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feat: Add linter to detect
ifs that should be switches.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,71 @@ | ||
| {-# LANGUAGE OverloadedStrings #-} | ||
| {-# LANGUAGE PatternSynonyms #-} | ||
| {-# LANGUAGE Strict #-} | ||
| {-# LANGUAGE StrictData #-} | ||
| module Tokstyle.Linter.SwitchIf (analyse) where | ||
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| import Control.Monad.State.Strict (State) | ||
| import qualified Control.Monad.State.Strict as State | ||
| import Data.Fix (Fix (..)) | ||
| import Data.List (nub) | ||
| import Data.Text (Text) | ||
| import Language.Cimple (BinaryOp (..), Lexeme (..), | ||
| LiteralType (..), Node, | ||
| NodeF (..), lexemeText) | ||
| import Language.Cimple.Diagnostics (warn) | ||
| import Language.Cimple.TraverseAst (AstActions, astActions, doNode, | ||
| traverseAst) | ||
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| pattern EqualsConst :: Lexeme Text -> Node (Lexeme Text) | ||
| pattern EqualsConst lhs <- Fix (BinaryExpr (Fix (VarExpr lhs)) BopEq (Fix (LiteralExpr ConstId _))) | ||
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| data IfInfo = IfInfo | ||
| { ifConds :: Maybe [(Text, Lexeme Text)] | ||
| , ifBranches :: [Node (Lexeme Text)] | ||
| } deriving (Show) | ||
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| instance Semigroup IfInfo where | ||
| a <> b = IfInfo ((<>) <$> ifConds a <*> ifConds b) (ifBranches a <> ifBranches b) | ||
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| collectInfo :: Node (Lexeme Text) -> IfInfo | ||
| collectInfo (Fix (IfStmt (EqualsConst lhs) t Nothing)) = | ||
| IfInfo (Just [(lexemeText lhs, lhs)]) [t] | ||
| collectInfo (Fix (IfStmt (EqualsConst lhs) t (Just e))) = | ||
| IfInfo (Just [(lexemeText lhs, lhs)]) [t] <> collectInfo e | ||
| collectInfo (Fix (IfStmt _ t Nothing)) = | ||
| IfInfo Nothing [t] | ||
| collectInfo (Fix (IfStmt _ t (Just e))) = | ||
| IfInfo Nothing [t] <> collectInfo e | ||
| collectInfo e = | ||
| IfInfo (Just []) [e] | ||
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| shouldDiagnose :: [(Text, Lexeme Text)] -> [Node (Lexeme Text)] -> Bool | ||
| shouldDiagnose cs branches = | ||
| length cs >= 2 && length (nub $ map fst cs) == 1 && not (all singleStatement branches) | ||
| where | ||
| singleStatement (Fix (CompoundStmt [_])) = True | ||
| singleStatement _ = False | ||
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| linter :: AstActions (State [Text]) Text | ||
| linter = astActions | ||
| { doNode = \file node act -> | ||
| case unFix node of | ||
| IfStmt{} -> do | ||
| let info = collectInfo node | ||
| case ifConds info of | ||
| Just cs@((_, c):_) | shouldDiagnose cs (ifBranches info) -> | ||
| warn file c "if-statement could be a switch" | ||
| _ -> return () | ||
| traverseAst linter (file, ifBranches info) | ||
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| _ -> act | ||
| } | ||
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| analyse :: (FilePath, [Node (Lexeme Text)]) -> [Text] | ||
| analyse = reverse . flip State.execState [] . traverseAst linter |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,126 @@ | ||
| {-# LANGUAGE OverloadedStrings #-} | ||
| module Tokstyle.Linter.SwitchIfSpec where | ||
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| import Test.Hspec (Spec, it, shouldBe) | ||
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| import Tokstyle.Linter (analyse) | ||
| import Tokstyle.LinterSpec (mustParse) | ||
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| spec :: Spec | ||
