gen: hide ks_cobuchi(), introduce aut_pattern()

* spot/gen/automata.hh, spot/gen/automata.cc: Hide ks_cobuchi() behind
introduce aut_pattern(), as we have already done for the formulas.
* bin/genaut.cc: Simplify using this interface.
* python/spot/gen.i: Introduce aut_patterns().
* tests/python/gen.ipynb, tests/python/gen.py: Adjust.

bin/genaut.cc

@@ -43,28 +43,14 @@
 
 using namespace spot;
 
-const char argp_program_doc[] ="\
-Generate omega automata from predefined patterns.";
-
-enum {
-  FIRST_CLASS = 256,
-  OPT_KS_COBUCHI = FIRST_CLASS,
-  LAST_CLASS,
-};
-
-const char* const class_name[LAST_CLASS - FIRST_CLASS] =
-  {
-    "ks-cobuchi",
-  };
-
-#define OPT_ALIAS(o) { #o, 0, nullptr, OPTION_ALIAS, nullptr, 0 }
+const char argp_program_doc[] ="Generate ω-automata from predefined patterns.";
 
 static const argp_option options[] =
   {
     /**************************************************/
     // Keep this alphabetically sorted (expect for aliases).
     { nullptr, 0, nullptr, 0, "Pattern selection:", 1},
-    { "ks-cobuchi", OPT_KS_COBUCHI, "RANGE", 0,
+    { "ks-cobuchi", gen::AUT_KS_COBUCHI, "RANGE", 0,
       "A co-Büchi automaton with 2N+1 states for which any equivalent "
       "deterministic co-Büchi automaton has at least 2^N/(2N+1) states.", 0},
     RANGE_DOC,
@@ -75,7 +61,7 @@ static const argp_option options[] =
 
 struct job
 {
-  int pattern;
+  gen::aut_pattern_id pattern;
   struct range range;
 };
 
@@ -94,7 +80,7 @@ static void
 enqueue_job(int pattern, const char* range_str)
 {
   job j;
-  j.pattern = pattern;
+  j.pattern = static_cast<gen::aut_pattern_id>(pattern);
   j.range = parse_range(range_str);
   jobs.push_back(j);
 }
@@ -102,35 +88,23 @@ enqueue_job(int pattern, const char* range_str)
 static int
 parse_opt(int key, char* arg, struct argp_state*)
 {
-  // This switch is alphabetically-ordered.
-  switch (key)
+  if (key >= gen::AUT_BEGIN && key < gen::AUT_END)
     {
-    case OPT_KS_COBUCHI:
       enqueue_job(key, arg);
-      break;
-    default:
-      return ARGP_ERR_UNKNOWN;
+      return 0;
     }
-  return 0;
+  return ARGP_ERR_UNKNOWN;
 }
 
 static void
-output_pattern(int pattern, int n)
+output_pattern(gen::aut_pattern_id pattern, int n)
 {
-  twa_graph_ptr aut = nullptr;
-  switch (pattern)
-    {
-      // Keep this alphabetically-ordered!
-    case OPT_KS_COBUCHI:
-      aut = spot::gen::ks_cobuchi(n);
-      break;
-    default:
-      error(100, 0, "internal error: pattern not implemented");
-    }
-
   process_timer timer;
+  timer.start();
+  twa_graph_ptr aut = spot::gen::aut_pattern(pattern, n);
+  timer.stop();
   automaton_printer printer;
-  printer.print(aut, timer, nullptr, class_name[pattern - FIRST_CLASS], n);
+  printer.print(aut, timer, nullptr, aut_pattern_name(pattern), n);
 }
 
 static void

python/spot/gen.i

@@ -85,4 +85,32 @@ def ltl_patterns(*args):
         raise RuntimeError("invalid pattern specification")
     for n in range(min, max + 1):
       yield ltl_pattern(pat, n)
+
+def aut_patterns(*args):
+  """
+  Generate automata patterns.
+
+  The arguments should be have one of these three forms:
+    - (id, n)
+    - (id, min, max)
+    - id
+  In the first case, the pattern id=n is generated.  In the second
+  case, all pattern id=n for min<=n<=max are generated.  The
+  third case is a shorthand for (id, 1, 10).
+  """
+  for spec in args:
+    if type(spec) is int:
+      pat = spec
+      min = 1
+      max = 10
+    else:
+      ls = len(spec)
+      if ls == 2:
+        pat, min, max = spec[0], spec[1], spec[1]
+      elif ls == 3:
+        pat, min, max = spec
+      else:
+        raise RuntimeError("invalid pattern specification")
+    for n in range(min, max + 1):
+      yield aut_pattern(pat, n)
 %}

