/*-------------------------------------------------------------------------*
 * GNU Prolog                                                              *
 *                                                                         *
 * Part  : Prolog to WAM compiler                                          *
 * File  : read_file.pl                                                    *
 * Descr.: source file reading                                             *
 * Author: Daniel Diaz                                                     *
 *                                                                         *
 * Copyright (C) 1999-2012 Daniel Diaz                                     *
 *                                                                         *
 * This file is part of GNU Prolog                                         *
 *                                                                         *
 * GNU Prolog is free software: you can redistribute it and/or             *
 * modify it under the terms of either:                                    *
 *                                                                         *
 *   - the GNU Lesser General Public License as published by the Free      *
 *     Software Foundation; either version 3 of the License, or (at your   *
 *     option) any later version.                                          *
 *                                                                         *
 * or                                                                      *
 *                                                                         *
 *   - the GNU General Public License as published by the Free             *
 *     Software Foundation; either version 2 of the License, or (at your   *
 *     option) any later version.                                          *
 *                                                                         *
 * or both in parallel, as here.                                           *
 *                                                                         *
 * GNU Prolog is distributed in the hope that it will be useful,           *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of          *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU       *
 * General Public License for more details.                                *
 *                                                                         *
 * You should have received copies of the GNU General Public License and   *
 * the GNU Lesser General Public License along with this program.  If      *
 * not, see http://www.gnu.org/licenses/.                                  *
 *-------------------------------------------------------------------------*/

/* $Id: read_file.pl,v 1.29 2012/11/22 14:48:40 diaz Exp $ */

/*-------------------------------------------------------------------------*
 * Data structures:                                                        *
 *                                                                         *
 * the stack of opened files (for nested includes):                        *
 *    global variable open_file_stack = [PlFile*Stream,...]                *
 *    from last to first.                                                  *
 *                                                                         *
 * the context (where occurs an error):                                    *
 *    global variable where = OpenFileStack+(L1-L2)                        *
 *    L1 = first line of the current clause (resp. directive).             *
 *    L2 = last  line of the current clause (resp. directive).             *
 *                                                                         *
 * read_predicate(Pred,N,LSrcCl):                                          *
 *    the structure of the compiler is a repeat/fail loop on 1 predicate   *
 *    calling read_predicate(Pred,N,LSrcCl) to obtain next predicate.      *
 *    Pred   = predicate name (an atom).                                   *
 *    N      = arity (an integer >=0).                                     *
 *    LSrcCl = [SrcCl,...], list of source clauses, with                   *
 *     SrcCl = Where+Cl where Cl is the source clause read.                *
 *                                                                         *
 * Buffers for special predicate management (with assert/retract):         *
 *                                                                         *
 * buff_aux_pred(Pred,N,LSrcCl):                                           *
 *    records the clauses of an auxiliary predicate.                       *
 *    Asserted by Pass 1 (syntactic sugar removing) when splitting ;/2,etc.*
 *    Retracted at the very next invocation of read_predicate/3 to         *
 *    ensure that aux. predicates always follow their "father" predicate.  *
 *                                                                         *
 * buff_discontig_clause(Pred,N,SrcCl):                                    *
 *    records a clause of a discontiguous predicate (:- discontiguous).    *
 *    Eacho clause of a discontiguous predicate is asserted when it is read*
 *    When the end of file is reached all clauses of a discontiguous pred  *
 *    are grouped to return a list of source clauses LSrcCl.               *
 *    Thus discontiguous predicates are always compiled after other        *
 *    predicates.                                                          *
 *                                                                         *
 * buff_dyn_interf_clause(Pred,N,SrcCl):                                   *
 *    records the interface clause of a dynamic predicate (:- dynamic).    *
 *    This clause is of the form Head:- call(Head) and only ensures that   *
 *    an external invocation to this predicate will not need to know that  *
 *    it is dynamic (and should be called by call/1).                      *
 *    Asserted as soon as a :- dynamic directive is encountered.           *
 *    Retracted only when the end of file is reached. All other clauses of *
 *    a dynamic predicate give rise to a system executable directive to    *
 *    assert(z) it.                                                        *
 *                                                                         *
 * empty_dyn_pred(Pred,N,Where):                                           *
 *    asserted when the declaration of a dynamic predicate is encoutered   *
 *    (:- dynamic). Retracted when a clause of a dynamic predicate is read.*
 *    At the end, only contains dynamic predicate with no clauses.         *
 *    Used then to define the interface clause.                            *
 *                                                                         *
 * ensure_linked(Pred,N):                                                  *
 *    asserted for each Pred/N occuring in a :- ensure_linked directive.   *
 *                                                                         *
 * module_export(Pred,N,Module):                                           *
 *    asserted for each imported Pred/N from Module.                       *
 *    asserted for each exported Pred/N from Module.                       *
 *                                                                         *
 * meta_pred(Pred,N,MetaDecl):                                             *
 *    asserted for each meta_predicate declaration.                        *
 *                                                                         *
 * Buffers for executable directive management (with assert/retract):      *
 *                                                                         *
 * buff_exe_system(SrcDirec)                                               *
 *     SrcDirec = Where+Body (i.e. source directive).                      *
 *     records a system directive.                                         *
 *     Asserted for dynamic clauses (to assertz it), and to execute, at    *
 *     run-time, op/3 set_prolog_flag/2, char_conversion/2.                *
 *     Retracted only when the end of file has been reached to provide a   *
 *     predicate '$exe_system':- Body.                                     *
 *                                                                         *
 * buff_exe_user(SrcDirec)                                                 *
 *     records user defined directives (:- initialization).                *
 *     Asserted when a :- initialization declaration is encountered.       *
 *     Retracted just after all '$buff_exe_system' to ensure that any user *
 *     directive has the needed environment.                               *
 *                                                                         *
 * Buffers for special clause management (with assert/retract):            *
 *                                                                         *
 * buff_clause(Pred,N,SrcCl):                                              *
 *    the reader needs a lookahead clause (to group clauses by predicates).*
 *    For such a clause we assert/retract(buff_clause(Pred,N,SrcCl)).      *
 *    Read at the very next invocation of get_next_clause/3.               *
 *-------------------------------------------------------------------------*/

