1/* Part of SWI-Prolog 2 3 Author: Jan Wielemaker 4 E-mail: jan@swi-prolog.org 5 WWW: https://www.swi-prolog.org 6 Copyright (c) 2010-2026, VU University Amsterdam 7 CWI, Amsterdam 8 SWI-Prolog Solutions b.v. 9 All rights reserved. 10 11 Redistribution and use in source and binary forms, with or without 12 modification, are permitted provided that the following conditions 13 are met: 14 15 1. Redistributions of source code must retain the above copyright 16 notice, this list of conditions and the following disclaimer. 17 18 2. Redistributions in binary form must reproduce the above copyright 19 notice, this list of conditions and the following disclaimer in 20 the documentation and/or other materials provided with the 21 distribution. 22 23 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 26 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 27 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 28 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 29 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 30 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 31 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 33 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 34 POSSIBILITY OF SUCH DAMAGE. 35*/ 36 37:- module(ansi_term, 38 [ ansi_format/3, % +Attr, +Format, +Args 39 ansi_format/4, % +Stream, +Attr, +Format, +Args 40 ansi_sgr/2, % +Attr, -Sequence 41 ansi_get_color/2, % +Which, -rgb(R,G,B) 42 ansi_hyperlink/2, % +Stream,+Location 43 ansi_hyperlink/3 % +Stream,+URL,+Label 44 ]). 45:- autoload(library(error), [domain_error/2, must_be/2, instantiation_error/1]). 46:- autoload(library(lists), [append/3, selectchk/3]). 47:- autoload(library(utf8), [utf8_codes/3]). 48:- autoload(library(apply), [maplist/2]).
73:- multifile 74 prolog:console_color/2, % +Term, -AnsiAttrs 75 supports_get_color/0, 76 hyperlink/2, % +Stream, +Spec 77 tty_url_hook/2. % +For, -URL 78 79color_term_flag_default(true) :- 80 stream_property(user_input, tty(true)), 81 stream_property(user_error, tty(true)), 82 stream_property(user_output, tty(true)), 83 \+ getenv('TERM', dumb), 84 !. 85color_term_flag_default(false). 86 87init_color_term_flag :- 88 color_term_flag_default(Default), 89 create_prolog_flag(color_term, Default, 90 [ type(boolean), 91 keep(true) 92 ]), 93 create_prolog_flag(hyperlink_term, false, 94 [ type(boolean), 95 keep(true) 96 ]). 97 98:- initialization 99 init_color_term_flag. 100 101:- multifile 102 user:message_property/2.
current_output is a
terminal, it adds ANSI escape sequences according to Attributes.
For example, to print a text in bold cyan, do
?- ansi_format([bold,fg(cyan)], 'Hello ~w', [world]).
Attributes is either a single attribute, a list thereof or a term that is mapped to concrete attributes based on the current theme (see prolog:console_color/2). The attribute names are derived from the ANSI specification. See the source for sgr_code/2 for details. Some commonly used attributes are:
fg(Color) and bg(Color), the colour name can be '#RGB' or
'#RRGGBB'h(Color)
or an integer 0..255.
Defined color constants are below. default can be used to access
the default color of the terminal.
ANSI sequences are sent if and only if
current_output has the property tty(true) (see
stream_property/2).color_term is true.147ansi_format(Attr, Format, Args) :- 148 ansi_format(current_output, Attr, Format, Args). 149 150ansi_format(Stream, Class, Format, Args) :- 151 stream_property(Stream, tty(true)), 152 current_prolog_flag(color_term, true), 153 class_attrs(Class, Attr), 154 Attr \== [], 155 !, 156 ( selectchk(href(HREF), Attr, Attr1) 157 -> true 158 ; Attr1 = Attr 159 ), 160 sgr_sequence(Attr1, Sequence), 161 with_output_to( 162 Stream, 163 ( write(Sequence), 164 format_content(Format, Args, HREF), 165 format('\e[0m') 166 ) 167 ), 168 flush_output. 169ansi_format(Stream, _Attr, Format, Args) :- 170 format(Stream, Format, Args). 171 172format_content(Format, Args, HREF) :- 173 var(HREF), 174 !, 175 format(Format, Args). 176format_content(Format, Args, HREF) :- 177 format(string(Label), Format, Args), 178 ansi_hyperlink(current_output, HREF, Label).
color_term is false or the class
resolves to no attributes.
