:- yap_flag( double_quotes, string ).

:- yap_flag( write_strings, on ).

:- style_check( all ).

:- use_module(library(lists)).
:- use_module(library(readutil)).

:- initialization(main).

:- dynamic val/2, item/2, last_node/2, indent/1, pred/4.

get_arg( Inp, Out ) :-
	unix( argv( [Inp, Out] ) ), !.
get_arg( Inp, 'yap.md' ) :-
	unix( argv( [Inp] ) ), !.
get_arg( 'yap.tex', 'yap.md' ) :-
	unix( argv( [] ) ).

main :-
	abolish( line/3 ),
	get_arg( Inp, Out ),
	scan_file( Inp ),
	open( Out, write, S , [encoding(utf8)] ),
	out( S ),
	close( S ).

:- dynamic buffer/2.

scan_file( Inp ) :-
	open( Inp , read, S , [encoding(utf8)] ),
	repeat,
	line_count( S, Lines ),
	read_line_to_string(S, Line0),
	assert_static( source( Inp, Lines, Line0 ) ),
	( Line0 == end_of_file ->
	  !,
	  % done
	  (
	   retract( buffer( Pos, BLine ) )
	  ->
	   % flush
	   assert_static( line( Inp, Pos, BLine ) )
	  ;
	   true
	  ),
	  retractall( item( _, _ ) ),
	  close( S )
	;
	  % fetch sub-file
	  jmp_blanks( Line0, Line ),
	  sub_string(Line, 0, _, Left, "@include "),
	  sub_string(Line, _, Left, 0, CLeft),
	  jmp_blanks(CLeft, NewString),
	  assert_static( line( Inp, Lines, "@include" ) ),
	  atom_string( NewFile, NewString )
	->
	  scan_file( NewFile ),
	  fail
	;
	  % look for indices
	  % with all predicates
	  first_text(Line0, "@findex", Rest)
	->
	  first_text(Rest, Pred, _),
	  atom_string( A1, Pred ),
	  item( Item0 , ItLines ),
	  atom_string(A2, Item0),
	  cvt_slash( Pred, Key ),
	  \+ pred(_, Key, _, _ ),
	  assert( pred( A1, Key, A2, Inp:ItLines ) ),
	  fail
	;
	  % look for predicates
	  first_word(Line0, "@item", _Rest),
	  retractall( item( _ , _ ) ),
	  jmp_blanks( Line0, Line ),
	  assert( item( Line, Lines ) ),
	  fail
	;
	  % output a line
	  jmp_blanks( Line0, Line ),
	  % pack all lines in a buffer.
	  (
	   % blank or @... and we have a buffer
	   singleton_line( Line )
	  ->
	   (
	    retract( buffer( Pos, BLine ) )
	  ->
	   % flush and dump
	    assert_static( line( Inp, Pos, BLine ) )
	   ;
	    true
	   ),
	   assert_static( line( Inp, Lines, Line ) ),
	   fail
	  ;
	   % blank or @... and we have a buffer
	   separating_line( Line ),
	   retract( buffer( Pos, BLine ) )
	  ->
	   % store it away and flush
	   assert( buffer( Lines, Line ) ),
	   assert_static( line( Inp, Pos, BLine ) ),
	   fail
	  ;
	   % expand buffer with extra text.
	   retract( buffer( Pos, BLine ) )
	  ->
	   string_concat( [BLine, " ", Line], ELine ),
	   assert( buffer( Pos, ELine ) ),
	   fail
	  ;
	   % stash initial buffer
	   assert( buffer( Lines, Line ) ),
	   fail	   
	)
	).

out( _S ) :-
	% init
	nb_setval(old_line, "here I go"),
	nb_setval(level, 0),
	nb_setval(item, indent(0,0)),
	retractall( stack(_, _) ),
	assert( indent( 0 ) ),
	nb_setval(do_buffer, true),
	nb_setval( min, 0 ),
	fail.
out( S ) :-
	line( F, Pos, Line0),
%( Pos = 5770  -> trace ; true ),
	jmp_blanks( Line0, Line),
	b_setval( line, F:Pos:Line ),
	process( Line , NewLine, F:Pos),
	offset( N ),
	( NewLine == no
	->
	  fail
	;
	  NewLine == ""
	->
	  nb_getval( old_line, OldLine ),
	  OldLine \= "",	  
	  format(string(SN), '~n', [])
	;
	  NewLine == force
	->
	  format(string(SN), '~n', [])
	;
	  ( speek( list, it(_Env, _, Level, _) ),
	    Level \= 0
	  ->
	    format( string(SN), '~*c~s~n', [N, 0' , NewLine]) % '
	  ;
	    format( string(SN), '~*c~s~n', [N, 0' , NewLine]) % '
	  )
	),
	format(S, '~s', [SN]),
	nb_setval( old_line, Line ),
	fail.
out( _ ).