:-	op(200, fx, ?).

read_file_init(PlFile) :-
	retractall(buff_clause(_, _, _)),
	retractall(buff_aux_pred(_, _, _)),
	retractall(buff_discontig_clause(_, _, _)),
	retractall(buff_dyn_interf_clause(_, _, _)),
	retractall(buff_exe_system(_)),
	retractall(buff_exe_user(_)),
	retractall(empty_dyn_pred(_, _, _)),
	retractall(ensure_linked(_, _)),
	retractall(pred_info(_, _, _)),
	retractall(module_export(_, _, _)),
	retractall(meta_pred(_, _, _)),
	g_assign(module, user),
	g_assign(module_already_seen, f),
	g_assign(default_kind, user),
	g_assign(reading_dyn_pred, f),
	g_assign(eof_reached, f),
	g_assign(open_file_stack, []),
	g_assign(if_stack, []),
	g_assign(where, 0),
	g_assign(syn_error_nb, 0),
	g_assign(in_lines, 0),
	g_assign(in_bytes, 0),
	open_new_prolog_file(PlFile).




read_file_term(Bytes, Lines) :-
	g_read(in_bytes, Bytes),
	g_read(in_lines, Lines).




read_file_error_nb(SynErrNb) :-
	g_read(syn_error_nb, SynErrNb).




open_new_prolog_file(PlFile0) :-
	g_read(open_file_stack, OpenFileStack),
	prolog_file_name(PlFile0, PlFile),
	open_new_prolog_file1(PlFile, OpenFileStack, PlFile1, Stream), !,
	g_assign(open_file_stack, [PlFile1 * Stream|OpenFileStack]),
	(   peek_char(Stream, '#'), % ignore #! starting line (for shebang support)
	    repeat,
	    get_char(Stream, X),
	    (X = '\n' ; X = end_of_file)
	;
	    true
	).


open_new_prolog_file1(user, _, user, Stream) :-
	current_input(Stream).
	
open_new_prolog_file1(PlFile, _, PlFile, Stream) :-
%	format('~n*** Trying to open ~a~n', [PlFile]),
	catch(open(PlFile, read, Stream), error(existence_error(source_sink, _), _), fail).

open_new_prolog_file1(PlFile, OpenFileStack, PlFile1, Stream) :-
%	format('file stack: ~w~n', [OpenFileStack]),
	is_relative_file_name(PlFile),
	try_other_directory(OpenFileStack, PlFile, PlFile1, Stream).

open_new_prolog_file1(PlFile, _, _, _) :-
	throw(error(existence_error(source_sink, PlFile), open/3)).


	/* If an included file is not found try to look in "parents" (includers) path.
	 * If found return the new name (to have correct error msg and file_name in .wam)
	 */

try_other_directory([PlFile1 * _|_], PlFile, PlFile2, Stream) :-
	decompose_file_name(PlFile1, Directory, _, _),
	Directory \== '',
	atom_concat(Directory, PlFile, PlFile2),
%	format('   fail.~n+++ Trying to open ~a~n', [PlFile2]),
	catch(open(PlFile2, read, Stream), _, fail).

try_other_directory([_|OpenFileStack], PlFile, PlFile1, Stream) :-
	try_other_directory(OpenFileStack, PlFile, PlFile1, Stream).



	


close_last_prolog_file :-
	g_read(open_file_stack, [_ * Stream|OpenFileStack]),
	g_assign(open_file_stack, OpenFileStack),
	g_read(in_bytes, Bytes1),
	g_read(in_lines, Lines1),
	character_count(Stream, Bytes2),
	line_count(Stream, Lines2),
	Bytes is Bytes1 + Bytes2,
	Lines is Lines1 + Lines2,
	g_assign(in_bytes, Bytes),
	g_assign(in_lines, Lines),
	close(Stream).




