1/* Part of SWI-Prolog 2 3 Author: Jan Wielemaker and Anjo Anjewierden 4 E-mail: J.Wielemaker@vu.nl 5 WWW: http://www.swi-prolog.org/ 6 Copyright (c) 2011-2018, University of Amsterdam 7 VU University Amsterdam 8 CWI, Amsterdam 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(prolog_breakpoints, 38 [ set_breakpoint/4, % +File, +Line, +CharPos, -Id 39 set_breakpoint/5, % +Owner, +File, +Line, +CharPos, -Id 40 delete_breakpoint/1, % +Id 41 breakpoint_property/2 % ?Id, ?Property 42 ]). 43:- use_module(library(prolog_clause)). 44:- use_module(library(debug)). 45:- use_module(library(error)).
62:- dynamic 63 user:prolog_event_hook/1. 64:- multifile 65 user:prolog_event_hook/1.
First, '$clause_from_source'/4 uses the SWI-Prolog clause-source information to find the last clause starting before Line. '$break_pc' generated (on backtracking), a list of possible break-points.
Note that in addition to setting the break-point, the system must be in debug mode for the breakpoint to take effect. With threading enabled, there are various different ways this may be done. See debug/0, tdebug/0 and tdebug/1. Therefore, this predicate does not enable debug mode.
89set_breakpoint(File, Line, Char, Id) :- 90 set_breakpoint(File, File, Line, Char, Id). 91set_breakpoint(Owner, File, Line, Char, Id) :- 92 debug(break, 'break_at(~q, ~d, ~d).', [File, Line, Char]), 93 '$clause_from_source'(Owner, File, Line, ClauseRef), 94 clause_info(ClauseRef, InfoFile, TermPos, _NameOffset), 95 ( InfoFile == File 96 -> '$break_pc'(ClauseRef, PC, NextPC), 97 debug(break, 'Clause ~p, PC=~p NextPC=~p', [ClauseRef, PC, NextPC]), 98 '$clause_term_position'(ClauseRef, NextPC, List), 99 debug(break, 'Location = ~w', [List]), 100 range(List, TermPos, A, Z), 101 debug(break, 'Term from ~w-~w', [A, Z]), 102 Z >= Char, !, 103 Len is Z - A, 104 b_setval('$breakpoint', file_location(File, Line, A, Len)) 105 ; print_message(warning, breakpoint(no_source(ClauseRef, File, Line))), 106 '$break_pc'(ClauseRef, PC, _), !, 107 nb_delete('$breakpoint') 108 ), 109 debug(break, 'Break at clause ~w, PC=~w', [ClauseRef, PC]), 110 '$break_at'(ClauseRef, PC, true), 111 nb_delete('$breakpoint'), 112 known_breakpoint(ClauseRef, PC, _Location, Id). 113 114range(_, Pos, _, _) :- 115 var(Pos), !, fail. 116range([], Pos, A, Z) :- 117 arg(1, Pos, A), 118 arg(2, Pos, Z). 119range([H|T], term_position(_, _, _, _, PosL), A, Z) :- 120 nth1(H, PosL, Pos), 121 range(T, Pos, A, Z). 122 123:- dynamic 124 known_breakpoint/4, % ClauseRef, PC, Location, Id 125 break_id/1. 126 127next_break_id(Id) :- 128 retract(break_id(Id0)), 129 !, 130 Id is Id0+1, 131 asserta(break_id(Id)). 132next_break_id(1) :- 133 asserta(break_id(1)).
print_message(breakpoint(delete, Id)) is called. Message hooks
working on this message may still call breakpoint_property/2.
143delete_breakpoint(Id) :- 144 integer(Id), 145 known_breakpoint(ClauseRef, PC, _Location, Id), 146 !, 147 '$break_at'(ClauseRef, PC, false). 148delete_breakpoint(Id) :- 149 existence_error(breakpoint, Id).
167breakpoint_property(Id, file(File)) :- 168 known_breakpoint(ClauseRef,_,_,Id), 169 clause_property(ClauseRef, file(File)). 170breakpoint_property(Id, line_count(Line)) :- 171 known_breakpoint(_,_,Location,Id), 172 location_line(Location, Line). 173breakpoint_property(Id, character_range(Start, Len)) :- 174 known_breakpoint(ClauseRef,PC,Location,Id), 175 ( Location = file_location(_File, _Line, Start, Len) 176 -> true 177 ; break_location(ClauseRef, PC, _File, Start-End), 178 Len is End+1-Start 179 ). 180breakpoint_property(Id, clause(Reference)) :- 181 known_breakpoint(Reference,_,_,Id). 182 183location_line(file_location(_File, Line, _Start, _Len), Line). 184location_line(file_character_range(File, Start, _Len), Line) :- 185 file_line(File, Start, Line). 186location_line(file_line(_File, Line), Line).
