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    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)  2010-2020, VU University Amsterdam
    7                              CWI, Amsterdam
    8    All rights reserved.
    9
   10    Redistribution and use in source and binary forms, with or without
   11    modification, are permitted provided that the following conditions
   12    are met:
   13
   14    1. Redistributions of source code must retain the above copyright
   15       notice, this list of conditions and the following disclaimer.
   16
   17    2. Redistributions in binary form must reproduce the above copyright
   18       notice, this list of conditions and the following disclaimer in
   19       the documentation and/or other materials provided with the
   20       distribution.
   21
   22    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   23    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   24    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   25    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   26    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   27    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   28    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   29    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   30    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   32    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   33    POSSIBILITY OF SUCH DAMAGE.
   34*/
   35
   36:- module(ansi_term,
   37          [ ansi_format/3,              % +Attr, +Format, +Args
   38            ansi_get_color/2            % +Which, -rgb(R,G,B)
   39          ]).   40:- autoload(library(error),[domain_error/2,must_be/2]).   41:- autoload(library(lists),[append/2,append/3]).   42:- if(exists_source(library(time))).   43:- autoload(library(time),[call_with_time_limit/2]).   44:- endif.

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:

See also
- http://en.wikipedia.org/wiki/ANSI_escape_code */
   61:- multifile
   62    prolog:console_color/2,                     % +Term, -AnsiAttrs
   63    supports_get_color/0.   64
   65
   66color_term_flag_default(true) :-
   67    stream_property(user_input, tty(true)),
   68    stream_property(user_error, tty(true)),
   69    stream_property(user_output, tty(true)),
   70    \+ getenv('TERM', dumb),
   71    !.
   72color_term_flag_default(false).
   73
   74init_color_term_flag :-
   75    color_term_flag_default(Default),
   76    create_prolog_flag(color_term, Default,
   77                       [ type(boolean),
   78                         keep(true)
   79                       ]).
   80
   81:- init_color_term_flag.   82
   83
   84:- meta_predicate
   85    keep_line_pos(+, 0).   86
   87:- multifile
   88    user:message_property/2.
 ansi_format(+ClassOrAttributes, +Format, +Args) is det
Format text with ANSI attributes. This predicate behaves as format/2 using Format and Args, but if the 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:

bold
underline
fg(Color),bg(Color),hfg(Color),hbg(Color)
For fg(Color) and bg(Color), the colour name can be '#RGB' or '#RRGGBB'
fg8(Spec),bg8(Spec)
8-bit color specification. Spec is a colour name, h(Color) or an integer 0..255.
fg(R, G, B),bg(R, G, B)
24-bit (direct color) specification. The components are integers in the range 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

  130ansi_format(Attr, Format, Args) :-
  131    ansi_format(current_output, Attr, Format, Args).
  132
  133ansi_format(Stream, Class, Format, Args) :-
  134    stream_property(Stream, tty(true)),
  135    current_prolog_flag(color_term, true),
  136    !,
  137    class_attrs(Class, Attr),
  138    phrase(sgr_codes_ex(Attr), Codes),
  139    atomic_list_concat(Codes, ;, Code),
  140    format(string(Fmt), '\e[~~wm~w\e[0m', [Format]),
  141    format(Stream, Fmt, [Code|Args]),
  142    flush_output.
  143ansi_format(Stream, _Attr, Format, Args) :-
  144    format(Stream, Format, Args).
  145
  146sgr_codes_ex(X) -->
  147    { var(X),
  148      !,
  149      instantiation_error(X)
  150    }.
  151sgr_codes_ex([]) -->
  152    !.
  153sgr_codes_ex([H|T]) -->
  154    !,
  155    sgr_codes_ex(H),
  156    sgr_codes_ex(T).
  157sgr_codes_ex(Attr) -->
  158    (   { sgr_code(Attr, Code) }
  159    ->  (   { is_list(Code) }
  160        ->  list(Code)
  161        ;   [Code]
  162        )
  163    ;   { domain_error(sgr_code, Attr) }
  164    ).