separating_line( "" ) :- !.
separating_line( First ) :-
	get_string_code(1, First, 0'@).		%' %

:- dynamic singletons/0.

singleton_line(L) :- string_concat("@item",_,L), 
	\+ speek(list,it("@table",_,_,_)), !.
singleton_line(L) :- string_concat("@c",_,L), !.
singleton_line(L) :- string_concat("@comment",_,L), !.
singleton_line(L) :- string_concat("@findex",_,L), !.
singleton_line(L) :- string_concat("@cindex",_,L), !.
singleton_line(L) :- string_concat("@cnindex",_,L), !.
singleton_line(L) :- string_concat("@cyindex",_,L), !.
singleton_line(L) :- string_concat("@cindex",_,L), !.
singleton_line(L) :- string_concat("@defindex",_,L), !.
singleton_line(L) :- string_concat("@caindex",_,L), !.
singleton_line(L) :- string_concat("@printindex",_,L), !.
singleton_line(L) :- string_concat("@vskip",_,L), !.
singleton_line(L) :- string_concat("@itemize",_R,L), !.
singleton_line(L) :- string_concat("@enumerate",_R,L), !.
singleton_line(L) :- string_concat("@table",_R,L), !.
singleton_line(L) :- string_concat("@example",_R,L), !, assert( singletons ).
singleton_line(L) :- string_concat("@ifplaintext",_R,L), !, assert( singletons ).
singleton_line(L) :- string_concat("@pl_example",_R,L), !, assert( singletons ).
singleton_line(L) :- string_concat("@c_example",_R,L), !, assert( singletons ).
singleton_line(L) :- string_concat("@simpleexample",_R,L), !, assert( singletons ).
singleton_line(L) :- string_concat("@end",R,L), !,
	( sub_string(R, _, _, _, "example") -> retract( singletons ) ; true ).
singleton_line(_L) :-
	singletons.

% blank line, flush and return empty
process( "" , NewLine , _Pos) :- !,
	NewLine = "" .
% skip mode: fails or end of skip mode?
process( Line , S, F:Pos ) :-
	speek(skip, verbatim ), !,
	(
	 first_word(Line, "@end", Rest)
	->
	 (
	  first_word(Rest, Env1, _Rest2),
	  sub_string( Env1, _, _, 0, "example" )
	 ->
	  ( S = "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" ;
	    pop( skip, verbatim ), fail
	  )
	 ;
	  first_word(Rest, Env1, _Rest2),
	  sub_string( Env1, _, _, 0, "plaintext" )
	 ->
	  ( S = "" ;
	    pop( skip, verbatim ), fail
	  )
	 )
	;
	 first_word(Line, "@cartouche", Rest)
	->
	 fail
	;
	 source(F, Pos, Line0),
	 escapes( S, Line0 )
	).
process( Line , "", _Pos ) :-
	speek(skip, W2 ), !,
	first_word(Line, Word, Rest),
	Word == "@end",
	first_word(Rest, Word2, _Rest),
	( W2 = Word2
	->
	  pop( skip, W2 )
	;
	  true
	).
% command: flush and continue
process( Command , NewLine , Pos) :-
	do_buffer(Command, NewLine, Pos ).

% found command word
do_buffer(Line, NewLine, Pos ) :-
	command( Line, Word, Rest ),
	!,
	process( Word, Line, Rest, NewLine, Pos).
do_buffer( List, NewList, _Pos ) :-
	jmp_blanks( List, First ),
	run( NewList, First).

command(Line) :-
	command( Line, _Word, _Rest ).

command( Line, Word, Rest ) :- 
	first_word(Line, Word, Rest),
	% ensure it is not an inline command
	( get_string_code(1, Rest, '{' ) ->
	  once((sub_string(Word,_,_,"ection") ;sub_string(Word,_,_,"apter") ; (sub_string(Word,_,_,"parag") )))
	;
	  true
	),
	% check for a legit keyword by looking for handlers
	clause( process( Word, _, _, _, _ ), _),
	!.

