/* Part of CHR (Constraint Handling Rules)
Author: Tom Schrijvers and Jan Wielemaker
E-mail: Tom.Schrijvers@cs.kuleuven.be
WWW: http://www.swi-prolog.org
Copyright (c) 2004-2025, K.U. Leuven
SWI-Prolog Solutions b.v.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/
%% SWI begin
:- module(chr,
[ op(1180, xfx, ==>),
op(1180, xfx, <=>),
op(1150, fx, constraints),
op(1150, fx, chr_constraint),
op(1150, fx, chr_preprocessor),
op(1150, fx, handler),
op(1150, fx, rules),
op(1100, xfx, \),
op(1200, xfx, @),
op(1190, xfx, pragma),
op( 500, yfx, #),
op(1150, fx, chr_type),
op(1150, fx, chr_declaration),
op(1130, xfx, --->),
op(1150, fx, (?)),
chr_show_store/1, % +Module
find_chr_constraint/1, % +Pattern
current_chr_constraint/1, % :Pattern
chr_trace/0,
chr_notrace/0,
chr_leash/1 % +Ports
]).
:- use_module(library(dialect), [expects_dialect/1]).
:- use_module(library(apply), [maplist/3]).
:- use_module(library(lists), [member/2]).
:- use_module(library(prolog_code), [pi_head/2]).
:- expects_dialect(swi).
:- set_prolog_flag(generate_debug_info, false).
:- multifile
debug_ask_continue/1,
preprocess/2.
:- multifile user:file_search_path/2.
:- dynamic user:file_search_path/2.
:- dynamic chr_translated_program/1.
user:file_search_path(chr, library(chr)).
:- load_files([ chr(chr_translate),
chr(chr_runtime),
chr(chr_messages),
chr(chr_hashtable_store),
chr(chr_compiler_errors)
],
[ if(not_loaded),
silent(true)
]).
:- use_module(library(lists), [member/2]).
%% SWI end
%% SICStus begin
%% :- module(chr,[
%% chr_trace/0,
%% chr_notrace/0,
%% chr_leash/0,
%% chr_flag/3,
%% chr_show_store/1
%% ]).
%%
%% :- op(1180, xfx, ==>),
%% op(1180, xfx, <=>),
%% op(1150, fx, constraints),
%% op(1150, fx, handler),
%% op(1150, fx, rules),
%% op(1100, xfx, \),
%% op(1200, xfx, @),
%% op(1190, xfx, pragma),
%% op( 500, yfx, #),
%% op(1150, fx, chr_type),
%% op(1130, xfx, --->),
%% op(1150, fx, (?)).
%%
%% :- multifile user:file_search_path/2.
%% :- dynamic chr_translated_program/1.
%%
%% user:file_search_path(chr, library(chr)).
%%
%%
%% :- use_module('chr/chr_translate').
%% :- use_module('chr/chr_runtime').
%% :- use_module('chr/chr_hashtable_store').
%% :- use_module('chr/hprolog').
%% SICStus end
:- multifile chr:'$chr_module'/1.
:- dynamic chr_term/3. % File, Term
:- dynamic chr_pp/2. % File, Term
% chr_expandable(+Term)
%
% Succeeds if Term is a rule that must be handled by the CHR
% compiler. Ideally CHR definitions should be between
%
% :- constraints ...
% ...
% :- end_constraints.
%
% As they are not we have to use some heuristics. We assume any
% file is a CHR after we've seen :- constraints ...
chr_expandable((:- constraints _)).
chr_expandable((constraints _)).
chr_expandable((:- chr_constraint _)).
chr_expandable((:- chr_type _)).
chr_expandable((chr_type _)).
chr_expandable((:- chr_declaration _)).
chr_expandable(option(_, _)).
chr_expandable((:- chr_option(_, _))).
chr_expandable((handler _)).
chr_expandable((rules _)).
chr_expandable((_ <=> _)).
chr_expandable((_ @ _)).
chr_expandable((_ ==> _)).
chr_expandable((_ pragma _)).
% chr_expand(+Term, -Expansion)
%
% Extract CHR declarations and rules from the file and run the
% CHR compiler when reaching end-of-file.
