1/*  Part of CHR (Constraint Handling Rules)
    2
    3    Author:        Tom Schrijvers and Jan Wielemaker
    4    E-mail:        Tom.Schrijvers@cs.kuleuven.be
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2004-2015, K.U. Leuven
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
   20
   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   28    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   31    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   32    POSSIBILITY OF SUCH DAMAGE.
   33*/
   34
   35%% SWI begin
   36:- module(chr,
   37	  [ op(1180, xfx, ==>),
   38	    op(1180, xfx, <=>),
   39	    op(1150, fx, constraints),
   40	    op(1150, fx, chr_constraint),
   41	    op(1150, fx, chr_preprocessor),
   42	    op(1150, fx, handler),
   43	    op(1150, fx, rules),
   44	    op(1100, xfx, \),
   45	    op(1200, xfx, @),
   46	    op(1190, xfx, pragma),
   47	    op( 500, yfx, #),
   48	    op(1150, fx, chr_type),
   49	    op(1150, fx, chr_declaration),
   50	    op(1130, xfx, --->),
   51	    op(1150, fx, (?)),
   52	    chr_show_store/1,		% +Module
   53	    find_chr_constraint/1,	% +Pattern
   54	    current_chr_constraint/1,	% :Pattern
   55	    chr_trace/0,
   56	    chr_notrace/0,
   57	    chr_leash/1			% +Ports
   58	  ]).   59:- use_module(library(dialect), [expects_dialect/1]).   60:- use_module(library(apply), [maplist/3]).   61:- use_module(library(lists), [member/2]).   62
   63:- expects_dialect(swi).   64
   65:- set_prolog_flag(generate_debug_info, false).   66
   67:- multifile
   68	debug_ask_continue/1,
   69	preprocess/2.   70
   71:- multifile user:file_search_path/2.   72:- dynamic   user:file_search_path/2.   73:- dynamic   chr_translated_program/1.   74
   75user:file_search_path(chr, library(chr)).
   76
   77:- load_files([ chr(chr_translate),
   78		chr(chr_runtime),
   79		chr(chr_messages),
   80		chr(chr_hashtable_store),
   81		chr(chr_compiler_errors)
   82	      ],
   83	      [ if(not_loaded),
   84		silent(true)
   85	      ]).   86
   87:- use_module(library(lists), [member/2]).   88%% SWI end
   89
   90%% SICStus begin
   91%% :- module(chr,[
   92%%	chr_trace/0,
   93%%	chr_notrace/0,
   94%%	chr_leash/0,
   95%%	chr_flag/3,
   96%%	chr_show_store/1
   97%%	]).
   98%%
   99%% :- op(1180, xfx, ==>),
  100%%	op(1180, xfx, <=>),
  101%%	op(1150, fx, constraints),
  102%%	op(1150, fx, handler),
  103%%	op(1150, fx, rules),
  104%%	op(1100, xfx, \),
  105%%	op(1200, xfx, @),
  106%%	op(1190, xfx, pragma),
  107%%	op( 500, yfx, #),
  108%%	op(1150, fx, chr_type),
  109%%	op(1130, xfx, --->),
  110%%	op(1150, fx, (?)).
  111%%
  112%% :- multifile user:file_search_path/2.
  113%% :- dynamic   chr_translated_program/1.
  114%%
  115%% user:file_search_path(chr, library(chr)).
  116%%
  117%%
  118%% :- use_module('chr/chr_translate').
  119%% :- use_module('chr/chr_runtime').
  120%% :- use_module('chr/chr_hashtable_store').
  121%% :- use_module('chr/hprolog').
  122%% SICStus end
  123
  124:- multifile chr:'$chr_module'/1.  125
  126:- dynamic chr_term/3.		% File, Term
  127
  128:- dynamic chr_pp/2.		% File, Term
  129
  130%	chr_expandable(+Term)
  131%
  132%	Succeeds if Term is a  rule  that   must  be  handled by the CHR
  133%	compiler. Ideally CHR definitions should be between
  134%
  135%		:- constraints ...
  136%		...
  137%		:- end_constraints.
  138%
  139%	As they are not we have to   use  some heuristics. We assume any
  140%	file is a CHR after we've seen :- constraints ...
