243 lines
7.3 KiB
Prolog
243 lines
7.3 KiB
Prolog
/* $Id$
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Part of SWI-Prolog
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Author: Jan Wielemaker
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E-mail: jan@swi.psy.uva.nl
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WWW: http://www.swi-prolog.org
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Copyright (C): 1985-2002, University of Amsterdam
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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As a special exception, if you link this library with other files,
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compiled with a Free Software compiler, to produce an executable, this
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library does not by itself cause the resulting executable to be covered
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by the GNU General Public License. This exception does not however
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invalidate any other reasons why the executable file might be covered by
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the GNU General Public License.
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*/
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:- module(read_util,
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[ read_line_to_codes/2, % +Fd, -Codes (without trailing \n)
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read_line_to_codes/3, % +Fd, -Codes, ?Tail
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read_stream_to_codes/2, % +Fd, -Codes
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read_stream_to_codes/3, % +Fd, -Codes, ?Tail
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read_file_to_codes/3, % +File, -Codes, +Options
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read_file_to_terms/3 % +File, -Terms, +Options
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]).
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:- use_module(library(shlib)).
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:- use_module(library(lists), [select/3]).
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:- use_module(library(error)).
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/** <module> Read utilities
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This library provides some commonly used reading predicates. As these
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predicates have proven to be time-critical in some applications we moved
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them to C. For compatibility as well as to reduce system dependency, we
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link the foreign code at runtime and fallback to the Prolog
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implementation if the shared object cannot be found.
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*/
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:- volatile
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read_line_to_codes/2,
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read_line_to_codes/3,
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read_stream_to_codes/2,
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read_stream_to_codes/3.
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link_foreign :-
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catch(load_foreign_library(foreign(readutil)), _, fail), !.
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link_foreign :-
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assertz((read_line_to_codes(Stream, Line) :-
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pl_read_line_to_codes(Stream, Line))),
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assertz((read_line_to_codes(Stream, Line, Tail) :-
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pl_read_line_to_codes(Stream, Line, Tail))),
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assertz((read_stream_to_codes(Stream, Content) :-
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pl_read_stream_to_codes(Stream, Content))),
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assertz((read_stream_to_codes(Stream, Content, Tail) :-
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pl_read_stream_to_codes(Stream, Content, Tail))),
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compile_predicates([ read_line_to_codes/2,
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read_line_to_codes/3,
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read_stream_to_codes/2,
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read_stream_to_codes/3
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]).
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:- initialization(link_foreign, now).
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/*******************************
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* LINES *
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*******************************/
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%% read_line_to_codes(+In:stream, -Line:codes) is det.
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%
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% Read a line of input from In into a list of character codes.
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% Trailing newline and or return are deleted. Upon reaching
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% end-of-file Line is unified to the atom =end_of_file=.
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pl_read_line_to_codes(Fd, Codes) :-
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get_code(Fd, C0),
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( C0 == -1
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-> Codes = end_of_file
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; read_1line_to_codes(C0, Fd, Codes0)
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),
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Codes = Codes0.
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read_1line_to_codes(-1, _, []) :- !.
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read_1line_to_codes(10, _, []) :- !.
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read_1line_to_codes(13, Fd, L) :- !,
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get_code(Fd, C2),
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read_1line_to_codes(C2, Fd, L).
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read_1line_to_codes(C, Fd, [C|T]) :-
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get_code(Fd, C2),
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read_1line_to_codes(C2, Fd, T).
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%% read_line_to_codes(+Fd, -Line, ?Tail) is det.
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%
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% Read a line of input as a difference list. This should be used
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% to read multiple lines efficiently. On reaching end-of-file,
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% Tail is bound to the empty list.
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pl_read_line_to_codes(Fd, Codes, Tail) :-
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get_code(Fd, C0),
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read_line_to_codes(C0, Fd, Codes0, Tail),
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Codes = Codes0.
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read_line_to_codes(-1, _, Tail, Tail) :- !,
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Tail = [].
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read_line_to_codes(10, _, [10|Tail], Tail) :- !.
