1/* Part of SWI-Prolog 2 3 Author: Jan Wielemaker 4 E-mail: J.Wielemaker@vu.nl 5 WWW: http://www.swi-prolog.org 6 Copyright (c) 2001-2022, University of Amsterdam 7 VU University Amsterdam 8 CWI, Amsterdam 9 SWI-Prolog Solutions b.v. 10 All rights reserved. 11 12 Redistribution and use in source and binary forms, with or without 13 modification, are permitted provided that the following conditions 14 are met: 15 16 1. Redistributions of source code must retain the above copyright 17 notice, this list of conditions and the following disclaimer. 18 19 2. Redistributions in binary form must reproduce the above copyright 20 notice, this list of conditions and the following disclaimer in 21 the documentation and/or other materials provided with the 22 distribution. 23 24 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 25 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 26 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 27 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 28 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 29 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 30 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 31 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 32 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 34 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35 POSSIBILITY OF SUCH DAMAGE. 36*/ 37 38:- module(read_util, 39 [ read_line_to_codes/2, % +Stream, -Codes (without trailing \n) 40 read_line_to_codes/3, % +Stream, -Codes, ?Tail 41 read_stream_to_codes/2, % +Stream, -Codes 42 read_stream_to_codes/3, % +Stream, -Codes, ?Tail 43 read_file_to_codes/3, % +File, -Codes, +Options 44 45 read_line_to_string/2, % +Stream, -Line (without trailing \n) 46 read_file_to_string/3, % +File, -Codes, +Options 47 48 read_file_to_terms/3 % +File, -Terms, +Options 49 ]). 50:- autoload(library(error),[must_be/2]). 51:- autoload(library(option),[option/3]).
66:- predicate_options(read_file_to_codes/3, 3, 67 [ tail(list_or_partial_list), 68 pass_to(system:open/4, 4) 69 ]). 70:- predicate_options(read_file_to_string/3, 3, 71 [ pass_to(system:open/4, 4) 72 ]). 73:- predicate_options(read_file_to_terms/3, 3, 74 [ tail(list_or_partial_list), 75 pass_to(read_stream_to_terms/4, 4), 76 pass_to(system:absolute_file_name/3, 3), 77 pass_to(system:open/4, 4) 78 ]). 79:- predicate_options(read_stream_to_terms/4, 4, 80 [ pass_to(read_term/3, 3) 81 ]). 82 83:- volatile 84 read_line_to_codes/2, 85 read_line_to_codes/3, 86 read_stream_to_codes/2, 87 read_stream_to_codes/3. 88 89link_foreign :- 90 catch(use_foreign_library(foreign(readutil)), _, fail), 91 !. 92link_foreign :- 93 assertz((read_line_to_codes(Stream, Line) :- 94 pl_read_line_to_codes(Stream, Line))), 95 assertz((read_line_to_codes(Stream, Line, Tail) :- 96 pl_read_line_to_codes(Stream, Line, Tail))), 97 assertz((read_stream_to_codes(Stream, Content) :- 98 pl_read_stream_to_codes(Stream, Content))), 99 assertz((read_stream_to_codes(Stream, Content, Tail) :- 100 pl_read_stream_to_codes(Stream, Content, Tail))), 101 compile_predicates([ read_line_to_codes/2, 102 read_line_to_codes/3, 103 read_stream_to_codes/2, 104 read_stream_to_codes/3 105 ]). 106 107:- initialization(link_foreign, now). 108 109 110 /******************************* 111 * LINES * 112 *******************************/
122pl_read_line_to_codes(Stream, Codes) :- 123 get_code(Stream, C0), 124 ( C0 == -1 125 -> Codes0 = end_of_file 126 ; read_1line_to_codes(C0, Stream, Codes0) 127 ), 128 Codes = Codes0. 129 130read_1line_to_codes(-1, _, []) :- !. 131read_1line_to_codes(10, _, []) :- !. 132read_1line_to_codes(13, Stream, L) :- 133 !, 134 get_code(Stream, C2), 135 read_1line_to_codes(C2, Stream, L). 136read_1line_to_codes(C, Stream, [C|T]) :- 137 get_code(Stream, C2), 138 read_1line_to_codes(C2, Stream, T).
read_header_data(Stream, Header) :-
read_line_to_codes(Stream, Header, Tail),
read_header_data(Header, Stream, Tail).
read_header_data("\r\n", _, _) :- !.
read_header_data("\n", _, _) :- !.
read_header_data("", _, _) :- !.
read_header_data(_, Stream, Tail) :-
read_line_to_codes(Stream, Tail, NewTail),
read_header_data(Tail, Stream, NewTail).
