python: better binding for is_parity()

* wrap/python/spot_impl.i: Here.
* wrap/python/tests/acc_cond.ipynb: Document it.
* spot/twa/acc.cc (is_parity): Always initialize max.

spot/twa/acc.cc

@@ -685,7 +685,10 @@ namespace spot
     odd = !u_inf.has(0);
     for (auto s: u_inf.sets())
       if ((s & 1) != odd)
+	{
+	  max = false;	     // just so the value is not uninitialized
 	  return false;
+	}
 
     auto max_code = acc_code::parity(true, odd, sets);
     if (max_code == code_)

wrap/python/spot_impl.i

@@ -221,8 +221,9 @@ namespace swig
 
 // For spot::emptiness_check_instantiator::construct and any other
 // function that return errors via a "char **err" argument.
-%typemap(in, numinputs=0) char** OUTPUT (char* temp)
+%typemap(in, numinputs=0) char** OUTPUT (char* temp) {
-  "$1 = &temp;";
+  $1 = &temp;
+}
 %typemap(argout) char** OUTPUT {
   PyObject *obj = SWIG_FromCharPtr(*$1);
   if (!$result) {
@@ -246,6 +247,25 @@ namespace swig
  };
 %apply char** OUTPUT { char** err };
 
+// This is mainly for acc_cond::is_parity()
+%typemap(in, numinputs=0) bool& (bool temp) {
+  $1 = &temp;
+ };
+%typemap(argout) bool& {
+  PyObject *obj = SWIG_From_bool(*$1);
+  if (!$result) {
+    $result = obj;
+  } else {
+    if (!PyList_Check($result)) {
+      PyObject *o2 = $result;
+      $result = PyList_New(1);
+      PyList_SetItem($result, 0, o2);
+    }
+    PyList_Append($result, obj);
+    Py_DECREF(obj);
+  }
+ };
+
 // Allow None to be passed for formula.  Some functions like
 // postprocessor::run() take an optional formula that defaults to
 // nullptr.  So it make sense to have function that take formulas that

wrap/python/tests/acc_cond.ipynb

@@ -17,7 +17,8 @@
    "pygments_lexer": "ipython3",
    "version": "3.4.3+"
   },
-  "name": ""
+  "name": "",
+  "signature": "sha256:bcc334639d07643d72b406a76d5aa91c5accb4e05a55128c0f909ad73b4b2491"
  },
  "nbformat": 3,
  "nbformat_minor": 0,
@@ -1085,7 +1086,7 @@
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "The `acc_cond` class has several methods for detecting acceptance conditions that match the named acceptance conditions of the HOA format.  Note that in the HOA format, `Inf(0)&Inf(1)&Inf(2)&Inf(3)` is only called generalized B\u00fcchi if exactly for acceptance sets are used.  So the following behavior should not be a surprise:"
+      "The `acc_cond` class has several methods for detecting acceptance conditions that match the named acceptance conditions of the HOA format.  Note that in the HOA format, `Inf(0)&Inf(1)&Inf(2)&Inf(3)` is only called generalized B\u00fcchi if exactly 4 acceptance sets are used.  So the following behavior should not be surprising:"
      ]
     },
     {
@@ -1148,14 +1149,105 @@
      ],
      "prompt_number": 42
     },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "The check for parity acceptance returns three Boolean in a list of the form `[matched, max?, odd?]`.  If `matched` is `False`, the other values should be ignored."
+     ]
+    },
     {
      "cell_type": "code",
-     "collapsed": true,
+     "collapsed": false,
+     "input": [
+      "code = spot.parse_acc_code('parity min odd 4')\n",
+      "acc = spot.acc_cond(code.used_sets().max_set(), code)\n",
+      "print(acc)\n",
+      "print(acc.is_parity())\n",
+      "acc.set_generalized_buchi()\n",
+      "print(acc)\n",
+      "print(acc.is_parity())"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "(4, Fin(0) & (Inf(1) | (Fin(2) & Inf(3))))\n",
+        "[True, False, True]\n",
+        "(4, Inf(0)&Inf(1)&Inf(2)&Inf(3))\n",
+        "[False, False, False]\n"
+       ]
+      }
+     ],
+     "prompt_number": 43
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "`acc_cond` contains a few function for manipulating `mark_t` instances, these are typically functions that require known the total number of accepting sets declared.\n",
+      "\n",
+      "For instance complementing a `mark_t`:"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "m = spot.mark_t([1, 3])\n",
+      "print(acc.comp(m))"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "{0,2}\n"
+       ]
+      }
+     ],
+     "prompt_number": 44
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "`all_sets()` returns a `mark_t` listing all the declared sets: "
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "acc.all_sets()"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "metadata": {},
+       "output_type": "pyout",
+       "prompt_number": 45,
+       "text": [
+        "{0,1,2,3}"
+       ]
+      }
+     ],
+     "prompt_number": 45
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
      "input": [],
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": null
+     "prompt_number": 45
     }
    ],
    "metadata": {}