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ENHANCED: Bidirectional char_type/2, addressing #2321.

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Suggested by @librarianmage, many thanks!
This commit is contained in:
Markus Triska
2024-02-07 20:05:07 +01:00
parent 89d3451767
commit 53b7d9eec9
1 changed files with 26 additions and 9 deletions
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35
src/lib/charsio.pl
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@@ -20,6 +20,7 @@ read and write chars.
:- use_module(library(iso_ext)). :- use_module(library(iso_ext)).
:- use_module(library(error)). :- use_module(library(error)).
:- use_module(library(lists)). :- use_module(library(lists)).
:- use_module(library(between)).
:- use_module(library(iso_ext), [partial_string/1,partial_string/3]). :- use_module(library(iso_ext), [partial_string/1,partial_string/3]).
fabricate_var_name(VarType, VarName, N) :- fabricate_var_name(VarType, VarName, N) :-
@@ -74,9 +75,10 @@ extend_var_list_([V|Vs], N, VarList, NewVarList, VarType) :-
). ).
%% char_type(+Char, -Type). %% char_type(?Char, ?Type).
% %
% Given a Char, Type is one of the categories that char fits in. % Type is one of the categories that Char fits in.
% At least one of the arguments must be ground.
% Possible categories are: % Possible categories are:
% %
% - `alnum` % - `alnum`
@@ -132,17 +134,32 @@ extend_var_list_([V|Vs], N, VarList, NewVarList, VarType) :-
% Note that uppercase and lowercase transformations use a string. This is because % Note that uppercase and lowercase transformations use a string. This is because
% some characters do not map 1:1 between lowercase and uppercase. % some characters do not map 1:1 between lowercase and uppercase.
char_type(Char, Type) :- char_type(Char, Type) :-
must_be(character, Char), can_be(character, Char),
( ground(Type) -> ( \+ ctype(Type) ->
( ctype(Type) -> domain_error(char_type, Type, char_type/2)
'$char_type'(Char, Type) ; true
; domain_error(char_type, Type, char_type/2) ),
) ( ground(Char) ->
; ctype(Type), ctype(Type),
'$char_type'(Char, Type) '$char_type'(Char, Type)
; ground(Type) ->
max_char_code(Max),
between(0, Max, Code),
char_code(Char, Code),
'$char_type'(Char, Type)
; must_be(character, Char)
). ).
max_char_code(Max) :-
catch((length(_, Code),
catch(char_code(Char, Code),
error(representation_error(_),_),
throw(max_char_code(Code))),
false),
max_char_code(Code),
Max is Code - 1).
ctype(alnum). ctype(alnum).
ctype(alpha). ctype(alpha).
ctype(alphabetic). ctype(alphabetic).