Fix: print line comment after arrow in lamda between paranthesis (#557)

* WIP: refactor IfThenElse

* WIP: refactor IfThenElse, more comments after keywords

* WIP: refactor IfThenElse, comments everywhere

* WIP: refactor IfThenElse, fix all tests

* WIP: refactor IfThenElse, added MaxIfThenElseShortWidth setting

* WIP: refactor IfThenElse, added MaxIfThenElseShortWidth setting to global tool

* Updated Documentation.md with --maxIfThenElseShortWidth

* Removed warnings introduced by IfThenElse refactor

* merged with master

docs/Documentation.md

@@ -183,6 +183,27 @@ match meh with
 
 will remain the same, the newline after `->` was detected and preserved.
 
+
+- `--maxIfThenElseShortWidth  <number>`: `number` if being set, controls when if/then/else expressions will be formatted as single line or as multiple lines.
+
+Fantomas tries to follow [the F# style guide](https://docs.microsoft.com/en-us/dotnet/fsharp/style-guide/formatting#formatting-if-expressions) as close as possible when formatting if expressions.
+
+The style guide says:
+
+> If either cond, e1 or e2 are longer, but not multi-line:
+
+```fsharp
+if cond
+then e1
+else e2
+```
+
+But what exactly is longer right? By default Fantomas will use 40 width to determine if the expression needs to be formatted to the example above or remain as a oneliner (`if cond then e1 else e2`).
+
+
+So if either `cond`, `e1` or `e2` is longer than `maxIfThenElseShortWidth` but not multiline, it will format on three lines.
+See [unit tests](https://github.com/fsprojects/fantomas/blob/9d4b499c09a1f06f5485835817844657cc51215b/src/Fantomas.Tests/IfThenElseTests.fs#L734) for more examples.
+
 That said, most of the preferences are very simple. 
 But they demonstrate the flexibility of Fantomas on a set of configurations. 
 More preferences will be added depending on use cases.

src/Fantomas.CoreGlobalTool/Program.fs

@@ -46,6 +46,7 @@ let [<Literal>] indentOnTryWithText = "Enable indentation on try/with block (def
 let [<Literal>] reorderOpenDeclarationText = "Enable reordering open declarations (default = false)."
 let [<Literal>] spaceAroundDelimiterText = "Disable spaces after starting and before ending of lists, arrays, sequences and records (default = true)."
 let [<Literal>] keepNewlineAfterText = "Keep newlines found after = in let bindings, -> in pattern matching and chained function calls (default = false)."
+let [<Literal>] maxIfThenElseShortWidthText = "Set the max length of any expression in an if expression before formatting on multiple lines (default = 40)."
 let [<Literal>] strictModeText = "Enable strict mode (ignoring directives and comments and printing literals in canonical forms) (default = false)."
 
 let time f =
@@ -129,6 +130,7 @@ let main _args =
     let spaceAroundDelimiter = ref FormatConfig.Default.SpaceAroundDelimiter
     let keepNewlineAfter = ref FormatConfig.Default.KeepNewlineAfter
     let strictMode = ref FormatConfig.Default.StrictMode
+    let maxIfThenElseShortWidth = ref FormatConfig.Default.MaxIfThenElseShortWidth
 
     let handleOutput s =
         if not !stdOut then
@@ -163,6 +165,13 @@ let main _args =
             eprintfn "Page width should be at least 60."
             exit 1
 
+    let handleMaxIfThenElseShortWidth i =
+        if i >= 0 then
+            maxIfThenElseShortWidth := i
+        else
+            eprintfn "Max IfThenElse short width should be greater than zero."
+            exit 1
+
     let fileToFile (inFile : string) (outFile : string) config =
         try
             printfn "Processing %s" inFile
@@ -244,7 +253,8 @@ let main _args =
            ArgInfo("--reorderOpenDeclaration", ArgType.Set reorderOpenDeclaration, reorderOpenDeclarationText);
 
            ArgInfo("--noSpaceAroundDelimiter", ArgType.Clear spaceAroundDelimiter, spaceAroundDelimiterText);
-           ArgInfo("--keepNewlineAfter", ArgType.Set keepNewlineAfter, keepNewlineAfterText);
+           ArgInfo("--keepNewlineAfter", ArgType.Set keepNewlineAfter, keepNewlineAfterText)
+           ArgInfo("--maxIfThenElseShortWidth", ArgType.Int handleMaxIfThenElseShortWidth, maxIfThenElseShortWidthText);
            ArgInfo("--strictMode", ArgType.Set strictMode, strictModeText) |]
 
     ArgParser.Parse(options, handleInput, sprintf "Fantomas <input_path>%sCheck out https://github.com/fsprojects/fantomas/blob/master/docs/Documentation.md#using-the-command-line-tool for more info." Environment.NewLine )
@@ -262,7 +272,8 @@ let main _args =
             ReorderOpenDeclaration = !reorderOpenDeclaration
             SpaceAroundDelimiter = !spaceAroundDelimiter
             StrictMode = !strictMode
-            KeepNewlineAfter = !keepNewlineAfter }
+            KeepNewlineAfter = !keepNewlineAfter
+            MaxIfThenElseShortWidth = !maxIfThenElseShortWidth }
 