| spec = do | ||
| it "accepts a single if/else" $ do | ||
| ast <- mustParse | ||
| [ "bool a(int b) {" | ||
| , " if (b == THE_FOO) {" | ||
| , " print_int(b);" | ||
| , " return true;" | ||
| , " } else {" | ||
| , " return false;" | ||
| , " }" | ||
| , "}" | ||
| ] | ||
| analyse ["switch-if"] ("test.c", ast) `shouldBe` [] | ||
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| it "ignores candidates where all branches are single statements" $ do | ||
| ast <- mustParse | ||
| [ "int a(int b) {" | ||
| , " if (b == THE_FOO) {" | ||
| , " return 0;" | ||
| , " } else if (b == THE_BAR) {" | ||
| , " return 1;" | ||
| , " }" | ||
| , "}" | ||
| ] | ||
| analyse ["switch-if"] ("test.c", ast) `shouldBe` [] | ||
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| it "diagnoses a series of if/else-if statements as candidate for switch" $ do | ||
| ast <- mustParse | ||
| [ "int a(int b) {" | ||
| , " if (b == THE_FOO) {" | ||
| , " print_int(b);" | ||
| , " return 0;" | ||
| , " } else if (b == THE_BAR) {" | ||
| , " return 1;" | ||
| , " }" | ||
| , "}" | ||
| ] | ||
| analyse ["switch-if"] ("test.c", ast) | ||
| `shouldBe` | ||
| [ "test.c:2: if-statement could be a switch [-Wswitch-if]" | ||
| ] | ||
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| it "diagnoses a series of if/else-if statements ending in `else` as candidate for switch" $ do | ||
| ast <- mustParse | ||
| [ "int a(int b) {" | ||
| , " if (b == THE_FOO) {" | ||
| , " print_int(b);" | ||
| , " return 0;" | ||
| , " } else if (b == THE_BAR) {" | ||
| , " return 1;" | ||
| , " } else {" | ||
| , " return 2;" | ||
| , " }" | ||
| , "}" | ||
| ] | ||
| analyse ["switch-if"] ("test.c", ast) | ||
| `shouldBe` | ||
| [ "test.c:2: if-statement could be a switch [-Wswitch-if]" | ||
| ] | ||
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| it "diagnoses a candidates for switch nested inside another `if`" $ do | ||
| ast <- mustParse | ||
| [ "int a(int b) {" | ||
| , " if (b != something) {" | ||
| , " if (b == THE_FOO) {" | ||
| , " print_int(b);" | ||
| , " return 0;" | ||
| , " } else if (b == THE_BAR) {" | ||
| , " return 1;" | ||
| , " } else {" | ||
| , " return 2;" | ||
| , " }" | ||
| , " }" | ||
| , "}" | ||
| ] | ||
| analyse ["switch-if"] ("test.c", ast) | ||
| `shouldBe` | ||
| [ "test.c:3: if-statement could be a switch [-Wswitch-if]" | ||
| ] | ||
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| it "diagnoses a candidates for switch nested inside an `else if`" $ do | ||
| ast <- mustParse | ||
| [ "int a(int b) {" | ||
| , " if (b != something) {" | ||
| , " /* nop */" | ||
| , " } else if (b != another_thing) {" | ||
| , " if (b == THE_FOO) {" | ||
| , " print_int(b);" | ||
| , " return 0;" | ||
| , " } else if (b == THE_BAR) {" | ||
| , " return 1;" | ||
| , " } else {" | ||
| , " return 2;" | ||
| , " }" | ||
| , " }" | ||
| , "}" | ||
| ] | ||
| analyse ["switch-if"] ("test.c", ast) | ||
| `shouldBe` | ||
| [ "test.c:5: if-statement could be a switch [-Wswitch-if]" | ||
| ] | ||
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| it "ignores if/else-if statements with different comparison targets" $ do | ||
| ast <- mustParse | ||
| [ "int a(int b, int c) {" | ||
| , " if (b == THE_FOO) {" | ||
| , " print_int(b);" | ||
| , " return 0;" | ||
| , " } else if (c == THE_BAR) {" | ||
| , " return 1;" | ||
| , " } else {" | ||
| , " return 2;" | ||
| , " }" | ||
| , "}" | ||
| ] | ||
| analyse ["switch-if"] ("test.c", ast) `shouldBe` [] |
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