          % Read of a predicate

read_predicate(Pred, N, LSrcCl) :-
	repeat,
	read_predicate1(Pred, N, LSrcCl),                % standard predicate
% !,
	(   g_read(reading_dyn_pred, f),
	    g_read(native_code, t) ->
	    read_predicate_next(Pred, N, LSrcCl)
	;   true
	).




read_predicate_next(Pred, N, LSrcCl) :-
	(test_pred_info(dyn, Pred, N) ; test_pred_info(multi, Pred, N)), !,
	LSrcCl = [Where + _|_],
	add_dyn_interf_clause(Pred, N, Where),
	create_exe_clauses_for_dyn_pred(LSrcCl, Pred, N),
	fail.                              % backtrack to repeat of main loop

read_predicate_next(Pred, N, LSrcCl) :-
	test_pred_info(pub, Pred, N), !,
	create_exe_clauses_for_pub_pred(LSrcCl).

read_predicate_next(_, _, _).




read_predicate1(Pred, N, LSrcCl) :-
	retract(buff_aux_pred(Pred, N, LSrcCl)), !.
                                                   % aux. pred (cf syn_sugar)

read_predicate1(Pred, N, LSrcCl) :-
	g_read(eof_reached, f), !,
	repeat,
	get_next_clause(Pred, N, SrcCl),
	SrcCl = _ + Cl,
	retractall(empty_dyn_pred(Pred, N, _)),
	(   test_pred_info(discontig, Pred, N) ->
	    assertz(buff_discontig_clause(Pred, N, SrcCl)),
	    define_predicate(Pred, N),
	    fail                               % backtrack to read_predicate1
	;   true
	),
	(   test_pred_info(def, Pred, N) ->
	    warn('discontiguous predicate ~q - clause ignored', [Pred / N]),
	    fail                               % backtrack to read_predicate1
	;   true
	), !,
	Cl \== end_of_file,                    % if end_of_file is read, fail
                                            % and backtrack to read_predicate
	define_predicate(Pred, N),
	group_clauses_by_pred(Pred, N, SrcCl, LSrcCl).

read_predicate1(Pred, N, [SrcCl|LSrcCl]) :-
	retract(buff_discontig_clause(Pred, N, SrcCl)), !,  % discontiguous pred
	recover_discontig_clauses(Pred, N, LSrcCl).

read_predicate1(Pred, N, [SrcCl]) :-
	g_assign(reading_dyn_pred, t),
	retract(buff_dyn_interf_clause(Pred, N, SrcCl)), !.     % dyn predicate

read_predicate1(Pred, N, [SrcCl]) :-
	g_assign(reading_dyn_pred, t),
	retract(empty_dyn_pred(Pred, N, Where)),        % empty dyn predicate
	define_predicate(Pred, N),
	(   g_read(native_code, t) ->
	    create_dyn_interf_clause(Pred, N, Where, SrcCl)
	;   SrcCl = Where + '$$empty$$predicate$$clause$$'
	), !.

read_predicate1(Pred, N, LSrcCl) :-
	g_assign(reading_dyn_pred, f),
	retract(buff_exe_system(Where + Body)),       % system exe directives
	Pred = '$exe_system',
	N = 0,
	LSrcCl = [Where + (Pred :- Body)], !.

read_predicate1(Pred, N, LSrcCl) :-
	retract(buff_exe_user(Where + Body)),           % user exe directives
	Pred = '$exe_user',
	N = 0,
	LSrcCl = [Where + (Pred :- Body)], !.

read_predicate1(Pred, N, LSrcCl) :-
	Pred = end_of_file,
	N = 0,
	LSrcCl = [],                                            % end of file
	             !.




group_clauses_by_pred(Pred, N, SrcCl, [SrcCl|LSrcCl1]) :-
	get_next_clause(Pred1, N1, SrcCl1),
	(   Pred = Pred1,
	    N = N1 ->
	    group_clauses_by_pred(Pred1, N1, SrcCl1, LSrcCl1)
	;   LSrcCl1 = [],
	    (   Pred1 = end_of_file,
	        N1 = 0 ->
	        true
	    ;   asserta(buff_clause(Pred1, N1, SrcCl1))
	    )
	).




add_dyn_interf_clause(Pred, N, _) :-
	clause(buff_dyn_interf_clause(Pred, N, _), true), !.  % already asserted

add_dyn_interf_clause(Pred, N, Where) :-
	create_dyn_interf_clause(Pred, N, Where, SrcCl),
	assertz(buff_dyn_interf_clause(Pred, N, SrcCl)).




create_dyn_interf_clause(Pred, N, Where, SrcCl) :-
	length(LArgs, N),
	Head =.. [Pred|LArgs],
	SrcCl = Where + (Head :- call(Head)).