  141
  142chr_expandable((:- constraints _)).
  143chr_expandable((constraints _)).
  144chr_expandable((:- chr_constraint _)).
  145chr_expandable((:- chr_type _)).
  146chr_expandable((chr_type _)).
  147chr_expandable((:- chr_declaration _)).
  148chr_expandable(option(_, _)).
  149chr_expandable((:- chr_option(_, _))).
  150chr_expandable((handler _)).
  151chr_expandable((rules _)).
  152chr_expandable((_ <=> _)).
  153chr_expandable((_ @ _)).
  154chr_expandable((_ ==> _)).
  155chr_expandable((_ pragma _)).
  156
  157%	chr_expand(+Term, -Expansion)
  158%
  159%	Extract CHR declarations and rules from the file and run the
  160%	CHR compiler when reaching end-of-file.
  161
  162%% SWI begin
  163extra_declarations([ (:- use_module(chr(chr_runtime))),
  164		     (:- style_check(-discontiguous)),
  165		     (:- style_check(-singleton)),
  166		     (:- style_check(-no_effect)),
  167		     (:- set_prolog_flag(generate_debug_info, false))
  168		   | Tail
  169		   ], Tail).
  170%% SWI end
  171
  172%% SICStus begin
  173%% extra_declarations([(:-use_module(chr(chr_runtime)))
  174%%		     , (:- use_module(chr(hprolog),[term_variables/2,term_variables/3]))
  175%%		     , (:-use_module(chr(hpattvars)))
  176%%		     | Tail], Tail).
  177%% SICStus end
  178
  179chr_expand(Term, []) :-
  180	chr_expandable(Term), !,
  181	prolog_load_context(source,Source),
  182	prolog_load_context(source,File),
  183	prolog_load_context(term_position,Pos),
  184	stream_position_data(line_count,Pos,SourceLocation),
  185	add_pragma_to_chr_rule(Term,source_location(File:SourceLocation),NTerm),
  186	assert(chr_term(Source, SourceLocation, NTerm)).
  187chr_expand(Term, []) :-
  188	Term = (:- chr_preprocessor Preprocessor), !,
  189	prolog_load_context(source,File),
  190	assert(chr_pp(File, Preprocessor)).
  191chr_expand(end_of_file, FinalProgram) :-
  192	extra_declarations(FinalProgram,Program),
  193	prolog_load_context(source,File),
  194	findall(T, retract(chr_term(File,_Line,T)), CHR0),
  195	CHR0 \== [],
  196	prolog_load_context(module, Module),
  197	add_debug_decl(CHR0, CHR1),
  198	add_optimise_decl(CHR1, CHR2),
  199	call_preprocess(CHR2, CHR3),
  200	CHR4 = [ (:- module(Module, [])) | CHR3 ],
  201	findall(P, retract(chr_pp(File, P)), Preprocessors),
  202	( Preprocessors = [] ->
  203		CHR4 = CHR
  204	; Preprocessors = [Preprocessor] ->
  205		chr_compiler_errors:chr_info(preprocessor,'\tPreprocessing with ~w.\n',[Preprocessor]),
  206		call_chr_preprocessor(Preprocessor,CHR4,CHR)
  207	;
  208		chr_compiler_errors:print_chr_error(error(syntax(Preprocessors),'Too many preprocessors! Only one is allowed!\n',[])),
  209		fail
  210	),
  211	catch(call_chr_translate(File,
  212			   [ (:- module(Module, []))
  213			   | CHR
  214			   ],
  215			   Program0),
  216		chr_error(Error),
  217		(	chr_compiler_errors:print_chr_error(Error),
  218			fail
  219		)
  220	),
  221	delete_header(Program0, Program).
  222
  223
  224delete_header([(:- module(_,_))|T0], T) :- !,
  225	delete_header(T0, T).
  226delete_header(L, L).
  227
  228add_debug_decl(CHR, CHR) :-
  229	member(option(Name, _), CHR), Name == debug, !.
  230add_debug_decl(CHR, CHR) :-
  231	member((:- chr_option(Name, _)), CHR), Name == debug, !.
