Only load the .fantomasignore file once, except for the daemon

docs/Documentation.md

@@ -1264,6 +1264,9 @@ Exclusion applies both to formatting and the format checking.
 *.fsx
 ```
 
+Note that Fantomas only reads the `.fantomasignore` file in its current working directory, if one exists; unlike Git, it does not traverse the filesystem to find an appropriate ignore file.
+(Technically this is not true of the Fantomas daemon. The daemon can't rely on being invoked from the right place, and indeed there may not even be a well-defined notion of "right place" for the formatting tasks the daemon is required to perform, so it does search the filesystem.)
+
 ## Using the API
 
 See [CodeFormatter.fsi](../src/Fantomas/CodeFormatter.fsi) to view the public API of Fantomas.

src/Fantomas.CoreGlobalTool/Daemon.fs

@@ -15,6 +15,7 @@ open Fantomas
 open Fantomas.SourceOrigin
 open Fantomas.FormatConfig
 open Fantomas.Extras.EditorConfig
+open Fantomas.Extras
 
 type FantomasDaemon(sender: Stream, reader: Stream) as this =
     let rpc: JsonRpc = JsonRpc.Attach(sender, reader, this)
@@ -44,7 +45,7 @@ type FantomasDaemon(sender: Stream, reader: Stream) as this =
     [<JsonRpcMethod(Methods.FormatDocument, UseSingleObjectParameterDeserialization = true)>]
     member _.FormatDocumentAsync(request: FormatDocumentRequest) : Task<FormatDocumentResponse> =
         async {
-            if Fantomas.Extras.IgnoreFile.isIgnoredFile request.FilePath then
+            if IgnoreFile.isIgnoredFile (IgnoreFile.find request.FilePath) request.FilePath then
                 return FormatDocumentResponse.IgnoredFile request.FilePath
             else
                 let config =

src/Fantomas.CoreGlobalTool/Program.fs

@@ -90,7 +90,7 @@ let rec allFiles isRec path =
     |> Seq.filter (fun f ->
         isFSharpFile f
         && not (isInExcludedDir f)
-        && not (IgnoreFile.isIgnoredFile f))
+        && not (IgnoreFile.isIgnoredFile (IgnoreFile.current.Force()) f))
 
 /// Fantomas assumes the input files are UTF-8
 /// As is stated in F# language spec: https://fsharp.org/specs/language-spec/4.1/FSharpSpec-4.1-latest.pdf#page=25
@@ -209,7 +209,7 @@ let runCheckCommand (recurse: bool) (inputPath: InputPath) : int =
     | InputPath.StdIn _ ->
         eprintfn "No input path provided. Nothing to do."
         0
-    | InputPath.File f when (IgnoreFile.isIgnoredFile f) ->
+    | InputPath.File f when (IgnoreFile.isIgnoredFile (IgnoreFile.current.Force()) f) ->
         printfn "'%s' was ignored" f
         0
     | InputPath.File path ->
@@ -418,7 +418,7 @@ let main argv =
     let filesAndFolders (files: string list) (folders: string list) : unit =
         files
         |> List.iter (fun file ->
-            if (IgnoreFile.isIgnoredFile file) then
+            if (IgnoreFile.isIgnoredFile (IgnoreFile.current.Force()) file) then
                 printfn "'%s' was ignored" file
             else
                 processFile file file)
@@ -448,7 +448,8 @@ let main argv =
             | InputPath.Unspecified, _ ->
                 eprintfn "Input path is missing..."