  165
  166list([]) --> [].
  167list([H|T]) --> [H], list(T).
 sgr_code(+Name, -Code)
True when code is the Select Graphic Rendition code for Name. The defined names are given below. Note that most terminals only implement this partially.
resetall 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)
-OffSwitch attributes off
hfg(Name)Color name
hbg(Name)Color name
See also
- http://en.wikipedia.org/wiki/ANSI_escape_code
  209sgr_code(reset, 0).
  210sgr_code(bold,  1).
  211sgr_code(faint, 2).
  212sgr_code(italic, 3).
  213sgr_code(underline, 4).
  214sgr_code(blink(slow), 5).
  215sgr_code(blink(rapid), 6).
  216sgr_code(negative, 7).
  217sgr_code(conceal, 8).
  218sgr_code(crossed_out, 9).
  219sgr_code(font(primary), 10) :- !.
  220sgr_code(font(N), C) :-
  221    C is 10+N.
  222sgr_code(fraktur, 20).
  223sgr_code(underline(double), 21).
  224sgr_code(intensity(normal), 22).
  225sgr_code(fg(Name), C) :-
  226    (   ansi_color(Name, N)
  227    ->  C is N+30
  228    ;   rgb(Name, R, G, B)
  229    ->  sgr_code(fg(R,G,B), C)
  230    ).
  231sgr_code(bg(Name), C) :-
  232    !,
  233    (   ansi_color(Name, N)
  234    ->  C is N+40
  235    ;   rgb(Name, R, G, B)
  236    ->  sgr_code(bg(R,G,B), C)
  237    ).
  238sgr_code(framed, 51).
  239sgr_code(encircled, 52).
  240sgr_code(overlined, 53).
  241sgr_code(ideogram(underline), 60).
  242sgr_code(right_side_line, 60).
  243sgr_code(ideogram(underline(double)), 61).
  244sgr_code(right_side_line(double), 61).
  245sgr_code(ideogram(overlined), 62).
  246sgr_code(left_side_line, 62).
  247sgr_code(ideogram(stress_marking), 64).
  248sgr_code(-X, Code) :-
  249    off_code(X, Code).
  250sgr_code(hfg(Name), C) :-
  251    ansi_color(Name, N),
  252    C is N+90.
  253sgr_code(hbg(Name), C) :-
  254    !,
  255    ansi_color(Name, N),
  256    C is N+100.
  257sgr_code(fg8(Name), [38,5,N]) :-
  258    ansi_color8(Name, N).
  259sgr_code(bg8(Name), [48,5,N]) :-
  260    ansi_color8(Name, N).
  261sgr_code(fg(R,G,B), [38,2,R,G,B]) :-
  262    between(0, 255, R),
  263    between(0, 255, G),
  264    between(0, 255, B).
  265sgr_code(bg(R,G,B), [48,2,R,G,B]) :-
  266    between(0, 255, R),
  267    between(0, 255, G),
  268    between(0, 255, B).
  269
  270off_code(italic_and_franktur, 23).
  271off_code(underline, 24).
  272off_code(blink, 25).
  273off_code(negative, 27).
  274off_code(conceal, 28).
  275off_code(crossed_out, 29).
  276off_code(framed, 54).
  277off_code(overlined, 55).
  278
  279ansi_color8(h(Name), N) :-
  280    !,
  281    ansi_color(Name, N0),
  282    N is N0+8.
  283ansi_color8(Name, N) :-
  284    atom(Name),
  285    !,
  286    ansi_color(Name, N).
  287ansi_color8(N, N) :-
  288    between(0, 255, N).
  289
  290ansi_color(black,   0).
  291ansi_color(red,     1).
  292ansi_color(green,   2).
  293ansi_color(yellow,  3).
  294ansi_color(blue,    4).
  295ansi_color(magenta, 5).
  296ansi_color(cyan,    6).
  297ansi_color(white,   7).
  298ansi_color(default, 9).
