/usr/lib/swi-prolog/library/fastrw.pl is in swi-prolog-nox 7.6.4+dfsg-1build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 | /* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2010-2016, VU University Amsterdam
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(fastrw,
[ fast_read/1, % -Term
fast_write/1, % +Term
fast_read/2, % +Stream, -Term
fast_write/2, % +Stream, +Term
fast_write_to_string/3 % +Term, -String, ?Tail
]).
:- use_module(library(lists)).
/** <module> Fast reading and writing of terms
This library provides the SICStus and Ciao library(fastrw) interface.
The idea behind this library is to design a fast serialization for
Prolog terms. Ideally, this should be portable between Prolog
implementation. Unfortunately there is no portably binary term format
defined.
The current implementation is based on PL_record_external(), which
provides a binary representation of terms that is processed efficiently
and can handle cycles as well as attributes. We try to keep the format
compatible between versions, but this is not guaranteed. Conversion is
always possible by reading a database using the old version, dump it
using write_canonical/1 and read it into the new version.
This library is built upon the following built in predicates:
- fast_term_serialized/2 translates between a term and its
serialization as a byte string.
- fast_read/2 and fast_write/2 read/write binary serializations.
@tbd Establish a portable binary format.
@compat The format is not compatible to SICStus/Ciao (which are not
compatible either). Funture versions of this library might
implement a different encoding.
@bug The current implementation of fast_read/1 *is not safe*.
It is guaranteed to safely read terms written using
fast_write/1, but may crash on arbitrary input. The
implementation does perform some basic sanity checks,
including validation of the magic start byte.
*/
%! fast_read(-Term)
%
% The next term is read from current standard input and is unified
% with Term. The syntax of the term must agree with fast_read /
% fast_write format. If the end of the input has been reached,
% Term is unified with the term =end_of_file=.
fast_read(Term) :-
fast_read(current_input, Term).
%! fast_write(+Term)
%
% Output Term in a way that fast_read/1 and fast_read/2 will be
% able to read it back.
fast_write(Term) :-
fast_write(current_output, Term).
%! fast_write_to_string(+Term, -String, ?Tail)
%
% Perform a fast-write to the difference-slist String\Tail.
fast_write_to_string(T, S, R) :-
fast_term_serialized(T, String),
string_codes(String, Codes),
append(Codes, R, S).
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