From a692242b51d5a43254cce183f43ed5d179b7fbbd Mon Sep 17 00:00:00 2001
From: Anthony Scemama <scemama@irsamc.ups-tlse.fr>
Date: Mon, 7 Nov 2022 11:24:20 +0100
Subject: [PATCH] Improved reading basis

---
 gaussian/lib/general_basis.ml  | 40 ++++++++++++++++++++++------------
 gaussian/lib/general_basis.mli |  2 +-
 2 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/gaussian/lib/general_basis.ml b/gaussian/lib/general_basis.ml
index c1e67c6..93c67e0 100644
--- a/gaussian/lib/general_basis.ml
+++ b/gaussian/lib/general_basis.ml
@@ -20,7 +20,7 @@ exception No_shell
 exception Malformed_shell of string
 
 
-let read_shell line_stream =
+let read_shell ?element line_stream =
   try
 
     let shell, n =
@@ -40,9 +40,15 @@ let read_shell line_stream =
                let line = Stream.next line_stream in
                try Scanf.sscanf line " %_d %f %f "
                      (fun exponent coefficient -> { exponent ; coefficient })
-               with _ -> raise (Malformed_shell (Printf.sprintf
-                     "Expected %d %c contractions, error at contraction %d:\n%s"
-                      n shell (n-i+1) line))
+               with _ -> raise (Malformed_shell 
+                     (match element with
+                      | Some element -> Printf.sprintf
+                         "In %s: Expected %d %c contractions.\nError at contraction %d:\n%s"
+                         (Element.to_string element) n shell (n-i+1) line
+                      | None -> Printf.sprintf
+                         "Expected %d %c contractions.\nError at contraction %d:\n%s"
+                         n shell (n-i+1) line
+                     ))
         in
         contraction :: loop (pred i)
     in
@@ -54,20 +60,26 @@ let read_shell line_stream =
 
 
 
-let read_element line_stream =
+let rec read_element line_stream =
   try
 
     let line = Stream.next line_stream in
-    let element =
-      Scanf.sscanf line " %s " Element.of_string
-    in
+    if String.length line = 0 || line.[0] = '!' then
+       read_element line_stream
+    else
+       let element =
+         try
+   	Scanf.sscanf line " %s " Element.of_string
+         with
+         | Element.ElementError _ -> Element.X
+       in
 
-    let rec loop () =
-      match read_shell line_stream with
-      | Some shell -> shell :: loop ()
-      | None -> []
-    in
-    Some (element, Array.of_list (loop ()) )
+       let rec loop () =
+         match read_shell line_stream ~element with
+         | Some shell -> shell :: loop ()
+         | None -> []
+       in
+       Some (element, Array.of_list (loop ()) )
 
   with
   | Stream.Failure -> None
diff --git a/gaussian/lib/general_basis.mli b/gaussian/lib/general_basis.mli
index f087e6c..60c5899 100644
--- a/gaussian/lib/general_basis.mli
+++ b/gaussian/lib/general_basis.mli
@@ -100,7 +100,7 @@ Some
 *)
   
 
-val read_shell : string Stream.t -> general_contracted_shell option
+val read_shell : ?element:Element.t -> string Stream.t -> general_contracted_shell option 
 (** Reads a shell from the input [string Stream]. The [string Stream] is a 
 stream of lines, like a text file split on the end-of-line character.
 For example,