spot/gen/automata.cc

@@ -17,75 +17,114 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#include <spot/twa/twagraph.hh>
 #include <spot/gen/automata.hh>
-#include <spot/twa/formula2bdd.hh>
 #include <spot/tl/parse.hh>
 
 namespace spot
 {
   namespace gen
   {
-
-    twa_graph_ptr
-    ks_cobuchi(unsigned n)
+    namespace
     {
-      if (n == 0)
-        throw std::runtime_error("ks_cobuchi() expects a positive argument");
-      // the alphabet has four letters:
-      // i, s (for sigma), p (for pi), h (for hash)
-      // we encode this four letters alphabet thanks to two AP a and b
-      // the exact encoding is not important
-      // each letter is a permutation of the set {1..2n}
-      // s = (1 2 .. 2n) the rotation
-      // p = (1 2) the swap of the first two elements
-      // i is the identity
-      // d is the identity on {2..2n} but is undefined on 1
+      static twa_graph_ptr
+      ks_cobuchi(unsigned n)
+      {
+        if (n == 0)
+          throw std::runtime_error("ks_cobuchi expects a positive argument");
+        // the alphabet has four letters:
+        // i, s (for sigma), p (for pi), h (for hash)
+        // we encode this four letters alphabet thanks to two AP a and b
+        // the exact encoding is not important
+        // each letter is a permutation of the set {1..2n}
+        // s = (1 2 .. 2n) the rotation
+        // p = (1 2) the swap of the first two elements
+        // i is the identity
+        // d is the identity on {2..2n} but is undefined on 1
+
+        // the automaton has 2n+1 states, numbered from 0 to 2n
+        // 0 is the initial state and the only non-deterministic state
+
+        auto dict = make_bdd_dict();
+        auto aut = make_twa_graph(dict);
+
+        // register aps
+        bdd a = bdd_ithvar(aut->register_ap("a"));
+        bdd b = bdd_ithvar(aut->register_ap("b"));
 
-      // the automaton has 2n+1 states, numbered from 0 to 2n
-      // 0 is the initial state and the only non-deterministic state
+        // name the four letters
+        bdd i = a & b;
+        bdd s = a & (!b);
+        bdd p = (!a) & b;
+        bdd h = (!a) & (!b);
 
-      auto dict = make_bdd_dict();
-      auto aut = make_twa_graph(dict);
+        // actually build the automaton
+        aut->new_states(2*n+1);
+        aut->set_init_state(0);
+        aut->set_acceptance(1, acc_cond::acc_code::cobuchi());
 
-      // register aps
-      aut->register_ap("a");
-      aut->register_ap("b");
+        // from 0, we can non-deterministically jump to any state
+        // (except 0) with any letter.
+        for (unsigned q = 1; q <= 2*n; ++q)
+          aut->new_edge(0, q, bddtrue, {0});
+        // i is the identity
+        for (unsigned q = 1; q <= 2*n; ++q)
+          aut->new_edge(q, q, i);
+        // p swaps 1 and 2, and leaves all other states invariant
+        aut->new_edge(1, 2, p);
+        aut->new_edge(2, 1, p);
+        for (unsigned q = 3; q <= 2*n; ++q)
+          aut->new_edge(q, q, p);
+        // s does to next state (mod 2*n, 0 excluded)
+        aut->new_edge(2*n, 1, s);
+        for (unsigned q = 1; q < 2*n; ++q)
+          aut->new_edge(q, q+1, s);
+        // h is the same as i, except on 1 where it goes back to the
+        // initial state
+        aut->new_edge(1, 0, h);
+        for (unsigned q = 2; q <= 2*n; ++q)
+          aut->new_edge(q, q, h);
 
