Add support for single-line if expressions

Closes #209

Author: rlefevre

parser/src/AST/Expression.hs

@@ -59,7 +59,7 @@ data Expr'
     | AccessFunction LowercaseIdentifier
 
     | Lambda [(Comments, Pattern.Pattern)] Comments Expr Bool
-    | If IfClause [(Comments, IfClause)] (Comments, Expr)
+    | If IfClause [(Comments, IfClause)] (Comments, Expr) Bool
     | Let [LetDeclaration] Comments Expr
     | Case (Commented Expr, Bool) [(Commented Pattern.Pattern, (Comments, Expr))]
 

parser/src/AST/Json.hs

@@ -373,7 +373,7 @@ instance ToJSON Expr where
                   , ("body", showJSON body)
                   ]
 
-          If (Commented _ cond' _, Commented _ thenBody' _) rest' (_, elseBody) ->
+          If (Commented _ cond' _, Commented _ thenBody' _) rest' (_, elseBody) _ ->
               let
                   ifThenElse :: Expr -> Expr -> [(Comments, IfClause)] -> JSValue
                   ifThenElse cond thenBody rest =

parser/src/Parse/Expression.hs

@@ -191,11 +191,18 @@ ifExpr elmVersion =
         >> whitespace
   in
     do
-      first <- ifClause elmVersion
-      rest <- many (try $ (,) <$> elseKeyword <*> ifClause elmVersion)
-      final <- (,) <$> elseKeyword <*> expr elmVersion
+      (first, firstMultiline) <- trackNewline $ ifClause elmVersion
+      (rest, restMultiline) <- trackNewline $ many (try $ (,) <$> elseKeyword <*> ifClause elmVersion)
+      (final, finalMultiline) <- trackNewline $ (,) <$> elseKeyword <*> expr elmVersion
 
-      return $ E.If first rest final
+
+      return $ E.If first rest final $
+          case (firstMultiline, restMultiline, finalMultiline) of
+            (JoinAll, JoinAll, JoinAll) ->
+                multilineToBool JoinAll
+
+            _ ->
+                multilineToBool SplitAll
 
 
 ifClause :: ElmVersion -> IParser E.IfClause

src/AST/MapExpr.hs

@@ -81,8 +81,8 @@ instance MapExpr Expr' where
         AccessFunction _ -> expr
         Lambda params pre body multi ->
             Lambda params pre (mapExpr f body) multi
-        If c1 elseIfs els ->
-            If (mapExpr f c1) (mapExpr f elseIfs) (mapExpr f els)
+        If c1 elseIfs els multiline ->
+            If (mapExpr f c1) (mapExpr f elseIfs) (mapExpr f els) multiline
         Let decls pre body ->
             Let (mapExpr f decls) pre body
         Case cond branches ->

src/ElmFormat/Render/Box.hs

@@ -1407,57 +1407,59 @@ formatExpression' elmVersion importInfo context aexpr =
                 (fmap (formatPreCommentedExpression elmVersion importInfo SpaceSeparated) args)
                 |> expressionParens SpaceSeparated context
 
-        AST.Expression.If if' elseifs (elsComments, els) ->
-            let
-                opening key cond =
-                    case (key, cond) of
-                        (SingleLine key', SingleLine cond') ->
-                            line $ row
-                                [ key'
-                                , space
-                                , cond'
-                                , space
-                                , keyword "then"
-                                ]
-                        _ ->
+        AST.Expression.If (cond, body) elseifs (elsComments, els) multiline ->
+            case
+                ( multiline
+                , formatCommentedExpression elmVersion importInfo SyntaxSeparated cond
+                , formatCommented_ True (formatExpression elmVersion importInfo SyntaxSeparated) body
+                , elseifs
+                , formatCommented_ True (formatExpression elmVersion importInfo SyntaxSeparated) (AST.Commented elsComments els [])
+                )
+            of
+                (False,  SingleLine cond',  SingleLine body', [], SingleLine els') ->
+                    line $ row
+                        [ keyword "if" , space , cond' , space , keyword "then" , space , body' , space , keyword "else" , space , els' ]
+                (_, ifCond, thenBody, _, elseBody) ->
+                    let
+                        opening (SingleLine key) (SingleLine cond') =
+                            line $ row [ key , space , cond' , space , keyword "then" ]
+                        opening key cond' =
                             stack1
                                 [ key
-                                , cond |> indent
+                                , cond' |> indent
                                 , line $ keyword "then"
                                 ]
 