  232add_debug_decl(CHR, [(:- chr_option(debug, Debug))|CHR]) :-
  233	(   chr_current_prolog_flag(generate_debug_info, true)
  234	->  Debug = on
  235	;   Debug = off
  236	).
  237
  238%% SWI begin
  239chr_current_prolog_flag(Flag,Val) :- current_prolog_flag(Flag,Val).
  240%% SWI end
  241
  242add_optimise_decl(CHR, CHR) :-
  243	\+(\+(memberchk((:- chr_option(optimize, _)), CHR))), !.
  244add_optimise_decl(CHR, [(:- chr_option(optimize, full))|CHR]) :-
  245	chr_current_prolog_flag(optimize, full), !.
  246add_optimise_decl(CHR, CHR).
  247
  248%%	call_preprocess(+CHR0, -CHR) is det.
  249%
  250%	Call user chr:preprocess(CHR0, CHR).
  251
  252call_preprocess(CHR0, CHR) :-
  253	preprocess(CHR0, CHR), !.
  254call_preprocess(CHR, CHR).
  255
  256%	call_chr_translate(+File, +In, -Out)
  257%
  258%	The entire chr_translate/2 translation may fail, in which case we'd
  259%	better issue a warning  rather  than   simply  ignoring  the CHR
  260%	declarations.
  261
  262call_chr_translate(File, In, _Out) :-
  263	( chr_translate_line_info(In, File, Out0) ->
  264	    nb_setval(chr_translated_program,Out0),
  265	    fail
  266	).
  267call_chr_translate(_, _In, Out) :-
  268	nb_current(chr_translated_program,Out), !,
  269	nb_delete(chr_translated_program).
  270
  271call_chr_translate(File, _, []) :-
  272	print_message(error, chr(compilation_failed(File))).
  273
  274call_chr_preprocessor(Preprocessor,CHR,_NCHR) :-
  275	( call(Preprocessor,CHR,CHR0) ->
  276		nb_setval(chr_preprocessed_program,CHR0),
  277		fail
  278	).
  279call_chr_preprocessor(_,_,NCHR)	:-
  280	nb_current(chr_preprocessed_program,NCHR), !,
  281	nb_delete(chr_preprocessed_program).
  282call_chr_preprocessor(Preprocessor,_,_) :-
  283	chr_compiler_errors:print_chr_error(error(preprocessor,'Preprocessor `~w\' failed!\n',[Preprocessor])).
  284
  285%% SWI begin
  286
  287		 /*******************************
  288		 *      SYNCHRONISE TRACER	*
  289		 *******************************/
  290
  291:- multifile
  292	user:message_hook/3,
  293	chr:debug_event/2,
  294	chr:debug_interact/3.  295:- dynamic
  296	user:message_hook/3.  297
  298user:message_hook(trace_mode(OnOff), _, _) :-
  299	(   OnOff == on
  300	->  chr_trace
  301	;   chr_notrace
  302	),
  303	fail.				% backtrack to other handlers
  304
  305:- public
  306	debug_event/2,
  307	debug_interact/3.  308
  309%%	debug_event(+State, +Event)
  310%
  311%	Hook into the CHR debugger.  At this moment we will discard CHR
  312%	events if we are in a Prolog `skip' and we ignore the
  313
  314debug_event(_State, _Event) :-
  315	tracing,			% are we tracing?
  316	prolog_skip_level(Skip, Skip),
  317	Skip \== very_deep,
  318	prolog_current_frame(Me),
  319	prolog_frame_attribute(Me, level, Level),
  320	Level > Skip, !.
  321
  322%%	debug_interact(+Event, +Depth, -Command)
  323%
  324%	Hook into the CHR debugger to display Event and ask for the next
  325%	command to execute. This  definition   causes  the normal Prolog
  326%	debugger to be used for the standard ports.
  327
  328debug_interact(Event, _Depth, creep) :-
  329	prolog_event(Event),
  330	tracing, !.
  331
  332prolog_event(call(_)).
  333prolog_event(exit(_)).
  334prolog_event(fail(_)).
  335
  336%%	debug_ask_continue(-Command) is semidet.
  337%
  338%	Hook to ask for a CHR debug   continuation. Must bind Command to
  339%	one of =creep=, =skip=, =ancestors=, =nodebug=, =abort=, =fail=,
  340%	=break=, =help= or =exit=.