Unlike ansi_format/4 this does not write to a stream and thus does
not require a terminal. It is used to decorate strings that are
handed to code that is not aware of colors, notably the toplevel
prompt (see the Prolog flag toplevel_prompt). As the caller
controls where the sequence ends up, the caller is also responsible
for verifying that the destination is a terminal and for emitting
the reset sequence `\e[0m`.
197ansi_sgr(Class, Sequence) :- 198 current_prolog_flag(color_term, true), 199 class_attrs(Class, Attr), 200 Attr \== [], 201 ( selectchk(href(_), Attr, Attr1) 202 -> true 203 ; Attr1 = Attr 204 ), 205 !, 206 sgr_sequence(Attr1, Sequence). 207ansi_sgr(_, "").
bg8(Color).214sgr_sequence(Attrs, Sequence) :- 215 phrase(sgr_codes_ex(Attrs), Codes), 216 codes_sequence(Codes, Sequence). 217 218codes_sequence(Codes, Sequence) :- 219 atomics_to_string(Codes, ;, Code), 220 format(string(Sequence), '\e[~wm', [Code]).
228sgr_codes(X) --> 229 { var(X), 230 !, 231 fail 232 }. 233sgr_codes([]) --> 234 !. 235sgr_codes([H|T]) --> 236 !, 237 sgr_codes(H), 238 sgr_codes(T). 239sgr_codes(Attr) --> 240 { sgr_code(Attr, Code) }, 241 ( { is_list(Code) } 242 -> list(Code) 243 ; [Code] 244 ). 245 246sgr_codes_ex(X) --> 247 { var(X), 248 !, 249 instantiation_error(X) 250 }. 251sgr_codes_ex([]) --> 252 !. 253sgr_codes_ex([H|T]) --> 254 !, 255 sgr_codes_ex(H), 256 sgr_codes_ex(T). 257sgr_codes_ex(Attr) --> 258 ( { sgr_code(Attr, Code) } 259 -> ( { is_list(Code) } 260 -> list(Code) 261 ; [Code] 262 ) 263 ; { domain_error(sgr_code, Attr) } 264 ). 265 266list([]) --> []. 267list([H|T]) --> [H], list(T).
| reset | all attributes off |
| bold | |
| faint | |
| italic | |
| underline | |
blink(slow) | |
blink(rapid) | |
| negative | |
| conceal | |
| crossed_out | |
font(primary) | |
font(N) | Alternate font (1..8) |
| fraktur | |
underline(double) | |
intensity(normal) | |
fg(Name) | Color name |
bg(Name) | Color name |
| framed | |
| encircled | |
| overlined | |
ideogram(underline) | |
| right_side_line | |
ideogram(underline(double)) | |
right_side_line(double) | |
ideogram(overlined) | |
| left_side_line | |
ideogram(stress_marking) | |
| -Off | Switch attributes off |
hfg(Name) | Color name |
hbg(Name) | Color name |
309sgr_code(reset, 0). 310sgr_code(bold, 1). 311sgr_code(faint, 2). 312sgr_code(italic, 3). 313sgr_code(underline, 4). 314sgr_code(blink(slow), 5). 315sgr_code(blink(rapid), 6). 316sgr_code(negative, 7). 317sgr_code(conceal, 8). 318sgr_code(crossed_out, 9). 319sgr_code(font(primary), 10) :- !. 320sgr_code(font(N), C) :- 321 C is 10+N. 322sgr_code(fraktur, 20). 323sgr_code(underline(double), 21). 324sgr_code(intensity(normal), 22). 325sgr_code(fg(Name), C) :- 326 ( ansi_color(Name, N) 327 -> C is N+30 328 ; rgb(Name, R, G, B) 329 -> sgr_code(fg(R,G,B), C) 330 ). 331sgr_code(bg(Name), C) :- 332 !, 333 ( ansi_color(Name, N) 334 -> C is N+40 335 ; rgb(Name, R, G, B) 336 -> sgr_code(bg(R,G,B), C) 337 ). 338sgr_code(framed, 51). 339sgr_code(encircled, 52). 340sgr_code(overlined, 53). 341sgr_code(ideogram(underline), 60). 342sgr_code(right_side_line, 60). 343sgr_code(ideogram(underline(double)), 61). 344sgr_code(right_side_line(double), 61). 345sgr_code(ideogram(overlined), 62). 346sgr_code(left_side_line, 62). 347sgr_code(ideogram(stress_marking), 64). 348sgr_code(-X, Code) :- 349 off_code(X, Code). 350sgr_code(hfg(Name), C) :- 351 ansi_color(Name, N), 352 C is N+90. 