process("@item", _Line, _Rest, NewLine , _FilePos) :- 
	speek( list, it(_Env, _Item, _Pos, Numb)),
	Numb > 1,
	NewLine = "</li>".
process("@item", Line, Rest, NewLine , FilePos) :- 
	pop( list, it(Env, Item, Pos, Numb)), !,
	NNumb is Numb+1,
	run( Text, Rest ),
	jmp_blanks( Text, First ),
	Pos1 is Pos,
%	item_type(Item, Numb, Marker ),
	Marker = "",
	(
	    Env = "@table",
	     atom_string( A, Line ),
	     pred( _Pred, _Key, A, FilePos )
	     ->
		 push( list, it(Env, Item, Pos, NNumb) ),
		 (
		     % sendout the comand
		     format(string(NewLine), '~t~s ~*+<li>~s @anchor ~a', [Marker, Pos1, First,  _Key]),
		     push( indent, done )	
			 ;
			 NewLine = force
		     )
		 ;
		 format(string(NewLine), '~t~s ~*+<li>~s', [ Marker, Pos, First]),
		push( list, it(Env, Item, Pos, NNumb) ),
		push( indent, done )	
	). %,	writeln(+FilePos:Line), listing(stack).	
process("@end", _Line, _Rest, "</li>" , _Pos) :-
	once( speek(list,it(_Env,_,_LL,_)) ).
process("@end", _Line, Rest, NewLine , _Pos) :-
	speek(list,it(Env,_,_LL,_)),
	( Env = "@enumerate" ->		
	  NewLine = "</ol>"
	;
	  NewLine = "</ul>"
	),
	sub_string( Env, 1, _, 0, Env1 ),
	sub_string( Rest, _, _, _, Env1), !, % check
%	writeln(_Pos:_Line), listing(stack),
	pop( list, it(Env, _, _, _) ).
process("@end", Line, _Rest, NewLine , _Pos) :-
	sub_string(Line, _, _, 0, "ifnottex"), !, % check
	NewLine = "\\endhtmlonly".
process("@end", _Line, Rest, "" , _Pos) :-
	sub_string(Rest, _, _, _, "cartouche"), !. % check
process("@end", _Line, Rest, "" , _Pos) :-
	sub_string(Rest, _, _, _, "format"), !. % check
process("@end", _Line, Rest, "" , _Pos ) :-
	sub_string(Rest, _, _, _, "group"), !. % check
process("@end", Line, _Rest, NewLine , _Pos ) :-
	pop( match, End ),
	sub_string(Line, _, _, 0, End), !, % check
	gen_comment( Line, NewLine ).
process("@end", Line, _Rest, NewLine , _Pos) :-
	pop( language, End ),
	sub_string(Line, _, _, 0, End), !, % check
	gen_comment( Line, NewLine ).
process("@author", _Line, Rest, NewLine , _Pos) :- !,
	jmp_blanks( Rest, Firs ),
	format( string( NewLine), '\\author ~s', [ Firs ] ).
process("@*", _Line, _Rest, ""  , _Pos).
process("@*", _Line, Rest, Line  , _Pos) :-
	!,
	jmp_blanks( Rest, Firs ),
	run( Line, Firs ).
process("@c", _Line, Rest, NewLine , _Pos) :- !,
	gen_comment( Rest, NewLine ).
process("@comment", _Line, Rest, NewLine , _Pos) :- !,
	gen_comment( Rest, NewLine ).
process("@cartouche", _Line, _Rest, "" , _Pos) :- !.
process("@group", _Line, _Rest, "" , _Pos) :- !.
process("@printindex", _Line, _Rest, "" , _Pos) :- !.
process("@bye", _Line, _Rest, "" , _Pos) :- !.
process("@cnindex", _Line, _Rest, no, _Pos ) :- !.
process("@cyindex", _Line, _Rest, no, _Pos) :- !.
process("@chapter", _Line, Rest, NewLine, _Pos ) :- !,
	jmp_blanks( Rest, Firs ),
	run( Title, Firs ),
	nb_setval( level, 1 ),
	title_from_words(Firs, Id, _Pos),
	title( '@chapter', _, TitleDox ),
	format(string(NewLine), '~a ~s ~s', [TitleDox, Id,Title]).
%	( format( string(NewLine), '~s', [Title] ) ; NewLine = "======" ).
process("@cindex", _Line, _Rest,  no , _Pos) :- !.
process("@caindex", _Line, _Rest, no, _Pos ) :- !.
process("@defindex", Line, _Rest, NewLine , _Pos) :- !,
	gen_blank( Line, NewLine ).
process("@direntry", Line, _Rest, NewLine, _Pos ) :- !,
       gen_comment( Line, NewLine ),
       push(skip, "direntry" ).
process("@texinfo", Line, _Rest, NewLine, _Pos ) :- !,
       gen_comment( Line, NewLine ),
       push(skip, "texinfo" ).
process("@documentencoding", _Line, _Rest, "" , _Pos) :- !.
	% jmp_blanks( Rest, NewString ),
	% format( string( NewLine), '<meta charset="~s">', [ NewString ] ).
% unbalanced end
process("@end", Line, _Rest, NewLine , _Pos) :- !,
	gen_comment( Line, NewLine ).
process("@enumerate", _Line, _Rest, NewLine , _Pos) :-
	list( "@enumerate", "@enumerate", NewLine, _Pos).
process("@example", _Line, _Rest, "" , _Pos).
process("@example", _Line, _Rest, "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" , _Pos) :- !,
	push( skip, verbatim).
process("@ifplaintext", _Line, _Rest, "" , _Pos) :- !,
	push( skip, verbatim).
process("@pl_example", _Line, _Rest, "" , _Pos).
process("@pl_example", _Line, _Rest, "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.prolog}" , _Pos) :- !,