%% SWI begin
extra_declarations([ (:- use_module(chr(chr_runtime))),
(:- style_check(-discontiguous)),
(:- style_check(-singleton)),
(:- style_check(-no_effect)),
(:- set_prolog_flag(generate_debug_info, false))
| Tail
], Tail).
%% SWI end
%% SICStus begin
%% extra_declarations([(:-use_module(chr(chr_runtime)))
%% , (:- use_module(chr(hprolog),[term_variables/2,term_variables/3]))
%% , (:-use_module(chr(hpattvars)))
%% | Tail], Tail).
%% SICStus end
chr_expand(Term, []) :-
chr_expandable(Term),
!,
prolog_load_context(source,Source),
prolog_load_context(source,File),
prolog_load_context(term_position,Pos),
stream_position_data(line_count,Pos,SourceLocation),
add_pragma_to_chr_rule(Term,source_location(File:SourceLocation),NTerm),
assert(chr_term(Source, SourceLocation, NTerm)).
chr_expand(Term, []) :-
Term = (:- chr_preprocessor Preprocessor),
!,
prolog_load_context(source,File),
assert(chr_pp(File, Preprocessor)).
chr_expand(end_of_file, FinalProgram) :-
extra_declarations(FinalProgram,Program),
prolog_load_context(source,File),
findall(T, retract(chr_term(File,_Line,T)), CHR0),
CHR0 \== [],
prolog_load_context(module, Module),
add_debug_decl(CHR0, CHR1),
add_optimise_decl(CHR1, CHR2),
call_preprocess(CHR2, CHR3),
CHR4 = [ (:- module(Module, [])) | CHR3 ],
findall(P, retract(chr_pp(File, P)), Preprocessors),
( Preprocessors = [] ->
CHR4 = CHR
; Preprocessors = [Preprocessor] ->
chr_compiler_errors:chr_info(preprocessor,'\tPreprocessing with ~w.\n',[Preprocessor]),
call_chr_preprocessor(Preprocessor,CHR4,CHR)
;
chr_compiler_errors:print_chr_error(error(syntax(Preprocessors),'Too many preprocessors! Only one is allowed!\n',[])),
fail
),
catch(call_chr_translate(File,
[ (:- module(Module, []))
| CHR
],
Program0),
chr_error(Error),
( chr_compiler_errors:print_chr_error(Error),
fail
)
),
delete_header(Program0, Program).
delete_header([(:- module(_,_))|T0], T) :-
!,
delete_header(T0, T).
delete_header(L, L).
add_debug_decl(CHR, CHR) :-
member(option(Name, _), CHR), Name == debug,
!.
add_debug_decl(CHR, CHR) :-
member((:- chr_option(Name, _)), CHR), Name == debug,
!.
add_debug_decl(CHR, [(:- chr_option(debug, Debug))|CHR]) :-
( chr_current_prolog_flag(generate_debug_info, true)
-> Debug = on
; Debug = off
).
%% SWI begin
chr_current_prolog_flag(Flag,Val) :- current_prolog_flag(Flag,Val).
%% SWI end
add_optimise_decl(CHR, CHR) :-
\+(\+(memberchk((:- chr_option(optimize, _)), CHR))),
!.
add_optimise_decl(CHR, [(:- chr_option(optimize, full))|CHR]) :-
chr_current_prolog_flag(optimize, full),
!.
add_optimise_decl(CHR, CHR).
%! call_preprocess(+CHR0, -CHR) is det.
%
% Call user chr:preprocess(CHR0, CHR).
call_preprocess(CHR0, CHR) :-
preprocess(CHR0, CHR),
!.
call_preprocess(CHR, CHR).
% call_chr_translate(+File, +In, -Out)
%
% The entire chr_translate/2 translation may fail, in which case we'd
% better issue a warning rather than simply ignoring the CHR
% declarations.
call_chr_translate(File, In, _Out) :-
( chr_translate_line_info(In, File, Out0) ->
nb_setval(chr_translated_program,Out0),
fail
).
call_chr_translate(_, _In, Out) :-
nb_current(chr_translated_program,Out),
!,
nb_delete(chr_translated_program).
call_chr_translate(File, _, []) :-
print_message(error, chr(compilation_failed(File))).
call_chr_preprocessor(Preprocessor,CHR,_NCHR) :-
( call(Preprocessor,CHR,CHR0) ->
nb_setval(chr_preprocessed_program,CHR0),
fail
).
call_chr_preprocessor(_,_,NCHR) :-
nb_current(chr_preprocessed_program,NCHR),
!,
nb_delete(chr_preprocessed_program).
call_chr_preprocessor(Preprocessor,_,_) :-
chr_compiler_errors:print_chr_error(error(preprocessor,'Preprocessor `~w\' failed!\n',[Preprocessor])).
