/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (c) 1998-2022, University of Amsterdam CWI, Amsterdam SWI-Prolog Solutions b.v. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ :- module('$rc', [ open_resource/2, % +Name, -Stream open_resource/3, % +Name, +RW, -Stream current_resource/2 % :Name, ?File ]). :- meta_predicate open_resource(:, -), open_resource(:, -, +), current_resource(:, ?). :- dynamic user:resource/2, user:resource/3. :- multifile user:resource/2, user:resource/3. %! open_resource(:Name, -Stream) is det. %! open_resource(:Name, -Stream, +Options) is det. %! open_resource(:Name, ?Class, -Stream) is det. % % Open resource with given Name, returning a Stream. open_resource(Name, Handle) :- open_resource(Name, Handle, []). open_resource(Module:RcName, Stream, Options) :- is_list(Options), !, ( default_module(Module, RModule), current_resource(RModule:RcName, FileSpec) -> absolute_file_name(FileSpec, File), open(File, read, Stream, Options) ; '$rc_handle'(Zipper), zip_close(Zipper, Clone), tag_rc_name(Module, RcName, TaggedName), zipper_goto(Clone, file(TaggedName)) -> zipper_open_current(Clone, Stream, [ release(true) | Options ]), zip_close_(Clone, _) ; '$existence_error'(resource, Module:RcName) ). open_resource(Name, _Class, Stream) :- open_resource(Name, Stream). tag_rc_name(user, RcName, RcName) :- !. tag_rc_name(Module, RcName, TaggedName) :- atomic_list_concat([Module, ':', RcName], TaggedName). tag_rc_name(_, RcName, RcName). %! current_resource(:Name, ?File) is nondet. % % List all currently declared resources. Should eventually deal % with resources that are already part of the state. current_resource(M:Name, File) :- current_module(M), ( current_predicate(M:resource/2), M:resource(Name, File) ; current_predicate(M:resource/3), M:resource(Name, _Class, File) ). %! c_open_resource(:Name, +Mode, -Stream) % % Callback for PL_open_resource(). :- public c_open_resource/3. :- meta_predicate c_open_resource(:, +, -). c_open_resource(Name, Mode, Stream) :- atom_chars(Mode, Chars), ( Chars = [r|MChars] -> mode_options(MChars, Options), open_resource(Name, Stream, Options) ; '$domain_error'(open_resource_mode, Mode) ). mode_options([], []). mode_options([t|Chars], [type(text)|T]) :- !, mode_options(Chars, T). mode_options([b|Chars], [type(binary)|T]) :- !, mode_options(Chars, T). mode_options([_|Chars], T) :- mode_options(Chars, T). /******************************* * RESOURCES AS FILES * *******************************/ :- register_iri_scheme(res, res_iri_hook, []). %! res_iri_hook(+Action, +IRI, -Stream) is det. % % Define the =|res://|= IRI scheme, binding to the central resource % DB. For speed, the first call calls index_rc/0 that creates a % predicate associating IRIs to offsets in the central resource ZIP. res_iri_hook(open(Mode,Options), IRI, Stream) :- ( Mode == read -> setup_call_cleanup( iri_zipper(IRI, Zipper), zipper_open_current(Zipper, Stream, Options), zip_close_(Zipper, _)) ; '$permission_error'(open, source_sink, IRI) ). res_iri_hook(access(Mode), IRI0, True) :- ( read_mode(Mode), '$absolute_file_name'(IRI0, Canonical0), entry_name(Canonical0, Canonical), iri_offset(Canonical, _Offset) -> access_ok(Mode, Canonical, True) ; True = false ). res_iri_hook(time, IRI, Time) :- setup_call_cleanup( iri_zipper_ex(IRI, Zipper), zipper_file_property(Zipper, _, time, Time), zip_close_(Zipper, _)). res_iri_hook(size, IRI, Size) :- setup_call_cleanup( iri_zipper_ex(IRI, Zipper), zipper_file_property(Zipper, _, size, Size), zip_close_(Zipper, _)). read_mode(read). read_mode(exists). read_mode(file). read_mode(directory). entry_name(Entry, Entry). entry_name(Entry0, Entry) :- \+ sub_atom(Entry0, _, _, 0, /), atom_concat(Entry0, /, Entry). %! access_ok(+Access, +Entry, -Ok) is det. % % This assumes directories are added with a trailing / access_ok(directory, Entry, True) :- !, ( sub_atom(Entry, _, _, 0, /) -> True = true ; True = false ). access_ok(file, Entry, True) :- !, ( sub_atom(Entry, _, _, 0, /) -> True = false ; True = true ). access_ok(_, _, true). %! iri_zipper(+IRI, -Zipper) is semidet. %! iri_zipper_ex(+IRI, -Zipper) is det. % % Find and position a zipper for IRI. Fails if this cannot be found. iri_zipper(IRI, Clone) :- '$absolute_file_name'(IRI, Canonical), iri_offset(Canonical, Offset), '$rc_handle'(Zipper), zip_clone(Zipper, Clone), zipper_goto(Clone, offset(Offset)). iri_zipper_ex(IRI, Zipper) :- iri_zipper(IRI, Zipper), !. iri_zipper_ex(IRI, _Zipper) :- '$existence_error'(source_sink, IRI). %! iri_offset(+IRI, -Offset) is semidet. % % True when Offset is the zipper offset where we can find IRI. :- dynamic rc_index_db/2, rc_index_done/0. :- volatile rc_index_db/2, rc_index_done/0. iri_offset(Entry, Offset) :- rc_index_done, !, rc_index_db(Entry, Offset). iri_offset(Entry, Offset) :- with_mutex('$rc', index_rc), !, rc_index_db(Entry, Offset). index_rc :- rc_index_done, !. index_rc :- '$rc_handle'(Zipper), setup_call_cleanup( zip_clone(Zipper, Clone), ( zipper_goto(Clone, first), index_rc(Clone) ), zip_close_(Clone, _)), asserta(rc_index_done). index_rc(Zipper) :- zipper_file_property(Zipper, Name, offset, Offset), atom_concat('res://', Name, IRI), assertz(rc_index_db(IRI, Offset)), ( zipper_goto(Zipper, next) -> index_rc(Zipper) ; true ). %! zipper_file_property(+Zipper, -Name, +Prop, -Value) zipper_file_property(Zipper, Name, Prop, Value) :- zip_file_info_(Zipper, Name, Info), zip_prop_arg(Prop, Arg), arg(Arg, Info, Value). zip_prop_arg(size, 2). zip_prop_arg(time, 5). zip_prop_arg(offset, 6).