                 exit 1
-            | InputPath.File f, _ when (IgnoreFile.isIgnoredFile f) -> printfn "'%s' was ignored" f
+            | InputPath.File f, _ when (IgnoreFile.isIgnoredFile (IgnoreFile.current.Force()) f) ->
+                printfn "'%s' was ignored" f
             | InputPath.Folder p1, OutputPath.NotKnown -> processFolder p1 p1
             | InputPath.File p1, OutputPath.NotKnown -> processFile p1 p1
             | InputPath.File p1, OutputPath.IO p2 -> processFile p1 p2

src/Fantomas.Extras/FakeHelpers.fs

@@ -44,7 +44,7 @@ let private formatContentInternalAsync
     (file: string)
     (originalContent: string)
     : Async<FormatResult> =
-    if IgnoreFile.isIgnoredFile file then
+    if IgnoreFile.isIgnoredFile (IgnoreFile.current.Force()) file then
         async { return IgnoredFile file }
     else
         async {
@@ -99,7 +99,7 @@ let formatContentAsync = formatContentInternalAsync false
 let private formatFileInternalAsync (compareWithoutLineEndings: bool) (file: string) =
     let config = EditorConfig.readConfiguration file
 
-    if IgnoreFile.isIgnoredFile file then
+    if IgnoreFile.isIgnoredFile (IgnoreFile.current.Force()) file then
         async { return IgnoredFile file }
     else
         let originalContent = File.ReadAllText file
@@ -167,7 +167,10 @@ let checkCode (filenames: seq<string>) =
     async {
         let! formatted =
             filenames
-            |> Seq.filter (IgnoreFile.isIgnoredFile >> not)
+            |> Seq.filter (
+                IgnoreFile.isIgnoredFile (IgnoreFile.current.Force())
+                >> not
+            )
             |> Seq.map (formatFileInternalAsync true)
             |> Async.Parallel
 

src/Fantomas.Extras/IgnoreFile.fs

@@ -1,27 +1,39 @@
 namespace Fantomas.Extras
 
+open System.IO
+open MAB.DotIgnore
+
+type IgnoreFile =
+    { Location: FileInfo
+      IgnoreList: IgnoreList }
+
 [<RequireQualifiedAccess>]
 module IgnoreFile =
 
-    open System.IO
-    open MAB.DotIgnore
-
     [<Literal>]
     let IgnoreFileName = ".fantomasignore"
 
-    let rec private findIgnoreFile (filePath: string) : string option =
-        let allParents =
-            let rec addParent (di: DirectoryInfo) (finalContinuation: string list -> string list) =
-                if isNull di.Parent then
-                    finalContinuation [ di.FullName ]
-                else
-                    addParent di.Parent (fun parents -> di.FullName :: parents |> finalContinuation)
+    /// Find the `.fantomasignore` file above the given filepath, if one exists.
+    /// Note that this is intended for use only in the daemon; the command-line tool
+    /// does not support `.fantomasignore` files anywhere other than the current
+    /// working directory.
+    let find (filePath: string) : IgnoreFile option =
+        let rec walkUp (currentDirectory: DirectoryInfo) : IgnoreFile option =
+            if isNull currentDirectory then
+                None
+            else
+                let potentialFile =
+                    Path.Combine(currentDirectory.FullName, IgnoreFileName)
+                    |> FileInfo
 
-            addParent (Directory.GetParent filePath) id
+                if potentialFile.Exists then
+                    { Location = potentialFile
+                      IgnoreList = IgnoreList(potentialFile.FullName) }
+                    |> Some
+                else
+                    walkUp currentDirectory.Parent
 
-        allParents
-        |> List.tryFind (fun p -> Path.Combine(p, IgnoreFileName) |> File.Exists)
-        |> Option.map (fun p -> Path.Combine(p, IgnoreFileName))
+        walkUp (FileInfo(filePath).Directory)
 
     let private relativePathPrefix = sprintf ".%c" Path.DirectorySeparatorChar
 
@@ -31,17 +43,30 @@ module IgnoreFile =
         else
             path
 
-    let isIgnoredFile (file: string) =
-        let fullPath = Path.GetFullPath(file)
+    /// When executed from the command line, Fantomas only supports a `.fantomasignore` file in the
+    /// current working directory. This is that `.fantomasignore` file.
+    let current: Lazy<IgnoreFile option> =
+        lazy
+            let path =
+                Path.Combine(System.Environment.CurrentDirectory, IgnoreFileName)
+                |> FileInfo
+
+            if path.Exists then
+                { Location = path
+                  IgnoreList = IgnoreList(path.FullName) }
+                |> Some
+            else
+                None
 
-        match findIgnoreFile fullPath with
+    let isIgnoredFile (ignoreFile: IgnoreFile option) (file: string) : bool =
+        match ignoreFile with
         | None -> false
         | Some ignoreFile ->
-            let ignores = IgnoreList(ignoreFile)
+            let fullPath = Path.GetFullPath(file)
 
             try
-                let path = removeRelativePathPrefix file
-                ignores.IsIgnored(path, false)
+                let path = removeRelativePathPrefix fullPath
+                ignoreFile.IgnoreList.IsIgnored(path, false)
             with
             | ex ->
                 printfn "%A" ex