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read_line_to_codes(C, Fd, [C|T], Tail) :-
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get_code(Fd, C2),
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read_line_to_codes(C2, Fd, T, Tail).
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/*******************************
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* STREAM (ENTIRE INPUT) *
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*******************************/
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%% read_stream_to_codes(+Stream, -Codes) is det.
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%% read_stream_to_codes(+Stream, -Codes, ?Tail) is det.
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%
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% Read input from Stream to a list of character codes. The version
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% read_stream_to_codes/3 creates a difference-list.
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pl_read_stream_to_codes(Fd, Codes) :-
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pl_read_stream_to_codes(Fd, Codes, []).
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pl_read_stream_to_codes(Fd, Codes, Tail) :-
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get_code(Fd, C0),
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read_stream_to_codes(C0, Fd, Codes0, Tail),
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Codes = Codes0.
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read_stream_to_codes(-1, _, Tail, Tail) :- !.
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read_stream_to_codes(C, Fd, [C|T], Tail) :-
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get_code(Fd, C2),
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read_stream_to_codes(C2, Fd, T, Tail).
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%% read_stream_to_terms(+Stream, -Terms, ?Tail, +Options) is det.
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read_stream_to_terms(Fd, Terms, Tail, Options) :-
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read_term(Fd, C0, Options),
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read_stream_to_terms(C0, Fd, Terms0, Tail, Options),
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Terms = Terms0.
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read_stream_to_terms(end_of_file, _, Tail, Tail, _) :- !.
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read_stream_to_terms(C, Fd, [C|T], Tail, Options) :-
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read_term(Fd, C2, Options),
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read_stream_to_terms(C2, Fd, T, Tail, Options).
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/*******************************
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* FILE (ENTIRE INPUT) *
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*******************************/
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%% read_file_to_codes(+Spec, -Codes, +Options) is det.
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%
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% Read the file Spec into a list of Codes. Options is split into
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% options for absolute_file_name/3 and open/4.
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read_file_to_codes(Spec, Codes, Options) :-
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must_be(proper_list, Options),
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( select(tail(Tail), Options, Options1)
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-> true
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; Tail = [],
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Options1 = Options
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),
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split_options(Options1, file_option, FileOptions, OpenOptions),
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absolute_file_name(Spec,
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[ access(read)
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| FileOptions
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],
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Path),
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open(Path, read, Fd, OpenOptions),
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call_cleanup(read_stream_to_codes(Fd, Codes0, Tail),
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close(Fd)),
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Codes = Codes0.
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%% read_file_to_terms(+Spec, -Terms, +Options) is det.
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%
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% Read the file Spec into a list of terms. Options is split over
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% absolute_file_name/3, open/4 and read_term/3.
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read_file_to_terms(Spec, Terms, Options) :-
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must_be(proper_list, Options),
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( select(tail(Tail), Options, Options1)
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-> true
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; Tail = [],
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Options1 = Options
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),
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split_options(Options1, file_option, FileOptions, Options2),
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split_options(Options2, read_option, ReadOptions, OpenOptions),
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absolute_file_name(Spec,
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[ access(read)
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],
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Path),
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open(Path, read, Fd, OpenOptions),
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call_cleanup(read_stream_to_terms(Fd, Terms0, Tail, ReadOptions),
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close(Fd)),
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Terms = Terms0.
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split_options([], _, [], []).
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split_options([H|T], G, File, Open) :-
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( call(G, H)
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-> File = [H|FT],
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OT = Open
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; Open = [H|OT],
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FT = File
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),
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split_options(T, G, FT, OT).
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read_option(module(_)).
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read_option(syntax_errors(_)).
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read_option(character_escapes(_)).
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read_option(double_quotes(_)).
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read_option(backquoted_string(_)).
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file_option(extensions(_)).
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file_option(file_type(_)).
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file_option(file_errors(_)).
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file_option(relative_to(_)).
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file_option(expand(_)).
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/*******************************
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* XREF *
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*******************************/
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:- multifile prolog:meta_goal/2.
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:- dynamic prolog:meta_goal/2.
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prolog:meta_goal(split_options(_,G,_,_), [G+1]).
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