From 5a384b87fca6f4e7a93d9bfdf647fb4d68320276 Mon Sep 17 00:00:00 2001
From: Ollie Charles <ollie@ocharles.org.uk>
Date: Fri, 11 Dec 2020 10:38:32 +0000
Subject: [PATCH 1/2] Add the ability to ignore weeds

Fixes #56
---
 src/Weeder.hs        | 11 ++++++++++-
 src/Weeder/Config.hs |  7 ++++++-
 src/Weeder/Main.hs   | 15 +++++----------
 3 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/src/Weeder.hs b/src/Weeder.hs
index 5ac5aec..f80e1b2 100644
--- a/src/Weeder.hs
+++ b/src/Weeder.hs
@@ -22,6 +22,7 @@ module Weeder
 
     -- * Declarations
   , Declaration(..)
+  , declarationMatchesRegularExpression
   )
    where
 
@@ -65,7 +66,7 @@ import HieTypes
   , NodeInfo( NodeInfo, nodeIdentifiers, nodeAnnotations )
   , Scope( ModuleScope )
   )
-import Module ( Module, moduleStableString )
+import Module ( Module, moduleName, moduleNameString, moduleStableString )
 import Name ( Name, nameModule_maybe, nameOccName )
 import OccName
   ( OccName
@@ -84,6 +85,9 @@ import Control.Lens ( (%=) )
 -- mtl
 import Control.Monad.State.Class ( MonadState )
 
+-- regex-tdfa
+import Text.Regex.TDFA ( (=~) )
+
 -- transformers
 import Control.Monad.Trans.Maybe ( runMaybeT )
 
@@ -119,6 +123,11 @@ declarationStableName Declaration { declModule, declOccName } =
     intercalate "$" [ namespace, moduleStableString declModule, "$", occNameString declOccName ]
 
 
+declarationMatchesRegularExpression :: Declaration -> String -> Bool
+declarationMatchesRegularExpression d p =
+  ( moduleNameString ( moduleName ( declModule d ) ) <> "." <> occNameString ( declOccName d ) ) =~ p
+
+
 -- | All information maintained by 'analyseHieFile'.
 data Analysis =
   Analysis
diff --git a/src/Weeder/Config.hs b/src/Weeder/Config.hs
index b9a82f9..e697508 100644
--- a/src/Weeder/Config.hs
+++ b/src/Weeder/Config.hs
@@ -22,6 +22,10 @@ data Config = Config
     -- ^ If True, consider all declarations in a type class as part of the root
     -- set. Weeder is currently unable to identify whether or not a type class
     -- instance is used - enabling this option can prevent false positives.
+  , ignore :: Set String
+    -- ^ Any weeds matching these regular expressions will not be reported. This
+    -- is different from 'rootPatterns', which causes the weed to become a root,
+    -- while this option is purely about filtering the reporting output.
   }
 
 
@@ -31,7 +35,8 @@ data Config = Config
 config :: Dhall.Decoder Config
 config =
   Dhall.record do
-    rootPatterns <- Set.fromList <$> Dhall.field "roots" ( Dhall.list Dhall.string )
+    rootPatterns   <- Set.fromList <$> Dhall.field "roots" ( Dhall.list Dhall.string )
     typeClassRoots <- Dhall.field "type-class-roots" Dhall.bool
+    ignore         <- Set.fromList <$> Dhall.field "ignore" ( Dhall.list Dhall.string )
 
     return Config{..}
diff --git a/src/Weeder/Main.hs b/src/Weeder/Main.hs
index 7bebe29..6ef190a 100644
--- a/src/Weeder/Main.hs
+++ b/src/Weeder/Main.hs
@@ -46,9 +46,6 @@ import OccName ( occNameString )
 import SrcLoc ( realSrcSpanStart, srcLocCol, srcLocLine )
 import UniqSupply ( mkSplitUniqSupply )
 
--- regex-tdfa
-import Text.Regex.TDFA ( (=~) )
-
 -- optparse-applicative
 import Options.Applicative
 
@@ -94,7 +91,7 @@ main = do
 -- This will recursively find all @.hie@ files in the current directory, perform
 -- analysis, and report all unused definitions according to the 'Config'.
 mainWithConfig :: [FilePath] -> Config -> IO ()
-mainWithConfig hieDirectories Config{ rootPatterns, typeClassRoots } = do
+mainWithConfig hieDirectories Config{ rootPatterns, typeClassRoots, ignore } = do
   hieFilePaths <-
     concat <$>
       traverse getHieFilesIn
@@ -116,11 +113,7 @@ mainWithConfig hieDirectories Config{ rootPatterns, typeClassRoots } = do
   let
     roots =
       Set.filter
-        ( \d ->
-            any
-              ( ( moduleNameString ( moduleName ( declModule d ) ) <> "." <> occNameString ( declOccName d ) ) =~ )
-              rootPatterns
-        )
+        ( \d -> any ( declarationMatchesRegularExpression d ) rootPatterns )
         ( allDeclarations analysis )
 
     reachableSet =
@@ -142,6 +135,8 @@ mainWithConfig hieDirectories Config{ rootPatterns, typeClassRoots } = do
               spans <- Map.lookup d ( declarationSites analysis )
               guard $ not $ null spans
 
+              guard $ all (not . declarationMatchesRegularExpression d) ignore
+
               let snippets = do
                     srcSpan <- Set.toList spans
 
@@ -155,7 +150,7 @@ mainWithConfig hieDirectories Config{ rootPatterns, typeClassRoots } = do
         dead
 
   for_ ( Map.toList warnings ) \( path, declarations ) ->
-    for_ declarations \( ( start, snippet ), d ) -> do
+    for_ (declarations) \( ( start, snippet ), d ) -> do
       putStrLn $
         unwords
           [ foldMap ( <> ":" ) [ path, show ( srcLocLine start ), show ( srcLocCol start ) ]

From f128ee0b409e8530edf6eaef4354fe3a0ae05a4d Mon Sep 17 00:00:00 2001
From: Ollie Charles <ollie@ocharles.org.uk>
Date: Thu, 7 Jan 2021 22:09:03 +0000
Subject: [PATCH 2/2] Update Main.hs

---
 src/Weeder/Main.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Weeder/Main.hs b/src/Weeder/Main.hs
index 6ef190a..508451d 100644
--- a/src/Weeder/Main.hs
+++ b/src/Weeder/Main.hs
@@ -150,7 +150,7 @@ mainWithConfig hieDirectories Config{ rootPatterns, typeClassRoots, ignore } = d
         dead
 
   for_ ( Map.toList warnings ) \( path, declarations ) ->
-    for_ (declarations) \( ( start, snippet ), d ) -> do
+    for_ declarations \( ( start, snippet ), d ) -> do
       putStrLn $
         unwords
           [ foldMap ( <> ":" ) [ path, show ( srcLocLine start ), show ( srcLocCol start ) ]