(core) Add 'value' to trigger formula autocomplete

Summary:
API signature for autocomplete updated to add column ID, which is
necessary for exposing correct types for 'value'.

Test Plan: Unit tests.

Reviewers: alexmojaki

Reviewed By: alexmojaki

Subscribers: jarek, alexmojaki

Differential Revision: https://phab.getgrist.com/D2896

sandbox/grist/engine.py

@@ -1281,7 +1281,7 @@ class Engine(object):
     if not self._compute_stack:
       self._bring_lookups_up_to_date(doc_action)
 
-  def autocomplete(self, txt, table_id):
+  def autocomplete(self, txt, table_id, column_id):
     """
     Return a list of suggested completions of the python fragment supplied.
     """
@@ -1295,6 +1295,13 @@ class Engine(object):
     context = self._autocomplete_context.get_context()
     context['rec'] = table.sample_record
 
+    # Remove values from the context that need to be recomputed.
+    context.pop('value', None)
+
+    column = table.get_column(column_id) if table.has_column(column_id) else None
+    if column and not column.is_formula():
+      context['value'] = column.sample_value()
+
     completer = rlcompleter.Completer(context)
     results = []
     at = 0