/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@uva.nl WWW: http://www.swi-prolog.org Copyright (C): 2009, University of Amsterdam This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA As a special exception, if you link this library with other files, compiled with a Free Software compiler, to produce an executable, this library does not by itself cause the resulting executable to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU General Public License. */ :- module(charsio, [ format_to_chars/3, % +Format, +Args, -Codes format_to_chars/4, % +Format, +Args, -Codes, ?Tail write_to_chars/2, % +Term, -Codes write_to_chars/3, % +Term, -Codes, ?Tail atom_to_chars/2, % +Atom, -Codes atom_to_chars/3, % +Atom, -Codes, ?Tail number_to_chars/2, % +Number, -Codes number_to_chars/3, % +Number, -Codes, ?Tail % read predicates read_from_chars/2, % +Codes, -Term read_term_from_chars/3, % +Codes, -Term, +Options open_chars_stream/2, % +Codes, -Stream with_output_to_chars/2, % :Goal, -Codes with_output_to_chars/3, % :Goal, -Codes, ?Tail with_output_to_chars/4 % :Goal, -Stream, -Codes, ?Tail ]). :- use_module(library(error)). /* :- use_module(library(memfile)). */ % see open_chars_stream/2 :- meta_predicate with_output_to_chars(0, -), with_output_to_chars(0, -, ?), with_output_to_chars(0, -, -, ?). :- predicate_options(read_term_from_chars/3, 3, [pass_to(system:read_term/3, 3)]). /** I/O on Lists of Character Codes This module emulates the Quintus/SICStus library charsio.pl for reading and writing from/to lists of character codes. Most of these predicates are straight calls into similar SWI-Prolog primitives. Some can even be replaced by ISO standard predicates. @compat The naming of this library is not in line with the ISO standard. We believe that the SWI-Prolog native predicates form a more elegant alternative for this library. */ %% format_to_chars(+Format, +Args, -Codes) is det. % % Use format/2 to write to a list of character codes. format_to_chars(Format, Args, Codes) :- format(codes(Codes), Format, Args). %% format_to_chars(+Format, +Args, -Codes, ?Tail) is det. % % Use format/2 to write to a difference list of character codes. format_to_chars(Format, Args, Codes, Tail) :- format(codes(Codes, Tail), Format, Args). %% write_to_chars(+Term, -Codes) % % Write a term to a code list. True when Codes is a list of % character codes written by write/1 on Term. write_to_chars(Term, Codes) :- format(codes(Codes), '~w', [Term]). %% write_to_chars(+Term, -Codes, ?Tail) % % Write a term to a code list. Codes\Tail is a difference list of % character codes produced by write/1 on Term. write_to_chars(Term, Codes, Tail) :- format(codes(Codes, Tail), '~w', [Term]). %% atom_to_chars(+Atom, -Codes) is det. % % Convert Atom into a list of character codes. % % @deprecated Use ISO atom_codes/2. atom_to_chars(Atom, Codes) :- atom_codes(Atom, Codes). %% atom_to_chars(+Atom, -Codes, ?Tail) is det. % % Convert Atom into a difference list of character codes. atom_to_chars(Atom, Codes, Tail) :- format(codes(Codes, Tail), '~a', [Atom]). %% number_to_chars(+Number, -Codes) is det. % % Convert Atom into a list of character codes. % % @deprecated Use ISO number_codes/2. number_to_chars(Number, Codes) :- number_codes(Number, Codes). %% number_to_chars(+Number, -Codes, ?Tail) is det. % % Convert Number into a difference list of character codes. number_to_chars(Number, Codes, Tail) :- must_be(number, Number), format(codes(Codes, Tail), '~w', [Number]). %% read_from_chars(+Codes, -Term) is det. % % Read Codes into Term. % % @compat The SWI-Prolog version does not require Codes to end % in a full-stop. read_from_chars("", end_of_file) :- !. read_from_chars(List, Term) :- atom_to_term(List, Term, _). %% read_term_from_chars(+Codes, -Term, +Options) is det. % % Read Codes into Term. Options are processed by read_term/3. % % @compat sicstus read_term_from_chars(Codes, Term, Options) :- setup_call_cleanup( ( open_chars_stream(Codes, Stream, '\n.\n'), '$push_input_context'(read_from_chars) ), read_term(Stream, Term0, Options), ( '$pop_input_context', close(Stream) )), Term = Term0. %% open_chars_stream(+Codes, -Stream) is det. % % Open Codes as an input stream. % % @bug Depends on autoloading library(memfile). As many % applications do not need this predicate we do not % want to make the entire library dependent on % autoloading. open_chars_stream(Codes, Stream) :- open_chars_stream(Codes, Stream, ''). open_chars_stream(Codes, Stream, Postfix) :- new_memory_file(MF), setup_call_cleanup( open_memory_file(MF, write, Out), format(Out, '~s~w', [Codes, Postfix]), close(Out)), open_memory_file(MF, read, Stream, [ free_on_close(true) ]). %% with_output_to_chars(:Goal, -Codes) is det. % % Run Goal as with once/1. Output written to =current_output= % is collected in Codes. with_output_to_chars(Goal, Codes) :- with_output_to(codes(Codes), Goal). %% with_output_to_chars(:Goal, -Codes, ?Tail) is det. % % Run Goal as with once/1. Output written to =current_output= % is collected in Codes\Tail. with_output_to_chars(Goal, Codes, Tail) :- with_output_to(codes(Codes, Tail), Goal). %% with_output_to_chars(:Goal, -Stream, -Codes, ?Tail) is det. % % Same as with_output_to_chars/3 using an explicit stream. The % difference list Codes\Tail contains the character codes that % Goal has written to Stream. with_output_to_chars(Goal, Stream, Codes, Tail) :- with_output_to(codes(Codes, Tail), with_stream(Stream, Goal)). with_stream(Stream, Goal) :- current_output(Stream), call(Goal).