-      // retrieve the four letters, and name them
-      bdd i = formula_to_bdd(parse_formula("a&&b"), dict, aut);
-      bdd s = formula_to_bdd(parse_formula("a&&!b"), dict, aut);
-      bdd p = formula_to_bdd(parse_formula("!a&&b"), dict, aut);
-      bdd h = formula_to_bdd(parse_formula("!a&&!b"), dict, aut);
+        aut->merge_edges();
+        aut->prop_state_acc(true);
+        return aut;
+      }
+    }
 
-      // actually build the automaton
-      aut->new_states(2*n+1);
-      aut->set_init_state(0);
-      aut->set_acceptance(1, acc_cond::acc_code::cobuchi());
+    twa_graph_ptr aut_pattern(aut_pattern_id pattern, int n)
+    {
+      if (n < 0)
+        {
+          std::ostringstream err;
+          err << "pattern argument for " << aut_pattern_name(pattern)
+              << " should be positive";
+          throw std::runtime_error(err.str());
+        }
 
-      // from 0, we can non-deterministically jump to any state (except 0) with
-      // any letter.
-      for (unsigned q = 1; q <= 2*n; ++q)
-        aut->new_edge(0, q, bddtrue, {0});
-      // i is the identity
-      for (unsigned q = 1; q <= 2*n; ++q)
-        aut->new_edge(q, q, i);
-      // p swaps 1 and 2, and leaves all other states invariant
-      aut->new_edge(1, 2, p);
-      aut->new_edge(2, 1, p);
-      for (unsigned q = 3; q <= 2*n; ++q)
-        aut->new_edge(q, q, p);
-      // s does to next state (mod 2*n, 0 excluded)
-      aut->new_edge(2*n, 1, s);
-      for (unsigned q = 1; q < 2*n; ++q)
-        aut->new_edge(q, q+1, s);
-      // h is the same as i, except on 1 where it goes back to the initial state
-      aut->new_edge(1, 0, h);
-      for (unsigned q = 2; q <= 2*n; ++q)
-        aut->new_edge(q, q, h);
+      switch (pattern)
+        {
+          // Keep this alphabetically-ordered!
+        case AUT_KS_COBUCHI:
+          return ks_cobuchi(n);
+        case AUT_END:
+          break;
+        }
+      throw std::runtime_error("unsupported pattern");
+    }
 
-      aut->merge_edges();
-      aut->prop_state_acc(true);
-      return aut;
+    const char* aut_pattern_name(aut_pattern_id pattern)
+    {
+      static const char* const class_name[] =
+        {
+          "ks-cobuchi",
+        };
+      // Make sure we do not forget to update the above table every
+      // time a new pattern is added.
+      static_assert(sizeof(class_name)/sizeof(*class_name)
+                    == AUT_END - AUT_BEGIN, "size mismatch");
+      if (pattern < AUT_BEGIN || pattern >= AUT_END)
+        throw std::runtime_error("unsupported pattern");
+      return class_name[pattern - AUT_BEGIN];
     }
   }
 }

spot/gen/automata.hh

@@ -19,31 +19,48 @@
 
 #pragma once
 
-#include <spot/twa/twagraph.hh>
+#include <spot/misc/common.hh>
+#include <spot/twa/fwd.hh>
 
 namespace spot
 {
   namespace gen
   {
-    /// \brief A family of co-Büchi automata.
-    ///
-    /// ks_cobuchi(n) is a co-Büchi automaton of size 2n+1 that is
-    /// good-for-games and that has no equivalent deterministic co-Büchi
-    /// automaton with less than 2^n / (2n+1) states.
-    /// For details and other classes, see:
+    enum aut_pattern_id {
+      AUT_BEGIN = 256,
+      /// \brief A family of co-Büchi automata.
+      ///
+      /// ks_cobuchi(n) is a co-Büchi automaton of size 2n+1 that is
+      /// good-for-games and that has no equivalent deterministic co-Büchi
+      /// automaton with less than 2^n / (2n+1) states.
+      /// For details and other classes, see:
+      ///
+      /// @InProceedings{kuperberg2015determinisation,
+      ///     author={Kuperberg, Denis and Skrzypczak, Micha{\l}},
+      ///     title={On Determinisation of Good-for-Games Automata},
+      ///     booktitle={International Colloquium on Automata, Languages, and
+      ///                Programming},
+      ///     pages={299--310},
+      ///     year={2015},
+      ///     organization={Springer}
+      /// }
+      ///
+      /// Only defined for n>0
+      AUT_KS_COBUCHI = AUT_BEGIN,
+      AUT_END
+    };
+
+    /// \brief generate an automaton from a known pattern
     ///
-    /// @InProceedings{kuperberg2015determinisation,
-    ///     author={Kuperberg, Denis and Skrzypczak, Micha{\l}},
-    ///     title={On Determinisation of Good-for-Games Automata},
-    ///     booktitle={International Colloquium on Automata, Languages, and
-    ///                Programming},
-    ///     pages={299--310},
-    ///     year={2015},
-    ///     organization={Springer}
-    /// }
+    /// The pattern is specified using one value from the aut_pattern_id
+    /// enum.  See the man page of the `genaut` binary for a
+    /// description of those patterns, and bibliographic references.
+    SPOT_API twa_graph_ptr aut_pattern(aut_pattern_id pattern, int n);
+
+    /// \brief convert an aut_pattern_it value into a name
     ///
-    /// \pre n>0
-    SPOT_API twa_graph_ptr
-    ks_cobuchi(unsigned n);
+    /// The returned name is suitable to be used as an option
+    /// key for the genaut binary.
+    SPOT_API const char* aut_pattern_name(aut_pattern_id pattern);
   }
 }