353sgr_code(hbg(Name), C) :- 354 !, 355 ansi_color(Name, N), 356 C is N+100. 357sgr_code(fg8(Name), [38,5,N]) :- 358 ansi_color8(Name, N). 359sgr_code(bg8(Name), [48,5,N]) :- 360 ansi_color8(Name, N). 361sgr_code(fg(R,G,B), [38,2,R,G,B]) :- 362 between(0, 255, R), 363 between(0, 255, G), 364 between(0, 255, B). 365sgr_code(bg(R,G,B), [48,2,R,G,B]) :- 366 between(0, 255, R), 367 between(0, 255, G), 368 between(0, 255, B). 369 370off_code(italic_and_franktur, 23). 371off_code(underline, 24). 372off_code(blink, 25). 373off_code(negative, 27). 374off_code(conceal, 28). 375off_code(crossed_out, 29). 376off_code(framed, 54). 377off_code(overlined, 55). 378 379ansi_color8(h(Name), N) :- 380 !, 381 ansi_color(Name, N0), 382 N is N0+8. 383ansi_color8(Name, N) :- 384 atom(Name), 385 !, 386 ansi_color(Name, N). 387ansi_color8(N, N) :- 388 between(0, 255, N). 389 390ansi_color(black, 0). 391ansi_color(red, 1). 392ansi_color(green, 2). 393ansi_color(yellow, 3). 394ansi_color(blue, 4). 395ansi_color(magenta, 5). 396ansi_color(cyan, 6). 397ansi_color(white, 7). 398ansi_color(default, 9). 399 400rgb(Name, R, G, B) :- 401 atom_codes(Name, [0'#,R1,R2,G1,G2,B1,B2]), 402 hex_color(R1,R2,R), 403 hex_color(G1,G2,G), 404 hex_color(B1,B2,B). 405rgb(Name, R, G, B) :- 406 atom_codes(Name, [0'#,R1,G1,B1]), 407 hex_color(R1,R), 408 hex_color(G1,G), 409 hex_color(B1,B). 410 411hex_color(D1,D2,V) :- 412 code_type(D1, xdigit(V1)), 413 code_type(D2, xdigit(V2)), 414 V is 16*V1+V2. 415 416hex_color(D1,V) :- 417 code_type(D1, xdigit(V1)), 418 V is 16*V1+V1.
boot/messages.pl, default_theme/2.
Besides the classes used for messages (code, comment, var,
warning, error, truth(Truth), port(Port), message(Kind),
...), the interactive toplevel uses these:
?- prompt and its `| ` continuation.odd or even
and alternates over the answers of a single query, which allows
for striping the answers using a background color. Only an
answer that shows bindings, residual goals or delays uses this
class: true. and false. are not answers to stripe, and
neither is the empty line that separates the answer from the
next query.X = 1.
The debugger uses, besides frame(level) and port(Port):
odd or even
and alternates over the steps of a trace, which allows for
striping the goals using a background color. Match on Port to
color the goal by port instead of (or in addition to) striping.
Note that a background color on prompt, input or answer(_) is
painted up to the right margin using `\e[K`. A background on
goal(_,_) is not: the debugger writes its ? prompt on the same
line.
463 /******************************* 464 * HOOK * 465 *******************************/
nl. Resetting matters because a
terminal that scrolls while a background colour is in effect
paints the newly exposed line with it.Ctx is the message context. It is created by the handler for begin/2 as a term
ansi(Reset, ReInstall, EraseEol)
where Reset is the sequence written by end/1, ReInstall is a
Format-Args pair that re-installs the attributes of the message and
EraseEol is the sequence that paints the remainder of the line or
the empty atom. Callers must treat Ctx as opaque. It is left
unbound if Stream is not a terminal, if the color_term flag is
false or if the message has no attributes. All handlers that use
Ctx therefore fail if it is unbound, which makes
print_message_lines/3 fall back to writing plain text.
