1/*  Part of SWISH
    2
    3    Author:        Markus Triska
    4    E-mail:        triska@metalevel.at
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (C): 2016 Markus Triska
    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(swish_render_bdd,
   36          [ term_rendering//3                   % +Term, +Vars, +Options
   37          ]).   38:- use_module('../render').   39:- use_module(graphviz, []).   40:- use_module(library(clpb)).   41:- use_module(library(varnumbers)).   42
   43:- register_renderer(bdd, "Render BDDs corresponding to CLP(B) constraints").   44
   45/** <module> Render Binary Decision Diagrams (BDDs)
   46
   47This renderer draws Binary Decision Diagrams (BDDs) that express
   48CLP(B) constraints.
   49
   50Both kinds of residual goals that `library(bdd)` can emit are
   51supported by this renderer: By default, `library(clpb)` emits `sat/1`
   52residual goals. These are first translated to BDDs by reposting the
   53goals while temporarily setting `clpb_residuals` to `bdd`. The
   54translation of such BDDs to `dot/1` terms is straight-forward.
   55Alternatively, you can set `clpb_residuals` to `bdd` yourself. In that
   56case, residual goals are directly emitted as BDDs and are again
   57translated to `dot/1` terms by this renderer.
   58
   59In both cases, the graphviz renderer is used for the final output.
   60
   61*/
   62
   63%%      term_rendering(+Term, +Vars, +Options)//
   64%
   65%       Renders BDDs as emitted by library(clpb).
   66
   67term_rendering(Goal, Vars, Options) -->
   68        (   { Goal = clpb:'$clpb_bdd'(Ns),
   69              is_list(Ns) } -> []
   70        ;   { Goal = sat(Sat0) } ->
   71            { current_prolog_flag(clpb_residuals, OldFlag),
   72              varnumbers_names(Sat0, Sat, VNames),
   73              term_variables(Sat, Vs),
   74              setup_call_cleanup(set_prolog_flag(clpb_residuals, bdd),
   75                                 catch((sat(Sat),
   76                                        copy_term(Vs, Vs, [clpb:'$clpb_bdd'(Ns)]),
   77                                        % reset all attributes
   78                                        maplist(del_attrs, Vs),
   79                                        throw(nodes(Vs,Ns))),
   80                                       % Vs recreate the bindings in nodes Ns
   81                                       nodes(Vs,Ns),
   82                                       true),
   83                                 set_prolog_flag(clpb_residuals, OldFlag)),
   84              % for displaying the labels, unify each variable with its name
   85              maplist(eq, VNames) }
   86        ),
   87        { nodes_dot_digraph(Ns, Dot) },
   88        swish_render_graphviz:term_rendering(Dot, Vars, Options).
   89
   90eq(Name=Var) :- Name = Var.
   91
   92nodes_dot_digraph(Nodes, dot(digraph(Stmts))) :-
   93        maplist(node_then_else, Nodes, Thens, Elses),
   94        phrase((nodes_labels(Nodes),
   95                [node(false, [fontname='Palatino-Bold']),
   96                 node(true, [fontname='Palatino-Bold'])],
   97                [edge([style='filled'])],
   98                list(Thens),
   99                [edge([style='dotted'])],
  100                list(Elses)), Stmts).
  101
  102nodes_labels([]) --> [].
  103nodes_labels([node(N)-(v(Var,_) -> _ ; _)|Nodes]) -->
  104        [node(N, [label=Var])],
  105        nodes_labels(Nodes).
  106
  107node_then_else(Node-(_->Then0;Else0), (ID->Then), (ID->Else)) :-
  108        maplist(node_id, [Node,Then0,Else0], [ID,Then,Else]).
  109
  110node_id(node(N), N).
  111node_id(true, true).
  112node_id(false, false).
  113
  114list([]) --> [].
  115list([L|Ls]) --> [L], list(Ls)