	push( skip, verbatim).
process("@c_example", _Line, _Rest, "" , _Pos).
process("@c_example", _Line, _Rest, "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}" , _Pos) :- !,
	push( skip, verbatim).
process("@format", _Line, _Rest, "", _Pos ) :- !.
process("@alias", _Line, _Rest, "", _Pos ) :- !.
process("@dircategory", _Line, _Rest, "", _Pos ) :- !.
process("@smallexample", _Line, _Rest, "" , _Pos).
process("@smallexample", _Line, _Rest, "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" , _Pos) :- !,
	push( skip, verbatim).
process("@findexx", _Line, _Rest, "" , _Pos) :- !.
process("@ifnottex", _Line, _Rest, "\\htmlonly" , _Pos) :- !.
process("@itemize", _Line, Rest, NewLine  , _Pos) :- !,
	jmp_blanks( Rest, First ),
	list( "@itemize", First, NewLine, _Pos).
process("@menu", _Line, _Rest, "" , _Pos) :- !,
	push(skip, "menu" ).
process("@node", Line, Rest, NewLine, Pos ) :- !,
	jmp_blanks( Rest, First ),
        string_codes( First, S ),
	argument(AL, 0', , 0', , S, _), 
	string_codes(SF, AL),
	retractall(last_node(_,_)),
	assert( last_node( SF, Pos ) ),
	gen_blank( Line, NewLine ).
process("@page", _Line, _Rest, "", _Pos ) :- !.
process("@contents", _Line, _Rest, "" , _Pos) :- !.
process("@itemx", _Line, Rest, NewLine, _Pos ) :- !,
	process("@item", _Line, Rest, NewLine, _Pos ).
process("@saindex", _Line, Rest, NewLine, _Pos ) :- !,
	get_second( Rest, NewLine ).
process("@snindex", _Line, _Rest, "", _Pos ) :- !.
process("@syindex", _Line, _Rest, "" , _Pos) :- !.
process("@section", _Line, Rest, NewLine, Pos ) :- !,
	jmp_blanks( Rest, Title ),
	run( NewTitle, Title ),
	nb_setval( level, 2 ),
%	format(string(NewLine), '# ~s #', [NewTitle]).
	title( '@section', _, TitleDox ),
	title_from_words(NewTitle, Id, Pos),
	format(string(NewLine), '~a ~s ~s', [TitleDox,Id,NewTitle]).
%	format(string(NewLine), '# ~s #', [NewTitle]).
process("@appendix", _Line, Rest, NewLine, _Pos ) :- !,
	jmp_blanks( Rest, Title ),
	run( NewTitle, Title ),
	format(string(NewLine), '~n~n~s~n-------------------------~n~n', [NewTitle]).
process("@subsection", _Line, Rest, NewLine, _Pos ) :- !,
	jmp_blanks( Rest, Title ),
	run( NewTitle, Title ),
	nb_setval( level, 3 ),
	title( '@subsection', _, TitleDox ),
	title_from_words(NewTitle, Id, _Pos),
	format(string(NewLine), '~a ~s ~s', [TitleDox,Id,NewTitle]).
%	format(string(NewLine), '## ~s ##', [NewTitle]).
process("@unnumberedsubsubsec", _Line, Rest, NewLine, _Pos ) :- !,
 	nb_setval( level, 4 ),
	process("@subsubsection", _Line, Rest, NewLine, _Pos ).
process("@subsubsection", _Line, Rest, NewLine, _Pos ) :- !,
 	nb_setval( level, 4 ),
	jmp_blanks( Rest, Title ),
	run( NewTitle, Title ),
	title( '@subsubsection', _, TitleDox ),
	title_from_words(NewTitle, Id, _Pos),
	format(string(NewLine), '~a ~s', [TitleDox,Id,NewTitle]).
%	format(string(NewLine), '### ~s ###', [NewTitle]).
process("@set", _Line, Rest, NewLine , _Pos) :- !,
	first_word( Rest, V, SecC),
	jmp_blanks( SecC, Valu ),
	assert( val( V, Valu ) ),
	format(string(Assign), '~s=~s', [V, Valu]),
	gen_comment( Assign, NewLine ).
process("@noindent", _Line, Rest, NewLine, _Pos ) :- !,
	( Rest = ""
	->
	  NewLine = no
	;
	  run(NewLine, Rest )
	).
process("@setcontentsaftertitlepage", Line, _Rest, NewLine, _Pos ) :- !,
	gen_comment( Line, NewLine ).
process("@setchapternewpage", Line, _Rest, NewLine, _Pos ) :- !,
	gen_comment( Line, NewLine ).
process("@setfilename", Line, _Rest, NewLine, _Pos ) :- !,
	gen_comment( Line, NewLine ).
process("@settitle", _Line, _Rest, "" , _Pos) :- !.
process("@subtitle", _Line, _Rest, "", _Pos ) :- !.
process("@include", _Line, _Rest, "", _Pos ) :- !.
process("@table", _Line, Rest, NewLine , _Pos) :- !,
	jmp_blanks( Rest, First ),
	nb_getval( level, N1 ),
	N is N1+1,
	nb_setval( level, N ),
	list( "@table", First, NewLine, _Pos).
process("@title", _Line, _Rest, "" , _Pos) :- !.
process("@titlepage", _Line, _Rest, "", _Pos ) :- !.
process("@top", _Line, _Rest, "" , _Pos) :- !.
process("@unnumbered", _Line, Rest, NewLine , _Pos) :- !,
	jmp_blanks( Rest, Title ),
	run( NewTitle, Title ),
	format(string(NewLine), '## ~s ##', [NewTitle]).
process("@vskip", _Line, _Rest, "" , _Pos) :- !.
process("\\input", Line, _Rest, NewLine , _Pos) :- !,
	gen_comment( Line, NewLine ).

