Fix desugar patterns' bug exposed by FsCheck

src/Fantomas.Tests/PatternMatchingTests.fs

@@ -232,6 +232,15 @@ let UNIFY_ACCEPT_TAC mvs th (asl, w) =
     fun i [] -> INSTANTIATE i th'
 """
 
+[<Test>]
+let ``desugared lambdas again``() =
+    formatSourceString false """
+fun P -> T""" config
+    |> prepend newline
+    |> should equal """
+fun P -> T
+"""
+
 [<Test>]
 let ``should consume spaces before inserting comments``() =
     formatSourceString false """

src/Fantomas/CodeFormatter.fs

@@ -319,14 +319,11 @@ let isValidFSharpCode isFsiFile sourceCode =
         isValidAST (parse isFsiFile sourceCode)
     with _ -> false
 
-let internal split (str : string) =
-    str.Replace("\r\n", "\n").Replace("\r", "\n").Split('\n')
-
 let internal formatWith ast input config =
     // Use '\n' as the new line delimiter consistently
     // It would be easier for F# parser
     let sourceCode = defaultArg input ""
-    let normalizedSourceCode = sourceCode.Replace("\r\n", "\n").Replace("\r", "\n")
+    let normalizedSourceCode = String.normalizeNewLine sourceCode
     let formattedSourceCode =    
         Context.create config normalizedSourceCode 
         |> genParsedInput ASTContext.Default ast
@@ -455,7 +452,7 @@ let internal formatRange returnFormattedContentOnly isFsiFile (range : range) (l
         let sel = sourceCode.[start..finish].TrimEnd('\r')
         if startWithMember sel then
            (String.Join(String.Empty, "type T = ", Environment.NewLine, new String(' ', startCol), sel), TypeMember)
-        elif sel.TrimStart().StartsWith("and") then
+        elif String.startsWithOrdinal "and" (sel.TrimStart()) then
             let p = getPatch startCol lines.[..startLine-1]
             let pattern = Regex("and")
             let replacement = 
@@ -472,7 +469,7 @@ let internal formatRange returnFormattedContentOnly isFsiFile (range : range) (l
     let post =
         if finish < sourceCode.Length then 
             let post = sourceCode.[finish+1..]
-            if post.StartsWith("\n") then Environment.NewLine + post.[1..]
+            if String.startsWithOrdinal "\n" post then Environment.NewLine + post.[1..]
             else post
         else String.Empty
 
@@ -505,7 +502,7 @@ let internal formatRange returnFormattedContentOnly isFsiFile (range : range) (l
         // Get formatted selection with "type T = \n" patch
         let result = formatSelection isFsiFile selection config
         // Remove the patch
-        let contents = split result
+        let contents = String.normalizeThenSplitNewLine result
         if Array.isEmpty contents then
             if returnFormattedContentOnly then result
             else 
@@ -522,17 +519,17 @@ let internal formatRange returnFormattedContentOnly isFsiFile (range : range) (l
         let result = formatSelection isFsiFile selection config
         // Substitute by old contents
         let pattern = if patch = RecType then Regex("type") else Regex("let rec")
-        let formatteds = split (pattern.Replace(result, "and", 1))
+        let formatteds = String.normalizeThenSplitNewLine (pattern.Replace(result, "and", 1))
         reconstructSourceCode startCol formatteds pre post
     | Nothing ->
         let result = formatSelection isFsiFile selection config
-        let formatteds = split result
+        let formatteds = String.normalizeThenSplitNewLine result
         reconstructSourceCode startCol formatteds pre post
 
 /// Format a part of source string using given config, and return the (formatted) selected part only.
 /// Beware that the range argument is inclusive. If the range has a trailing newline, it will appear in the formatted result.
 let formatSelectionOnly isFsiFile (range : range) (sourceCode : string) config =
-    let lines = split sourceCode
+    let lines = String.normalizeThenSplitNewLine sourceCode
 
     // Move to the section with real contents
     let contentRange =
@@ -577,7 +574,7 @@ let formatSelectionOnly isFsiFile (range : range) (sourceCode : string) config =
 
  /// Format a selected part of source string using given config; expanded selected ranges to parsable ranges. 
 let formatSelectionExpanded isFsiFile (range : range) (sourceCode : string) config =
-    let lines = split sourceCode
+    let lines = String.normalizeThenSplitNewLine sourceCode
     let sourceTokenizer = SourceTokenizer([], "/tmp.fsx")
 