     // Handle inputs via pipeline
     let isKeyAvailable = ref false

src/Fantomas.Tests/ActivePatternTests.fs

@@ -47,18 +47,15 @@ let (|ParseRegex|_|) regex str =
     |> prepend newline
     |> should equal """
 let (|Even|Odd|) input =
-    if input % 2 = 0 then Even
-    else Odd
+    if input % 2 = 0 then Even else Odd
 
 let (|Integer|_|) (str: string) =
     let mutable intvalue = 0
-    if System.Int32.TryParse(str, &intvalue) then Some(intvalue)
-    else None
+    if System.Int32.TryParse(str, &intvalue) then Some(intvalue) else None
 
 let (|ParseRegex|_|) regex str =
     let m = Regex(regex).Match(str)
-    if m.Success then
-        Some(List.tail [ for x in m.Groups -> x.Value ])
-    else
-        None
+    if m.Success
+    then Some(List.tail [ for x in m.Groups -> x.Value ])
+    else None
 """

src/Fantomas.Tests/CommentTests.fs

@@ -326,12 +326,15 @@ else
 """  config
     |> prepend newline
     |> should equal """
-if a then ()
+if a then
+    ()
 else
-    // Comment 1
-    if b then ()
-    // Comment 2
-    else ()
+// Comment 1
+if b then
+    ()
+// Comment 2
+else
+    ()
 """
 
 [<Test>]
@@ -643,12 +646,13 @@ type substring =
     /// <returns>An integer that indicates the lexical relationship between the two comparands.</returns>
     static member CompareOrdinal(strA: substring, strB: substring) =
         // If both substrings are empty they are considered equal, regardless of their offset or underlying string.
-        if strA.Length = 0 && strB.Length = 0 then 0
-        elif
+        if strA.Length = 0 && strB.Length = 0 then
+            0
 
-            // OPTIMIZATION : If the substrings have the same (identical) underlying string
-            // and offset, the comparison value will depend only on the length of the substrings.
-            strA.String == strB.String && strA.Offset = strB.Offset then compare strA.Length strB.Length
+        // OPTIMIZATION : If the substrings have the same (identical) underlying string
+        // and offset, the comparison value will depend only on the length of the substrings.
+        elif strA.String == strB.String && strA.Offset = strB.Offset then
+            compare strA.Length strB.Length
 
         else
             (* Structural comparison on substrings -- this uses the same comparison
@@ -675,8 +679,10 @@ if true then //comment
 else 0""" config
     |> prepend newline
     |> should equal """
-if true then 1 //comment
-else 0
+if true then //comment
+    1
+else
+    0
 """
 
 [<Test>]
@@ -687,8 +693,11 @@ if //comment
 else 0""" config
     |> prepend newline
     |> should equal """
-if true then 1 //comment
-else 0
+if //comment
+    true then
+    1
+else
+    0
 """
 
 [<Test>]
@@ -699,6 +708,8 @@ else //comment
     0""" config
     |> prepend newline
     |> should equal """
-if true then 1
-else 0 //comment
+if true then
+    1
+else //comment
+    0
 """

src/Fantomas.Tests/ControlStructureTests.fs

@@ -27,8 +27,7 @@ then printfn "You are only %d years old and already learning F#? Wow!" age""" co
 let rec tryFindMatch pred list =
     match list with
     | head :: tail ->
-        if pred (head) then Some(head)
-        else tryFindMatch pred tail
+        if pred (head) then Some(head) else tryFindMatch pred tail
     | [] -> None
 
 let test x y =
@@ -138,8 +137,7 @@ let ``try/with and finally``() =
 let function1 x y =
     try
         try
-            if x = y then raise (InnerError("inner"))
-            else raise (OuterError("outer"))
+            if x = y then raise (InnerError("inner")) else raise (OuterError("outer"))
         with
         | Failure _ -> ()
         | InnerError(str) -> printfn "Error1 %s" str
@@ -222,9 +220,10 @@ let x =
 let x =
     if try
         true
-       with Failure _ -> false
-    then ()
-    else ()
+       with Failure _ -> false then
+        ()
+    else
+        ()
 """
 
 [<Test>]
@@ -297,8 +296,7 @@ let ``multiline if in tuple``() =
     """ config
     |> prepend newline
     |> should equal """
-((if true then 1
-  else 2), 3)
+((if true then 1 else 2), 3)
 """
 
 // https://docs.microsoft.com/en-us/dotnet/fsharp/style-guide/formatting#formatting-if-expressions
@@ -435,9 +433,8 @@ let a ex =
     if null = ex then
         fooo()
         None
-    elif
-        // this was None
-        ex.GetType() = typeof<obj> then
+    // this was None
+    elif ex.GetType() = typeof<obj> then
         Some ex
     else
         None

src/Fantomas.Tests/DynamicOperatorTests.fs

@@ -28,7 +28,8 @@ let ``keep () when dynamic operator inside boolean expr, #476`` () =
     |> prepend newline
     |> should equal """
 let fieldColor (fieldNameX: string) =
-    if f.errors?(fieldNameY) && f.touched?(fieldNameZ) then IsDanger
+    if f.errors?(fieldNameY) && f.touched?(fieldNameZ)
+    then IsDanger
     else NoColor
     |> Input.Color
 """

src/Fantomas.Tests/Fantomas.Tests.fsproj

@@ -56,6 +56,7 @@
     <Compile Include="KeepNewlineAfterTests.fs" />
     <Compile Include="ElmishTests.fs" />
     <Compile Include="LambdaTests.fs" />
+    <Compile Include="IfThenElseTests.fs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Fantomas\Fantomas.fsproj" />