% html style comments
% pandoc compatible.
gen_comment( _Line, "" ). %NewLine ) :-
%	format( string( NewLine ) , '<!-- ~s -->', [_Line] ).


get_second( Rest, Title ) :-
	first_word( Rest, _V, Rest2 ),
	jmp_blanks( Rest2, First2 ),
	run( Title, First2 ).


%
% clear the buffer first.
%
list( Env, Line, New, _Pos) :-
	first_word( Line, V, Rest),
	jmp_blanks( Rest, End ),
	( 
	  speek( list, it(_, _, _Pos, _) ) ->
	   Pos1 is 0 % Pos + 4
	;
	  Pos1 = 0 %4
	),
	push( list, it( Env, V, Pos1, 1 ) ),
	% b_getval( pos, _Pos ),
	% writeln(add:_Pos:Env:Pos1:End),
	% listing(stack),
	run( New, End).
list( Env, _Line, NewLine, _Pos) :-
	( Env = "@enumerate" ->		
	  NewLine = "<ol>"
	;
	  NewLine = "<ul>"
	).	    

item_type("@bullet", _, "-" ).
item_type("@code", _, "-" ).
item_type("@option", _, "+" ).
item_type("@i", _, "-" ).
item_type("", _, "-" ).
item_type("@enumerate", 1, "1." ).
item_type("@enumerate", 2, "2." ).
item_type("@enumerate", 3, "3." ).
item_type("@enumerate", 4, "4." ).
item_type("@enumerate", 5, "5." ).
item_type("@enumerate", 6, "6." ).
item_type("@enumerate", 7, "7." ).
item_type("@enumerate", 8, "8." ).
item_type("@enumerate", 9, "9." ).
	    
offset( 0 ) :- 
	pop( indent, done ), !.
offset( 0 ) :- 
	speek( skip, verbatim ), !.
offset( Pos ) :-
	speek( list, it(_, _,Pos,_) ), !.
offset( 0 ).

gen_blank( _Line, "" ).