recover_discontig_clauses(Pred, N, [SrcCl|LSrcCl]) :-
	retract(buff_discontig_clause(Pred, N, SrcCl)), !,
	recover_discontig_clauses(Pred, N, LSrcCl).

recover_discontig_clauses(_, _, []).




create_exe_clauses_for_dyn_pred([], _, _).

create_exe_clauses_for_dyn_pred([SrcCl|LSrcCl], Pred, N) :-
	SrcCl = Where + Cl,
	get_file_name(Where, PlFile),
	add_wrapper_to_dyn_clause(Pred, N, Where + Cl, AuxName),
	handle_initialization(system, ('$call_c'('Pl_Emit_BC_Execute_Wrapper'(Pred, N, '&', AuxName, N), [by_value]), '$add_clause_term'(Cl, PlFile)), Where),
	create_exe_clauses_for_dyn_pred(LSrcCl, Pred, N).




create_exe_clauses_for_pub_pred([]).

create_exe_clauses_for_pub_pred([Where + Cl|LSrcCl]) :-
	get_file_name(Where, PlFile),
	handle_initialization(system, '$add_clause_term'(Cl, PlFile), Where),
	create_exe_clauses_for_pub_pred(LSrcCl).


get_file_name([PlFile * _|_] + _, PlFile).




get_next_clause(Pred, N, SrcCl) :-
	retract(buff_clause(Pred, N, SrcCl)),
	SrcCl = Where + _,
	g_assign(where, Where), !.

get_next_clause(Pred, N, SrcCl) :-
	g_read(open_file_stack, OpenFileStack),
	OpenFileStack = [_ * Stream|_],
	'$catch'(read_term(Stream, Cl, [singletons(SingNames)]), error(syntax_error(Err), _), after_syn_error, any, 0, false),
	(   var(Err) ->
	    last_read_start_line_column(L1, _),
	    '$catch'(expand_term(Cl, Cl1), error(Err, _), dcg_error(Err), any, 0, false),
	    stream_line_column(Stream, Line, Col),
	    (   Col = 1 ->
	        L2 is Line - 1
	    ;   L2 = Line
	    ),
	    Where = OpenFileStack + (L1 - L2),
	    g_assign(where, Where),
	    get_next_clause1(Cl1, Where, SingNames, Pred, N, SrcCl)
	;   get_next_clause(Pred, N, SrcCl)
	), !.



get_next_clause1(end_of_file, _, _, Pred, N, SrcCl) :-
	close_last_prolog_file,
	g_read(open_file_stack, OpenFileStack),
	(   OpenFileStack = [] ->
	    Pred = end_of_file,
	    N = 0,
	    SrcCl = _ + end_of_file,
	    g_assign(eof_reached, t),
	    (   g_read(if_stack, []) ->
		true
	    ;
		error('endif directive expected', [])
	    )

	;   get_next_clause(Pred, N, SrcCl)
	).

				% +++++ begin preprocessor management +++++
get_next_clause1((:- if(Goal)), _, _, Pred, N, SrcCl) :-
	!,
	g_read(if_stack, IfStack),
	(   '$catch'(Goal, Err, (warn('if directive caused exception: ~w', [Err]), fail), any, 0, false) ->
	    g_assign(if_stack, [if(then, 1)|IfStack])
	;
	    g_assign(if_stack, [if(then, 0)|IfStack])
	),
	get_next_clause(Pred, N, SrcCl).

get_next_clause1((:- elif(Goal)), _, _, Pred, N, SrcCl) :-
	!,
	(   g_read(if_stack, [if(then, Keep)|IfStack]) ->
	    (   Keep = 0 ->
		(   '$catch'(Goal, Err, (warn('elif directive caused exception: ~w', [Err]), fail), any, 0, false) ->
		    g_assign(if_stack, [if(then, 1)|IfStack])
		;
		    g_assign(if_stack, [if(then, 0)|IfStack])
		)
	    ;
		g_assign(if_stack, [if(then, 2)|IfStack])  % 2 means ignore both the then and else part
	    )
	;
	    error('unexpected elif directive', [])
	),
	get_next_clause(Pred, N, SrcCl).

get_next_clause1((:- else), _, _, Pred, N, SrcCl) :-
	!,
	(   g_read(if_stack, [if(then, Keep)|IfStack]) ->
	    Keep1 is 1 - Keep,
	    g_assign(if_stack, [if(else, Keep1)|IfStack])
	;
	    error('unexpected else directive', [])
	),
	get_next_clause(Pred, N, SrcCl).


get_next_clause1((:- endif), _, _, Pred, N, SrcCl) :-
	!,
	(   g_read(if_stack, [if(_, _)|IfStack]) ->
	    g_assign(if_stack, IfStack)
	;
	    error('unexpected endif directive', [])
	),
	get_next_clause(Pred, N, SrcCl).

