ltlfilt: add --sonf and --sonf-aps flags

* bin/ltlfilt.cc: Here.
* NEWS: Mention new ltlfilt flags.
* tests/Makefile.am, tests/core/sonf.test: Test these flags.

NEWS

@@ -9,6 +9,11 @@ New in spot 2.10.4.dev  (net yet released)
   - autfilt has a new --to-finite option, illustrated on
     https://spot.lrde.epita.fr/tut12.html
 
+  - ltlfilt has a new --sonf option to produce a formula's Suffix
+    Operator Normal Form, described in [cimatti.06.fmcad].  The
+    associated option --sonf-aps allows listing the newly introduced
+    atomic propositions.
+
   Library:
 
   - The new function suffix_operator_normal_form() implements

bin/ltlfilt.cc

@@ -38,6 +38,7 @@
 #include <spot/misc/hash.hh>
 #include <spot/misc/timer.hh>
 #include <spot/tl/simplify.hh>
+#include <spot/tl/sonf.hh>
 #include <spot/tl/length.hh>
 #include <spot/tl/relabel.hh>
 #include <spot/tl/unabbrev.hh>
@@ -100,6 +101,8 @@ enum {
   OPT_SIZE_MAX,
   OPT_SIZE_MIN,
   OPT_SKIP_ERRORS,
+  OPT_SONF,
+  OPT_SONF_APS,
   OPT_STUTTER_INSENSITIVE,
   OPT_SUSPENDABLE,
   OPT_SYNTACTIC_GUARANTEE,
@@ -127,6 +130,11 @@ static const argp_option options[] =
     { "negate", OPT_NEGATE, nullptr, 0, "negate each formula", 0 },
     { "nnf", OPT_NNF, nullptr, 0,
       "rewrite formulas in negative normal form", 0 },
+    { "sonf", OPT_SONF, "PREFIX", OPTION_ARG_OPTIONAL,
+      "rewrite formulas in suffix operator normal form", 0 },
+    { "sonf-aps", OPT_SONF_APS, "FILENAME", OPTION_ARG_OPTIONAL,
+      "when used with --sonf, output the newly introduced atomic "
+      "propositions", 0 },
     { "relabel", OPT_RELABEL, "abc|pnn", OPTION_ARG_OPTIONAL,
       "relabel all atomic propositions, alphabetically unless " \
       "specified otherwise", 0 },
@@ -316,6 +324,7 @@ static range opt_nth = { 0, std::numeric_limits<int>::max() };
 static int opt_max_count = -1;
 static long int match_count = 0;
 static const char* from_ltlf = nullptr;
+static const char* sonf = nullptr;
 
 
 // We want all these variables to be destroyed when we exit main, to
@@ -327,6 +336,7 @@ static struct opt_t
   spot::bdd_dict_ptr dict = spot::make_bdd_dict();
   spot::exclusive_ap excl_ap;
   std::unique_ptr<output_file> output_define = nullptr;
+  std::unique_ptr<output_file> output_sonf = nullptr;
   spot::formula implied_by = nullptr;
   spot::formula imply = nullptr;
   spot::formula equivalent_to = nullptr;
@@ -460,6 +470,12 @@ parse_opt(int key, char* arg, struct argp_state*)
     case OPT_NNF:
       nnf = true;
       break;
+    case OPT_SONF:
+      sonf = arg ? arg : "sonf_";
+      break;
+    case OPT_SONF_APS:
+      opt->output_sonf.reset(new output_file(arg ? arg : "-"));
+      break;
     case OPT_OBLIGATION:
       obligation = true;
       break;
@@ -650,6 +666,25 @@ namespace
       if (nnf)
         f = simpl.negative_normal_form(f);
 
+      if (sonf != nullptr)
+        {
+          std::vector<std::string> new_aps;
+          std::tie(f, new_aps) = suffix_operator_normal_form(f, sonf);
+
+          if (opt->output_sonf
+              && output_format != count_output
+              && output_format != quiet_output)
+            {
+              for (size_t i = 0; i < new_aps.size(); ++i)
+                {
+                  if (i > 0)
+                    opt->output_sonf->ostream() << ' ';
+                  opt->output_sonf->ostream() << new_aps[i];
+                }
+              opt->output_sonf->ostream() << '\n';
+            }
+        }
+
       switch (relabeling)
         {
         case ApRelabeling:

tests/Makefile.am

@@ -198,7 +198,8 @@ TESTS_tl = \
   core/stutter-ltl.test \
   core/hierarchy.test \
   core/mempool.test \
-  core/format.test
+  core/format.test \
+  core/sonf.test
 
