WIP (add-parens-to-binary)

elm-format.cabal

@@ -91,6 +91,7 @@ library
         ElmFormat.Filesystem
         ElmFormat.FileStore
         ElmFormat.Operation
+        ElmFormat.Render.GroupBinops
         ElmFormat.Version
         Flags
         Messages.Formatter.Format

src/ElmFormat/Render/Box.hs

@@ -21,6 +21,7 @@ import Data.Maybe (fromMaybe, maybeToList)
 import qualified Data.Text as Text
 import qualified ElmFormat.Render.ElmStructure as ElmStructure
 import qualified ElmFormat.Render.Markdown
+import qualified ElmFormat.Render.GroupBinops as GroupBinops
 import qualified ElmFormat.Version
 import qualified Parse.Parse as Parse
 import qualified Reporting.Annotation as RA
@@ -791,7 +792,7 @@ formatDefinition elmVersion name args comments expr =
     body =
       stack1 $ concat
         [ map formatComment comments
-        , [ formatExpression elmVersion SyntaxSeparated expr ]
+        , [ formatExpression elmVersion SyntaxSeparated (GroupBinops.extractAnds expr) ] -- TODO: use extractAnds for all expressions
         ]
   in
     ElmStructure.definition "=" True

src/ElmFormat/Render/GroupBinops.hs

@@ -0,0 +1,72 @@
+module ElmFormat.Render.GroupBinops (extractAnds) where
+
+import AST.V0_16
+import AST.Expression
+import Reporting.Annotation
+import qualified AST.Variable as Var
+import qualified Reporting.Region as Region
+
+
+-- TODO: handle Ors also
+-- TODO: ensure it only groups comparison operators?
+-- TODO: make it work for expression that aren't directly the body of a definition
+extractAnds :: Expr -> Expr
+extractAnds expr =
+    case expr of
+        A loc (Binops left ops multiline) ->
+            A loc $ done multiline $ foldl step (left, [], []) ops
+
+        _ ->
+            expr
+
+
+type State = (Expr, [(Comments, Var.Ref, Comments, Expr)], [(Expr, Var.Ref)])
+
+shiftReverse :: [(a, b)] -> a -> [(b, a)] -> (a, [(b, a)])
+shiftReverse [] last acc = (last, acc)
+shiftReverse ((prev, op):rest) last acc =
+    shiftReverse rest prev ((op, last) : acc)
+
+
+step :: State -> (Comments, Var.Ref, Comments, Expr) -> State
+step (left, inners, conditions) (pre, op, post, next) =  -- TODO: Handle comments
+  case op of
+    Var.OpRef (SymbolIdentifier opSymbol) ->
+      if opSymbol == "&&" || opSymbol == "<|" then
+        ( next, [], (Var.OpRef (SymbolIdentifier opSymbol), packageCondition left inners) : conditions )
+      else
+        ( left, (pre, op, post, next) : inners, conditions )
+
+    _ ->
+      ( left, (pre, op, post, next) : inners, conditions )
+
+
+packageCondition :: Expr -> [(Comments, Var.Ref, Comments, Expr)] -> Expr
+packageCondition left [] = left
+packageCondition left inners =
+    noRegion $ Binops left (reverse inners) False
+
+
+done :: Bool -> State -> Expr'
+done multiline (left, inners, []) = (Binops left (reverse inners) multiline)
+done multiline (left, inners, conditions) =
+  let
+    finalConditions =
+      reverse $ packageCondition left inners : conditions
+
+    buildOp right =
+      ([], Var.OpRef (SymbolIdentifier "&&"), [], right)
+  in
+    case finalConditions of
+      first : r ->
+        (Binops first (fmap buildOp r) multiline)
+
+
+nowhere :: Region.Position
+nowhere =
+    Region.Position 0 0
+
+
+noRegion :: a -> Located a
+noRegion =
+    at nowhere nowhere

tests/run-tests.sh

@@ -297,6 +297,8 @@ echo "# elm-format test suite"
 
 checkWaysToRun
 
+checkTransformation 0.18 AddParensForAndOr.elm
+
 checkGood 0.16 Simple.elm
 checkGood 0.16 AllSyntax/0.16/AllSyntax.elm
 checkGoodAllSyntax 0.16 Module

tests/test-files/transform/AddParensForAndOr.elm

@@ -0,0 +1,43 @@
+
+
+addParensToAnd =
+    1 == 2 && 3 /= 4 && 5 < 6 && 7 > 8 && 9 <= 10 && 11 >= 12
+
+addParensToAndWithComplexConditions =
+    1 == 2 + 3 && 4 /= 5 && 6 < 7 + 8 && 9 > 10 && 11 <= 12 && 13 >= 14 + 15
+
+addParensToAndMultiline =
+    1
+    == 2 && 3 /= 4 && 5 < 6 && 7 > 8 && 9 <= 10 && 11 >= 12
+
+makesGroupedExpressionsSingleLine =
+  1
+    ==
+      2
+    +
+      7
+    *
+      5
+    -
+      6
+    +
+      -8
+    &&
+      3
+    /=
+      4
+
+
+doesntAddParensAroundParens =
+  (1 == 2) && (3 /= 4) && 5/= 6 && (7 /= 8)
+
+keepsNewLinesInExistingParens =
+  (1
+    == 2
+    + 3 * 4 - 5 + 6) && 7 /= 8
+
+doesntGroupPipes f =
+  f <| True && False
+
+doesntGroupPipes2 f =
+  True && False |> f

tests/test-files/transform/AddParensForAndOr.formatted.elm

@@ -0,0 +1,38 @@
+module Main exposing (..)
+
+
+addParensToAnd =
+    (1 == 2) && (3 /= 4) && (5 < 6) && (7 > 8) && (9 <= 10) && (11 >= 12)
+
+
+addParensToAndWithComplexConditions =
+    (1 == 2 + 3) && (4 /= 5) && (6 < 7 + 8) && (9 > 10) && (11 <= 12) && (13 >= 14 + 15)
+
+
+addParensToAndMultiline =
+    (1 == 2)
+        && (3 /= 4)
+        && (5 < 6)
+        && (7 > 8)
+        && (9 <= 10)
+        && (11 >= 12)
+
+
+makesGroupedExpressionsSingleLine =
+    (1 == 2 + 7 * 5 - 6 + -8)
+        && (3 /= 4)
+
+
+doesntAddParensAroundParens =
+    (1 == 2) && (3 /= 4) && (5 /= 6) && (7 /= 8)
+
+
+keepsNewLinesInExistingParens =
+    (1
+        == 2
+        + 3
+        * 4
+        - 5
+        + 6
+    )
+        && (7 /= 8)