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:- autoload(library(debug),[debug/3]). 44:- autoload(library(error),[existence_error/2]). 45:- autoload(library(lists),[nth1/3]). 46:- autoload(library(prolog_clause),[clause_info/4,clause_name/2]).
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.
85set_breakpoint(File, Line, Char, Id) :- 86 set_breakpoint(File, File, Line, Char, Id). 87set_breakpoint(Owner, File, Line, Char, Id) :- 88 debug(break, 'break_at(~q, ~d, ~d).', [File, Line, Char]), 89 '$clause_from_source'(Owner, File, Line, ClauseRef), 90 clause_info(ClauseRef, InfoFile, TermPos, _NameOffset), 91 ( InfoFile == File 92 -> '$break_pc'(ClauseRef, PC, NextPC), 93 debug(break, 'Clause ~p, PC=~p NextPC=~p', [ClauseRef, PC, NextPC]), 94 '$clause_term_position'(ClauseRef, NextPC, List), 95 debug(break, 'Location = ~w', [List]), 96 range(List, TermPos, A, Z), 97 debug(break, 'Term from ~w-~w', [A, Z]), 98 Z >= Char, !, 99 Len is Z - A, 100 b_setval('$breakpoint', file_location(File, Line, A, Len)) 101 ; print_message(warning, breakpoint(no_source(ClauseRef, File, Line))), 102 '$break_pc'(ClauseRef, PC, _), !, 103 nb_delete('$breakpoint') 104 ), 105 debug(break, 'Break at clause ~w, PC=~w', [ClauseRef, PC]), 106 '$break_at'(ClauseRef, PC, true), 107 nb_delete('$breakpoint'), 108 known_breakpoint(ClauseRef, PC, _Location, Id). 109 110range(_, Pos, _, _) :- 111 var(Pos), !, fail. 112range([], Pos, A, Z) :- 113 arg(1, Pos, A), 114 arg(2, Pos, Z). 115range([H|T], term_position(_, _, _, _, PosL), A, Z) :- 116 nth1(H, PosL, Pos), 117 range(T, Pos, A, Z). 118 119:- dynamic 120 known_breakpoint/4, % ClauseRef, PC, Location, Id 121 break_id/1. 122 123next_break_id(Id) :- 124 retract(break_id(Id0)), 125 !, 126 Id is Id0+1, 127 asserta(break_id(Id)). 128next_break_id(1) :- 129 asserta(break_id(1)).
print_message(breakpoint(delete, Id)) is called. Message hooks
working on this message may still call breakpoint_property/2.
139delete_breakpoint(Id) :- 140 integer(Id), 141 known_breakpoint(ClauseRef, PC, _Location, Id), 142 !, 143 '$break_at'(ClauseRef, PC, false). 144delete_breakpoint(Id) :- 145 existence_error(breakpoint, Id).
163breakpoint_property(Id, file(File)) :- 164 known_breakpoint(ClauseRef,_,_,Id), 165 clause_property(ClauseRef, file(File)). 166breakpoint_property(Id, line_count(Line)) :- 167 known_breakpoint(_,_,Location,Id), 168 location_line(Location, Line). 169breakpoint_property(Id, character_range(Start, Len)) :- 170 known_breakpoint(ClauseRef,PC,Location,Id), 171 ( Location = file_location(_File, _Line, Start, Len) 172 -> true 173 ; break_location(ClauseRef, PC, _File, Start-End), 174 Len is End+1-Start 175 ). 176breakpoint_property(Id, clause(Reference)) :- 177 known_breakpoint(Reference,_,_,Id). 178 179location_line(file_location(_File, Line, _Start, _Len), Line). 180location_line(file_character_range(File, Start, _Len), Line) :- 181 file_line(File, Start, Line). 182location_line(file_line(_File, Line), Line).