  299
  300rgb(Name, R, G, B) :-
  301    atom_codes(Name, [0'#,R1,R2,G1,G2,B1,B2]),
  302    hex_color(R1,R2,R),
  303    hex_color(G1,G2,G),
  304    hex_color(B1,B2,B).
  305rgb(Name, R, G, B) :-
  306    atom_codes(Name, [0'#,R1,G1,B1]),
  307    hex_color(R1,R),
  308    hex_color(G1,G),
  309    hex_color(B1,B).
  310
  311hex_color(D1,D2,V) :-
  312    code_type(D1, xdigit(V1)),
  313    code_type(D2, xdigit(V2)),
  314    V is 16*V1+V2.
  315
  316hex_color(D1,V) :-
  317    code_type(D1, xdigit(V1)),
  318    V is 16*V1+V1.
 prolog:console_color(+Term, -AnsiAttributes) is semidet
Hook that allows for mapping abstract terms to concrete ANSI attributes. This hook is used by theme files to adjust the rendering based on user preferences and context. Defaults are defined in the file boot/messages.pl.
See also
- library(theme/dark) for an example implementation and the Term values used by the system messages.
  331                 /*******************************
  332                 *             HOOK             *
  333                 *******************************/
 prolog:message_line_element(+Stream, +Term) is semidet
Hook implementation that deals with ansi(+Attr, +Fmt, +Args) in message specifications.
  340prolog:message_line_element(S, ansi(Class, Fmt, Args)) :-
  341    class_attrs(Class, Attr),
  342    ansi_format(S, Attr, Fmt, Args).
  343prolog:message_line_element(S, ansi(Class, Fmt, Args, Ctx)) :-
  344    class_attrs(Class, Attr),
  345    ansi_format(S, Attr, Fmt, Args),
  346    (   nonvar(Ctx),
  347        Ctx = ansi(_, RI-RA)
  348    ->  keep_line_pos(S, format(S, RI, RA))
  349    ;   true
  350    ).
  351prolog:message_line_element(S, begin(Level, Ctx)) :-
  352    level_attrs(Level, Attr),
  353    stream_property(S, tty(true)),
  354    current_prolog_flag(color_term, true),
  355    !,
  356    (   is_list(Attr)
  357    ->  sgr_codes(Attr, Codes),
  358        atomic_list_concat(Codes, ;, Code)
  359    ;   sgr_code(Attr, Code)
  360    ),
  361    keep_line_pos(S, format(S, '\e[~wm', [Code])),
  362    Ctx = ansi('\e[0m', '\e[0m\e[~wm'-[Code]).
  363prolog:message_line_element(S, end(Ctx)) :-
  364    nonvar(Ctx),
  365    Ctx = ansi(Reset, _),
  366    keep_line_pos(S, write(S, Reset)).
  367
  368sgr_codes([], []).
  369sgr_codes([H0|T0], [H|T]) :-
  370    sgr_code(H0, H),
  371    sgr_codes(T0, T).
  372
  373level_attrs(Level,         Attrs) :-
  374    user:message_property(Level, color(Attrs)),
  375    !.
  376level_attrs(Level,         Attrs) :-
  377    class_attrs(message(Level), Attrs).
  378
  379class_attrs(Class, Attrs) :-
  380    user:message_property(Class, color(Attrs)),
  381    !.
  382class_attrs(Class, Attrs) :-
  383    prolog:console_color(Class, Attrs),
  384    !.
  385class_attrs(Class, Attrs) :-
  386    '$messages':default_theme(Class, Attrs),
  387    !.
  388class_attrs(Attrs, Attrs).
 keep_line_pos(+Stream, :Goal)
Run goal without changing the position information on Stream. This is used to avoid that the exchange of ANSI sequences modifies the notion of, notably, the line_pos notion.
  396keep_line_pos(S, G) :-
  397    stream_property(S, position(Pos)),
  398    !,
  399    setup_call_cleanup(
  400        stream_position_data(line_position, Pos, LPos),
  401        G,
  402        set_stream(S, line_position(LPos))).
