Fix unnecessary big indentation (fsprojects#418)

* atColumn

* delayed atColumn

* TestExternalProjects: add fulma-demo

* atColumn fixes

* tests update

* comments

* merge fix

* merge fix

* comments

src/Fantomas.Tests/ClassTests.fs

@@ -345,7 +345,7 @@ System.String.Concat
     ("a",
      "b"
      + (longNamedFunlongNamedFunlongNamedFunlongNamedFunlongNamedFun
-            (longNamedClasslongNamedClasslongNamedClasslongNamedClasslongNamedClasslongNamedClass)).Property)
+         (longNamedClasslongNamedClasslongNamedClasslongNamedClasslongNamedClasslongNamedClass)).Property)
 """
 
 [<Test>]
@@ -360,5 +360,5 @@ type Exception with
 type Exception with
     member inline __.FirstLine =
         (__.Message.Split
-             ([| Environment.NewLine |], StringSplitOptions.RemoveEmptyEntries)).[0]
+            ([| Environment.NewLine |], StringSplitOptions.RemoveEmptyEntries)).[0]
 """

src/Fantomas.Tests/ControlStructureTests.fs

@@ -222,7 +222,7 @@ let x =
     |> should equal """
 let x =
     if try
-           true
+        true
        with Failure _ -> false
     then ()
     else ()

src/Fantomas.Tests/DataStructureTests.fs

@@ -108,8 +108,8 @@ let ``should keep -> notation``() =
     |> should equal """
 let environVars target =
     [ for e in Environment.GetEnvironmentVariables target ->
-          let e1 = e :?> Collections.DictionaryEntry
-          e1.Key, e1.Value ]
+        let e1 = e :?> Collections.DictionaryEntry
+        e1.Key, e1.Value ]
 """
 
 [<Test>]
@@ -140,7 +140,7 @@ let a2 = [| 0..99 |]
 
 let a3 =
     [| for n in 1..100 do
-           if isPrime n then yield n |]
+        if isPrime n then yield n |]
 """
 
 [<Test>]

src/Fantomas.Tests/FormattingSelectionTests.fs

@@ -223,7 +223,7 @@ let a3 =
     |> should equal """
 let a3 =
     [| for n in 1..100 do
-           if isPrime n then yield n |]"""
+        if isPrime n then yield n |]"""
 
 [<Test>]
 let ``should format around the cursor inside an object expression``() =
@@ -233,7 +233,7 @@ let ``should format around the cursor inside an object expression``() =
     |> should equal """
 let obj1 =
     { new System.Object() with
-          member x.ToString() = "F#" }"""
+        member x.ToString() = "F#" }"""
 
 [<Test>]
 let ``should format around the cursor inside a computation expression``() =

src/Fantomas.Tests/InterfaceTests.fs

@@ -55,7 +55,7 @@ let ``object expressions``() =
     |> should equal """
 let obj1 =
     { new System.Object() with
-          member x.ToString() = "F#" }
+        member x.ToString() = "F#" }
 """
 
 [<Test>]
@@ -72,8 +72,8 @@ let ``object expressions and interfaces``() =
     |> should equal """
 let implementer() =
     { new ISecond with
-          member this.H() = ()
-          member this.J() = ()
+        member this.H() = ()
+        member this.J() = ()
       interface IFirst with
           member this.F() = ()
           member this.G() = () }
@@ -92,7 +92,7 @@ let f () =
     |> should equal """
 let f() =
     { new obj() with
-          member x.ToString() = "INotifyEnumerableInternal"
+        member x.ToString() = "INotifyEnumerableInternal"
       interface INotifyEnumerableInternal<'T>
       interface IEnumerable<_> with
           member x.GetEnumerator() = null }

src/Fantomas.Tests/LetBindingTests.fs

@@ -76,7 +76,7 @@ let f () =
     |> should equal """let f() =
     let x = 1
     (while true do
-         ()
+        ()
      x)
 """
 
