From 54e55518261ee5f3c68758ea070b1bac41400e54 Mon Sep 17 00:00:00 2001
From: acondolu <andrea.condoluci@unibo.it>
Date: Sun, 23 Jul 2017 22:23:34 +0200
Subject: [PATCH] Better error messages in parser

---
 ocaml/parser.ml | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/ocaml/parser.ml b/ocaml/parser.ml
index 6bcb70d..34b62ba 100644
--- a/ocaml/parser.ml
+++ b/ocaml/parser.ml
@@ -18,7 +18,7 @@ let mk_var' (bound, free) x =
 ;;
 
 let mk_app' = function
-  | [] ->  raise (ParsingError "bug")
+  | [] ->  assert false
   | t :: ts -> List.fold_left mk_app t ts
 ;;
 
@@ -73,12 +73,12 @@ let rec read_smt vars =
       | Some varname, cs ->
       let vars' = (varname::bound, free) in
       (match strip_spaces cs with
-        | [] -> raise (ParsingError "manca dopo variabile lambda")
+        | [] -> raise (ParsingError "Lambda expression incomplete")
         | c::cs -> (if c = '.' then (match read_smt vars' cs with
-          | None, _, _ -> raise (ParsingError "manca corpo lambda")
+          | None, _, _ -> raise (ParsingError "Lambda body expected")
           | Some [x], y, (_, free) -> Some [mk_lam x], y, (bound, free)
-          | Some _, _, _ -> raise (ParsingError "???")
-          ) else raise (ParsingError "manca . nel lambda")
+          | Some _, _, _ -> assert false
+          ) else raise (ParsingError "Expected `.` after variable in lambda")
         ))
       | _, _ -> assert false
  ) in let rec aux vars cs =
@@ -96,7 +96,7 @@ let rec read_smt vars =
           | None, cs, vars -> Some [tm], cs, vars
           | Some ts, cs, vars -> Some (tm :: ts), cs, vars
         )
-      | Some _ -> raise (ParsingError "bug")
+      | Some _ -> assert false
       | None -> None, x, vars
   in fun cs -> match aux vars cs with
     | None, cs, vars -> None, cs, vars
@@ -108,20 +108,20 @@ and read_pars vars = function
     let cs = strip_spaces cs in
     match cs with
       | [] -> None, [], vars
-      | c::cs -> if c = ')' then tm, cs, vars else raise (ParsingError ") mancante")
-    ) else raise (ParsingError "???")
+      | c::cs -> if c = ')' then tm, cs, vars else raise (ParsingError "Missing `)`")
+    ) else assert false
 ;;
 
 let parse x =
   match read_smt ([],[]) (explode x) with
   | Some [y], [], _ -> y
-  | _, _, _ -> raise (ParsingError "???")
+  | _, _, _ -> assert false
 ;;
 
 let parse_many strs =
   let f (x, y) z = match read_smt y (explode z) with
   | Some[tm], [], vars -> (tm :: x, vars)
-  | _, _, _ -> raise (ParsingError "???")
+  | _, _, _ -> assert false
   in let aux = List.fold_left f ([], ([], [])) (* index zero is reserved *)
   in let (tms, (_, free)) = aux strs
   in (List.rev tms, free)
@@ -169,7 +169,7 @@ let problem_of_string s =
  let strs = [div] @ ps @ conv in
 
  if List.length ps = 0 && List.length conv = 0
-  then raise (ParsingError "empty problem");
+  then raise (ParsingError "Parsed empty problem");
 
  (* parse' *)
  let (tms, free) = parse_many strs in
@@ -187,6 +187,7 @@ let problem_of_string s =
  let open Num in
  let exclude_bottom = function
  | #nf_nob as t -> t
+ (* actually, the following may be assert false *)
  | `Bottom -> raise (ParsingError "Input term not in normal form") in
  let rec aux_nob lev : nf_nob -> nf = function
  | `I((n,_), args) -> `I((n,(if lev = 0 then 0 else 1) + Listx.length args), Listx.map (fun t -> exclude_bottom (aux_nob lev t)) args)
@@ -206,17 +207,17 @@ let div = if not div_provided || div = `Bottom
  then None
  else match div with
   | `I _ as t -> Some t
-  | _ -> raise (ParsingError "div is not an inert or BOT in the initial problem") in
+  | _ -> raise (ParsingError "D is not an inert in the initial problem") in
 let conv = Util.filter_map (
  function
  | #i_n_var as t -> Some t
  | `Lam _ -> None
- | _ -> raise (ParsingError "A term in conv is not i_n_var")
+ | _ -> raise (ParsingError "A C-term is not i_n_var")
  ) conv in
 let ps = List.map (
  function
   | #i_n_var as y -> y
-  | _ as y -> raise (ParsingError ("A term in num is not i_n_var" ^ Num.string_of_nf y))
+  | _ -> raise (ParsingError "An N-term is not i_n_var")
  ) ps in
  name, div, conv, ps, free
 ;;
-- 
2.39.2