refactor(uri): switch [of_path] to an ocamllex implementation

lsp/src/import.ml

@@ -34,6 +34,9 @@ module String = struct
     let prefix_len = length prefix in
     len >= prefix_len && check_prefix s ~prefix prefix_len 0
 
+  let add_prefix_if_not_exists s ~prefix =
+    if is_prefix s ~prefix then s else prefix ^ s
+
   let next_occurrence ~pattern text from =
     let plen = String.length pattern in
     let last = String.length text - plen in

lsp/src/uri0.ml

@@ -25,30 +25,10 @@ let slash_to_backslash =
     | '/' -> '\\'
     | c -> c)
 
-let add_prefix_if_not_exists s ~prefix =
-  if String.is_prefix s ~prefix then s else prefix ^ s
-
 let of_path path =
   let path = if !Private.win32 then backslash_to_slash path else path in
-  let path, authority =
-    let len = String.length path in
-    if len = 0 then ("/", "")
-    else if String.is_prefix path ~prefix:"//" then
-      let offset = 2 in
-      let idx = String.index_from_opt path offset '/' in
-      match idx with
-      | None -> ("/", String.sub path ~pos:offset ~len:(len - offset))
-      | Some i ->
-        let authority = String.sub path ~pos:offset ~len:(i - offset) in
-        let path =
-          let path = String.sub path ~pos:i ~len:(len - i) in
-          if String.is_empty path then "/" else path
-        in
-        (path, authority)
-    else (path, "")
-  in
-  let path = add_prefix_if_not_exists path ~prefix:"/" in
-  { scheme = "file"; authority; path }
+  let Uri_lexer.{ scheme; authority; path } = Uri_lexer.of_path path in
+  { scheme; authority; path }
 
 let to_path { path; authority; scheme } =
   let path =

lsp/src/uri_lexer.mli

@@ -5,3 +5,5 @@ type t =
   }
 
 val of_string : string -> t
+
+val of_path : string -> t

lsp/src/uri_lexer.mll

@@ -11,6 +11,7 @@ rule uri = parse
 ("//" ([^'/''?''#']* as authority)) ?
 ([^'?''#']* as path)
 { 
+  let open Import in
   let scheme = scheme |> Option.value ~default:"file" in
   let authority =
     authority |> Option.map Uri.pct_decode |> Option.value ~default:""
@@ -19,14 +20,31 @@ rule uri = parse
     let path = path |> Uri.pct_decode in
     match scheme with
     | "http" | "https" | "file" ->
-      if Import.String.is_prefix path ~prefix:"/" then path else "/" ^ path
+      String.add_prefix_if_not_exists path ~prefix:"/"
     | _ -> path
   in
-  {scheme ; authority; path;} 
+  { scheme; authority; path; } 
+}
+
+and path = parse
+| "" { { scheme = "file"; authority = ""; path = "/" } }
+| "//" ([^ '/']* as authority) (['/']_* as path) { { scheme = "file"; authority; path } }
+| "//" ([^ '/']* as authority) { { scheme = "file"; authority; path = "/" } }
+| _* as path 
+{ 
+  let open Import in
+  { scheme = "file"
+  ; authority = ""
+  ; path = String.add_prefix_if_not_exists path ~prefix:"/"
+  }
 }
 
 {
   let of_string s =
     let lexbuf = Lexing.from_string s in
     uri lexbuf
+
+  let of_path s =
+    let lexbuf = Lexing.from_string s in
+    path lexbuf
 }