Better recovery after an error — prevent an infinite loop

2 files changed, 14 insertions, 44 deletions

diff --git a/lib/qparser/lexbuf.mli b/lib/qparser/lexbuf.mli
index ac3b262..f9812a7 100644
--- a/lib/qparser/lexbuf.mli
+++ b/lib/qparser/lexbuf.mli
@@ -64,7 +64,8 @@ type state =
   | String of stringWraper  (** String enclosed by [''] *)
   | MString of int  (** String enclosed by [{}]*)
   | EndString of stringWraper
-      (** State raised just before closing the string *)
+      (** State raised just before closing the string. 
+          The buffer is rollbacked and the position is the closing symbol. *)
   | Expression  (** Expression where [!] is an operator *)
 
 val pp_state : Format.formatter -> state -> unit
diff --git a/lib/qparser/lexer.ml b/lib/qparser/lexer.ml
index 4e9aa27..5c093b1 100644
--- a/lib/qparser/lexer.ml
+++ b/lib/qparser/lexer.ml
@@ -119,6 +119,10 @@ let rec read_quoted_string : Lexbuf.stringWraper -> Lexbuf.buffer_builder =
   let lexbuf = Lexbuf.buffer buffer in
   match%sedlex lexbuf with
   | "<<" ->
+      (* Enter into embed code. We enter here into a new state until the
+         matching >>.
+         If we already got some text before, report the literal token, then
+         rollback to read the embeded code again. *)
       if not nested then (
         match Buffer.length buf with
         | 0 ->
@@ -276,50 +280,15 @@ let rec discard buffer =
   let lexbuf = Lexbuf.buffer buffer in
 
   match%sedlex lexbuf with
-  | '\'' -> (
-      match Lexbuf.state buffer with
-      | Some (Lexbuf.String _) | Some (Lexbuf.EndString _) ->
-          (* If we are inside a string, or just beforce closing it, close it.
-           *)
-          Lexbuf.leave_state buffer;
-          discard buffer
-      | _ ->
-          (* Otherwise wait skip until the end of the starting one *)
-          Lexbuf.enter_state buffer (Lexbuf.String Lex_state.quotedStringWraper);
-          (try
-             ignore
-               (read_quoted_string Lex_state.quotedStringWraper
-                  (Buffer.create 16) buffer)
-           with e ->
-             Printexc.print_backtrace stdout;
-
-             raise e);
-          discard buffer)
-  | '"' -> (
-      match Lexbuf.state buffer with
-      | Some (Lexbuf.String _) | Some (Lexbuf.EndString _) ->
-          Lexbuf.leave_state buffer;
-          discard buffer
-      | _ ->
-          Lexbuf.enter_state buffer
-            (Lexbuf.String Lex_state.dQuotedStringWraper);
-          ignore
-            (read_quoted_string Lex_state.dQuotedStringWraper (Buffer.create 16)
-               buffer);
-          discard buffer)
-  | '}' -> (
-      match Lexbuf.state buffer with
-      | Some (Lexbuf.MString _) ->
-          Lexbuf.leave_state buffer;
-          discard buffer
-      | _ ->
-          ignore (read_long_string 0 (Buffer.create 16) buffer);
-          discard buffer)
-  | '{' ->
-      ignore (read_long_string 0 (Buffer.create 16) buffer);
-      Lexbuf.leave_state buffer;
-      discard buffer
   | '-', Plus '-', Star (Sub (any, ('\r' | '\n'))) ->
+      (* If something looks like the end of a location, get out the discard
+         mode.
+         We can’t really be sure if it is effectively the end of a
+         location (because we can be in a text), but trying to figure if it is
+         or not just don’t make sense.
+
+         We are here because an error was raised, so can have any situation
+         (for example a missing quote). *)
       leave_expression buffer;
       ()
   | '!' ->