510prolog:message_line_element(S, ansi(Class, Fmt, Args)) :- 511 class_attrs(Class, Attr), 512 ansi_format(S, Attr, Fmt, Args). 513prolog:message_line_element(S, ansi(Class, Fmt, Args, Ctx)) :- 514 class_attrs(Class, Attr), 515 ansi_format(S, Attr, Fmt, Args), 516 reinstall_message_attrs(S, Ctx). 517prolog:message_line_element(S, nl(Ctx)) :- 518 nonvar(Ctx), 519 Ctx = ansi(_, _, EOL), 520 write(S, EOL), 521 nl(S). 522prolog:message_line_element(S, flush(Ctx)) :- 523 nonvar(Ctx), 524 Ctx = ansi(_, _, EOL), 525 write(S, EOL), 526 flush_output(S). 527prolog:message_line_element(S, eol(Ctx)) :- 528 nonvar(Ctx), 529 Ctx = ansi(Reset, _, EOL), 530 write(S, EOL), 531 write(S, Reset). 532prolog:message_line_element(S, url(Location)) :- 533 ansi_hyperlink(S, Location). 534prolog:message_line_element(S, url(URL, Label)) :- 535 link_label(Label, Class, Fmt, Args, Ctx), 536 !, 537 format(string(Text), Fmt, Args), 538 ( ansi_sgr_for(S, Class, Sequence) 539 -> write(S, Sequence), 540 ansi_hyperlink(S, URL, Text), 541 write(S, '\e[0m'), 542 reinstall_message_attrs(S, Ctx) 543 ; ansi_hyperlink(S, URL, Text) 544 ). 545prolog:message_line_element(S, url(URL, Label)) :- 546 ansi_hyperlink(S, URL, Label). 547prolog:message_line_element(S, begin(Level, Ctx)) :- 548 level_attrs(Level, Attr), 549 Attr \== [], 550 stream_property(S, tty(true)), 551 current_prolog_flag(color_term, true), 552 phrase(sgr_codes(Attr), Codes), % fails on a kind without a theme 553 !, 554 codes_sequence(Codes, Sequence), 555 write(S, Sequence), 556 erase_eol(Attr, EOL), 557 Ctx = ansi('\e[0m', '\e[0m~w'-[Sequence], EOL). 558prolog:message_line_element(S, end(Ctx)) :- 559 nonvar(Ctx), 560 Ctx = ansi(Reset, _, _), 561 write(S, Reset).
568reinstall_message_attrs(S, Ctx) :-
569 ( nonvar(Ctx),
570 Ctx = ansi(_, RI-RA, _)
571 -> format(S, RI, RA)
572 ; true
573 ).580link_label(Fmt-Args, -, Fmt, Args, _) :- 581 atom(Fmt), 582 is_list(Args), 583 !. 584link_label(ansi(Class, Fmt, Args), Class, Fmt, Args, _). 585link_label(ansi(Class, Fmt, Args, Ctx), Class, Fmt, Args, Ctx).
593ansi_sgr_for(S, Class, Sequence) :-
594 Class \== (-),
595 stream_property(S, tty(true)),
596 ansi_sgr(Class, Sequence),
597 Sequence \== "".606erase_eol(Attrs, EOL) :- 607 ( is_list(Attrs), 608 has_background(Attrs) 609 -> EOL = '\e[K' 610 ; EOL = '' 611 ). 612 613has_background([H|T]) :- 614 ( background(H) 615 -> true 616 ; has_background(T) 617 ). 618 619background(bg(_)). 620background(bg(_,_,_)). 621background(bg8(_)). 622background(hbg(_)). 623 624level_attrs(Level, Attrs) :- 625 user:message_property(Level, color(Attrs)), 626 !. 627level_attrs(Level, Attrs) :- 628 class_attrs(message(Level), Attrs). 629 630class_attrs(Class, Attrs) :- 631 user:message_property(Class, color(Attrs)), 632 !. 633class_attrs(Class, Attrs) :- 634 prolog:console_color(Class, Attrs), 635 !. 636class_attrs(Class, Attrs) :- 637 '$messages':default_theme(Class, Attrs), 638 !. 639class_attrs(Attrs, Attrs).
OSC 8
escape sequence. Location is one of
File:LineFile:Line:ColumnThere is no official standard for encoding the Line and Column. We emit
``file://AbsFileName[#Line[:Column]]``
Both Line and Column count from 1, as in the messages we
print and as used by e.g., rg --hyperlink-format=.... Note that
a capital L before the line, as used by GitHub, is accepted by
Epilog as well.