@@ -110,8 +110,8 @@ let x =
 let x =
     [| 1..2 |]
     |> Array.mapi (fun _ _ ->
-           let num =
-               ""
-                   .PadLeft(9)
-           num)
+        let num =
+            ""
+                .PadLeft(9)
+        num)
 """

src/Fantomas.Tests/PatternMatchingTests.fs

@@ -203,8 +203,8 @@ with
 try
     fst
         (find
-             (fun (s, (s', ty) : int * int) ->
-             s' = s0 && can (type_match ty ty0) []) (!the_interface))
+            (fun (s, (s', ty) : int * int) ->
+            s' = s0 && can (type_match ty ty0) []) (!the_interface))
 with Failure _ -> s0
 """
 

src/Fantomas.Tests/PipingTests.fs

@@ -73,6 +73,6 @@ let prefetchImages =
 let prefetchImages =
     [ playerOImage; playerXImage ]
     |> List.map (fun img ->
-           link [ Rel "prefetch"
-                  Href img ])
+        link [ Rel "prefetch"
+               Href img ])
 """    

src/Fantomas.Tests/TypeDeclarationTests.fs

@@ -619,7 +619,7 @@ type BlobHelper(Account : CloudStorageAccount) =
             configSettingPublisher.Invoke(connectionString) |> ignore)
         BlobHelper
             (CloudStorageAccount.FromConfigurationSetting
-                 (configurationSettingName))
+                (configurationSettingName))
 """
 
 [<Test>]

src/Fantomas/CodeFormatterImpl.fs

@@ -541,7 +541,7 @@ let formatRange returnFormattedContentOnly (range : range) (lines : _ []) config
         // Mono version of indent text writer behaves differently from .NET one,
         // So we add an empty string first to regularize it
         |> if returnFormattedContentOnly then Context.str String.Empty else Context.str pre
-        |> Context.atIndentLevel startCol (Context.col Context.sepNln formatteds Context.str)
+        |> Context.atIndentLevel true startCol (Context.col Context.sepNln formatteds Context.str)
         |> if returnFormattedContentOnly then Context.str String.Empty else Context.str post
         |> Context.dump
 

src/Fantomas/CodePrinter.fs

@@ -518,7 +518,7 @@ and genExpr astContext synExpr =
             (sepOpenL +> atCurrentColumn (colAutoNlnSkip0 sepWithPreserveEndOfLine xs (genExpr astContext)) +> sepCloseL)
 
     | Record(inheritOpt, xs, eo) -> 
-        let recordExpr = opt (!- " with ") eo (genExpr astContext) +> atCurrentColumn (col sepSemiNln xs (genRecordFieldName astContext))
+        let recordExpr = opt (!- " with ") eo (genExpr astContext) +> atCurrentColumnIndent (col sepSemiNln xs (genRecordFieldName astContext))
         sepOpenS 
         +> atCurrentColumn (opt (if xs.IsEmpty then sepNone else ifElseCtx (futureNlnCheck recordExpr sepNone) sepNln sepSemi) inheritOpt
             (fun (typ, expr) -> !- "inherit " +> genType astContext false typ +> genExpr astContext expr))

src/Fantomas/Context.fs

@@ -13,13 +13,26 @@ type ColumnIndentedTextWriter(tw : TextWriter) =
     let indentWriter = new IndentedTextWriter(tw, " ")
     let mutable col = indentWriter.Indent
 
+    // on newline, bigger from Indent and atColumn is selected
+    // that way we avoid bigger than indentSpace indentation when indent is used after atCurrentColumn
+    let mutable atColumn = 0
+
+    let applyAtColumn f =
+        let newIndent = f atColumn
+        indentWriter.Indent <- newIndent
+
+    member __.ApplyAtColumn f = applyAtColumn f
+
     member __.Write(s : string) =
         match s.LastIndexOf('\n') with
         | -1 -> col <- col + s.Length
-        | i -> col <- s.Length - i - 1
+        | i ->
+            applyAtColumn (fun x -> max indentWriter.Indent x)
+            col <- s.Length - i - 1
         indentWriter.Write(s)
 
     member __.WriteLine(s : string) =
+        applyAtColumn (fun x -> max indentWriter.Indent x)
         col <- indentWriter.Indent
         indentWriter.WriteLine(s)
 