tests/python/gen.ipynb

@@ -45,7 +45,7 @@
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 13
+     "prompt_number": 1
     },
     {
      "cell_type": "markdown",
@@ -71,13 +71,13 @@
        ],
        "metadata": {},
        "output_type": "pyout",
-       "prompt_number": 14,
+       "prompt_number": 2,
        "text": [
         "GFp1 & GFp2 & GFp3"
        ]
       }
      ],
-     "prompt_number": 14
+     "prompt_number": 2
     },
     {
      "cell_type": "code",
@@ -94,13 +94,13 @@
        ],
        "metadata": {},
        "output_type": "pyout",
-       "prompt_number": 15,
+       "prompt_number": 3,
        "text": [
         "F(p & Xp & XXp & XXXp) & F(q & Xq & XXq & XXXq)"
        ]
       }
      ],
-     "prompt_number": 15
+     "prompt_number": 3
     },
     {
      "cell_type": "markdown",
@@ -289,7 +289,7 @@
        ]
       }
      ],
-     "prompt_number": 20
+     "prompt_number": 4
     },
     {
      "cell_type": "markdown",
@@ -304,7 +304,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "sg.ks_cobuchi(3).show('.a')"
+      "sg.aut_pattern(sg.AUT_KS_COBUCHI, 3).show('.a')"
      ],
      "language": "python",
      "metadata": {},
@@ -312,7 +312,7 @@
       {
        "metadata": {},
        "output_type": "pyout",
-       "prompt_number": 23,
+       "prompt_number": 5,
        "svg": [
         "<svg height=\"295pt\" viewBox=\"0.00 0.00 734.00 295.41\" width=\"734pt\" xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">\n",
         "<g class=\"graph\" id=\"graph0\" transform=\"scale(0.906173 0.906173) rotate(0) translate(4 322)\">\n",
@@ -491,7 +491,43 @@
        ]
       }
      ],
-     "prompt_number": 23
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Multiple automata can be generated using the `aut_patterns()` function, which works similarly to `ltl_patterns()`."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "for aut in sg.aut_patterns(sg.AUT_KS_COBUCHI):\n",
+      "    print(aut.num_states())"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "3\n",
+        "5\n",
+        "7\n",
+        "9\n",
+        "11\n",
+        "13\n",
+        "15\n",
+        "17\n",
+        "19\n",
+        "21\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
     },
     {
      "cell_type": "code",

tests/python/gen.py

@@ -24,7 +24,7 @@
 import spot.gen as gen
 from sys import exit
 
-k2 = gen.ks_cobuchi(2)
+k2 = gen.aut_pattern(gen.AUT_KS_COBUCHI, 2)
 assert k2.prop_state_acc()
 assert k2.num_states() == 5
 # to_str is defined in the spot package, so this makes sure
@@ -32,7 +32,7 @@ assert k2.num_states() == 5
 assert 'to_str' in dir(k2)
 
 try:
-    gen.ks_cobuchi(0)
+    gen.aut_pattern(gen.AUT_KS_COBUCHI, 0)
 except RuntimeError as e:
     assert 'positive argument' in str(e)
 else: