Introducing a specific exception for formatted input functions.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@4922 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

2 files changed, 20 insertions, 12 deletions

diff --git a/stdlib/scanf.ml b/stdlib/scanf.ml
index 86af010e9..648d27213 100644
--- a/stdlib/scanf.ml
+++ b/stdlib/scanf.ml
@@ -130,12 +130,14 @@ let from_function f = create f;;
 end;;
 
 (** Formatted input functions. *)
+exception Scan_failure of string;;
 
 let bad_input ib s =
   let i = Scanning.char_count ib in
-  failwith
-    (Printf.sprintf "scanf: bad input at char number %i%s"
-       i (if s = "" then s else Printf.sprintf ", while scanning %s" s));;
+  raise
+    (Scan_failure
+       (Printf.sprintf "scanf: bad input at char number %i%s"
+          i (if s = "" then s else Printf.sprintf ", while scanning %s" s)));;
 
 let bad_input_buff ib = bad_input ib (Scanning.token ib);;
 
diff --git a/stdlib/scanf.mli b/stdlib/scanf.mli
index e4add0dd5..07982009e 100644
--- a/stdlib/scanf.mli
+++ b/stdlib/scanf.mli
@@ -44,12 +44,19 @@ val from_function : (unit -> char) -> scanbuf;;
 
 end;;
 
-val fscanf : in_channel -> ('a, Scanning.scanbuf, 'b) format -> 'a -> 'b;;
-(** [fscanf inchan format f] reads tokens from the channel [inchan] according
+exception Scan_failure of string;;
+(** The exception that formatted input functions raise when the input
+   cannot be read according to the given format. *)
+
+val bscanf :
+  Scanning.scanbuf -> ('a, Scanning.scanbuf, 'b) format -> 'a -> 'b;;
+(** [bscanf ib format f] reads tokens from the scanning buffer [ib] according
    to the format string [format], converts these tokens to values, and
    applies the function [f] to these values.
    The result of this application of [f] is the result of the whole construct.
 
+   Raise [Scanf.Scan_failure] if the given input does not match the format.
+
    The format is a character string which contains three types of
    objects:
    - plain characters, which are simply matched with the
@@ -114,12 +121,11 @@ val fscanf : in_channel -> ('a, Scanning.scanbuf, 'b) format -> 'a -> 'b;;
    lexing and parsing; if you need efficient language syntactic analysis,
    use the corresponding devoted libraries. *)
 
-val scanf : ('a, Scanning.scanbuf, 'b) format -> 'a -> 'b;;
-(** Same as {!Scanf.fscanf}, but inputs from [stdin]. *)
-
-val bscanf :
-  Scanning.scanbuf -> ('a, Scanning.scanbuf, 'b) format -> 'a -> 'b;;
-(** Same as {!Scanf.fscanf}, but inputs from the buffer argument. *)
+val fscanf : in_channel -> ('a, Scanning.scanbuf, 'b) format -> 'a -> 'b;;
+(** Same as {!Scanf.bscanf}, but inputs from the channel argument. *)
 
 val sscanf : string -> ('a, Scanning.scanbuf, 'b) format -> 'a -> 'b;;
-(** Same as {!Scanf.fscanf}, but inputs from the string argument. *)
+(** Same as {!Scanf.bscanf}, but inputs from the string argument. *)
+
+val scanf : ('a, Scanning.scanbuf, 'b) format -> 'a -> 'b;;
+(** Same as {!Scanf.bscanf}, but inputs from [stdin]. *)