The sequence is emitted if and only if the Prolog flag
hyperlink_term is true and Stream has the property tty(true).
ansi_format/4 is guarded the same way for color_term, so that a
message captured using with_output_to/2 is plain text.
669ansi_hyperlink(Stream, Location) :- 670 hyperlink(Stream, url(Location)), 671 !. 672ansi_hyperlink(Stream, Location) :- 673 location_label(Location, Label), 674 ansi_hyperlink(Stream, Location, Label). 675 676location_label(File:Line:Column, Label) => 677 format(string(Label), '~w:~w:~w', [File,Line,Column]). 678location_label(File:Line, Label) => 679 format(string(Label), '~w:~w', [File,Line]). 680location_label(File, Label) => 681 format(string(Label), '~w', [File]). 682 683ansi_hyperlink(Stream, Location, Label), 684 hyperlink(Stream, url(Location, Label)) => 685 true. 686ansi_hyperlink(Stream, Location, Label) => 687 ( hyperlink_stream(Stream), 688 location_url(Location, URL) 689 -> format(Stream, '\e]8;;~w\e\\', [URL]), 690 format(Stream, '~w', [Label]), 691 format(Stream, '\e]8;;\e\\', []) 692 ; format(Stream, '~w', [Label]) 693 ).
700hyperlink_stream(Stream) :-
701 current_prolog_flag(hyperlink_term, true),
702 stream_property(Stream, tty(true)).709is_url(URL) :- 710 ( atom(URL) 711 -> true 712 ; string(URL) 713 ), 714 sub_string(URL, Before, _, _, :), 715 !, 716 Before > 0, 717 sub_string(URL, 0, Before, _, Scheme), 718 atom_codes(Scheme, Codes), 719 maplist(between(0'a, 0'z), Codes), 720 not_drive_scheme(Scheme). 721 722:- if(current_prolog_flag(windows, true)). 723not_drive_scheme(Scheme) :- 724 \+ string_length(Scheme, 1). 725:- else. 726not_drive_scheme(_). 727:- endif.
735location_url(Location, URL), 736 tty_url_hook(Location, URL0) => 737 URL = URL0. 738location_url(File:Line:Column, URL) => 739 url_file_name(FileURL, File), 740 format(string(URL), '~w#~d:~d', [FileURL, Line, Column]). 741location_url(File:Line, URL) => 742 url_file_name(FileURL, File), 743 format(string(URL), '~w#~w', [FileURL, Line]). 744location_url(File, URL) => 745 url_file_name(URL, File).
clib package and its foreign support.757url_file_name(URL, File) :- 758 is_url(File), !, 759 URL = File. 760url_file_name(URL, File) :- 761 absolute_file_name(File, AbsFile), 762 ensure_leading_slash(AbsFile, AbsFile1), 763 url_encode_path(AbsFile1, Encoded), 764 format(string(URL), 'file://~s', [Encoded]). 765 766ensure_leading_slash(Path, SlashPath) :- 767 ( sub_atom(Path, 0, _, _, /) 768 -> SlashPath = Path 769 ; atom_concat(/, Path, SlashPath) 770 ). 771 772url_encode_path(Name, Encoded) :- 773 atom_codes(Name, Codes), 774 phrase(utf8_codes(Codes), UTF8), 775 phrase(encode(UTF8), Encoded). 776 777encode([]) --> []. 778encode([H|T]) --> encode1(H), encode(T). 779 780encode1(C) --> 781 { reserved(C), 782 !, 783 format(codes([C1,C2]), '~`0t~16r~2|', [C]) 784 }, 785 "%", [C1,C2]. 786encode1(C) --> 787 [C]. 788 789reserved(C) :- C =< 0'\s. 790reserved(C) :- C >= 127. 791reserved(0'#).
foreground and background. This predicate sends a request to the
console (user_output) and reads the reply. This assumes an xterm
compatible terminal.