 TESTS_graph = \
   core/graph.test \

tests/core/sonf.test

@@ -0,0 +1,85 @@
+#!/bin/sh
+# -*- coding: utf-8 -*-
+# Copyright (C) 2021 Laboratoire de Recherche et Développement de
+# l'Epita (LRDE).
+#
+# This file is part of Spot, a model checking library.
+#
+# Spot is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# Spot is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. ./defs
+set -e
+
+cat >input <<EOF
+G(c -> Fa) & G(b -> ({x[*]}[]-> c))
+{x[*]}[]-> F({y[*]}<>-> GFz)
+<>(({{p12}[*0..3]}[]-> ((p9) || (!(p17)))) V ((true) U (p17)))
+{{true} || {[*0]}}[]-> (false)
+{{p14} & {{p0}[*]}}[]-> (p11)
+{{{!{p6}} -> {!{p3}}}[*]}[]-> ((p3)V((p3) || ((X((false))) && ((p2)V(p18)))))
+X({{true} || {[*0]}}[]-> ((p17) U ((p8) && (p17))))
+({{{p4} || {p5} || {{p16} <-> {{p15} -> {p11}}}}[*]}[]-> (false)) -> (p8)
+{[*1..6]}[]-> ((p9) V ((p9) || (!((p4) && (p19)))))
+X({{{[*0]} || {{{p10};{p14}}[:*2..3]}}[:*]}<>-> (p8))
+{{true} && {{p8}[*]}}<>-> (!(p10))
+<>(!(({{p7}[*1..2]}<>-> (p11)) V ((!(p9)) && ([]((p11) || (X(p10)))))))
+<>({{!{{p5} || {{!{p2}} <-> {p7}}}} & {[*]}}<>-> (p17))
+{{p0} || {{{[*0..2]}[:*2]}[*]}}<>-> ((p1) && (p6))
+EOF
+
+cat >expected <<EOF
+G(!c|Fa)&G(!b|({x[*]}[]-> c))
+s1&G(!s2|GFz)&G(!s0|({y[*]}<>-> s2))&G(!s3|Fs0)&G(!s1|({x[*]}[]-> s3))
+F(s0 R (1 U p17))&G(p9|!p17|!s1)&G(!s0|({p12[*0..3]}[]-> s1))
+s0&G!s1&G(!s0|({1|[*0]}[]-> s1))
+s0&G(!s0|({p14&p0[*]}[]-> p11))
+s0&G(!s1|(p3 R (p3|(X(0)&(p2 R p18)))))&G(!s0|({{!p3|p6}[*]}[]-> s1))
+Xs0&G(!s1|(p17 U (p8&p17)))&G(!s0|({1|[*0]}[]-> s1))
+(p8|s0)&G(!s0|({{p4|p5|{p16 && {p11|!p15}}|{!p11 && p15 && !p16}}[*]}<>-> s1))
+s0&G(!s1|(p9 R (!p4|p9|!p19)))&G(!s0|({[*1..6]}[]-> s1))
+G(!s0|({{[*0]|{p10;p14}[:*2..3]}[:*]}<>-> p8))&Xs0
+s0&G(!p10|!s1)&G(!s0|({1 && p8[*]}<>-> s1))
+F(s0 U (p9|F(!p11&X!p10)))&G(!p11|!s1)&G(!s0|({p7[*1..2]}[]-> s1))
+G(!s0|({{!p5 && {{!p2 && !p7}|{p2 && p7}}}&[*]}<>-> p17))&Fs0
+s0&G(!s1|(p1&p6))&G(!s0|({p0|[*0..2][:*2][*]}<>-> s1))
+EOF
+
+cat >expected-aps <<EOF
+
+s0 s1 s2 s3
+s0 s1
+s0 s1
+s0
+s0 s1
+s0 s1
+s0 s1
+s0 s1
+s0
+s0 s1
+s0 s1
+s0
+s0 s1
+EOF
+
+ltlfilt -F input --sonf=s --sonf-aps=stdout-aps \
+    | sed 's/ \([|&]\) /\1/g' > stdout
+diff expected stdout
+diff expected-aps stdout-aps
+
+# check idempotence
+ltlfilt -F expected --sonf=s --sonf-aps=stdout-aps \
+    | sed 's/ \([|&]\) /\1/g' > stdout
+diff expected stdout
+# should be 14 empty lines, no new aps introduced this time
+test "$(wc -l -m stdout-aps | awk '{print $1 " " $2}')" = "14 14"