jmp_blanks(SpacesNewFile, NewString) :-
	  strip_blanks( SpacesNewFile, 1, NonBlank1 ),
	  NonBlank is NonBlank1 - 1,
	  sub_string(SpacesNewFile, NonBlank, _, 0, NewString), !.

title_from_words(_Title, Id, F:Pos) :-
	last_node( Lab, F:Pos1),
	Pos1 < Pos,
	Pos < Pos1+3, !,
	from_word( Lab, Id ).
title_from_words(Title, Id, _Pos) :-
	from_word( Title, Id ).

from_word( Line, Id ) :-
	 jmp_blanks( Line, Line2 ),
	 string_codes( Line2, C0 ),
	 simplify( C1, C0, []), 
	 string_codes( Id, C1 ).

simplify( [0'_|L]) --> " ", !, %'
	  simplify(L).
simplify( [0's,0'T|L]) --> "*", !, %'
	  simplify(L).
simplify( [0'a,0'A|L]) --> "@", !, 
	  simplify(L).
simplify( [0'b,0'A|L]) --> "'", !,
	  simplify(L).
simplify( [0'b,0'B|L]) --> "(", !,
	  simplify(L).
simplify( [0'b,0'Q|L]) --> "\\", !,
	  simplify(L).
simplify( [0'b,0'C|L]) --> ")", !,
	  simplify(L).
simplify( [0'c,0'C|L]) --> ":", !,
	  simplify(L).
simplify( [0'c,0'O|L]) --> ",", !,
	  simplify(L).
simplify( [0'c,0'U|L]) --> "[", !,
	  simplify(L).
simplify( [0'c,0'R|L]) --> "]", !,
	  simplify(L).
simplify( [0'd,0'O|L]) --> ".", !,
	  simplify(L).
simplify( [0'd,0'Q|L]) --> "\"", !,
	  simplify(L).
simplify( [0'e,0'E|L]) --> "&", !,
	  simplify(L).
simplify( [0'e,0'X|L]) --> "!", !,
	  simplify(L).
simplify( [0'g,0'G|L]) --> ">", !,
	  simplify(L).
simplify( [0'h,0'Y|L]) --> "-", !,
	  simplify(L).
simplify( [0'm,0'M|L]) --> ";", !,
	  simplify(L).
simplify( [0'q,0'Q|L]) --> "=", !,
	  simplify(L).
simplify( [0'q,0'U|L]) --> "?", !,
	  simplify(L).
simplify( [] ) --> "/",
	  number, !.
simplify( [0's,0'S|L]) --> "<", !,
	  simplify(L).
simplify( [0'u,0'U|L]) --> "\v", !,
	  simplify(L).
simplify( [0'v,0'V|L]) --> "|", !,
	  simplify(L).
simplify( [0'y,0'Y|L]) --> "{", !,
	  simplify(L).
simplify( [0'z,0'Z|L]) --> "}", !,
	  simplify(L).
simplify( [0'_|L]) --> "\t", !,
	  simplify(L).
simplify( [0'_|L]) --> "_", !,
	  simplify(L).
simplify( [C|L]) --> [C], { C >= "0", C =< "9"}, !,
	  simplify(L).
simplify( [C|L]) --> [C], { C >= "a", C =< "z"}, !,
	  simplify(L).
simplify( [C|L]) --> [C], { C >= "A", C =< "Z"}, !, % {CN is C+"a"-"A"},
	  simplify(L).
simplify( L) --> [_], !,
	  simplify(L).
simplify( []) --> [].

number --> [].
number --> [C],
	{ C >= "0" , C =< "9" },
	number.


first_word(Line, Word, Rest) :-
	jmp_blanks( Line, Line2 ),
	got_to_blanks_and_brackets(Line2, 1, N1),
	sub_string( Line2, 0, N1, _R, Word),
	sub_string( Line2, N1, _, 0, Rest).

first_text(Line, Word, Rest) :-
	jmp_blanks( Line, Line2 ),
	got_to_blanks(Line2, 1, N1),
	sub_string( Line2, 0, N1, _R, Word),
	sub_string( Line2, N1, _, 0, Rest).

strip_blanks( Word, I0, I ) :-
	get_string_code(I0, Word, Code ),
	( Code =:= " " -> ! ;
	  Code =:= "	" -> !
	),
	I1 is I0+1,
	strip_blanks( Word, I1, I ).
strip_blanks( _Word, I0, I0 ).


