/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (c) 2019-2023, CWI, Amsterdam 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. */ :- module(prolog_trace, [ trace/1, % :Spec trace/2, % :Spec, +Ports tracing/2, % :Spec, -Ports notraceall/0 ]). :- autoload(library(apply),[maplist/2]). :- autoload(library(error),[instantiation_error/1]). :- autoload(library(prolog_wrap),[wrap_predicate/4]). :- autoload(library(prolog_code), [pi_head/2]). /** Print access to predicates This library prints accesses to specified predicates by wrapping the predicate. @see library(debug) for adding conditional print statements to a program. */ :- meta_predicate trace(:), trace(:, +), tracing(:, -). :- dynamic tracing_mask/2. :- volatile tracing_mask/2. %! trace(:Pred) is det. %! trace(:Pred, +PortSpec) is det. % % Print passes through _ports_ of specified predicates. Pred is a, % possible partial, specification of a predicate as it is also used be % spy/1 and similar predicates. Where a full predicate specification % is of the shape `Module:Name/Arity` (or `//Arity for non-terminals), % both the module and arity may be omitted in which case Pred refers % to all matching predicates. PortSpec is either a single port % (`call`, `exit`, `fail` or `redo`), preceded with `+` or `-` or a % list of these. The predicate modifies the current trace % specification and then installs a suitable wrapper for the predicate % using wrap_predicate/4. For example: % % ``` % ?- trace(append). % % lists:append/2: [all] % % lists:append/3: [all] % % append/1: [all] % true. % % ?- append([a,b], [c], L). % T Call: lists:append([a, b], [c], _10478) % T Call: lists:append([b], [c], _11316) % T Call: lists:append([], [c], _11894) % T Exit: lists:append([], [c], [c]) % T Exit: lists:append([b], [c], [b, c]) % T Exit: lists:append([a, b], [c], [a, b, c]) % L = [a, b, c]. % % ?- trace(append, -all). % % lists:append/2: Not tracing % % lists:append/3: Not tracing % % append/1: Not tracing % % @compat This library replaces prior built-in functionality. Unlike % the built-in version, ports are printed regardless of the `debug` % flag. The built-in version printed the call-stack depth. That is % currently not provided by this replacement. trace(Pred) :- trace(Pred, +all). trace(Pred, Spec) :- '$find_predicate'(Pred, Preds), Preds \== [], maplist(set_trace(Spec), Preds). set_trace(Spec, Pred) :- ( tracing_mask(Pred, Spec0) -> true ; Spec0 = 0 ), modify(Spec, Spec0, Spec1), retractall(tracing_mask(Pred, _)), ( Spec1 == [] ; Spec1 == 0 -> true ; asserta(tracing_mask(Pred, Spec1)) ), mask_ports(Spec1, Ports), pi_head(Pred, Head0), ( predicate_property(Head0, imported_from(M)) -> requalify(Head0, M, Head) ; Head = Head0 ), ( Spec1 == 0 -> unwrap_predicate(Head, trace), print_message(informational, trace(Head, Ports)) ; wrapper(Spec1, Head, Wrapped, Wrapper), wrap_predicate(Head, trace, Wrapped, Wrapper), print_message(informational, trace(Head, Ports)) ). requalify(Term, M, M:Plain) :- strip_module(Term, _, Plain). modify(Var, _, _) :- var(Var), !, instantiation_error(Var). modify([], Spec, Spec) :- !. modify([H|T], Spec0, Spec) :- !, modify(H, Spec0, Spec1), modify(T, Spec1, Spec). modify(+Port, Spec0, Spec) :- !, port_mask(Port, Mask), Spec is Spec0 \/ Mask. modify(-Port, Spec0, Spec) :- !, port_mask(Port, Mask), Spec is Spec0 /\ \Mask. modify(Port, Spec0, Spec) :- port_mask(Port, Mask), Spec is Spec0 \/ Mask. port_mask(all, 0x0f). port_mask(call, 0x01). port_mask(exit, 0x02). port_mask(redo, 0x04). port_mask(fail, 0x08). mask_ports(0, []) :- !. mask_ports(Pattern, [H|T]) :- is_masked(Pattern, H, Pattern1), mask_ports(Pattern1, T). wrapper(Ports, Head, Wrapped, Wrapper) :- wrapper(Ports, Head, Id-Level, Wrapped, Wrapped1), Wrapper = ( prolog_current_frame(Id), prolog_frame_attribute(Id, level, Level), Wrapped1 ). wrapper(0, _, _, Wrapped, Wrapped) :- !. wrapper(Pattern, Head, Id, Wrapped, Call) :- is_masked(Pattern, call, Pattern1), !, wrapper(Pattern1, Head, Id, Wrapped, Call0), Call = ( print_message(debug, frame(Head, trace(call, Id))), Call0 ). wrapper(Pattern, Head, Id, Wrapped, Call) :- is_masked(Pattern, exit, Pattern1), !, wrapper(Pattern1, Head, Id, Wrapped, Call0), Call = ( Call0, print_message(debug, frame(Head, trace(exit, Id))) ). wrapper(Pattern, Head, Id, Wrapped, Call) :- is_masked(Pattern, redo, Pattern1), !, wrapper(Pattern1, Head, Id, Wrapped, Call0), Call = ( call_cleanup(Call0, Det = true), ( Det == true -> true ; true ; print_message(debug, frame(Head, trace(redo, Id))), fail ) ). wrapper(Pattern, Head, Id, Wrapped, Call) :- is_masked(Pattern, fail, Pattern1), !, wrapper(Pattern1, Head, Id, Wrapped, Call0), Call = call(( call_cleanup(Call0, Det = true), ( Det == true -> ! ; true ) ; print_message(debug, frame(Head, trace(fail, Id))), fail )). is_masked(Pattern0, Port, Pattern) :- port_mask(Port, Mask), Pattern0 /\ Mask =:= Mask, !, Pattern is Pattern0 /\ \Mask. %! tracing(:Spec, -Ports) % % True if Spec is traced using Ports tracing(Spec, Ports) :- tracing_mask(Spec, Mask), mask_ports(Mask, Ports). %! notraceall is det. % % Remove all trace points notraceall :- forall(tracing(M:Spec, _Ports), trace(M:Spec, -all)).