get_next_clause1(_, _, _, Pred, N, SrcCl) :- % preprocessor ignores a clause
	g_read(if_stack, [if(_, Keep)|_]), Keep \== 1, !, % ignore Keep = 0 and Keep = 2 or 1-2 = -1
	get_next_clause(Pred, N, SrcCl).
				% +++++ end preprocessor management +++++

get_next_clause1((:- D), Where, SingNames, Pred, N, SrcCl) :-
	display_singletons(SingNames, directive),
	(   g_read(foreign_only, f)
	;   functor(D, foreign, _)
	),
	(   handle_directive(D, Where)
	;   error('invalid directive ~q', [D])
	), !,
	get_next_clause(Pred, N, SrcCl).

get_next_clause1(Cl, Where, SingNames, Pred, N, Where + Cl) :-
	g_read(foreign_only, f), !,
	(   Cl = (Head :- _)
	;   Cl = Head
	),
	(   nonvar(Head) ->
	    true
	;   error('head is a variable', [])
	),
	(   callable(Head) ->
	    true
	;   error('head is not a callable (~q)', [Head])
	),
	functor(Head, Pred, N),
	check_head_is_module_free(Head),
	check_module_clash(Pred, N),
	check_predicate(Pred, N),
	display_singletons(SingNames, Pred / N).

                                          % ignore clause with --foreign-only
get_next_clause1(_, _, _, Pred, N, SrcCl) :-
	get_next_clause(Pred, N, SrcCl).




after_syn_error :-
	g_read(syn_error_nb, SynErrNb),
	SynErrNb1 is SynErrNb + 1,
	g_assign(syn_error_nb, SynErrNb1),
	syntax_error_info(_, Line, Column, Msg),
	g_read(open_file_stack, OpenFileStack),
	g_assign(where, OpenFileStack + (Line - Line)),
	disp_msg('syntax error', Column, '~a', [Msg]).




dcg_error(Err) :-
	last_read_start_line_column(Line, _),
	g_read(open_file_stack, OpenFileStack),
	g_assign(where, OpenFileStack + (Line - Line)),
	error('DCG error raised: ~w', [Err]).




display_singletons(SingNames, PI) :-
	g_read(singl_warn, t), !,
	get_singletons(SingNames, Sing),
	(   Sing = [] ->
	    true
	;   warn('singleton variables ~w for ~q', [Sing, PI])
	).

display_singletons(_, _).




get_singletons([], []).

get_singletons([X = _|SingNames], Sing1) :-
	(   sub_atom(X, 0, 1, _, '_') ->
	    Sing1 = Sing
	;   Sing1 = [X|Sing]
	),
	get_singletons(SingNames, Sing).




:-	discontiguous(handle_directive / 3).

handle_directive(D, Where) :-
	D =.. [DName|DLst],
	handle_directive(DName, DLst, Where).


handle_directive(public, DLst, _) :-
	!,
	DLst \== [],
	set_flag_for_preds(DLst, pub).

handle_directive(dynamic, DLst, Where) :-
	!,
	DLst \== [],
	set_flag_for_preds(DLst, dyn),
	set_flag_for_preds(DLst, pub),
	add_empty_dyn(DLst, Where).

handle_directive(multifile, DLst, Where) :-
	!,
	DLst \== [],
	set_flag_for_preds(DLst, multi),
	add_empty_dyn(DLst, Where).

handle_directive(discontiguous, DLst, _) :-
	!,
	DLst \== [],
	set_flag_for_preds(DLst, discontig).

handle_directive(built_in, DLst, _) :-
	!,
	(   DLst == [],
	    g_assign(default_kind, built_in)
	;   DLst \== [],
	    set_flag_for_preds(DLst, bpl)
	), !.

handle_directive(built_in_fd, DLst, _) :-
	!,
	(   DLst == [],
	    g_assign(default_kind, built_in_fd)
	;   DLst \== [],
	    set_flag_for_preds(DLst, bfd)
	).

handle_directive(ensure_linked, DLst, _) :-
	!,
	(   g_read(native_code, f) ->
	    warn('ensure_linked directive ignored in byte-code compilation mode', [])
	;   DLst \== [],
	    add_ensure_linked(DLst)
	).

handle_directive(encoding, _, _) :-
	!,
	warn('encoding directive not supported - directive ignored', []).

handle_directive(ensure_loaded, _, _) :-
	!,
	warn('ensure_loaded directive not supported - directive ignored', []).

handle_directive(include, [PlFile], _) :-
	!,
	open_new_prolog_file(PlFile).

handle_directive(op, [X, Y, Z], Where) :-
	!,
	exec_directive(op(X, Y, Z)),
	handle_initialization(system, op(X, Y, Z), Where).

handle_directive(char_conversion, [X, Y], Where) :-
	!,
	exec_directive(char_conversion(X, Y)),
	handle_initialization(system, char_conversion(X, Y), Where).

handle_directive(set_prolog_flag, [X, Y], Where) :-
	!,
	exec_directive(set_prolog_flag(X, Y)),
	(   current_prolog_flag(singleton_warning, off) ->
	    g_assign(singl_warn, f)
	;   g_assign(singl_warn, t)
	),
	handle_initialization(system, set_prolog_flag(X, Y), Where).