%% SWI begin
/*******************************
* SYNCHRONISE TRACER *
*******************************/
:- multifile
user:message_hook/3,
chr:debug_event/2,
chr:debug_interact/3.
:- dynamic
user:message_hook/3.
user:message_hook(trace_mode(OnOff), _, _) :-
( OnOff == on
-> chr_trace
; chr_notrace
),
fail. % backtrack to other handlers
:- public
debug_event/2,
debug_interact/3.
%! debug_event(+State, +Event)
%
% Hook into the CHR debugger. At this moment we will discard CHR
% events if we are in a Prolog `skip' and we ignore the
debug_event(_State, _Event) :-
tracing, % are we tracing?
prolog_skip_level(Skip, Skip),
Skip \== very_deep,
prolog_current_frame(Me),
prolog_frame_attribute(Me, level, Level),
Level > Skip,
!.
%! debug_interact(+Event, +Depth, -Command)
%
% Hook into the CHR debugger to display Event and ask for the next
% command to execute. This definition causes the normal Prolog
% debugger to be used for the standard ports.
debug_interact(Event, _Depth, creep) :-
prolog_event(Event),
tracing,
!.
prolog_event(call(_)).
prolog_event(exit(_)).
prolog_event(fail(_)).
%! debug_ask_continue(-Command) is semidet.
%
% Hook to ask for a CHR debug continuation. Must bind Command to
% one of =creep=, =skip=, =ancestors=, =nodebug=, =abort=, =fail=,
% =break=, =help= or =exit=.
/*******************************
* MESSAGES *
*******************************/
:- multifile
prolog:message/3.
prolog:message(chr(CHR)) -->
chr_message(CHR).
:- multifile
check:trivial_fail_goal/1.
check:trivial_fail_goal(_:Goal) :-
functor(Goal, Name, _),
sub_atom(Name, 0, _, _, '$chr_store_constants_').
/*******************************
* TOPLEVEL PRINTING *
*******************************/
:- create_prolog_flag(chr_toplevel_show_store, true, []).
:- residual_goals(chr_residuals).
%! chr_residuals// is det.
%
% Find the CHR constraints from the store. These are accessible
% through the nondet predicate current_chr_constraint/1. Doing a
% findall/4 however would loose the bindings. We therefore rolled
% findallv/4, which exploits non-backtrackable assignment and
% realises a copy of the template without disturbing the bindings
% using this strangely looking construct. Note that the bindings
% created by the unifications are in New, which is newer then the
% latest choicepoint and therefore the bindings are not trailed.
%
% ==
% duplicate_term(Templ, New),
% New = Templ
% ==
chr_residuals(Residuals, Tail) :-
chr_current_prolog_flag(chr_toplevel_show_store,true),
nb_current(chr_global, _),
!,
Goal = _:_,
findallv(Goal, current_chr_constraint(Goal), Residuals, Tail).
chr_residuals(Residuals, Residuals).
:- meta_predicate
findallv(?, 0, ?, ?).
findallv(Templ, Goal, List, Tail) :-
List2 = [x|_],
State = state(List2),
( call(Goal),
arg(1, State, L),
duplicate_term(Templ, New),
New = Templ,
Cons = [New|_],
nb_linkarg(2, L, Cons),
nb_linkarg(1, State, Cons),
fail
; List2 = [x|List],
arg(1, State, Last),
arg(2, Last, Tail)
).
/*******************************
* MUST BE LAST! *
*******************************/
%! in_chr_context is semidet.
%
% True if we are expanding into a context where the chr module is
% loaded.
in_chr_context :-
prolog_load_context(module, M),
( current_op(1180, xfx, M:(==>))
-> true
; module_property(chr, exports(PIs)),
member(PI, PIs),
pi_head(PI, Head),
predicate_property(M:Head, imported_from(chr))
-> true
).
:- multifile system:term_expansion/2.