-                formatIf (cond, body) =
+                        formatElseIf (ifComments, (cond', body')) =
+                            let
+                                key =
+                                    case (formatHeadCommented id (ifComments, line $ keyword "if")) of
+                                        SingleLine key' ->
+                                            line $ row [ keyword "else", space, key' ]
+                                        key' ->
+                                            stack1
+                                                [ line $ keyword "else"
+                                                , key'
+                                                ]
+                            in
+                            stack1
+                                [ blankLine
+                                , opening key $ formatCommentedExpression elmVersion importInfo SyntaxSeparated cond'
+                                , indent $ formatCommented_ True (formatExpression elmVersion importInfo SyntaxSeparated) body'
+                                ]
+                    in
                     stack1
-                        [ opening (line $ keyword "if") $ formatCommentedExpression elmVersion importInfo SyntaxSeparated cond
-                        , indent $ formatCommented_ True (formatExpression elmVersion importInfo SyntaxSeparated) body
+                        [ opening (line $ keyword "if") ifCond
+                        , indent thenBody
                         ]
-
-                formatElseIf (ifComments, (cond, body)) =
-                  let
-                    key =
-                      case (formatHeadCommented id (ifComments, line $ keyword "if")) of
-                        SingleLine key' ->
-                          line $ row [ keyword "else", space, key' ]
-                        key' ->
-                          stack1
-                            [ line $ keyword "else"
-                            , key'
+                        |> andThen (map formatElseIf elseifs)
+                        |> andThen
+                            [ blankLine
+                            , line $ keyword "else"
+                            , indent $ elseBody
                             ]
-                  in
-                    stack1
-                      [ blankLine
-                      , opening key $ formatCommentedExpression elmVersion importInfo SyntaxSeparated cond
-                      , indent $ formatCommented_ True (formatExpression elmVersion importInfo SyntaxSeparated) body
-                      ]
-            in
-                formatIf if'
-                    |> andThen (map formatElseIf elseifs)
-                    |> andThen
-                        [ blankLine
-                        , line $ keyword "else"
-                        , indent $ formatCommented_ True (formatExpression elmVersion importInfo SyntaxSeparated) (AST.Commented elsComments els [])
-                        ]
-                    |> expressionParens AmbiguousEnd context
+            |> expressionParens AmbiguousEnd context
+
 
         AST.Expression.Let defs bodyComments expr ->
             let

tests/Parse/ExpressionTest.hs

@@ -259,10 +259,10 @@ tests =
         ]
 
