From 350cd98661307c6bebcf2fcb13a08bbffe7aa7c0 Mon Sep 17 00:00:00 2001
From: Francesco Mecca <code@francescomecca.eu>
Date: Sat, 7 Dec 2024 14:27:39 +0100
Subject: [PATCH] path.exists

---
 Pentole/native.fs   |  2 +-
 Pentole/path.fs     | 42 +++++++++++++++++++++++++-----------------
 tests/path_tests.fs |  6 ++++++
 3 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/Pentole/native.fs b/Pentole/native.fs
index 570e700..398a8cf 100644
--- a/Pentole/native.fs
+++ b/Pentole/native.fs
@@ -2,6 +2,7 @@ module internal Pentole.Native
 
 open System
 open System.Runtime.InteropServices
+open System.Runtime.CompilerServices
 
 
 [<DllImport("libc", EntryPoint = "realpath", SetLastError = true, CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)>]
@@ -10,7 +11,6 @@ extern nativeint _realpath (string _path, nativeint _resolved_path)
 [<DllImport("libc", EntryPoint = "strerror", SetLastError = true, CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)>]
 extern nativeint _strerror (int _errnum)
 
-
 let realpath (path: string) =
     let ptr = _realpath(path, IntPtr.Zero)
     if ptr = IntPtr.Zero then
diff --git a/Pentole/path.fs b/Pentole/path.fs
index 312f1c3..8df2dee 100644
--- a/Pentole/path.fs
+++ b/Pentole/path.fs
@@ -2,8 +2,8 @@ namespace Pentole
 
 open System
 
-
-module Internal =
+/// don't use
+module PathInternal =
    let private invalid_chars = System.IO.Path.GetInvalidPathChars ()
 
    let trim (a: string) =
@@ -28,13 +28,20 @@ module Internal =
 
 type IPath =
     abstract member ToString: unit -> string
+    /// The string value of the path. Mainly useful for C# interop.
     abstract member string_value: string
     inherit IEquatable<IPath>
     inherit IComparable
 
+/// Specifies a location in the file system from the root
+/// directory. It is not dependent on the current working directory
+/// and provides a complete path to a file or directory. Note that an
+/// `AbsolutePath` does not have to correspond to an actual file or
+/// directory on the file system. To verify its existence or resolve
+/// it to a real file, additional methods in the FileSystem module are provided
 [<Struct>]    
 [<CustomEquality>]    
-[<CustomComparison>]    
+[<CustomComparison>]
 type AbsolutePath internal (path: string) =
     interface IPath with
         member _.ToString () = $"AbsolutePath {path}"
@@ -50,8 +57,15 @@ type AbsolutePath internal (path: string) =
 
     interface IEquatable<IPath> with
         member _.Equals (o: IPath) =
-            Internal.trim o.string_value = path
-        
+            PathInternal.trim o.string_value = path
+
+/// Specifies a location in the file system relative to the current
+/// working directory. It does not provide a complete path and is
+/// dependent on the context in which it is used. Similar to
+/// `AbsolutePath`, a `RelativePath` does not have to correspond to an
+/// actual file or directory.  To verify its existence or resolve
+/// it to a real file, additional methods in the FileSystem module are provided
+/// should be used.
 [<Struct>]    
 [<CustomEquality>]    
 [<CustomComparison>]    
@@ -69,11 +83,12 @@ type RelativePath internal (path: string) =
 
     interface IEquatable<IPath> with
         member _.Equals (o: IPath) =
-            Internal.trim o.string_value = path
+            PathInternal.trim o.string_value = path
 
 module Path =
+    /// Construct a IPath object from the given path.
     let of_string (path: string): Result<IPath, string> =
-        match Internal.construct path with
+        match PathInternal.construct path with
         | Ok (path, true) -> AbsolutePath path :> IPath |> Ok
         | Ok (path, false) -> RelativePath path :> IPath |> Ok
         | Error e -> Error e
@@ -121,13 +136,6 @@ module Path =
     /// Returns the parent directory of the given path.
     ///
     /// If the path is the root directory or does not have a parent, the original path is returned.
-    ///
-    /// # Arguments
-    ///
-    /// * `path`: The path to get the parent directory of.
-    ///
-    /// # Returns
-    /// The parent directory of the given path, or the original path if it has no parent
     let parent (path: IPath) =
         let parent = IO.Path.GetDirectoryName path.string_value
         if parent = null then
@@ -135,12 +143,12 @@ module Path =
         else
             parent |> should_not_fail
 
-        
-// impure functions
-// https://docs.python.org/3.8/library/pathlib.html
 module FileSystem =
     let resolve (path: IPath) =
         Native.realpath path.string_value |> Result.bind Path.of_string
+
+    let exists (path: IPath)  =
+         IO.Path.Exists path.string_value
 (*
 
 let relative_to (parent: Path) (child: Path) =
diff --git a/tests/path_tests.fs b/tests/path_tests.fs
index 19b83c0..7a7c67b 100644
--- a/tests/path_tests.fs
+++ b/tests/path_tests.fs
@@ -75,3 +75,9 @@ let parent_test () =
     "/etc/conf"     |> test |> Assert.are_equal (p "/etc")
     "/etc/../etc"  |> test |> Assert.are_equal (p "/etc/../")
     "etc/../etc"  |> test |> Assert.are_equal (p "etc/../")
+
+[<Test>]
+let exitsts_test () =
+    let p (n: string ) = Path.of_string n |> Result.Unsafe.get
+    FileSystem.exists (p "/tmp/") |> Assert.is_true
+    FileSystem.exists (p "/IHOPE_this_DOESNT_exist/") |> Assert.is_false