handle_directive(initialization, [Body], Where) :-
	!,
	handle_initialization(user, Body, Where).


handle_directive(module, [Module, DLst], _) :-
	!,
	(   g_read(module_already_seen, f) ->
	    check_module_name(Module, false),
	    g_assign(module_already_seen, t),
	    g_assign(module, Module),
	    add_module_export_info(DLst, Module)
	;
	    error('directive module/2 already declared', [])
	).

handle_directive(use_module, [Module, DLst], _) :-
	!,
	check_module_name(Module, false),
	add_module_export_info(DLst, Module).

handle_directive(meta_predicate, [MetaDecl], _) :-
	!,
	(   callable(MetaDecl) ->
	    functor(MetaDecl, Pred, N),
	    set_flag_for_preds(Pred/N, meta),
	    assertz(meta_pred(Pred, N, MetaDecl))
	;
	    error('invalide directive meta_predicate/1 ~w', [MetaDecl])
	).

handle_directive(foreign, [Template], Where) :-
	!,
	handle_directive(foreign, [Template, []], Where).

handle_directive(foreign, _, _) :-
	g_read(call_c, f), !,
	warn('foreign directive ignored (not allowed in this mode)', []).

handle_directive(foreign, [Template, Options], Where) :-
	!,
	callable(Template),
	list(Options),
	functor(Template, Pred, N),
	(   test_pred_info(pub, Pred, N) ->
	    error('foreign predicate ~q should not be public/dynamic', [Pred/N])
	;   true),
	define_predicate(Pred, N),
	g_assign(foreign_fct_name, Pred),
	g_assign(foreign_return, boolean),
	g_assign(foreign_bip, Pred/N),
	g_assign(foreign_choice_size, -1),
	foreign_get_options(Options),
	foreign_check_types(0, N, Template, LType),
	g_read(foreign_fct_name, FctName),
	g_read(foreign_return, Return),
	g_read(foreign_bip, BipPred),
	g_read(foreign_choice_size, ChcSize),
	no_internal_transf(args(FctName, Return, BipPred, ChcSize, LType), Args),
	functor(Head, Pred, N),
	SrcCl = Where + (Head :- '$foreign_call_c'(Args)),
	assertz(buff_discontig_clause(Pred, N, SrcCl)),
	add_ensure_linked('$force_foreign_link' / 0).
                     % to force the link of foreign.o and then foreign_supp.o




foreign_get_options([]).

foreign_get_options([X|Options]) :-
	foreign_get_options1(X), !,
	foreign_get_options(Options).


foreign_get_options1(fct_name(FctName)) :-
	atom(FctName),
	g_assign(foreign_fct_name, FctName).

foreign_get_options1(return(Return)) :-
	atom(Return),
	(   Return = none
	;   Return = boolean
	;   Return = jump
	),
	g_assign(foreign_return, Return).

foreign_get_options1(bip_name(X)) :-
	nonvar(X),
	X = none,
	g_assign(foreign_bip, ''/ -1).

foreign_get_options1(bip_name(BipName, BipArity)) :-
	atom(BipName),
	integer(BipArity),
	g_assign(foreign_bip, BipName/BipArity).

foreign_get_options1(bip_name(BipName/BipArity)) :-
	atom(BipName),
	integer(BipArity),
	g_assign(foreign_bip, BipName/BipArity).

foreign_get_options1(choice_size(ChcSize)) :-
	integer(ChcSize),
	g_assign(foreign_choice_size, ChcSize).




foreign_check_types(N, N, _, []) :-
	!.

foreign_check_types(I, N, Template, [(Mode, A)|LArgType]) :-
	I1 is I + 1,
	arg(I1, Template, Arg),
	nonvar(Arg),
	(   Arg = + A,
	    Mode = in
	;   Arg = - A,
	    Mode = out
	;   Arg = ? A,
	    Mode = in_out
	;   Arg = term,
	    A = term,
	    Mode = in
	),                                                     % term = +term
	nonvar(A),
	foreign_check_arg(A),
	foreign_check_types(I1, N, Template, LArgType).

foreign_check_arg(integer).
foreign_check_arg(positive).
foreign_check_arg(float).
foreign_check_arg(number).
foreign_check_arg(atom).
foreign_check_arg(boolean).
foreign_check_arg(char).
foreign_check_arg(in_char).
foreign_check_arg(code).
foreign_check_arg(in_code).
foreign_check_arg(byte).
foreign_check_arg(in_byte).
foreign_check_arg(string).
foreign_check_arg(chars).
foreign_check_arg(codes).
foreign_check_arg(term).




handle_directive(DName, LArgs, _) :-
	length(LArgs, N),
	warn('unknown directive ~q - maybe use initialization/1 - directive ignored', [DName / N]).