got_to_blanks_and_brackets( Word, I0, I ) :-
	get_string_code(I0, Word, Code ), !,
	( Code =:= " " -> I is I0-1 ;
	  Code =:= "	" -> I is I0-1 ;
	  Code =:= "(" -> I is I0-1 ;
	  Code =:= "{" -> I is I0-1 ;
	  Code =:= "[" -> I is I0-1 ;
	  
	  I1 is I0+1,
	  got_to_blanks_and_brackets( Word, I1, I ) ).
got_to_blanks_and_brackets( _Word, I0, I ) :-
	I is I0-1.

got_to_blanks( Word, I0, I ) :-
	get_string_code(I0, Word, Code ), !,
	( Code =:= " " -> I is I0-1 ;
	  Code =:= "	" -> I is I0-1 ;
	  I1 is I0+1,
	  got_to_blanks_and_brackets( Word, I1, I ) ).
got_to_blanks( _Word, I0, I ) :-
	I is I0-1.


:- dynamic stack/2.

pop(Type, Val) :-
	stack(T, V), !,
	T = Type,
	V = Val,
	once( retract(stack(T,V)) ).

push(Type, Val) :-
	asserta(stack(Type,Val)).

speek(Type, Val) :-
	stack(Type, V), !,
	V = Val.

run(N, S) :-
	string( S ), !,
	string_codes(S, SL),
	run(NL, SL, []),
	string_codes(N, NL).
run(N, SL) :-
	run(NL, SL, []),
	string_codes(N, NL).

run( L) --> "@code{", !,
	argument(AL, 0'{, 0'} ), 
	{ 
	  atom_codes( Word, AL ),
	  pred( Word, Key, _ , _)
	  ->
	  format( codes( L, R ), '[~a](@ref ~a)', [Word, Key])
	  ;
	  format(codes(L, R), '`~s`', [AL] )
	}, 
	run(R).
run( [C|L]) --> "@", escaped(C), !,
	run( L ).
run( [0'.,0'.,0'.|L]) --> "@dots", !,
	run( L ).
run( [0'\t|L]) --> "@tab", !,
	run( L ).
run( L) --> "@samp{", !, %'
	argument(AL, 0'{, 0'}),
	{  run(AL1, AL),
	   format(codes(L, R), '`~s`' , [AL1] )  }, %'
	run(R).
run( L) --> "@option{", !, %'
	argument(AL, 0'{, 0'}),
	{  run(AL1, AL),
	   format(codes(L, R), '`~s`' , [AL1] )  }, %'
	run(R).
run( L) --> "@env{", !, %'
	argument(AL, 0'{, 0'}),
	{  run(AL1, AL),
	   format(codes(L, R), '`~s`' , [AL1] )  }, %'
	run(R).
run( L) --> "@key{", !, %'
	argument(AL, 0'{, 0'}),
	{  run(AL1, AL),
	   format(codes(L, R), '`~s`' , [AL1] )  }, %'
	run(R).
run( L) --> "@command{", !, %'
	argument(AL, 0'{, 0'}),
	{  run(AL1, AL),
	   format(codes(L, R), '`~s`' , [AL1] )  }, %'
	run(R).
run( L) --> "@value{", !,
	argument(AL, 0'{, 0'}), 
	{ string_codes( S, AL),
	  val( S, V ),
	  string_codes(V, VS) },
	{ append(VS, R, L) },
	run(R).
run( L) --> "@pxref{", !,
	argument(AL, 0'{, 0'}),
	{
	 string_codes(S, AL),
	 from_word(S, Id),
	 format(codes(L, R), ' (see [~s](@ref ~s))', [AL,Id] )  }, %' %
	run(R).
run( L) --> "@ref{", !,
	argument(AL, 0'{, 0'}),
	{  
	 string_codes(S, AL),
	 from_word(S, Id),
	 format(codes(L, R), '[~s](@ref ~s)', [AL,Id] )  }, %'
	run(R).
run( L) --> "@strong{", !,
	argument(AL, 0'{, 0'}),
	{  run(AL1, AL),
	   format( codes(L, R), ' *~s*' ,[AL1])  }, %' %
	run(R).
run( L) --> "@noindent", !,
	run( L ).
run( L) --> "@t{", !,
	argument(AL, 0'{, 0'}),
	{  run(AL1, AL),
	   format( codes(L, R), '<tt>~s</tt>' ,[AL1])  }, %'
	run(R).
run( L) --> "@i{", !,
	argument(AL, 0'{, 0'}),
	{  run(AL1, AL),
	   format( codes(L, R), '\\a ~s' ,[AL1])  }, %'@code
	run(R).
run( L) --> "@var{", !,
	argument(AL, 0'{, 0'}),
	{  
	   format( codes(L, R), ' _~s_' ,[AL])   }, %' %
	run(R).
run( L) --> "@*", !, run(L).
run( L) --> "@file{",
	argument(AL, 0'{, 0'}), !,
	{ format( codes(L, R), '~s' ,[AL]) },
	run(R).
run( L) --> "@email{",
	argument(AL, 0'{, 0'}), !,
	{ format( codes(L, R), '<~s>' ,[AL]) },
	run(R).
run( L) --> "@url{",
	argument(AL, 0'{, 0'}), !, 
	{ format( codes(L, R), '<~s>' ,[AL]) },
	run(R).
run( L) --> "@uref{",
	argument(AL, 0'{, 0'}), !, %
	{ format( codes(L, R), '<~s>' ,[AL]) },
	run(R).
run(L) --> "@emph{" ,
	argument(AL, 0'{, 0'}), !, %
	!, 
	{ format( codes(L, R), '<em>~s</em>' ,[AL]) },
	run(R).
run(L) --> "@cite{" ,
	!,
	argument(AL, 0'{, 0'}), !,
	{ format( codes(L, R), '@cite ~s ' ,[AL]) },
	run(R).
run([0'©|L]) --> "@copyright{" , !, spaces, "}", run(L). %'
run([0'\\,C|L]) --> [C], %'
	{ md_escaped(C) }, !,
	run(L).
run([C|L]) --> [C], run(L).
run([]) --> [].