     // Move to the section with real contents
@@ -619,7 +616,7 @@ let makePos line col = mkPos line col
 
 /// Infer selection around cursor by looking for a pair of '[' and ']', '{' and '}' or '(' and ')'. 
 let inferSelectionFromCursorPos (cursorPos : pos) (sourceCode : string) = 
-    let lines = split sourceCode
+    let lines = String.normalizeThenSplitNewLine sourceCode
     let sourceTokenizer = SourceTokenizer([], "/tmp.fsx")
     let openDelimiters = dict ["[", List; "[|", Array; "{", SequenceOrRecord; "(", Tuple]
     let closeDelimiters = dict ["]", List; "|]", Array; "}", SequenceOrRecord; ")", Tuple]

src/Fantomas/CodeFormatter.fsx

@@ -21,13 +21,6 @@ let test (s : string) =
 fsi.AddPrinter (fun (p : Microsoft.FSharp.Compiler.Range.pos) -> p.ToString())
 fsi.AddPrinter (fun (r : Microsoft.FSharp.Compiler.Range.range) -> r.ToString())
 
-// A bug exposed by FsCheck
-parse false """
-fun P -> R
-d
-s
-""";;
-
 // FAILS - sticky-right comment becomes sticky-left
 test """
 1 +

src/Fantomas/Fantomas.fsproj

@@ -56,6 +56,7 @@
   <Import Project="$(SolutionDir)\.nuget\NuGet.targets" />
   <ItemGroup>
     <Compile Include="AssemblyInfo.fs" />
+    <Compile Include="Utils.fs" />
     <Compile Include="TokenMatcher.fs" />
     <Compile Include="FormatConfig.fs" />
     <Compile Include="SourceParser.fs" />

src/Fantomas/FormatConfig.fs

@@ -7,7 +7,7 @@ open System.Text.RegularExpressions
 open System.CodeDom.Compiler
 
 open Microsoft.FSharp.Compiler.Range
-
+open Fantomas
 open Fantomas.TokenMatcher
 
 type FormatException(msg : string) =
@@ -137,7 +137,7 @@ type internal Context =
           Content = ""; Positions = [||]; Comments = Dictionary(); Directives = Dictionary() }
 
     static member create config (content : string) =
-        let content = content.Replace("\r\n", "\n").Replace("\r", "\n")
+        let content = String.normalizeNewLine content
         let positions = 
             content.Split('\n')
             |> Seq.map (fun s -> String.length s + 1)

src/Fantomas/SourceParser.fs

@@ -56,7 +56,7 @@ let (|LongIdent|) (li : LongIdent) =
     |> String.concat "."
     |> fun s ->
         // Assume that if it starts with base, it's going to be the base keyword
-        if s.StartsWith "``base``." then
+        if String.startsWithOrdinal "``base``." s then
             String.Join("", "base.", s.[9..])
         else s
 
@@ -99,7 +99,7 @@ let (|OpNameFull|) (x : Identifier) =
     let s' = DecompileOpName s
     if IsActivePatternName s || IsInfixOperator s || IsPrefixOperator s || IsTernaryOperator s || s = "op_Dynamic" then
         /// Use two spaces for symmetry
-        if s'.StartsWith "*" && s' <> "*" then
+        if String.startsWithOrdinal "*" s' && s' <> "*" then
             sprintf "( %s )" s'
         else sprintf "(%s)" s'
     else
@@ -616,6 +616,16 @@ let (|Var|_|) = function
         Some s
     | _ -> None
 
+// Compiler-generated patterns often have "_arg" prefix    
+let (|ComputerGeneratedVar|_|) = function
+    | SynExpr.Ident(IdentOrKeyword(OpName s)) when String.startsWithOrdinal "_arg" s ->
+        Some s
+    | SynExpr.LongIdent(_, LongIdentWithDots.LongIdentWithDots(LongIdentOrKeyword(OpName s), _), opt, _) ->
+        match opt with
+        | Some _ -> Some s
+        | None -> if String.startsWithOrdinal "_arg" s then Some s else None
+    | _ -> None
+
 /// Get all application params at once
 let (|App|_|) e =
     let rec loop = function
@@ -913,10 +923,9 @@ let (|RecordField|) = function
 let (|Clause|) (SynMatchClause.Clause(p, eo, e, _, _)) = (p, e, eo)
 
