autocomplete entity names in the repl (#798)

src/Swarm/TUI/Controller.hs

@@ -784,23 +784,64 @@ handleREPLEvent = \case
         newform <- use $ uiState . to (set promptUpdateL t)
         uiState . uiReplForm .= newform
 
--- | Try to complete the last word in a partially entered REPL prompt using
---   things reserved words and names in scope.
+data CompletionType
+  = FunctionName
+  | EntityName
+  deriving (Eq)
+
+-- | Try to complete the last word in a partially-entered REPL prompt using
+--   reserved words and names in scope (in the case of function names) or
+--   entity names (in the case of string literals).
 tabComplete :: AppState -> REPLPrompt -> REPLPrompt
 tabComplete _ p@(SearchPrompt {}) = p
 tabComplete s (CmdPrompt t mms)
-  | (m : ms) <- mms = CmdPrompt (replaceLast m t) (ms ++ [m])
-  | T.null lastWord = CmdPrompt t []
-  | otherwise = case matches of
+  -- Case 1: If completion candidates have already been
+  -- populated via case (3), cycle through them.
+  -- Note that tabbing through the candidates *does* update the value
+  -- of "t", which one might think would narrow the candidate list
+  -- to only that match and therefore halt the cycling.
+  -- However, the candidate list only gets recomputed (repopulated)
+  -- if the user subsequently presses a non-Tab key. Thus the current
+  -- value of "t" is ignored for all Tab presses subsequent to the
+  -- first.
+  | (m : ms) <- mms = CmdPrompt (replacementFunc m) (ms ++ [m])
+  -- Case 2: Require at least one letter to be typed in order to offer completions for
+  -- function names.
+  -- We allow suggestions for Entity Name strings without anything having been typed.
+  | T.null lastWord && completionType == FunctionName = CmdPrompt t []
+  -- Case 3: Typing another character in the REPL clears the completion candidates from
+  -- the CmdPrompt, so when Tab is pressed again, this case then gets executed and
+  -- repopulates them.
+  | otherwise = case candidateMatches of
     [] -> CmdPrompt t []
     [m] -> CmdPrompt (completeWith m) []
+    -- Perform completion with the first candidate, then populate the list
+    -- of all candidates with the current completion moved to the back
+    -- of the queue.
     (m : ms) -> CmdPrompt (completeWith m) (ms ++ [m])
  where
-  completeWith m = T.append t (T.drop (T.length lastWord) m)
-  lastWord = T.takeWhileEnd isIdentChar t
+  -- checks the "parity" of the number of quotes. If odd, then there is an open quote.
+  hasOpenQuotes = (== 1) . (`mod` 2) . T.count "\""
+
+  completionType =
+    if hasOpenQuotes t
+      then EntityName
+      else FunctionName
+
+  replacementFunc = T.append $ T.dropWhileEnd replacementBoundaryPredicate t
+  completeWith m = T.append t $ T.drop (T.length lastWord) m
+  lastWord = T.takeWhileEnd replacementBoundaryPredicate t
+  candidateMatches = filter (lastWord `T.isPrefixOf`) replacementCandidates
+
+  (replacementCandidates, replacementBoundaryPredicate) = case completionType of
+    EntityName -> (entityNames, (/= '"'))
+    FunctionName -> (possibleWords, isIdentChar)
+
   names = s ^.. gameState . baseRobot . robotContext . defTypes . to assocs . traverse . _1
   possibleWords = reservedWords ++ names
-  matches = filter (lastWord `T.isPrefixOf`) possibleWords
+
+  theEntityMap = s ^. gameState . entityMap
+  entityNames = M.keys $ entitiesByName theEntityMap
 
 -- | Validate the REPL input when it changes: see if it parses and
 --   typechecks, and set the color accordingly.