From aa7710982ba96ed4ac3246d3c04b85ffb66ee6f0 Mon Sep 17 00:00:00 2001
From: Joey Hess <joeyh@joeyh.name>
Date: Tue, 14 May 2019 13:08:51 -0400
Subject: [PATCH] avoid list lookup by parseToken

Minor optimisation to parsing of a preferred content expression.
---
 Annex/FileMatcher.hs        |  6 +++---
 CmdLine/GitAnnex/Options.hs |  4 ++--
 Limit.hs                    |  6 +++---
 Logs/PreferredContent.hs    |  2 +-
 Utility/Matcher.hs          | 20 ++++++++------------
 5 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/Annex/FileMatcher.hs b/Annex/FileMatcher.hs
index b2c626c5a6..162161984e 100644
--- a/Annex/FileMatcher.hs
+++ b/Annex/FileMatcher.hs
@@ -84,9 +84,9 @@ data ParseToken t
 type ParseResult t = Either String (Token t)
 
 parseToken :: [ParseToken t] -> String -> ParseResult t
-parseToken l t
-	| t `elem` tokens = Right $ token t
-	| otherwise = go l
+parseToken l t = case syntaxToken t of
+	Right st -> Right st
+	Left _ -> go l
   where
 	go [] = Left $ "near " ++ show t
 	go (SimpleToken s r : _) | s == t = r
diff --git a/CmdLine/GitAnnex/Options.hs b/CmdLine/GitAnnex/Options.hs
index a1beef7e98..760529013c 100644
--- a/CmdLine/GitAnnex/Options.hs
+++ b/CmdLine/GitAnnex/Options.hs
@@ -324,8 +324,8 @@ combiningOptions =
 	, shortopt ')' "close group of options"
 	]
   where
-	longopt o h = globalFlag (Limit.addToken o) ( long o <> help h <> hidden )
-	shortopt o h = globalFlag (Limit.addToken [o]) ( short o <> help h <> hidden )
+	longopt o h = globalFlag (Limit.addSyntaxToken o) ( long o <> help h <> hidden )
+	shortopt o h = globalFlag (Limit.addSyntaxToken [o]) ( short o <> help h <> hidden )
 
 jsonOptions :: [GlobalOption]
 jsonOptions = 
diff --git a/Limit.hs b/Limit.hs
index bb1b64f5a4..6c48100564 100644
--- a/Limit.hs
+++ b/Limit.hs
@@ -63,9 +63,9 @@ add l = Annex.changeState $ \s -> s { Annex.limit = prepend $ Annex.limit s }
 	prepend (BuildingMatcher ls) = BuildingMatcher $ l:ls
 	prepend _ = error "internal"
 
-{- Adds a new token. -}
-addToken :: String -> Annex ()
-addToken = add . Utility.Matcher.token
+{- Adds a new syntax token. -}
+addSyntaxToken :: String -> Annex ()
+addSyntaxToken = either error add . Utility.Matcher.syntaxToken
 
 {- Adds a new limit. -}
 addLimit :: Either String (MatchFiles Annex) -> Annex ()
diff --git a/Logs/PreferredContent.hs b/Logs/PreferredContent.hs
index c8605b083f..5101575f3a 100644
--- a/Logs/PreferredContent.hs
+++ b/Logs/PreferredContent.hs
@@ -34,7 +34,7 @@ import qualified Annex.Branch
 import qualified Annex
 import Logs
 import Logs.UUIDBased
-import Utility.Matcher hiding (tokens)
+import Utility.Matcher
 import Annex.FileMatcher
 import Annex.UUID
 import Types.Group
diff --git a/Utility/Matcher.hs b/Utility/Matcher.hs
index badf72acfd..faf53c3e9a 100644
--- a/Utility/Matcher.hs
+++ b/Utility/Matcher.hs
@@ -20,8 +20,7 @@
 module Utility.Matcher (
 	Token(..),
 	Matcher(..),
-	token,
-	tokens,
+	syntaxToken,
 	generate,
 	match,
 	matchM,
@@ -47,16 +46,13 @@ data Matcher op = MAny
 	deriving (Show, Eq)
 
 {- Converts a word of syntax into a token. Doesn't handle operations. -}
-token :: String -> Token op
-token "and" = And
-token "or" = Or
-token "not" = Not
-token "(" = Open
-token ")" = Close
-token t = error $ "unknown token " ++ t
-
-tokens :: [String]
-tokens = words "and or not ( )"
+syntaxToken :: String -> Either String (Token op)
+syntaxToken "and" = Right And
+syntaxToken "or" = Right Or
+syntaxToken "not" = Right Not
+syntaxToken "(" = Right Open
+syntaxToken ")" = Right Close
+syntaxToken t = Left $ "unknown token " ++ t
 
 {- Converts a list of Tokens into a Matcher. -}
 generate :: [Token op] -> Matcher op