
+            if replacement == word_before_cursor:
+                return  # Don't complete what is already completed
+
+            offset = len(replacement) - len(word_before_cursor)
+            final_text = text[:pos] + replacement[-offset:] + text[pos:]
+            self.set_edit_text(final_text)
+            self.set_edit_pos(pos + offset)
+
     def keypress(self, p_size, p_key):
         dispatch = {
             'enter': self._emit_command,
             'esc': self._blur,
             'up': self._history_back,
-            'down': self._history_next
+            'down': self._history_next,
+            'tab': self._complete
         }
 
         try:

topydo/ui/columns/Main.py

@@ -26,6 +26,7 @@ from string import ascii_uppercase
 
 from topydo.Commands import get_subcommand
 from topydo.lib.Config import config, ConfigError
+from topydo.lib.Completer import CompleterBase
 from topydo.lib.Sorter import Sorter
 from topydo.lib.Filter import get_filter_list, RelevanceFilter, DependencyFilter
 from topydo.lib.Utils import get_terminal_size
@@ -123,7 +124,8 @@ class UIApplication(CLIApplicationBase):
 
         self.columns = urwid.Columns([], dividechars=0,
             min_width=config().column_width())
-        self.commandline = CommandLineWidget('topydo> ')
+        completer = CompleterBase(self.todolist)
+        self.commandline = CommandLineWidget(completer, 'topydo> ')
         self.keystate_widget = KeystateWidget()
         self.status_line = urwid.Columns([
             ('weight', 1, urwid.Filler(self.commandline)),