1/*  Part of ClioPatria
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@cs.vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (C): 2010, VU University Amsterdam
    7
    8    This program is free software; you can redistribute it and/or
    9    modify it under the terms of the GNU General Public License
   10    as published by the Free Software Foundation; either version 2
   11    of the License, or (at your option) any later version.
   12
   13    This program is distributed in the hope that it will be useful,
   14    but WITHOUT ANY WARRANTY; without even the implied warranty of
   15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   16    GNU General Public License for more details.
   17
   18    You should have received a copy of the GNU General Public
   19    License along with this library; if not, write to the Free Software
   20    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   21
   22    As a special exception, if you link this library with other files,
   23    compiled with a Free Software compiler, to produce an executable, this
   24    library does not by itself cause the resulting executable to be covered
   25    by the GNU General Public License. This exception does not however
   26    invalidate any other reasons why the executable file might be covered by
   27    the GNU General Public License.
   28*/
   29
   30:- module(html_messages,
   31	  [ call_showing_messages/2
   32	  ]).   33:- use_module(library(http/html_write)).   34:- use_module(library(http/html_head)).   35:- use_module(library(option)).

   43:- meta_predicate
   44	call_showing_messages(0, +).

 call_showing_messages(:Goal, +Options) is det

Execute Goal, showing the feedback in the browser. This predicate builds a default application page with a placeholder for the messages. It then sends all HTML upto the placeholder and flushes the output to the browser. During execution, all output from Goal emitted through print_message/2 is caught in the message-box. After completion of Goal the page is completed.

This predicate is intended for action such as loading RDF files, while providing feedback on files loaded and possible error messages. Note that this call creates a complete page.

bug

- This call uses chunked transfer encoding to send the page in parts. Not all browsers support this and not all browsers update the page incrementally.

   63:- create_prolog_flag(html_messages, false, [type(boolean)]).   64
   65assert_message_hook :-
   66	Head = message_hook(_Term, Level, Lines),
   67	Body = send_message(Level, Lines),
   68	(   clause(user:Head, Body)
   69	->  true
   70	;   asserta((user:Head :- Body))
   71	).
   72
   73:- initialization
   74	assert_message_hook.   75
   76call_showing_messages(Goal, Options) :-
   77	option(style(Style), Options, default),
   78	option(head(Head), Options, title('SWI-Prolog -- make')),
   79	option(header(Header), Options,
   80	       div(class(msg_header),
   81		   h4('Messages ...'))),
   82	(   option(footer(Footer), Options)
   83	->  true
   84	;   (   option(return_to(ReturnURI), Options)
   85	    ->  FooterRest = [ p(['Go ', a(href(ReturnURI), 'back'),
   86				  ' to the previous page']) ]
   87	    ;	FooterRest = []
   88	    ),
   89	    Footer = div(class(msg_footer), [ h4('Done') | FooterRest ])
   90	),
   91	format('Content-Type: text/html~n'),
   92	format('Transfer-Encoding: chunked~n~n'),
   93	header(Style, Head, Header, Footer, FooterTokens),
   94	setup_call_cleanup(
   95	    set_prolog_flag(html_messages, true),
   96	    catch(Goal, E, print_message(error, E)),
   97	    set_prolog_flag(html_messages, false)), !,
   98	footer(FooterTokens).
   99
  100send_message(Level, Lines) :-
  101	current_prolog_flag(html_messages, true),
  102	level_css_class(Level, Class),
  103	phrase(html(pre(class(Class), \html_message_lines(Lines))), Tokens),
  104	with_mutex(html_messages, print_html(Tokens)),
  105	flush_output,
  106	fail.
  107
  108level_css_class(informational, msg_informational).
  109level_css_class(warning,       msg_warning).
  110level_css_class(error,	       msg_error).
  111
  112html_message_lines([]) -->
  113	[].
  114html_message_lines([nl|T]) --> !,
  115	html('\n'),			% we are in a <pre> environment
  116	html_message_lines(T).
  117html_message_lines([flush]) -->
  118	[].
  119html_message_lines([H|T]) --> !,
  120	html(H),
  121	html_message_lines(T).

 header(+Style, +Head, +Header, +Footer, -FooterTokens)

Emit all tokens upto the placeholder for the actual messages and return the remaining page-tokens in FooterTokens. Style and Head are passed

  130header(Style, Head, Header, Footer, FooterTokens) :-
  131	Magic = '$$$MAGIC$$$',
  132	Body = [ Header,
  133		 \(html_messages:html_requires(css('messages.css'))),
  134		 div(class(messages), Magic),
  135		 Footer
  136	       ],
  137	phrase(html_write:page(Style, Head, Body), Tokens),
  138	html_write:mailman(Tokens),
  139	append(HeaderTokens, [Magic|FooterTokens], Tokens), !,
  140	current_output(Out),
  141	html_write:write_html(HeaderTokens, Out),
  142	flush_output(Out).
  143
  144footer(Footer) :-
  145	current_output(Out),
  146	html_write:write_html(Footer, Out)