  341
  342
  343		 /*******************************
  344		 *	      MESSAGES		*
  345		 *******************************/
  346
  347:- multifile
  348	prolog:message/3.  349
  350prolog:message(chr(CHR)) -->
  351	chr_message(CHR).
  352
  353:- multifile
  354        check:trivial_fail_goal/1.  355
  356check:trivial_fail_goal(_:Goal) :-
  357        functor(Goal, Name, _),
  358        sub_atom(Name, 0, _, _, '$chr_store_constants_').
  359
  360		 /*******************************
  361		 *	 TOPLEVEL PRINTING	*
  362		 *******************************/
  363
  364:- create_prolog_flag(chr_toplevel_show_store, true, []).  365
  366:- residual_goals(chr_residuals).  367
  368%%	chr_residuals// is det.
  369%
  370%	Find the CHR constraints from the   store.  These are accessible
  371%	through the nondet predicate   current_chr_constraint/1. Doing a
  372%	findall/4 however would loose the  bindings. We therefore rolled
  373%	findallv/4,  which  exploits  non-backtrackable  assignment  and
  374%	realises a copy of the template  without disturbing the bindings
  375%	using this strangely looking construct.   Note that the bindings
  376%	created by the unifications are in New,  which is newer then the
  377%	latest choicepoint and therefore the bindings are not trailed.
  378%
  379%	  ==
  380%	  duplicate_term(Templ, New),
  381%	  New = Templ
  382%	  ==
  383
  384chr_residuals(Residuals, Tail) :-
  385	chr_current_prolog_flag(chr_toplevel_show_store,true),
  386	nb_current(chr_global, _), !,
  387	Goal = _:_,
  388	findallv(Goal, current_chr_constraint(Goal), Residuals, Tail).
  389chr_residuals(Residuals, Residuals).
  390
  391:- meta_predicate
  392	findallv(?, 0, ?, ?).  393
  394findallv(Templ, Goal, List, Tail) :-
  395	List2 = [x|_],
  396	State = state(List2),
  397	(   call(Goal),
  398	    arg(1, State, L),
  399	    duplicate_term(Templ, New),
  400	    New = Templ,
  401	    Cons = [New|_],
  402	    nb_linkarg(2, L, Cons),
  403	    nb_linkarg(1, State, Cons),
  404	    fail
  405	;   List2 = [x|List],
  406	    arg(1, State, Last),
  407	    arg(2, Last, Tail)
  408	).
  409
  410
  411		 /*******************************
  412		 *	   MUST BE LAST!	*
  413		 *******************************/
  414
  415:- multifile system:term_expansion/2.  416:- dynamic   system:term_expansion/2.  417
  418system:term_expansion(In, Out) :-
  419	\+ current_prolog_flag(xref, true),
  420	chr_expand(In, Out).
  421%% SWI end
  422
  423%% SICStus begin
  424%
  425% :- dynamic
  426%	current_toplevel_show_store/1,
  427%	current_generate_debug_info/1,
  428%	current_optimize/1.
  429%
  430% current_toplevel_show_store(on).
  431%
  432% current_generate_debug_info(false).
  433%
  434% current_optimize(off).
  435%
  436% chr_current_prolog_flag(generate_debug_info, X) :-
  437%	chr_flag(generate_debug_info, X, X).
  438% chr_current_prolog_flag(optimize, X) :-
  439%	chr_flag(optimize, X, X).
  440%
  441% chr_flag(Flag, Old, New) :-
  442%	Goal = chr_flag(Flag,Old,New),
  443%	g must_be(Flag, oneof([toplevel_show_store,generate_debug_info,optimize]), Goal, 1),
  444%	chr_flag(Flag, Old, New, Goal).
  445%
  446% chr_flag(toplevel_show_store, Old, New, Goal) :-
  447%	clause(current_toplevel_show_store(Old), true, Ref),
  448%	(   New==Old -> true
  449%	;   must_be(New, oneof([on,off]), Goal, 3),
  450%	    erase(Ref),
  451%	    assertz(current_toplevel_show_store(New))
  452%	).
