unikernel/duniverse/astring/test/examples.ml

@@ -0,0 +1,87 @@
+(* This code is in the public domain *)
+
+open Astring
+
+(* Version number (v|V).major.minor[.patch][(+|-)info] *)
+
+let parse_version : string -> (int * int * int * string option) option =
+fun s -> try
+  let parse_opt_v s = match String.Sub.head s with
+  | Some ('v'|'V') -> String.Sub.tail s
+  | Some _ -> s
+  | None -> raise Exit
+  in
+  let parse_dot s = match String.Sub.head s with
+  | Some '.' -> String.Sub.tail s
+  | Some _ | None -> raise Exit
+  in
+  let parse_int s =
+    match String.Sub.span ~min:1 ~sat:Char.Ascii.is_digit s with
+    | (i, _) when String.Sub.is_empty i -> raise Exit
+    | (i, s) ->
+        match String.Sub.to_int i with
+        | None -> raise Exit | Some i -> i, s
+  in
+  let maj, s = parse_int (parse_opt_v (String.sub s)) in
+  let min, s = parse_int (parse_dot s) in
+  let patch, s = match String.Sub.head s with
+  | Some '.' -> parse_int (parse_dot s)
+  | _ -> 0, s
+  in
+  let info = match String.Sub.head s with
+  | Some ('+' | '-') -> Some (String.Sub.(to_string (tail s)))
+  | Some _ -> raise Exit
+  | None -> None
+  in
+  Some (maj, min, patch, info)
+with Exit -> None
+
+(* Key value bindings *)
+
+let parse_env : string -> string String.map option =
+fun s -> try
+  let skip_white s = String.Sub.drop ~sat:Char.Ascii.is_white s in
+  let parse_key s =
+    let id_char c = Char.Ascii.is_letter c || c = '_' in
+    match String.Sub.span ~min:1 ~sat:id_char s with
+    | (key, _) when String.Sub.is_empty key -> raise Exit
+    | (key, rem) -> (String.Sub.to_string key), rem
+  in
+  let parse_eq s = match String.Sub.head s with
+  | Some '=' -> String.Sub.tail s
+  | Some _ | None -> raise Exit
+  in
+  let parse_value s = match String.Sub.head s with
+  | Some '"' -> (* quoted *)
+      let is_data = function '\\' | '"' -> false | _ -> true in
+      let rec loop acc s =
+        let data, rem = String.Sub.span ~sat:is_data s in
+        match String.Sub.head rem with
+        | Some '"' ->
+            let acc = List.rev (data :: acc) in
+            String.Sub.(to_string @@ concat acc), (String.Sub.tail rem)
+        | Some '\\' ->
+            let rem = String.Sub.tail rem in
+            begin match String.Sub.head rem with
+            | Some ('"' | '\\' as c) ->
+                let acc = String.(sub (of_char c)) :: data :: acc in
+                loop acc (String.Sub.tail rem)
+            | Some _ | None -> raise Exit
+            end
+        | None | Some _ -> raise Exit
+      in
+      loop [] (String.Sub.tail s)
+  | Some _ ->
+      let is_data c = not (Char.Ascii.is_white c) in
+      let data, rem = String.Sub.span ~sat:is_data s in
+      String.Sub.to_string data, rem
+  | None -> "", s
+  in
+  let rec parse_bindings acc s =
+    if String.Sub.is_empty s then acc else
+    let key, s = parse_key s in
+    let value, s = s |> skip_white |> parse_eq |> skip_white |> parse_value in
+    parse_bindings (String.Map.add key value acc) (skip_white s)
+  in
+  Some (String.sub s |> skip_white |> parse_bindings String.Map.empty)
+with Exit -> None