/*************************************************************************
*									 *
*	 YAP Prolog 							 *
*									 *
*	Yap Prolog was developed at NCCUP - Universidade do Porto	 *
*									 *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
*									 *
**************************************************************************
*									 *
* File:		checker.yap						 *
* comments:	style checker for Prolog				 *
*									 *
* Last rev:     $Date: 2008-03-31 22:56:22 $,$Author: vsc $		 *
*									 *
*************************************************************************/

/**
 * @file 	checker.yap
 *
 */
:- system_module( style_checker, [no_style_check/1,
        style_check/1], ['$check_term'/5,
        '$sv_warning'/2,
        '$syntax_check_discontiguous'/2,
        '$syntax_check_multiple'/2,
        '$syntax_check_single_var'/2]).

/**

   @defgroup   YAPStyleChecker Style Checker
   @ingroup  YAPCompilerSettings
   @{

YAP implements a style-checker thay currently verifies whether:

1 named variables occur once in a clause.

2 clauses from dofferent predicates are mixed together.

3 clauses for the same predicate occur in different files.

One can declare a predicate to be discontiguous (see the
discontiguous/1 declaration) and/or multifile/1.

*/

/*
@pred style_check(+ _X_)

Turns on style checking according to the attribute specified by  _X_,
which must be one of the following:

    + single_var
      Checks single occurrences of named variables in a clause.

    + discontiguous
      Checks non-contiguous clauses for the same predicate in a file.

    + multiple
      Checks the presence of clauses for the same predicate in more than one
      file when the predicate has not been declared as `multifile`

    + all
      Performs style checking for all the cases mentioned above.


By default, style checking is disabled in YAP unless we are in
`sicstus` or `iso` language mode.

The style_check/1 built-in is now deprecated. Please use
`set_prolog_flag/1` instead.

  **/
%
% A Small style checker for YAP


style_check(V) :- var(V), !, fail.
style_check(V) :-
	\+atom(V),
	\+ is_list(V),
	V \= + _,
	V \= - _, !,
	'$do_error'( type_error('+|-|?(Flag)', V), style_check(V) ).
style_check(V) :-
	\+atom(V),
	\+ is_list(V),
	V \= + _,
	V \= + _, !,
	'$do_error'( domain_error(style_name, V), style_check(V) ).


style_check(all) :-
	style_check( [ singleton, discontiguous, multiple ] ).
style_check(+X) :-
	style_check(X).
style_check(single_var) :-
	style_check( singleton ).
style_check(singleton) :-
	yap_flag( single_var_warnings, true ).
style_check(-single_var) :-
	yap_flag( single_var_warnings, false ).
style_check(-singleton) :-
	yap_flag( single_var_warnings, false ).
style_check(discontiguous) :-
	yap_flag( discontiguous_warnings, true ).
style_check(-discontiguous) :-
	yap_flag( discontiguous_warnings, false ).
style_check(multiple) :-
	yap_flag( redefine_warnings, true ).
style_check(-multiple) :-
	yap_flag( redefine_warnings, false ).
style_check(no_effect).
style_check(+no_effect) .
style_check(-no_effect).
style_check(var_branches).
style_check(+var_branches) :-
	'$style_checker'( [  var_branches ] ).
style_check(-var_branches) :-
	'$style_checker'( [  -var_branches ] ).
style_check(atom).
style_check(+atom) :-
	'$style_checker'( [  atom ] ).
style_check(-atom) :-
	'$style_checker'( [  -atom ] ).
style_check(charset) :-
	'$style_checker'( [  charset ] ).
style_check(+charset) :-
	'$style_checker'( [  charset ] ).
style_check(-charset) :-
	'$style_checker'( [  -charset ] ).
style_check('?'(Info) ) :-
	L =  [ singleton, discontiguous, multiple ],
	( lists:member(Style, L ) -> Info = +Style ; Info = -Style ).
style_check([]).
style_check([H|T]) :- style_check(H), style_check(T).

/** @pred no_style_check(+ _X_)

Turns off style checking according to the attribute specified by
 _X_, which have the same meaning as in style_check/1.

The no_style_check/1 built-in is now deprecated. Please use
`set_prolog_flag/1` instead.

**/
no_style_check(V) :- var(V), !, fail.
no_style_check(all) :-
	'$style_checker'( [ -singleton, -discontiguous, -multiple ] ).
no_style_check(-single_var) :-
	'$style_checker'( [ -singleton ] ).
no_style_check(-singleton) :-
	'$style_checker'( [ -singleton ] ).
no_style_check(-discontiguous) :-
	'$style_checker'( [ -discontiguous ] ).
no_style_check(-multiple) :-
	'$style_checker'( [  -multiple ] ).
no_style_check([]).
no_style_check([H|T]) :- no_style_check(H), no_style_check(T).

/** 
  * @pred discontiguous(+ G) is iso, directive
    Avoid warnings from the sytax checker.

Declare that the predicate _G_ or list of predicates are discontiguous
procedures, that is, clauses for discontigous procedures may be
separated by clauses from other procedures.

*/

discontiguous(P) :- '$discontiguous'(P).

/**
@}
*/