     , testGroup "if statement"
-        [ example "" "if x then y else z" $ at 1 1 1 19 (If (Commented [] (at 1 4 1 5 (VarExpr (VarRef [] $ LowercaseIdentifier "x"))) [],Commented [] (at 1 11 1 12 (VarExpr (VarRef [] $ LowercaseIdentifier "y"))) []) [] ([],at 1 18 1 19 (VarExpr (VarRef [] $ LowercaseIdentifier "z"))))
-        , example "comments" "if{-A-}x{-B-}then{-C-}y{-D-}else{-E-}if{-F-}x_{-G-}then{-H-}y_{-I-}else{-J-}z" $ at 1 1 1 78 (If (Commented [BlockComment ["A"]] (at 1 8 1 9 (VarExpr (VarRef [] $ LowercaseIdentifier "x"))) [BlockComment ["B"]],Commented [BlockComment ["C"]] (at 1 23 1 24 (VarExpr (VarRef [] $ LowercaseIdentifier "y"))) [BlockComment ["D"]]) [([BlockComment ["E"]],(Commented [BlockComment ["F"]] (at 1 45 1 47 (VarExpr (VarRef [] $ LowercaseIdentifier "x_"))) [BlockComment ["G"]],Commented [BlockComment ["H"]] (at 1 61 1 63 (VarExpr (VarRef [] $ LowercaseIdentifier "y_"))) [BlockComment ["I"]]))] ([BlockComment ["J"]],at 1 77 1 78 (VarExpr (VarRef [] $ LowercaseIdentifier "z"))))
-        , example "else if" "if x1 then y1 else if x2 then y2 else if x3 then y3 else z" $ at 1 1 1 59 (If (Commented [] (at 1 4 1 6 (VarExpr (VarRef [] $ LowercaseIdentifier "x1"))) [],Commented [] (at 1 12 1 14 (VarExpr (VarRef [] $ LowercaseIdentifier "y1"))) []) [([],(Commented [] (at 1 23 1 25 (VarExpr (VarRef [] $ LowercaseIdentifier "x2"))) [],Commented [] (at 1 31 1 33 (VarExpr (VarRef [] $ LowercaseIdentifier "y2"))) [])),([],(Commented [] (at 1 42 1 44 (VarExpr (VarRef [] $ LowercaseIdentifier "x3"))) [],Commented [] (at 1 50 1 52 (VarExpr (VarRef [] $ LowercaseIdentifier "y3"))) []))] ([],at 1 58 1 59 (VarExpr (VarRef [] $ LowercaseIdentifier "z"))))
-        , example "newlines" "if\n x\n then\n y\n else\n z" $ at 1 1 6 3 (If (Commented [] (at 2 2 2 3 (VarExpr (VarRef [] $ LowercaseIdentifier "x"))) [],Commented [] (at 4 2 4 3 (VarExpr (VarRef [] $ LowercaseIdentifier "y"))) []) [] ([],at 6 2 6 3 (VarExpr (VarRef [] $ LowercaseIdentifier "z"))))
+        [ example "" "if x then y else z" $ at 1 1 1 19 (If (Commented [] (at 1 4 1 5 (VarExpr (VarRef [] $ LowercaseIdentifier "x"))) [],Commented [] (at 1 11 1 12 (VarExpr (VarRef [] $ LowercaseIdentifier "y"))) []) [] ([],at 1 18 1 19 (VarExpr (VarRef [] $ LowercaseIdentifier "z"))) False)
+        , example "comments" "if{-A-}x{-B-}then{-C-}y{-D-}else{-E-}if{-F-}x_{-G-}then{-H-}y_{-I-}else{-J-}z" $ at 1 1 1 78 (If (Commented [BlockComment ["A"]] (at 1 8 1 9 (VarExpr (VarRef [] $ LowercaseIdentifier "x"))) [BlockComment ["B"]],Commented [BlockComment ["C"]] (at 1 23 1 24 (VarExpr (VarRef [] $ LowercaseIdentifier "y"))) [BlockComment ["D"]]) [([BlockComment ["E"]],(Commented [BlockComment ["F"]] (at 1 45 1 47 (VarExpr (VarRef [] $ LowercaseIdentifier "x_"))) [BlockComment ["G"]],Commented [BlockComment ["H"]] (at 1 61 1 63 (VarExpr (VarRef [] $ LowercaseIdentifier "y_"))) [BlockComment ["I"]]))] ([BlockComment ["J"]],at 1 77 1 78 (VarExpr (VarRef [] $ LowercaseIdentifier "z"))) False)
+        , example "else if" "if x1 then y1 else if x2 then y2 else if x3 then y3 else z" $ at 1 1 1 59 (If (Commented [] (at 1 4 1 6 (VarExpr (VarRef [] $ LowercaseIdentifier "x1"))) [],Commented [] (at 1 12 1 14 (VarExpr (VarRef [] $ LowercaseIdentifier "y1"))) []) [([],(Commented [] (at 1 23 1 25 (VarExpr (VarRef [] $ LowercaseIdentifier "x2"))) [],Commented [] (at 1 31 1 33 (VarExpr (VarRef [] $ LowercaseIdentifier "y2"))) [])),([],(Commented [] (at 1 42 1 44 (VarExpr (VarRef [] $ LowercaseIdentifier "x3"))) [],Commented [] (at 1 50 1 52 (VarExpr (VarRef [] $ LowercaseIdentifier "y3"))) []))] ([],at 1 58 1 59 (VarExpr (VarRef [] $ LowercaseIdentifier "z"))) False)
+        , example "newlines" "if\n x\n then\n y\n else\n z" $ at 1 1 6 3 (If (Commented [] (at 2 2 2 3 (VarExpr (VarRef [] $ LowercaseIdentifier "x"))) [],Commented [] (at 4 2 4 3 (VarExpr (VarRef [] $ LowercaseIdentifier "y"))) []) [] ([],at 6 2 6 3 (VarExpr (VarRef [] $ LowercaseIdentifier "z"))) True)
         ]
 
     , testGroup "let statement"

tests/test-files/transform/Elm-0.18/Examples.formatted.elm

@@ -2,31 +2,15 @@ module Main exposing (bar, multilineList, ratio)
 
 
 ratio =
-    graphHeight
-        / (if range == 0 then
-            0.1
-
-           else
-            toFloat range
-          )
+    graphHeight / (if range == 0 then 0.1 else toFloat range)
 
 
 
 -- foo=(case x of {True->1;False->3})
 
 
 bar =
-    if
-        if a then
-            True
-
-        else
-            False
-    then
-        "a"
-
-    else
-        "b"
+    if if a then True else False then "a" else "b"
 
 
 multilineList =