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]).
65:- predicate_options(read_file_to_codes/3, 3, 66 [ tail(list_or_partial_list), 67 pass_to(system:open/4, 4) 68 ]). 69:- predicate_options(read_file_to_string/3, 3, 70 [ pass_to(system:open/4, 4) 71 ]). 72:- predicate_options(read_file_to_terms/3, 3, 73 [ tail(list_or_partial_list), 74 pass_to(read_stream_to_terms/4, 4), 75 pass_to(system:absolute_file_name/3, 3), 76 pass_to(system:open/4, 4) 77 ]). 78:- predicate_options(read_stream_to_terms/4, 4, 79 [ pass_to(read_term/3, 3) 80 ]). 81 82:- volatile 83 read_line_to_codes/2, 84 read_line_to_codes/3, 85 read_stream_to_codes/2, 86 read_stream_to_codes/3. 87 88link_foreign :- 89 context_module(Here), 90 catch('$syspreds':use_foreign_library_noi(Here:foreign(readutil)), 91 error(_,_), fail), 92 !. 93link_foreign :- 94 assertz((read_line_to_codes(Stream, Line) :- 95 pl_read_line_to_codes(Stream, Line))), 96 assertz((read_line_to_codes(Stream, Line, Tail) :- 97 pl_read_line_to_codes(Stream, Line, Tail))), 98 assertz((read_stream_to_codes(Stream, Content) :- 99 pl_read_stream_to_codes(Stream, Content))), 100 assertz((read_stream_to_codes(Stream, Content, Tail) :- 101 pl_read_stream_to_codes(Stream, Content, Tail))), 102 compile_predicates([ read_line_to_codes/2, 103 read_line_to_codes/3, 104 read_stream_to_codes/2, 105 read_stream_to_codes/3 106 ]). 107 108:- initialization(link_foreign, now). 109 110 111 /******************************* 112 * LINES * 113 *******************************/
123pl_read_line_to_codes(Stream, Codes) :- 124 get_code(Stream, C0), 125 ( C0 == -1 126 -> Codes0 = end_of_file 127 ; read_1line_to_codes(C0, Stream, Codes0) 128 ), 129 Codes = Codes0. 130 131read_1line_to_codes(-1, _, []) :- !. 132read_1line_to_codes(10, _, []) :- !. 133read_1line_to_codes(13, Stream, L) :- 134 !, 135 get_code(Stream, C2), 136 read_1line_to_codes(C2, Stream, L). 137read_1line_to_codes(C, Stream, [C|T]) :- 138 get_code(Stream, C2), 139 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).
163pl_read_line_to_codes(Stream, Codes, Tail) :- 164 get_code(Stream, C0), 165 read_line_to_codes(C0, Stream, Codes0, Tail), 166 Codes = Codes0. 167 168read_line_to_codes(-1, _, Tail, Tail) :- 169 !, 170 Tail = []. 171read_line_to_codes(10, _, [10|Tail], Tail) :- !. 172read_line_to_codes(C, Stream, [C|T], Tail) :- 173 get_code(Stream, C2), 174 read_line_to_codes(C2, Stream, T, Tail).
end_of_file
if the end of the file is reached.
186read_line_to_string(Stream, String) :- 187 read_string(Stream, '\n', '\r', Sep, String0), 188 ( Sep \== -1 189 -> String = String0 190 ; String0 == "" 191 -> String = end_of_file 192 ; String = String0 193 ). 194 195 196 /******************************* 197 * STREAM (ENTIRE INPUT) * 198 *******************************/
206pl_read_stream_to_codes(Stream, Codes) :- 207 pl_read_stream_to_codes(Stream, Codes, []). 208pl_read_stream_to_codes(Stream, Codes, Tail) :- 209 get_code(Stream, C0), 210 read_stream_to_codes(C0, Stream, Codes0, Tail), 211 Codes = Codes0. 212 213read_stream_to_codes(-1, _, Tail, Tail) :- !. 214read_stream_to_codes(C, Stream, [C|T], Tail) :- 215 get_code(Stream, C2), 216 read_stream_to_codes(C2, Stream, T, Tail).
221read_stream_to_terms(Stream, Terms, Tail, Options) :- 222 read_term(Stream, C0, Options), 223 read_stream_to_terms(C0, Stream, Terms0, Tail, Options), 224 Terms = Terms0. 225 226read_stream_to_terms(end_of_file, _, Tail, Tail, _) :- !. 227read_stream_to_terms(C, Stream, [C|T], Tail, Options) :- 228 read_term(Stream, C2, Options), 229 read_stream_to_terms(C2, Stream, T, Tail, Options). 230 231 232 /******************************* 233 * FILE (ENTIRE INPUT) * 234 *******************************/
247read_file_to_codes(Spec, Codes, Options) :-
248 must_be(list, Options),
249 option(tail(Tail), Options, []),
250 absolute_file_name(Spec,
251 [ access(read)
252 | Options
253 ],
254 Path),
255 setup_call_cleanup(
256 open(Path, read, Stream, Options),
257 read_stream_to_codes(Stream, Codes, Tail),
258 close(Stream)).
267read_file_to_string(Spec, Codes, Options) :-
268 must_be(list, Options),
269 absolute_file_name(Spec,
270 [ access(read)
271 | Options
272 ],
273 Path),
274 setup_call_cleanup(
275 open(Path, read, Stream, Options),
276 read_string(Stream, _Len, Codes),
277 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.
293read_file_to_terms(Spec, Terms, Options) :-
294 must_be(list, Options),
295 option(tail(Tail), Options, []),
296 absolute_file_name(Spec,
297 [ access(read)
298 | Options
299 ],
300 Path),
301 setup_call_cleanup(
302 open(Path, read, Stream, Options),
303 read_stream_to_terms(Stream, Terms, Tail, Options),
304 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.