%====================================================================================
%
% YPP: Yap PreProcessing
%
% Author: Nuno Fonseca (nunofonseca@acm.org)
% Date: 2005-05-14
% $Id: ypp.yap,v 1.1 2005/06/06 05:10:37 vsc Exp $
%
%====================================================================================

%====================================================================================
% Module declarations
%====================================================================================

:-module(ypp,[
	      ypp_state/1,	% ypp_state(on|off)
	      ypp_define/2,     % persistent defines  ypp_define(+NAME,VALUE)
	      ypp_undefine/1,   % persistent defines  ypp_undefine(+NAME)
	      ypp_extcmd/1,	% ypp_extcmd(?command)
	      ypp_consult/1,    % similiar to standard consult but with preprocessing
	      ypp_reconsult/1
    ]
    ).
%====================================================================================
% Public Predicates
%====================================================================================

ypp_state(State):-
	ground(State),!,
	set_state(State).

ypp_state(State):-
	get_state(State),
	!.

ypp_define(Name,Value):-
	ground(Name),ground(Value),
	store_define(Name,Value).

ypp_undefine(Name):-
	ground(Name),
ypp_extcmd(Cmd):-
	ground(Cmd),!,
	eraseall('____ypp_extcmd'),
	recorda('____ypp_extcmd',Cmd,_).
ypp_extcmd(Cmd):-
	\+ ground(Cmd),
	recorded('____ypp_extcmd',Cmd,_).

ypp_consult(File):-
	(get_state(on)->ypp_file(File,NFile);NFile=File),
	consult(NFile).

ypp_reconsult(File):-
	(get_state(on)->ypp_file(File,NFile);NFile=File),
	reconsult(NFile),
%====================================================================================
% Private Predicates
%====================================================================================

set_state(on):-set_value('____ypp_state',1).
set_state(off):-set_value('____ypp_state',0).

get_state(State):-
	get_value('____ypp_state',Val),
	(Val==0->State=off;State=on).


store_define(Name,Value):-
	(recorded('___ypp',def(Name,_),Ref)->erase(Ref);true),
	recordz('___ypp',def(Name,Value),_).

del_define(Name):-
	(recorded('___ypp',def(Name,_),Ref)->erase(Ref);true),
	!.

%defines2string(-DefineString)
defines2string(S):-
	findall(d(Name,Val),recorded('___ypp',def(Name,Val),_),AllDefs),
	mergedefs(AllDefs,'-D',S),
	!.

mergedefs([],_,'').
mergedefs([d(Name,Val)|RDefs],Pref,S):-
	mergedefs(RDefs,Pref,S1),
	atom_concat([Pref,Name,'=',Val,' ',S1],S).


ypp_file(File,PPFile):-
	% ppfile
	atom_concat([File,'.ypp'],PPFile),
	% Cmdline
	defines2string(Defs),ypp_extcmd(Cmd),
	atom_concat([Cmd,' ',PPFile,' ',Defs,' ',File],Cmdline),
	write(Cmdline),nl,
%	current_module(M1,M2),
%	write(M1:M2),nl,
	system(Cmdline),
	!.

% initialization
:-set_state(on),
	ypp_extcmd('cpp -E -w -o ').
%	ypp_extcmd('gpp -o').

