feature: add some re parser that don't raise (#542)

CHANGES.md

@@ -4,6 +4,9 @@ Unreleased
 * Introduce [Re.Pcre.get_named_substring_opt]. A non raising version of
   [Re.Pcre.get_named_substring] (#525)
 
+* Introduce parsing functions in `Re.{Perl,Pcre,Emacs,Glob}` that return a
+  result instead of raising. (#542)
+
 1.13.1 (30-Sep-2024)
 --------------------
 

lib/emacs.ml

@@ -121,5 +121,12 @@ let re ?(case = true) s =
   if case then r else Re.no_case r
 ;;
 
+let re_result ?case s =
+  match re ?case s with
+  | s -> Ok s
+  | exception Not_supported -> Error `Not_supported
+  | exception Parse_error -> Error `Parse_error
+;;
+
 let compile = Re.compile
 let compile_pat ?(case = true) s = compile (re ~case s)

lib/emacs.mli

@@ -30,6 +30,8 @@ exception Not_supported
 (** Parsing of an Emacs-style regular expression *)
 val re : ?case:bool -> string -> Core.t
 
+val re_result : ?case:bool -> string -> (Core.t, [ `Not_supported | `Parse_error ]) result
+
 (** Regular expression compilation *)
 val compile : Core.t -> Core.re
 

lib/glob.ml

@@ -316,6 +316,22 @@ let glob
   if expand_braces then Re.alt (List.map to_re (explode s)) else to_re s
 ;;
 
+let glob_result
+  ?anchored
+  ?pathname
+  ?match_backslashes
+  ?period
+  ?expand_braces
+  ?double_asterisk
+  s
+  =
+  match
+    glob ?anchored ?pathname ?match_backslashes ?period ?expand_braces ?double_asterisk s
+  with
+  | re -> Ok re
+  | exception Parse_error -> Error `Parse_error
+;;
+
 let glob' ?anchored period s = glob ?anchored ~period s
 let globx ?anchored s = glob ?anchored ~expand_braces:true s
 let globx' ?anchored period s = glob ?anchored ~expand_braces:true ~period s

lib/glob.mli

@@ -68,6 +68,16 @@ val glob
   -> string
   -> Core.t
 
+val glob_result
+  :  ?anchored:bool
+  -> ?pathname:bool
+  -> ?match_backslashes:bool
+  -> ?period:bool
+  -> ?expand_braces:bool
+  -> ?double_asterisk:bool
+  -> string
+  -> (Core.t, [ `Parse_error ]) result
+
 (** Same, but allows to choose whether dots at the beginning of a
     file name need to be explicitly matched (true) or not (false)
 

lib/pcre.ml

@@ -33,6 +33,13 @@ let re ?(flags = []) pat =
   Perl.re ~opts pat
 ;;
 
+let re_result ?flags s =
+  match re ?flags s with
+  | s -> Ok s
+  | exception Not_supported -> Error `Not_supported
+  | exception Parse_error -> Error `Parse_error
+;;
+
 let regexp ?flags pat = Re.compile (re ?flags pat)
 let extract ~rex s = Re.Group.all (Re.exec rex s)
 let exec ~rex ?pos s = Re.exec rex ?pos s

lib/pcre.mli

@@ -24,6 +24,11 @@ type split_result =
 (** [re ~flags s] creates the regexp [s] using the pcre syntax. *)
 val re : ?flags:flag list -> string -> Core.t
 
+val re_result
+  :  ?flags:flag list
+  -> string
+  -> (Core.t, [ `Not_supported | `Parse_error ]) result
+
 (** [re ~flags s] compiles the regexp [s] using the pcre syntax. *)
 val regexp : ?flags:flag list -> string -> regexp
 

lib/perl.ml

@@ -338,3 +338,10 @@ let re ?(opts = []) s =
 
 let compile = Re.compile
 let compile_pat ?(opts = []) s = compile (re ~opts s)
+
+let re_result ?opts s =
+  match re ?opts s with
+  | s -> Ok s
+  | exception Not_supported -> Error `Not_supported
+  | exception Parse_error -> Error `Parse_error
+;;

lib/perl.mli

@@ -39,6 +39,11 @@ type opt =
 (** Parsing of a Perl-style regular expression *)
 val re : ?opts:opt list -> string -> Core.t
 
+val re_result
+  :  ?opts:opt list
+  -> string
+  -> (Core.t, [ `Not_supported | `Parse_error ]) result
+
 (** (Same as [Re.compile]) *)
 val compile : Core.t -> Core.re