Allow symbol identifiers in tactics (#1920)

* Allow symbol identifiers in tactics

* Cleanup imports

* Also allow pipes and backslash

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Author: isovector

plugins/hls-tactics-plugin/src/Wingman/Metaprogramming/Lexer.hs

@@ -8,6 +8,7 @@ module Wingman.Metaprogramming.Lexer where
 import           Control.Applicative
 import           Control.Monad
 import           Control.Monad.Reader (ReaderT)
+import           Data.Foldable (asum)
 import           Data.Text (Text)
 import qualified Data.Text as T
 import           Data.Void
@@ -17,7 +18,7 @@ import           Name
 import qualified Text.Megaparsec as P
 import qualified Text.Megaparsec.Char as P
 import qualified Text.Megaparsec.Char.Lexer as L
-import Wingman.Types (Context)
+import           Wingman.Types (Context)
 
 
 ------------------------------------------------------------------------------
@@ -45,6 +46,31 @@ sc = L.space P.space1 lineComment blockComment
 ichar :: Parser Char
 ichar = P.alphaNumChar <|> P.char '_' <|> P.char '\''
 
+symchar :: Parser Char
+symchar = asum
+  [ P.symbolChar
+  , P.char '!'
+  , P.char '#'
+  , P.char '$'
+  , P.char '%'
+  , P.char '^'
+  , P.char '&'
+  , P.char '*'
+  , P.char '-'
+  , P.char '='
+  , P.char '+'
+  , P.char ':'
+  , P.char '<'
+  , P.char '>'
+  , P.char ','
+  , P.char '.'
+  , P.char '/'
+  , P.char '?'
+  , P.char '~'
+  , P.char '|'
+  , P.char '\\'
+  ]
+
 lexeme :: Parser a -> Parser a
 lexeme = L.lexeme sc
 
@@ -66,14 +92,18 @@ parens = P.between (symbol "(") (symbol ")")
 identifier :: Text -> Parser ()
 identifier i = lexeme (P.string i *> P.notFollowedBy ichar)
 
--- FIXME [Reed M. 2020-10-18] Check to see if the variables are in the reserved list
 variable :: Parser OccName
 variable = lexeme $ do
-    c <- P.alphaNumChar
-    cs <- P.many ichar
-    pure $ mkVarOcc (c:cs)
+    c <- P.alphaNumChar <|> P.char '('
+    fmap mkVarOcc $ case c of
+      '(' -> do
+        cs <- P.many symchar
+        void $ P.char ')'
+        pure cs
+      _ -> do
+        cs <- P.many ichar
+        pure $ c : cs
 
--- FIXME [Reed M. 2020-10-18] Check to see if the variables are in the reserved list
 name :: Parser Text
 name = lexeme $ do
     c <- P.alphaNumChar

plugins/hls-tactics-plugin/test/CodeAction/RunMetaprogramSpec.hs

@@ -33,4 +33,5 @@ spec = do
     metaTest 11 11 "MetaUseMethod"
     metaTest  9 38 "MetaCataCollapse"
     metaTest  7 16 "MetaCataCollapseUnary"
+    metaTest  4 28 "MetaUseSymbol"
 

plugins/hls-tactics-plugin/test/golden/MetaUseSymbol.expected.hs

@@ -0,0 +1,4 @@
+import Data.Monoid
+
+resolve :: Sum Int
+resolve = _ <> _

plugins/hls-tactics-plugin/test/golden/MetaUseSymbol.hs

@@ -0,0 +1,4 @@
+import Data.Monoid
+
+resolve :: Sum Int
+resolve = [wingman| use (<>) |]