:- dynamic system:term_expansion/2.
system:term_expansion(In, Out) :-
\+ current_prolog_flag(xref, true),
in_chr_context,
chr_expand(In, Out).
%% SWI end
%% SICStus begin
%
% :- dynamic
% current_toplevel_show_store/1,
% current_generate_debug_info/1,
% current_optimize/1.
%
% current_toplevel_show_store(on).
%
% current_generate_debug_info(false).
%
% current_optimize(off).
%
% chr_current_prolog_flag(generate_debug_info, X) :-
% chr_flag(generate_debug_info, X, X).
% chr_current_prolog_flag(optimize, X) :-
% chr_flag(optimize, X, X).
%
% chr_flag(Flag, Old, New) :-
% Goal = chr_flag(Flag,Old,New),
% g must_be(Flag, oneof([toplevel_show_store,generate_debug_info,optimize]), Goal, 1),
% chr_flag(Flag, Old, New, Goal).
%
% chr_flag(toplevel_show_store, Old, New, Goal) :-
% clause(current_toplevel_show_store(Old), true, Ref),
% ( New==Old -> true
% ; must_be(New, oneof([on,off]), Goal, 3),
% erase(Ref),
% assertz(current_toplevel_show_store(New))
% ).
% chr_flag(generate_debug_info, Old, New, Goal) :-
% clause(current_generate_debug_info(Old), true, Ref),
% ( New==Old -> true
% ; must_be(New, oneof([false,true]), Goal, 3),
% erase(Ref),
% assertz(current_generate_debug_info(New))
% ).
% chr_flag(optimize, Old, New, Goal) :-
% clause(current_optimize(Old), true, Ref),
% ( New==Old -> true
% ; must_be(New, oneof([full,off]), Goal, 3),
% erase(Ref),
% assertz(current_optimize(New))
% ).
%
%
% all_stores_goal(Goal, CVAs) :-
% chr_flag(toplevel_show_store, on, on), !,
% findall(C-CVAs, find_chr_constraint(C), Pairs),
% andify(Pairs, Goal, CVAs).
% all_stores_goal(true, _).
%
% andify([], true, _).
% andify([X-Vs|L], Conj, Vs) :- andify(L, X, Conj, Vs).
%
% andify([], X, X, _).
% andify([Y-Vs|L], X, (X,Conj), Vs) :- andify(L, Y, Conj, Vs).
%
% :- multifile user:term_expansion/6.
%
% user:term_expansion(In, _, Ids, Out, [], [chr|Ids]) :-
% nonvar(In),
% nonmember(chr, Ids),
% chr_expand(In, Out), !.
%
%% SICStus end
%%% for SSS %%%
add_pragma_to_chr_rule((Name @ Rule), Pragma, Result) :-
!,
add_pragma_to_chr_rule(Rule,Pragma,NRule),
Result = (Name @ NRule).
add_pragma_to_chr_rule((Rule pragma Pragmas), Pragma, Result) :-
!,
Result = (Rule pragma (Pragma,Pragmas)).
add_pragma_to_chr_rule((Head ==> Body), Pragma, Result) :-
!,
Result = (Head ==> Body pragma Pragma).
add_pragma_to_chr_rule((Head <=> Body), Pragma, Result) :-
!,
Result = (Head <=> Body pragma Pragma).
add_pragma_to_chr_rule(Term,_,Term).
/*******************************
* SANDBOX SUPPORT *
*******************************/
:- multifile
sandbox:safe_primitive/1.
% CHR uses a lot of global variables. We don't really mind as long as
% the user does not mess around with global variable that may have a
% predefined meaning.
sandbox:safe_primitive(system:b_setval(V, _)) :-
chr_var(V).
sandbox:safe_primitive(system:nb_linkval(V, _)) :-
chr_var(V).
sandbox:safe_primitive(chr:debug_event(_,_)).
sandbox:safe_primitive(chr:debug_interact(_,_,_)).
chr_var(Name) :- sub_atom(Name, 0, _, _, '$chr').
chr_var(Name) :- sub_atom(Name, 0, _, _, 'chr').
/*******************************
* SYNTAX HIGHLIGHTING *
*******************************/
:- multifile
prolog_colour:term_colours/2,
prolog_colour:goal_colours/2.