190file_line(File, Start, Line) :- 191 setup_call_cleanup( 192 prolog_clause:try_open_source(File, In), 193 stream_line(In, Start, 1, Line), 194 close(In)). 195 196stream_line(In, _, Line0, Line) :- 197 at_end_of_stream(In), 198 !, 199 Line = Line0. 200stream_line(In, Index, Line0, Line) :- 201 skip(In, 0'\n), 202 character_count(In, At), 203 ( At > Index 204 -> Line = Line0 205 ; Line1 is Line0+1, 206 stream_line(In, Index, Line1, Line) 207 ). 208 209 210 /******************************* 211 * FEEDBACK * 212 *******************************/ 213 214:- initialization 215 prolog_unlisten(break, onbreak), 216 prolog_listen(break, onbreak). 217 218onbreak(exist, ClauseRef, PC) :- 219 known_breakpoint(ClauseRef, PC, _Location, Id), 220 !, 221 break_message(breakpoint(exist, Id)). 222onbreak(true, ClauseRef, PC) :- 223 !, 224 debug(break, 'Trap in Clause ~p, PC ~d', [ClauseRef, PC]), 225 with_mutex('$break', next_break_id(Id)), 226 ( nb_current('$breakpoint', Location) 227 -> true 228 ; break_location(ClauseRef, PC, File, A-Z) 229 -> Len is Z+1-A, 230 Location = file_character_range(File, A, Len) 231 ; clause_property(ClauseRef, file(File)), 232 clause_property(ClauseRef, line_count(Line)) 233 -> Location = file_line(File, Line) 234 ; Location = unknown 235 ), 236 asserta(known_breakpoint(ClauseRef, PC, Location, Id)), 237 break_message(breakpoint(set, Id)). 238onbreak(false, ClauseRef, PC) :- 239 debug(break, 'Remove breakpoint from ~p, PC ~d', [ClauseRef, PC]), 240 clause(known_breakpoint(ClauseRef, PC, _Location, Id), true, Ref), 241 call_cleanup(break_message(breakpoint(delete, Id)), erase(Ref)). 242onbreak(gc, ClauseRef, PC) :- 243 debug(break, 'Remove breakpoint from ~p, PC ~d (due to CGC)', 244 [ClauseRef, PC]), 245 retractall(known_breakpoint(ClauseRef, PC, _Location, _Id)). 246 247break_message(Message) :- 248 print_message(informational, Message).
258break_location(ClauseRef, PC, File, A-Z) :- 259 clause_info(ClauseRef, File, TermPos, _NameOffset), 260 '$fetch_vm'(ClauseRef, PC, NPC, _VMI), 261 '$clause_term_position'(ClauseRef, NPC, List), 262 debug(break, 'ClausePos = ~w', [List]), 263 range(List, TermPos, A, Z), 264 debug(break, 'Range: ~d .. ~d', [A, Z]). 265 266 267 /******************************* 268 * MESSAGES * 269 *******************************/ 270 271:- multifile 272 prolog:message/3. 273 274prologmessage(breakpoint(no_source(ClauseRef, _File, Line))) --> 275 [ 'Failed to find line ~d in body of clause ~p. Breaking at start of body.'- 276 [Line, ClauseRef] 277 ]. 278prologmessage(breakpoint(SetClear, Id)) --> 279 setclear(SetClear), 280 breakpoint(Id). 281 282setclear(set) --> 283 ['Breakpoint ']. 284setclear(exist) --> 285 ['Existing breakpoint ']. 286setclear(delete) --> 287 ['Deleted breakpoint ']. 288 289breakpoint(Id) --> 290 breakpoint_name(Id), 291 ( { breakpoint_property(Id, file(File)), 292 file_base_name(File, Base), 293 breakpoint_property(Id, line_count(Line)) 294 } 295 -> [ ' at ~w:~d'-[Base, Line] ] 296 ; [] 297 ). 298 299breakpoint_name(Id) --> 300 { breakpoint_property(Id, clause(ClauseRef)) }, 301 ( { clause_property(ClauseRef, erased) } 302 -> ['~w'-[Id]] 303 ; { clause_name(ClauseRef, Name) }, 304 ['~w in ~w'-[Id, Name]] 305 )
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. */