1/* Part of SWI-Prolog 2 3 Author: Jan Wielemaker 4 E-mail: J.Wielemaker@vu.nl 5 WWW: http://www.swi-prolog.org 6 Copyright (c) 2011-2012, VU University Amsterdam 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:- module(prolog_autoload, 36 [ autoload/0, 37 autoload/1 % +Options 38 ]). 39:- use_module(library(option)). 40:- use_module(library(error)). 41:- use_module(library(aggregate)). 42:- use_module(library(prolog_codewalk)). 43 44:- predicate_options(autoload/1, 1, 45 [ verbose(boolean), 46 undefined(oneof([ignore,error])) 47 ]).

Autoload all dependencies

The autoloader is there to smoothen program development. It liberates the programmer from finding the library that defines some particular predicate and including the proper use_module/1,2 directive in the sources. This is even better at the toplevel, where just using maplist/3 is way more comfortable than first having to load library(apply). In addition, it reduces the startup time of applications by only loading the necessary bits.

Of course, there is also a price. One is that it becomes less obvious from where some predicate is loaded and thus whether you have the right definition. The second issue is that it is harder to create a stand-alone executable because this executable, without access to the development system, can no longer rely on autoloading. Finally, program analysis becomes harder because the program may be incomplete.

This library provides autoload/0 and autoload/1 to autoload all predicates that are referenced by the program. Now, this is not possible in Prolog because the language allows for constructing arbitrary goals and runtime and calling them (e.g., read(X), call(X)).

The classical version relied on the predicate_property undefined. The current version relies on code analysis of the bodies of all clauses and all initialization goals. */

91autoload :- 92 autoload([]). 93 94autoload(Options) :- 95 must_be(list, Options), 96 statistics(cputime, T0), 97 aggregate_all(count, source_file(_), OldFileCount), 98 autoload(0, Iterations, Options), 99 aggregate_all(count, source_file(_), NewFileCount), 100 statistics(cputime, T1), 101 Time is T1-T0, 102 information_level(Level, Options), 103 NewFiles is NewFileCount - OldFileCount, 104 print_message(Level, autoload(completed(Iterations, Time, NewFiles))). 105 106 107autoload(Iteration0, Iterations, Options) :- 108 statistics(cputime, T0), 109 autoload_step(NewFiles, NewPreds, Options), 110 statistics(cputime, T1), 111 Time is T1-T0, 112 succ(Iteration0, Iteration), 113 ( NewFiles > 0 114 -> information_level(Level, Options), 115 print_message(Level, autoload(reiterate(Iteration, 116 NewFiles, NewPreds, Time))), 117 autoload(Iteration, Iterations, Options) 118 ; Iterations = Iteration 119 ). 120 121information_level(Level, Options) :- 122 ( option(verbose(true), Options, true) 123 -> Level = informational 124 ; Level = silent 125 ).

136autoload_step(NewFiles, NewPreds, Options) :- 137 option(verbose(Verbose), Options, true), 138 aggregate_all(count, source_file(_), OldFileCount), 139 setup_call_cleanup( 140 ( current_prolog_flag(autoload, OldAutoLoad), 141 current_prolog_flag(verbose_autoload, OldVerbose), 142 set_prolog_flag(autoload, true), 143 set_prolog_flag(verbose_autoload, Verbose), 144 assert_autoload_hook(Ref), 145 asserta(autoloaded_count(0)) 146 ), 147 prolog_walk_code(Options), 148 ( retract(autoloaded_count(Count)), 149 erase(Ref), 150 set_prolog_flag(autoload, OldAutoLoad), 151 set_prolog_flag(verbose_autoload, OldVerbose) 152 )), 153 aggregate_all(count, source_file(_), NewFileCount), 154 NewPreds = Count, 155 NewFiles is NewFileCount - OldFileCount. 156 157assert_autoload_hook(Ref) :- 158 asserta((user:message_hook(autoload(Module:Name/Arity, Library), _, _) :- 159 autoloaded(Module:Name/Arity, Library)), Ref). 160 161:- public 162 autoloaded/2. 163 164autoloaded(_, _) :- 165 retract(autoloaded_count(N)), 166 succ(N, N2), 167 asserta(autoloaded_count(N2)), 168 fail. % proceed with other hooks 169 170 171 /******************************* 172 * MESSAGES * 173 *******************************/ 174 175:- multifile 176 prolog:message//1. 177 178prolog:message(autoload(reiterate(Iteration, NewFiles, NewPreds, Time))) --> 179 [ 'Autoloader: iteration ~D resolved ~D predicates \c 180 and loaded ~D files in ~3f seconds. Restarting ...'- 181 [Iteration, NewFiles, NewPreds, Time] 182 ]. 183prolog:message(autoload(completed(Iterations, Time, NewFiles))) --> 184 [ 'Autoloader: loaded ~D files in ~D iterations in ~3f seconds'- 185 [NewFiles, Iterations, Time] ]

`NewFiles`	- is unified to the number of files loaded
`NewPreds`	- is unified to the number of predicates imported using the autoloader.