handle_initialization(system, Body, Where) :-
	assertz(buff_exe_system(Where + Body)).

handle_initialization(user, Body, Where) :-
	assertz(buff_exe_user(Where + Body)).




exec_directive(Goal) :-
	'$catch'(Goal, Err, exec_directive_exception(Goal, Err), any, 0, false), !.

exec_directive(Goal) :-
	warn('directive failed (~q)', [Goal]).

exec_directive_exception(Goal, Err) :-
	warn('directive failed (~q) with exception (~q)', [Goal, Err]).



used_bips_via_call :-                     % to enforce the link of these bips
	op(_, _, _),
	char_conversion(_, _),
	set_prolog_flag(_, _),
	expand_term(_, _).




add_empty_dyn([], _) :-
	!.

add_empty_dyn([P1|P2], Where) :-
	!,
	add_empty_dyn(P1, Where),
	add_empty_dyn(P2, Where).

add_empty_dyn((P1, P2), Where) :-
	!,
	add_empty_dyn(P1, Where),
	add_empty_dyn(P2, Where).

add_empty_dyn(Pred / N, Where) :-
	(   clause(empty_dyn_pred(Pred, N, _), _) ->
	    true
	;
	    assertz(empty_dyn_pred(Pred, N, Where))
	).




add_ensure_linked([]) :-
	!.

add_ensure_linked([P1|P2]) :-
	!,
	add_ensure_linked(P1),
	add_ensure_linked(P2).

add_ensure_linked((P1, P2)) :-
	!,
	add_ensure_linked(P1),
	add_ensure_linked(P2).

add_ensure_linked(Pred / N) :-
	clause(ensure_linked(Pred, N), true), !.

add_ensure_linked(Pred / N) :-
	assertz(ensure_linked(Pred, N)).




add_module_export_info([], _) :-
	!.

add_module_export_info([P1|P2], Module) :-
	!,
	add_module_export_info(P1, Module),
	add_module_export_info(P2, Module).

add_module_export_info((P1, P2), Module) :-
	!,
	add_module_export_info(P1, Module),
	add_module_export_info(P2, Module).

add_module_export_info(Pred / N, _) :-
	clause(module_export(Pred, N, Module1), true), !,
	error('predicate ~w already exported from module ~w', [Pred/N, Module1]).

add_module_export_info(Pred / N, Module) :-
	assertz(module_export(Pred, N, Module)),
	(   test_pred_info(def, Pred, N) ->
	    check_module_clash(Pred, N)
	;
	    true
	).


check_module_name(Module, true) :-
	var(Module), !.

check_module_name(Module, _) :-
	atom(Module), !.

check_module_name(Module, _) :-
	error('invalid module name (~q) should be an atom', [Module]).

/*
check_module_name(Module, _) :-
	atom(Module),
	\+ atom_property(Module, needs_quotes), !.

check_module_name(Module, _) :-
	error('invalid module name (~q) should only containts lower chars', [Module]).
*/



check_head_is_module_free(Module:Head) :-
	!,
	error('module qualification is not allowed for the head of a clause (~w)', [Module:Head]).

check_head_is_module_free(_).




check_module_clash(Pred, N) :-  % Pred/N is defined in current module check for clash with an import
	clause(module_export(Pred, N, Module), true),
	g_read(module, Module1),
	Module \== Module1, !,
	error('clash on ~q - defined in module ~q (here) and imported from ~w', [Pred / N, Module1, Module]).

check_module_clash(_, _).





get_owner_module(Pred, N, Module) :-
	clause(module_export(Pred, N, Module), true),
	Module \== system, !.

get_owner_module(_, _, _).



is_exported(Pred, N) :-
	clause(module_export(Pred, N, _), true), !.




get_module_of_cur_pred(Module) :-
	cur_pred(Pred, N),
	(   test_pred_info(bpl, Pred, N) ->
	    Module = system
	;   test_pred_info(bfd, Pred, N) ->
	    Module = system
	;
	    g_read(module, Module)
	).




set_flag_for_preds([], _) :-
	!.

set_flag_for_preds([P1|P2], Flag) :-
	!,
	set_flag_for_preds(P1, Flag),
	set_flag_for_preds(P2, Flag).

set_flag_for_preds((P1, P2), Flag) :-
	!,
	set_flag_for_preds(P1, Flag),
	set_flag_for_preds(P2, Flag).

set_flag_for_preds(Pred / N, Flag) :-
	atom(Pred),
	integer(N),
	(   test_pred_info(def, Pred, N) ->
	    warn('directive occurs after definition of ~q - directive ignored', [Pred / N])
	;   (   Flag = bpl,
	        unset_pred_info(bfd, Pred, N)
	    ;   Flag = bfd,
	        unset_pred_info(bpl, Pred, N)
	    ;   true
	    ), !,
	    set_pred_info(Flag, Pred, N)
	).




define_predicate(F, N) :-
	set_pred_info(def, F, N),
	test_pred_info(bpl, F, N), !.