194file_line(File, Start, Line) :- 195 setup_call_cleanup( 196 prolog_clause:try_open_source(File, In), 197 stream_line(In, Start, 1, Line), 198 close(In)). 199 200stream_line(In, _, Line0, Line) :- 201 at_end_of_stream(In), 202 !, 203 Line = Line0. 204stream_line(In, Index, Line0, Line) :- 205 skip(In, 0'\n), 206 character_count(In, At), 207 ( At > Index 208 -> Line = Line0 209 ; Line1 is Line0+1, 210 stream_line(In, Index, Line1, Line) 211 ). 212 213 214 /******************************* 215 * FEEDBACK * 216 *******************************/
callEventHook() from '$break_at'/3. This hook is called with
signal handling disabled, i.e., as an atomic action.223user:prolog_event_hook(break(ClauseRef, PC, Set)) :- 224 break(Set, ClauseRef, PC). 225 226break(exist, ClauseRef, PC) :- 227 known_breakpoint(ClauseRef, PC, _Location, Id), 228 !, 229 break_message(breakpoint(exist, Id)). 230break(true, ClauseRef, PC) :- 231 !, 232 debug(break, 'Trap in Clause ~p, PC ~d', [ClauseRef, PC]), 233 with_mutex('$break', next_break_id(Id)), 234 ( nb_current('$breakpoint', Location) 235 -> true 236 ; break_location(ClauseRef, PC, File, A-Z) 237 -> Len is Z+1-A, 238 Location = file_character_range(File, A, Len) 239 ; clause_property(ClauseRef, file(File)), 240 clause_property(ClauseRef, line_count(Line)) 241 -> Location = file_line(File, Line) 242 ; Location = unknown 243 ), 244 asserta(known_breakpoint(ClauseRef, PC, Location, Id)), 245 break_message(breakpoint(set, Id)). 246break(false, ClauseRef, PC) :- 247 debug(break, 'Remove breakpoint from ~p, PC ~d', [ClauseRef, PC]), 248 clause(known_breakpoint(ClauseRef, PC, _Location, Id), true, Ref), 249 call_cleanup(break_message(breakpoint(delete, Id)), erase(Ref)). 250break(gc, ClauseRef, PC) :- 251 debug(break, 'Remove breakpoint from ~p, PC ~d (due to CGC)', 252 [ClauseRef, PC]), 253 retractall(known_breakpoint(ClauseRef, PC, _Location, _Id)). 254 255break_message(Message) :- 256 print_message(informational, Message).
266break_location(ClauseRef, PC, File, A-Z) :- 267 clause_info(ClauseRef, File, TermPos, _NameOffset), 268 '$fetch_vm'(ClauseRef, PC, NPC, _VMI), 269 '$clause_term_position'(ClauseRef, NPC, List), 270 debug(break, 'ClausePos = ~w', [List]), 271 range(List, TermPos, A, Z), 272 debug(break, 'Range: ~d .. ~d', [A, Z]). 273 274 275 /******************************* 276 * MESSAGES * 277 *******************************/ 278 279:- multifile 280 prolog:message/3. 281 282prologmessage(breakpoint(no_source(ClauseRef, _File, Line))) --> 283 [ 'Failed to find line ~d in body of clause ~p. Breaking at start of body.'- 284 [Line, ClauseRef] 285 ]. 286prologmessage(breakpoint(SetClear, Id)) --> 287 setclear(SetClear), 288 breakpoint(Id). 289 290setclear(set) --> 291 ['Breakpoint ']. 292setclear(exist) --> 293 ['Existing breakpoint ']. 294setclear(delete) --> 295 ['Deleted breakpoint ']. 296 297breakpoint(Id) --> 298 breakpoint_name(Id), 299 ( { breakpoint_property(Id, file(File)), 300 file_base_name(File, Base), 301 breakpoint_property(Id, line_count(Line)) 302 } 303 -> [ ' at ~w:~d'-[Base, Line] ] 304 ; [] 305 ). 306 307breakpoint_name(Id) --> 308 { breakpoint_property(Id, clause(ClauseRef)) }, 309 ( { clause_property(ClauseRef, erased) } 310 -> ['~w'-[Id]] 311 ; { clause_name(ClauseRef, Name) }, 312 ['~w in ~w'-[Id, Name]] 313 )
Manage Prolog break-points
This module provides an interface for development tools to set and delete break-points, giving a location in the source. Development tools that want to track changes to breakpoints must use user:message_hook/3 to intercept these message terms:
breakpoint(set, Id)breakpoint(delete, Id)Note that the hook must fail after creating its side-effects to give other hooks the opportunity to react. */