  453% chr_flag(generate_debug_info, Old, New, Goal) :-
  454%	clause(current_generate_debug_info(Old), true, Ref),
  455%	(   New==Old -> true
  456%	;   must_be(New, oneof([false,true]), Goal, 3),
  457%	    erase(Ref),
  458%	    assertz(current_generate_debug_info(New))
  459%	).
  460% chr_flag(optimize, Old, New, Goal) :-
  461%	clause(current_optimize(Old), true, Ref),
  462%	(   New==Old -> true
  463%	;   must_be(New, oneof([full,off]), Goal, 3),
  464%	    erase(Ref),
  465%	    assertz(current_optimize(New))
  466%	).
  467%
  468%
  469% all_stores_goal(Goal, CVAs) :-
  470%	chr_flag(toplevel_show_store, on, on), !,
  471%	findall(C-CVAs, find_chr_constraint(C), Pairs),
  472%	andify(Pairs, Goal, CVAs).
  473% all_stores_goal(true, _).
  474%
  475% andify([], true, _).
  476% andify([X-Vs|L], Conj, Vs) :- andify(L, X, Conj, Vs).
  477%
  478% andify([], X, X, _).
  479% andify([Y-Vs|L], X, (X,Conj), Vs) :- andify(L, Y, Conj, Vs).
  480%
  481% :- multifile user:term_expansion/6.
  482%
  483% user:term_expansion(In, _, Ids, Out, [], [chr|Ids]) :-
  484%	nonvar(In),
  485%	nonmember(chr, Ids),
  486%	chr_expand(In, Out), !.
  487%
  488%% SICStus end
  489
  490%%% for SSS %%%
  491
  492add_pragma_to_chr_rule((Name @ Rule), Pragma, Result) :- !,
  493	add_pragma_to_chr_rule(Rule,Pragma,NRule),
  494	Result = (Name @ NRule).
  495add_pragma_to_chr_rule((Rule pragma Pragmas), Pragma, Result) :- !,
  496	Result = (Rule pragma (Pragma,Pragmas)).
  497add_pragma_to_chr_rule((Head ==> Body), Pragma, Result) :- !,
  498	Result = (Head ==> Body pragma Pragma).
  499add_pragma_to_chr_rule((Head <=> Body), Pragma, Result) :- !,
  500	Result = (Head <=> Body pragma Pragma).
  501add_pragma_to_chr_rule(Term,_,Term).
  502
  503
  504		 /*******************************
  505		 *	  SANDBOX SUPPORT	*
  506		 *******************************/
  507
  508:- multifile
  509	sandbox:safe_primitive/1.  510
  511% CHR uses a lot of global variables. We   don't  really mind as long as
  512% the user does not mess around  with   global  variable that may have a
  513% predefined meaning.
  514
  515sandbox:safe_primitive(system:b_setval(V, _)) :-
  516	chr_var(V).
  517sandbox:safe_primitive(system:nb_linkval(V, _)) :-
  518	chr_var(V).
  519sandbox:safe_primitive(chr:debug_event(_,_)).
  520sandbox:safe_primitive(chr:debug_interact(_,_,_)).
  521
  522chr_var(Name) :- sub_atom(Name, 0, _, _, '$chr').
  523chr_var(Name) :- sub_atom(Name, 0, _, _, 'chr').
  524
  525
  526		 /*******************************
  527		 *     SYNTAX HIGHLIGHTING	*
  528		 *******************************/
  529
  530:- multifile
  531	prolog_colour:term_colours/2,
  532	prolog_colour:goal_colours/2.  533
  534%%	term_colours(+Term, -Colours)
  535%
  536%	Colourisation of a toplevel term as read from the file.
  537
  538term_colours((_Name @ Rule), delimiter - [ identifier, RuleColours ]) :- !,
  539	term_colours(Rule, RuleColours).
  540term_colours((Rule pragma _Pragma), delimiter - [RuleColours,pragma]) :- !,
  541	term_colours(Rule, RuleColours).
  542term_colours((Head <=> Body), delimiter - [ HeadColours, BodyColours ]) :- !,
  543	chr_head(Head, HeadColours),
  544	chr_body(Body, BodyColours).