define_predicate(F, N) :-
	test_pred_info(bfd, F, N), !.

define_predicate(F, N) :-
	g_read(default_kind, built_in), !,
	set_pred_info(bpl, F, N).

define_predicate(F, N) :-
	g_read(default_kind, built_in_fd), !,
	set_pred_info(bfd, F, N).

define_predicate(_, _).




flag_bit(def, 0).
flag_bit(dyn, 1).
flag_bit(pub, 2).
flag_bit(bpl, 3).
flag_bit(bfd, 4).
flag_bit(discontig, 5).
flag_bit(cut, 6).
flag_bit(meta, 7).
flag_bit(multi, 8).




set_pred_info(Flag, F, N) :-
	flag_bit(Flag, Bit),
	(   retract(pred_info(F, N, X))
	;   X = 0
	), !,
	X1 is X \/ 1 << Bit,
	assertz(pred_info(F, N, X1)).




unset_pred_info(Flag, F, N) :-
	flag_bit(Flag, Bit),
	retract(pred_info(F, N, X)), !,
	X1 is X /\ \ (1 << Bit),
	assertz(pred_info(F, N, X1)).

unset_pred_info(_, _, _).




test_pred_info(Flag, F, N) :-
	flag_bit(Flag, Bit),
	clause(pred_info(F, N, X), _),
	X /\ 1 << Bit > 0 .




check_predicate(Pred, N) :-
	g_read(redef_error, t),
	control_construct(Pred, N), !,
	error('redefining control construct ~q', [Pred / N]).

check_predicate(Pred, N) :-
	g_read(redef_error, t),
	bip(Pred, N), !,
	error('redefining built-in predicate ~q', [Pred / N]).

check_predicate(Pred, N) :-
	g_read(susp_warn, t),
	suspicious_predicate(Pred, N), !,
	warn('suspicious predicate ~q', [Pred / N]).

check_predicate(Pred, N) :-
	'$aux_name'(Pred), !,
	warn('using system auxiliary predicate ~q', [Pred / N]).

check_predicate(_, _).



bip(F, N) :-
	'$predicate_property1'(F, N, built_in), !.
/* no longer needed built_in_fd ==> built_in
bip(F, N) :-
	'$predicate_property1'(F, N, built_in_fd).
*/


control_construct(',', 2).
control_construct(;, 2).
control_construct(->, 2).
control_construct(!, 0).
control_construct(fail, 0).
control_construct(true, 0).
control_construct(call, 1).
control_construct(catch, 3).
control_construct(throw, 1).

%suspicious_predicate(',', 2).
%suspicious_predicate(;, 2).
%suspicious_predicate(->, 2).
%suspicious_predicate(!, 0).
suspicious_predicate(:, 2).
suspicious_predicate(:-, 1).
suspicious_predicate(:-, 2).
suspicious_predicate(-->, 2).
suspicious_predicate({}, X) :- X < 2.
suspicious_predicate(+, 2).
suspicious_predicate(-, 2).
suspicious_predicate(*, 2).
suspicious_predicate(/, 2).
suspicious_predicate(//, 2).




warn(Msg, LArg) :-
	disp_msg(warning, 0, Msg, LArg).




error(Msg, LArg) :-
	disp_msg('fatal error', 0, Msg, LArg),
	repeat,                                      % close all opened files
	(   close_last_prolog_file ->
	    fail
	;   !
	),
	abort.




disp_msg(MsgType, Column, Msg, LArg) :-
	numbervars(LArg),
	g_read(where, Where),
	(   Where = OpenFileStack + L12,
	    L12 = _ - _ ->
	    disp_file_name(OpenFileStack, _),
	    disp_lines(L12),
	    disp_column(Column)
	;   true
	),
	format('~a: ', [MsgType]),
	format(Msg, LArg),
	nl(user_output).




disp_file_name([], '') :-
	!.

disp_file_name([FileName * _|OpenFileStack], ' including ') :-
	disp_file_name(OpenFileStack, Before),
	format('~a~a', [Before, FileName]).




disp_lines(L - L) :-
	!,
	format(':~d', [L]).

disp_lines(L1 - L2) :-
	format(':~d-~d', [L1, L2]).



disp_column(Column) :-
	Column > 0, !,
	format(':~d: ', [Column]).

disp_column(_) :-
	write(': ').




          % Exception recovery

exception(error(syntax_error(_), _)) :-
	!,
	syntax_error_info(_, Line, Char, Msg),
	g_read(open_file_stack, OpenFileStack),
	g_assign(where, OpenFileStack + (Line - Line)),
	error('syntax error: ~a (char:~d)', [Msg, Char]).

exception(error(existence_error(source_sink, File), _)) :-
	!,
	error('cannot open file ~a - does not exist', [File]).

exception(error(permission_error(open, source_sink, File), _)) :-
	!,
	error('cannot open file ~a - permission error', [File]).

exception(Err) :-
	error('exception raised: ~q', [Err]).
