Simple globbing support

Using glob(3) this adds simple glob support. I'm sure this isn't
sufficient for all of the pattern-matching that is possible in POSIX
shell's, but it is a good start.

TODO.md

···
  - [ ] Conditionals
  - [ ] Substitutions
    - [ ] Globs
+     - [x] Simple support via glob(3)
  - [ ] Traps
  - [ ] Background Tasks
  - [ ] Interactive Mode

src/lib/ast.ml

···
       String.concat " " (List.map word_component_to_string s)
   | WordSingleQuoted s ->
       String.concat " " (List.map word_component_to_string s)
+  | WordGlobAll -> "*"
+  | WordGlobAny -> "?"
   | v ->
       Fmt.failwith "Conversion of %a" Yojson.Safe.pp
         (word_component_to_yojson v)

src/lib/eval.ml

···
 
   let cwd_of_ctx ctx = S.cwd ctx.state |> Fpath.to_string |> ( / ) ctx.fs
 
+  let needs_glob_expansion : Ast.word_component -> bool = function
+    | WordGlobAll | WordGlobAny -> true
+    | _ -> false
+
+  let glob_expand wc =
+    Ast.word_components_to_string wc |> Globlon.glob |> Array.to_list
+
+  let args swc =
+    List.concat_map
+      (function
+        | Ast.Suffix_redirect _ -> []
+        | Suffix_word wc ->
+            if List.exists needs_glob_expansion wc then glob_expand wc
+            else [ Ast.word_components_to_string wc ])
+      swc
+
   let execute_commands initial_ctx local_switch p =
     let rec loop ctx
         ((status_of_previous, stdout_of_previous) :
···
                   loop ctx (res, some_read) rest))
       | Ast.SimpleCommand (Named (executable, Some suffix)) :: rest -> (
           let args =
-            List.filter_map
-              (function
-                | Ast.Suffix_word w ->
-                    Some
-                      (String.concat ""
-                      @@ List.map Ast.word_component_to_string w)
-                | Ast.Suffix_redirect _ -> None)
-              suffix
+            args suffix
+            (* List.filter_map *)
+            (*   (function *)
+            (*     | Ast.Suffix_word w -> *)
+            (*         Some *)
+            (*           (String.concat "" *)
+            (*           @@ List.map Ast.word_component_to_string w) *)
+            (*     | Ast.Suffix_redirect _ -> None) *)
+            (*   suffix *)
           in
           match
             Built_ins.of_args (Ast.word_components_to_string executable :: args)

test/paths.t

···
+Here we test some specific semantics of how a shell should handle paths. In
+particular, things like globbing.
+
+  $ touch hello.txt; touch world.txt
+  $ osh -c "basename --suffix='.txt' *.txt"
+  hello
+  world
+  $ touch Hello.txt
+  $ osh -c "basename --suffix='.txt' ?ello.txt"
+  Hello
+  hello