%! term_colours(+Term, -Colours)
%
% Colourisation of a toplevel term as read from the file.
term_colours((_Name @ Rule), delimiter - [ identifier, RuleColours ]) :-
!,
term_colours(Rule, RuleColours).
term_colours((Rule pragma _Pragma), delimiter - [RuleColours,pragma]) :-
!,
term_colours(Rule, RuleColours).
term_colours((Head <=> Body), delimiter - [ HeadColours, BodyColours ]) :-
!,
chr_head(Head, HeadColours),
chr_body(Body, BodyColours).
term_colours((Head ==> Body), delimiter - [ HeadColours, BodyColours ]) :-
!,
chr_head(Head, HeadColours),
chr_body(Body, BodyColours).
chr_head(_C#_Id, delimiter - [ head, identifier ]) :- !.
chr_head((A \ B), delimiter - [ AC, BC ]) :-
!,
chr_head(A, AC),
chr_head(B, BC).
chr_head((A, B), functor - [ AC, BC ]) :-
!,
chr_head(A, AC),
chr_head(B, BC).
chr_head(_, head).
chr_body((Guard|Goal), delimiter - [ GuardColour, GoalColour ]) :-
!,
chr_body(Guard, GuardColour),
chr_body(Goal, GoalColour).
chr_body(_, body).
%! goal_colours(+Goal, -Colours)
%
% Colouring of special goals.
goal_colours(constraints(Decls), deprecated-[DeclColours]) :-
chr_constraint_colours(Decls, DeclColours).
goal_colours(chr_constraint(Decls), built_in-[DeclColours]) :-
chr_constraint_colours(Decls, DeclColours).
goal_colours(chr_type(TypeDecl), built_in-[DeclColours]) :-
chr_type_decl_colours(TypeDecl, DeclColours).
goal_colours(chr_option(Option,Value), built_in-[OpC,ValC]) :-
chr_option_colours(Option, Value, OpC, ValC).
chr_constraint_colours(Var, instantiation_error(Var)) :-
var(Var),
!.
chr_constraint_colours((H,T), classify-[HeadColours,BodyColours]) :-
!,
chr_constraint_colours(H, HeadColours),
chr_constraint_colours(T, BodyColours).
chr_constraint_colours(PI, Colours) :-
pi_to_term(PI, Goal),
!,
Colours = predicate_indicator-[ goal(constraint(0), Goal),
arity
].
chr_constraint_colours(Goal, Colours) :-
atom(Goal),
!,
Colours = goal(constraint(0), Goal).
chr_constraint_colours(Goal, Colours) :-
compound(Goal),
!,
compound_name_arguments(Goal, _Name, Args),
maplist(chr_argspec, Args, ArgColours),
Colours = goal(constraint(0), Goal)-ArgColours.
chr_argspec(Term, mode(Mode)-[chr_type(Type)]) :-
compound(Term),
compound_name_arguments(Term, Mode, [Type]),
chr_mode(Mode).
chr_mode(+).
chr_mode(?).
chr_mode(-).
pi_to_term(Name/Arity, Term) :-
atom(Name), integer(Arity), Arity >= 0,
!,
functor(Term, Name, Arity).
chr_type_decl_colours((Type ---> Def), built_in-[chr_type(Type), DefColours]) :-
chr_type_colours(Def, DefColours).
chr_type_decl_colours((Type == Alias), built_in-[chr_type(Type), chr_type(Alias)]).
chr_type_colours(Var, classify) :-
var(Var),
!.
chr_type_colours((A;B), control-[CA,CB]) :-
!,
chr_type_colours(A, CA),
chr_type_colours(B, CB).
chr_type_colours(T, chr_type(T)).
chr_option_colours(Option, Value, identifier, ValCol) :-
chr_option_range(Option, Values),
!,
( nonvar(Value),
memberchk(Value, Values)
-> ValCol = classify
; ValCol = error
).
chr_option_colours(_, _, error, classify).
chr_option_range(check_guard_bindings, [on,off]).
chr_option_range(optimize, [off, full]).
chr_option_range(debug, [on, off]).
prolog_colour:term_colours(Term, Colours) :-
term_colours(Term, Colours).
prolog_colour:goal_colours(Term, Colours) :-
goal_colours(Term, Colours).