escapes( New, Old ) :-
	string_codes(Old, Cs),
	escapes( NCs, Cs, [] ),
	string_codes(New, NCs).

escapes([0'@|L]) --> "@@", !, %'
	escapes(L).
escapes([0'{|L]) --> "@{", !, %'
	escapes(L).
escapes([0'}|L]) --> "@}", !, %'
	escapes(L).
/*
  escapes([0'\\,0'\\|L]) --> "\\", !,
	escapes(L).
escapes([0'\\,0'&|L]) --> "&", !,
	escapes(L).
escapes([0'\\,0'<|L]) --> "<", !,
	escapes(L).
escapes([0'\\,0'>|L]) --> ">", !,
	escapes(L).
escapes([0'\\,0'"|L]) --> "\"", !, %"
	escapes(L).
*/
escapes([C|L]) --> [C], !,
	escapes(L).
escapes([]) --> [].


text(End, C, End) --> [C], !.
text([D|L], C, End ) --> [D], !,
	text( L, C, End).

argument(L, C0, C) -->
	argument0(L0, 0, C0, C), !,
	{ run(L, L0, []) }.
argument(L, _C0, _C, L, []) :-
	b_getval( line, Line),
	format(user_error, 'Line ~w :-~n argument ~c~s~c does not close in same line.~n', [Line, _C0, L, _C]).

argument0([], 0, _, C ) --> [C], !.
argument0([C|L], I0, C0, C ) --> [C], !,
	{ I0 > 0, I is I0-1 },
	argument0( L, I, C0, C).
argument0([C0|L], I0, C0, C ) --> [C0], !,
	{ I is I0+1 },
	argument0( L, I, C0, C).

% follow escaped characters.
argument0([0'@,Escaped|L], I, C0, C) -->
	[0'@],
	escaped(Escaped), !,
	argument0( L, I, C0, C).
argument0([D|L], I, C0, C) --> [D], !,
	argument0( L, I, C0, C).


spaces --> " ", !,
	spaces.
spaces --> "	", !, spaces.
spaces --> [].

escaped(0'@) --> "@". %'
escaped(0'{) --> "{". %'
escaped(0'}) --> "}". %'

md_escaped(0'\\). %'
%md_escaped(0'_). %'
md_escaped(0'&). %'
md_escaped(0'<). %'
md_escaped(0'>). %'
md_escaped(0'*). %'

cvt_slash( F0, Key  ) :-
	   from_word( F0, Key ).

:- dynamic i/1.

i(0).

id(X) :-
	retract(i(X)),
	X1 is X+100,
	assert(i(X1)).

title(TexTitle, Level, DoxTitle) :-
	title( Level, TexTitle),
%	Level1 is Level + 1,
	title( Level, DoxTitle ), !.

title(1, '@page' ).
title(1, '@chapter' ).
title(2, '@section' ).
title(3, '@subsection' ).
title(4, '@subsubsection' ).
title(5, '@paragraph' ).
title(6, '@paragraph' ).

%:- spy title_from_words.