811ansi_get_color(Which0, RGB) :- 812 \+ current_prolog_flag(console_menu, true), 813 stream_property(user_input, tty(true)), 814 stream_property(user_output, tty(true)), 815 stream_property(user_error, tty(true)), 816 supports_get_color, 817 ( color_alias(Which0, Which) 818 -> true 819 ; must_be(between(0,15),Which0) 820 -> Which = Which0 821 ), 822 catch(ansi_get_color_(Which, RGB), 823 error(timeout_error(_,_), _), 824 no_xterm). 825 826supports_get_color :- 827 \+ current_prolog_flag(windows, true), 828 getenv('TERM', Term), 829 sub_atom(Term, 0, _, _, xterm), 830 \+ getenv('TERM_PROGRAM', 'Apple_Terminal'). 831 832color_alias(foreground, 10). 833color_alias(background, 11). 834 835ansi_get_color_(Which, RGB) :- 836 stream_property(user_input, timeout(Old)), 837 setup_call_cleanup( 838 set_stream(user_input, timeout(0.05)), 839 with_tty_raw(exchange_color(Which, RGB)), 840 set_stream(user_input, timeout(Old))), 841 !. 842 843no_xterm :- 844 print_message(warning, ansi(no_xterm_get_colour)), 845 fail.
851exchange_color(Which, RGB) :-
852 format(user_output, '\e]~w;?\a', [Which]),
853 flush_output(user_output),
854 format(codes(Id), '~w', [Which]),
855 read_osc_reply(user_input, Id, Codes),
856 phrase(color_reply(RGB), Codes).ESC ] Param ; and the string terminator. Terminals reply with
either BEL or ST (ESC \), so we accept both.
Anything that is not our reply is echoed: it was typed by the user while we were waiting rather than sent by the terminal.
867read_osc_reply(In, Param, Body) :- 868 get_code(In, C), 869 C \== -1, 870 ( C == 0'\e, 871 osc_reply(In, Param, Body0) 872 -> Body = Body0 873 ; put_code(user_output, C), 874 read_osc_reply(In, Param, Body) 875 ). 876 877osc_reply(In, Param, Body) :- 878 get_code(In, 0']), 879 read_osc_param(In, Param), 880 read_osc_string(In, Body). 881 882read_osc_param(In, Param) :- 883 read_osc_param_(In, Codes), 884 Codes == Param. 885 886read_osc_param_(In, Codes) :- 887 get_code(In, C), 888 C \== -1, 889 ( C == 0'; 890 -> Codes = [] 891 ; Codes = [C|T], 892 read_osc_param_(In, T) 893 ). 894 895read_osc_string(In, Codes) :- 896 get_code(In, C), 897 C \== -1, 898 ( C == 0'\a % BEL 899 -> Codes = [] 900 ; C == 0'\e % ST: ESC \ 901 -> get_code(In, 0'\\), 902 Codes = [] 903 ; Codes = [C|T], 904 read_osc_string(In, T) 905 ).
916color_reply(rgb(R,G,B)) --> 917 "rgb:", !, 918 hex_component(R), "/", hex_component(G), "/", hex_component(B). 919color_reply(rgb(R,G,B)) --> % #RGB, #RRGGBB, ... 920 "#", 921 hex_digits(Ds), 922 { length(Ds, Len), 923 N is Len//3, 924 N > 0, N =< 4, 925 length(RDs, N), length(GDs, N), length(BDs, N), 926 append(RDs, Rest, Ds), 927 append(GDs, BDs, Rest), 928 hex_value(RDs, R), 929 hex_value(GDs, G), 930 hex_value(BDs, B) 931 }. 932 933hex_component(V) --> 934 hex_digits(Ds), 935 { Ds \== [], 936 length(Ds, N), 937 N =< 4, 938 hex_value(Ds, V) 939 }. 940 941hex_digits([H|T]) --> 942 [H], 943 { code_type(H, xdigit(_)) }, 944 !, 945 hex_digits(T). 946hex_digits([]) --> 947 [].
prefer_rationals.955hex_value(Ds, V) :- 956 hex_value(Ds, 0, V0), 957 length(Ds, N), 958 Max is 16^N - 1, 959 V is float(V0)/Max. 960 961hex_value([], V, V). 962hex_value([D|T], V0, V) :- 963 code_type(D, xdigit(DV)), 964 V1 is V0*16+DV, 965 hex_value(T, V1, V). 966 967:- multifile prolog:message//1. 968 969prologmessage(ansi(no_xterm_get_colour)) --> 970 [ 'Terminal claims to be xterm compatible,'-[], nl, 971 'but does not report colour info'-[] 972 ]
Print decorated text to ANSI consoles
This library allows for exploiting the color and attribute facilities of most modern terminals using ANSI escape sequences. This library provides the following:
The behavior of this library is controlled by two Prolog flags:
true, activate the color output for this library. Otherwise simply call format/3.url(Location)andurl(URL, Label)elements of Prolog messages.