  545term_colours((Head ==> Body), delimiter - [ HeadColours, BodyColours ]) :- !,
  546	chr_head(Head, HeadColours),
  547	chr_body(Body, BodyColours).
  548
  549chr_head(_C#_Id, delimiter - [ head, identifier ]) :- !.
  550chr_head((A \ B), delimiter - [ AC, BC ]) :- !,
  551	chr_head(A, AC),
  552	chr_head(B, BC).
  553chr_head((A, B), functor - [ AC, BC ]) :- !,
  554	chr_head(A, AC),
  555	chr_head(B, BC).
  556chr_head(_, head).
  557
  558chr_body((Guard|Goal), delimiter - [ GuardColour, GoalColour ]) :- !,
  559	chr_body(Guard, GuardColour),
  560	chr_body(Goal, GoalColour).
  561chr_body(_, body).
  562
  563
  564%%	goal_colours(+Goal, -Colours)
  565%
  566%	Colouring of special goals.
  567
  568goal_colours(constraints(Decls), deprecated-[DeclColours]) :-
  569	chr_constraint_colours(Decls, DeclColours).
  570goal_colours(chr_constraint(Decls), built_in-[DeclColours]) :-
  571	chr_constraint_colours(Decls, DeclColours).
  572goal_colours(chr_type(TypeDecl), built_in-[DeclColours]) :-
  573	chr_type_decl_colours(TypeDecl, DeclColours).
  574goal_colours(chr_option(Option,Value), built_in-[OpC,ValC]) :-
  575	chr_option_colours(Option, Value, OpC, ValC).
  576
  577chr_constraint_colours(Var, instantiation_error(Var)) :-
  578	var(Var), !.
  579chr_constraint_colours((H,T), classify-[HeadColours,BodyColours]) :- !,
  580	chr_constraint_colours(H, HeadColours),
  581	chr_constraint_colours(T, BodyColours).
  582chr_constraint_colours(PI, Colours) :-
  583	pi_to_term(PI, Goal), !,
  584	Colours = predicate_indicator-[ goal(constraint(0), Goal),
  585					arity
  586				      ].
  587chr_constraint_colours(Goal, Colours) :-
  588	atom(Goal), !,
  589	Colours = goal(constraint(0), Goal).
  590chr_constraint_colours(Goal, Colours) :-
  591	compound(Goal), !,
  592	compound_name_arguments(Goal, _Name, Args),
  593	maplist(chr_argspec, Args, ArgColours),
  594	Colours = goal(constraint(0), Goal)-ArgColours.
  595
  596chr_argspec(Term, mode(Mode)-[chr_type(Type)]) :-
  597	compound(Term),
  598	compound_name_arguments(Term, Mode, [Type]),
  599	chr_mode(Mode).
  600
  601chr_mode(+).
  602chr_mode(?).
  603chr_mode(-).
  604
  605pi_to_term(Name/Arity, Term) :-
  606	atom(Name), integer(Arity), Arity >= 0, !,
  607	functor(Term, Name, Arity).
  608
  609chr_type_decl_colours((Type ---> Def), built_in-[chr_type(Type), DefColours]) :-
  610	chr_type_colours(Def, DefColours).
  611chr_type_decl_colours((Type == Alias), built_in-[chr_type(Type), chr_type(Alias)]).
  612
  613chr_type_colours(Var, classify) :-
  614	var(Var), !.
  615chr_type_colours((A;B), control-[CA,CB]) :- !,
  616	chr_type_colours(A, CA),
  617	chr_type_colours(B, CB).
  618chr_type_colours(T, chr_type(T)).
  619
  620chr_option_colours(Option, Value, identifier, ValCol) :-
  621	chr_option_range(Option, Values), !,
  622	(   nonvar(Value),
  623	    memberchk(Value, Values)
  624	->  ValCol = classify
  625	;   ValCol = error
  626	).
  627chr_option_colours(_, _, error, classify).
  628
  629chr_option_range(check_guard_bindings, [on,off]).
  630chr_option_range(optimize, [off, full]).
  631chr_option_range(debug, [on, off]).
  632
  633prolog_colour:term_colours(Term, Colours) :-
  634	term_colours(Term, Colours).
  635prolog_colour:goal_colours(Term, Colours) :-
  636	goal_colours(Term, Colours)