@@ -32,6 +45,10 @@ type ColumnIndentedTextWriter(tw : TextWriter) =
         with get() = indentWriter.Indent
         and set i = indentWriter.Indent <- i
 
+    member __.AtColumn 
+        with get() = atColumn
+        and set i = atColumn <- i    
+
     member __.InnerWriter = indentWriter.InnerWriter
 
     interface IDisposable with
@@ -74,6 +91,7 @@ type internal Context =
     member x.With(writer : ColumnIndentedTextWriter) =
         writer.Indent <- x.Writer.Indent
         writer.Column <- x.Writer.Column
+        writer.AtColumn <- x.Writer.AtColumn
         // Use infinite column width to encounter worst-case scenario
         let config = { x.Config with PageWidth = Int32.MaxValue }
         { x with Writer = writer; Config = config }
@@ -86,11 +104,13 @@ let internal dump (ctx: Context) =
 /// Indent one more level based on configuration
 let internal indent (ctx : Context) = 
     ctx.Writer.Indent <- ctx.Writer.Indent + ctx.Config.IndentSpaceNum
+    // if atColumn is bigger then after indent, then we use atColumn as base for indent
+    ctx.Writer.ApplyAtColumn (fun x -> if x >= ctx.Writer.Indent then x + ctx.Config.IndentSpaceNum else ctx.Writer.Indent)
     ctx
 
 /// Unindent one more level based on configuration
 let internal unindent (ctx : Context) = 
-    ctx.Writer.Indent <- max 0 (ctx.Writer.Indent - ctx.Config.IndentSpaceNum)
+    ctx.Writer.Indent <- max ctx.Writer.AtColumn (ctx.Writer.Indent - ctx.Config.IndentSpaceNum)
     ctx
 
 /// Increase indent by i spaces
@@ -104,18 +124,37 @@ let internal decrIndent i (ctx : Context) =
     ctx
 
 /// Apply function f at an absolute indent level (use with care)
-let internal atIndentLevel level (f : Context -> Context) ctx =
+let internal atIndentLevel alsoSetIndent level (f : Context -> Context) ctx =
     if level < 0 then
         invalidArg "level" "The indent level cannot be negative."
     let oldLevel = ctx.Writer.Indent
-    ctx.Writer.Indent <- level
+    let oldColumn = ctx.Writer.AtColumn
+    if alsoSetIndent then ctx.Writer.Indent <- level
+    ctx.Writer.AtColumn <- level
     let result = f ctx
+    ctx.Writer.AtColumn <- oldColumn
     ctx.Writer.Indent <- oldLevel
     result
 
-/// Write everything at current column indentation
+/// Set minimal indentation (`atColumn`) at current column position - next newline will be indented on `max indent atColumn`
+/// Example:
+/// { X = // indent=0, atColumn=2
+///     "some long string" // indent=4, atColumn=2
+///   Y = 1 // indent=0, atColumn=2
+/// }
+/// `atCurrentColumn` was called on `X`, then `indent` was called, but "some long string" have indent only 4, because it is bigger than `atColumn` (2).
 let internal atCurrentColumn (f : _ -> Context) (ctx : Context) =
-    atIndentLevel ctx.Writer.Column f ctx
+    atIndentLevel false ctx.Writer.Column f ctx
+
+/// Write everything at current column indentation, set `indent` and `atColumn` on current column position
+/// /// Example (same as above):
+/// { X = // indent=2, atColumn=2
+///       "some long string" // indent=6, atColumn=2
+///   Y = 1 // indent=2, atColumn=2
+/// }
+/// `atCurrentColumn` was called on `X`, then `indent` was called, "some long string" have indent 6, because it is indented from `atCurrentColumn` pos (2).
+let internal atCurrentColumnIndent (f : _ -> Context) (ctx : Context) =
+    atIndentLevel true ctx.Writer.Column f ctx
 
 /// Function composition operator
 let internal (+>) (ctx : Context -> Context) (f : _ -> Context) x =