  403keep_line_pos(_, G) :-
  404    call(G).
 ansi_get_color(+Which, -RGB) is semidet
Obtain the RGB color for an ANSI color parameter. Which is either a color alias or an integer ANSI color id. Defined aliases are foreground and background. This predicate sends a request to the console (user_output) and reads the reply. This assumes an xterm compatible terminal.
Arguments:
RGB- is a term rgb(Red,Green,Blue). The color components are integers in the range 0..65535.
  418:- if(current_predicate(call_with_time_limit/2)).  419ansi_get_color(Which0, RGB) :-
  420    stream_property(user_input, tty(true)),
  421    stream_property(user_output, tty(true)),
  422    stream_property(user_error, tty(true)),
  423    supports_get_color,
  424    (   color_alias(Which0, Which)
  425    ->  true
  426    ;   must_be(between(0,15),Which0)
  427    ->  Which = Which0
  428    ),
  429    catch(keep_line_pos(user_output,
  430                        ansi_get_color_(Which, RGB)),
  431          time_limit_exceeded,
  432          no_xterm).
  433
  434supports_get_color :-
  435    getenv('TERM', Term),
  436    sub_atom(Term, 0, _, _, xterm),
  437    \+ getenv('TERM_PROGRAM', 'Apple_Terminal').
  438
  439color_alias(foreground, 10).
  440color_alias(background, 11).
  441
  442ansi_get_color_(Which, rgb(R,G,B)) :-
  443    format(codes(Id), '~w', [Which]),
  444    hex4(RH),
  445    hex4(GH),
  446    hex4(BH),
  447    append([`\e]`, Id, `;rgb:`, RH, `/`, GH, `/`, BH, `\a`], Pattern),
  448    call_with_time_limit(0.05,
  449                         with_tty_raw(exchange_pattern(Which, Pattern))),
  450    !,
  451    hex_val(RH, R),
  452    hex_val(GH, G),
  453    hex_val(BH, B).
  454
  455no_xterm :-
  456    print_message(warning, ansi(no_xterm_get_colour)),
  457    fail.
  458
  459hex4([_,_,_,_]).
  460
  461hex_val([D1,D2,D3,D4], V) :-
  462    code_type(D1, xdigit(V1)),
  463    code_type(D2, xdigit(V2)),
  464    code_type(D3, xdigit(V3)),
  465    code_type(D4, xdigit(V4)),
  466    V is (V1<<12)+(V2<<8)+(V3<<4)+V4.
  467
  468exchange_pattern(Which, Pattern) :-
  469    format(user_output, '\e]~w;?\a', [Which]),
  470    flush_output(user_output),
  471    read_pattern(user_input, Pattern, []).
  472
  473read_pattern(From, Pattern, NotMatched0) :-
  474    copy_term(Pattern, TryPattern),
  475    append(Skip, Rest, NotMatched0),
  476    append(Rest, RestPattern, TryPattern),
  477    !,
  478    echo(Skip),
  479    try_read_pattern(From, RestPattern, NotMatched, Done),
  480    (   Done == true
  481    ->  Pattern = TryPattern
  482    ;   read_pattern(From, Pattern, NotMatched)
  483    ).
 try_read_pattern(+From, +Pattern, -NotMatched)
  487try_read_pattern(_, [], [], true) :-
  488    !.
  489try_read_pattern(From, [H|T], [C|RT], Done) :-
  490    get_code(C),
  491    (   C = H
  492    ->  try_read_pattern(From, T, RT, Done)
  493    ;   RT = [],
  494        Done = false
  495    ).
  496
  497echo([]).
  498echo([H|T]) :-
  499    put_code(user_output, H),
  500    echo(T).
  501
  502:- else.  503ansi_get_color(_Which0, _RGB) :-
  504    fail.
  505:- endif.  506
  507
  508
  509:- multifile prolog:message//1.  510
  511prolog:message(ansi(no_xterm_get_colour)) -->
  512    [ 'Terminal claims to be xterm compatible,'-[], nl,
  513      'but does not report colour info'-[]
  514    ]