162pl_read_line_to_codes(Stream, Codes, Tail) :- 163 get_code(Stream, C0), 164 read_line_to_codes(C0, Stream, Codes0, Tail), 165 Codes = Codes0. 166 167read_line_to_codes(-1, _, Tail, Tail) :- 168 !, 169 Tail = []. 170read_line_to_codes(10, _, [10|Tail], Tail) :- !. 171read_line_to_codes(C, Stream, [C|T], Tail) :- 172 get_code(Stream, C2), 173 read_line_to_codes(C2, Stream, T, Tail).
end_of_file
if the end of the file is reached.
185read_line_to_string(Stream, String) :- 186 read_string(Stream, '\n', '\r', Sep, String0), 187 ( Sep \== -1 188 -> String = String0 189 ; String0 == "" 190 -> String = end_of_file 191 ; String = String0 192 ). 193 194 195 /******************************* 196 * STREAM (ENTIRE INPUT) * 197 *******************************/
205pl_read_stream_to_codes(Stream, Codes) :- 206 pl_read_stream_to_codes(Stream, Codes, []). 207pl_read_stream_to_codes(Stream, Codes, Tail) :- 208 get_code(Stream, C0), 209 read_stream_to_codes(C0, Stream, Codes0, Tail), 210 Codes = Codes0. 211 212read_stream_to_codes(-1, _, Tail, Tail) :- !. 213read_stream_to_codes(C, Stream, [C|T], Tail) :- 214 get_code(Stream, C2), 215 read_stream_to_codes(C2, Stream, T, Tail).
220read_stream_to_terms(Stream, Terms, Tail, Options) :- 221 read_term(Stream, C0, Options), 222 read_stream_to_terms(C0, Stream, Terms0, Tail, Options), 223 Terms = Terms0. 224 225read_stream_to_terms(end_of_file, _, Tail, Tail, _) :- !. 226read_stream_to_terms(C, Stream, [C|T], Tail, Options) :- 227 read_term(Stream, C2, Options), 228 read_stream_to_terms(C2, Stream, T, Tail, Options). 229 230 231 /******************************* 232 * FILE (ENTIRE INPUT) * 233 *******************************/
246read_file_to_codes(Spec, Codes, Options) :-
247 must_be(list, Options),
248 option(tail(Tail), Options, []),
249 absolute_file_name(Spec,
250 [ access(read)
251 | Options
252 ],
253 Path),
254 setup_call_cleanup(
255 open(Path, read, Stream, Options),
256 read_stream_to_codes(Stream, Codes, Tail),
257 close(Stream)).
266read_file_to_string(Spec, Codes, Options) :-
267 must_be(list, Options),
268 absolute_file_name(Spec,
269 [ access(read)
270 | Options
271 ],
272 Path),
273 setup_call_cleanup(
274 open(Path, read, Stream, Options),
275 read_string(Stream, _Len, Codes),
276 close(Stream)).
Note that the output options of read_term/3, such as
variable_names or subterm_positions will cause
read_file_to_terms/3 to fail if Spec contains multiple terms
because the values for the different terms will not unify.
292read_file_to_terms(Spec, Terms, Options) :-
293 must_be(list, Options),
294 option(tail(Tail), Options, []),
295 absolute_file_name(Spec,
296 [ access(read)
297 | Options
298 ],
299 Path),
300 setup_call_cleanup(
301 open(Path, read, Stream, Options),
302 read_stream_to_terms(Stream, Terms, Tail, Options),
303 close(Stream))
Read utilities
This library provides some commonly used reading predicates. As these predicates have proven to be time-critical in some applications we moved them to C. For compatibility as well as to reduce system dependency, we link the foreign code at runtime and fallback to the Prolog implementation if the shared object cannot be found.