Added a sorted flag to FactBase.asp_str() for sorted output

clorm/orm/factbase.py

@@ -41,6 +41,8 @@
 # PEP 257 (modified for Python 3): https://www.python.org/dev/peps/pep-0257/
 # ------------------------------------------------------------------------------
 
+_builtin_sorted=sorted
+
 def _format_asp_facts(iterator,output,width):
     tmp1=""
     for f in iterator:
@@ -360,22 +362,51 @@ def facts(self):
         tmp = [ fm.factset for fm in self._factmaps.values() if fm]
         return list(itertools.chain(*tmp))
 
-    def asp_str(self,width=0,commented=False):
-        """Return a string representation of the fact base that is suitable for adding
-        to an ASP program
+    def asp_str(self,*,width=0,commented=False,sorted=False):
+        """Return a ASP string representation of the fact base.
+
+        This ASP string representation is syntactically correct ASP code so is
+        suitable for adding as the input to to an ASP program (or writing to a
+        file for later use in an ASP program).
+
+        By default the order of the facts in the string is arbitrary. Because
+        `FactBase` is built on a `OrderedDict` (which preserves insertion
+        order) the order of the facts will be deterministic between runs of the
+        same program. However two FactBases containing the same facts but
+        constructed in different ways will not produce the same output
+        string. In order to guarantee the same output the `sorted` flag can be
+        specified.
+
+        Args (keyword arguments only):
+
+            width=0: tries to fill to a given width by putting more than one
+                     fact on a line if necessary.
+
+            commented=False: produces commented ASP code by adding a predicate
+                             signature and turning the Predicate sub-class
+                             docstring into a ASP comments.
+
+            sorted=False: sort the output facts
 
         """
         self._check_init()  # Check for delayed init
         out = io.StringIO()
 
-        if not commented:
-            _format_asp_facts(self,out,width)
+        first=True
+        if sorted:
+            names = _builtin_sorted(self._factmaps.keys(),key=lambda pt:
+                                    (pt.meta.name, pt.meta.arity,pt.__name__))
+            fms = [self._factmaps[n] for n in names]
         else:
-            first=True
-            for fm in self._factmaps.values():
+            fms = self._factmaps.values()
+        for fm in fms:
+            if commented:
                 if first: first=False
                 else: print("",file=out)
                 _format_commented(fm,out)
+            if sorted:
+                _format_asp_facts(_builtin_sorted(fm.factset),out,width)
+            else:
                 _format_asp_facts(fm.factset,out,width)
 
         data = out.getvalue()

tests/test_orm_factbase.py

@@ -553,6 +553,52 @@ class Meta: name="a_very_long_predicate_name_that_cause_wrapping_well"
         cfactspre="% Predicate signature:\n%     {}(n,s)\n".format(C.meta.name)
         self.assertTrue(aspstr.startswith(cfactspre))
 
+    #--------------------------------------------------------------------------
+    # Test the asp output string with the sorted flag
+    # --------------------------------------------------------------------------
+    def test_factbase_aspstr_sorted(self):
+        class A(Predicate):
+            a = IntegerField
+            class Meta: name="bb"
+        class B(Predicate):
+            a = IntegerField
+            class Meta: name="aa"
+        class C(Predicate):
+            a = IntegerField
+            b = IntegerField
+            class Meta: name="aa"
+
+        def tostr(facts):
+            return ".\n".join([str(f) for f in facts])
+
+        def sig(ptype):
+            cstr = ("% -------------------\n"
+                    "% Predicate signature\n"
+                    "%     {}(a)\n"
+                    "% -------------------\n").format(ptype.__name__)
+            return cstr
+
+        afacts = [A(100),A(50),A(99)]
+        bfacts = [B(100),B(50),B(99)]
+        cfacts = [C(100,100),C(50,50),C(99,99)]
+        fb=FactBase()
+        fb.add(cfacts)
+        fb.add(bfacts)
+        fb.add(afacts)
+
+        expected1 = tostr(cfacts) + ".\n" + tostr(bfacts) + ".\n" + \
+            tostr(afacts) + ".\n"
+        self.assertEqual(fb.asp_str(), expected1)
+
+        expected2 = tostr(sorted(bfacts)) + ".\n" + tostr(sorted(cfacts)) + \
+            ".\n" + tostr(sorted(afacts)) + ".\n"
+        self.assertEqual(fb.asp_str(sorted=True), expected2)
+
+        expected3 = \
+            sig(A) + tostr(sorted(bfacts)) + ".\n" + \
+            sig(B) + tostr(sorted(bfacts)) + ".\n" + \
+            sig(C) + tostr(sorted(afacts)) + ".\n"
+        self.assertTrue(fb.asp_str(commented=True,sorted=True), expected3)
 
 #------------------------------------------------------------------------------
 # Test QueryAPI version 1 (called via FactBase.select() and FactBase.delete())