 let rec private (|DesugaredMatch|_|) = function
-    // Compiler-generated patterns has "_arg" prefix
-    | SynExpr.Match(_, Var s, [Clause(p, DesugaredMatch(ss, e), None)], _, _) when s.StartsWith "_arg" ->
+    | SynExpr.Match(_, ComputerGeneratedVar s, [Clause(p, DesugaredMatch(ss, e), None)], _, _) ->
         Some((s, p)::ss, e)
-    | SynExpr.Match(_, Var s, [Clause(p, e, None)], _, _) when s.StartsWith "_arg" ->
+    | SynExpr.Match(_, ComputerGeneratedVar s, [Clause(p, e, None)], _, _) ->
         Some([(s, p)], e)
     | _ -> None
 

src/Fantomas/SourceTransformer.fs

@@ -113,7 +113,7 @@ let genConst (Unresolved(c, r, s)) =
 
 /// Check whether a range starting with a specified token
 let startWith prefix (r : range) ctx = 
-    lookup r ctx |> Option.exists (fun s -> s.StartsWith(prefix))
+    lookup r ctx |> Option.exists (String.startsWithOrdinal prefix)
 
 // A few active patterns for printing purpose
 

src/Fantomas/TokenMatcher.fs

@@ -24,7 +24,7 @@ type Token =
 let tokenize defines (content : string) =
     seq { 
         let sourceTokenizer = SourceTokenizer(defines, "/tmp.fsx")
-        let lines = content.Replace("\r\n","\n").Split('\r', '\n')
+        let lines = String.normalizeThenSplitNewLine content
         let lexState = ref 0L
         for (i, line) in lines |> Seq.zip [1..lines.Length] do 
             let lineTokenizer = sourceTokenizer.CreateLineTokenizer line
@@ -501,7 +501,7 @@ let integrateComments (originalText : string) (newText : string) =
             addText Environment.NewLine
             for x in tokensText do addText x
             let moreNewTokens =
-                if text.StartsWith("#endif") then
+                if String.startsWithOrdinal "#endif" text then
                     match newTokens with
                     | WhiteSpaces(ws, moreNewTokens) ->
                         // There are some whitespaces, use them up
@@ -513,7 +513,7 @@ let integrateComments (originalText : string) (newText : string) =
                         restoreIndent id
                         newTokens
                     | [] -> []
-                else if text.StartsWith("#if") then
+                elif String.startsWithOrdinal "#if" text then
                     // Save current indentation for #else branch
                     let indent = getIndent newTokens 
                     saveIndent indent
@@ -529,13 +529,13 @@ let integrateComments (originalText : string) (newText : string) =
         | (InactiveCodeChunk (tokensText, moreOrigTokens)),  _ ->
             Debug.WriteLine("injecting inactive code '{0}'", String.concat "" tokensText |> box)
             let text = String.concat "" tokensText
-            let lines = text.Replace("\r\n", "\n").Replace("\r", "\n").Split([|'\n'|], StringSplitOptions.RemoveEmptyEntries)
+            let lines = (String.normalizeNewLine text).Split([|'\n'|], StringSplitOptions.RemoveEmptyEntries)
             // What is current indentation of this chunk
             let numSpaces = countStartingSpaces lines
             Debug.WriteLine("the number of starting spaces is {0}", numSpaces)
             // Write the chunk in the same indentation with #if branch
             for line in lines do
-                if line.[numSpaces..].StartsWith("#") then
+                if String.startsWithOrdinal "#" line.[numSpaces..] then
                     // Naive recognition of inactive preprocessors
                     addText Environment.NewLine
                     addText line.[numSpaces..]

src/Fantomas/Utils.fs

@@ -0,0 +1,15 @@
+[<AutoOpen>]
+module internal Fantomas.Utils
+
+open System
+
+[<RequireQualifiedAccess>]
+module String =
+    let normalizeNewLine (str : string) =
+        str.Replace("\r\n", "\n").Replace("\r", "\n")
+
+    let normalizeThenSplitNewLine (str : string) =
+        (normalizeNewLine str).Split('\n')
+
+    let startsWithOrdinal (prefix : string) (str : string) =
+        str.StartsWith(prefix, StringComparison.Ordinal)

src/fantomas.sln

@@ -1,6 +1,6 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio 2012
+# Visual Studio 2013
 Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "Fantomas", "Fantomas\Fantomas.fsproj", "{919ADF2D-DF2E-4F4D-9F8B-0376346535C9}"
 EndProject
 Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "Fantomas.Tests", "Fantomas.Tests\Fantomas.Tests.fsproj", "{28E90D4B-75CE-48D3-ACFE-3AB37179233B}"