Fixed EvalEvaluator when there is nothing to evaluate

docs/blog.rst

@@ -750,3 +750,21 @@ The [Non]TerminalNode
     represents what was found. So similarly to the ConceptNode, you will find the start, end and token attributes
 
 That's all for today !
+
+2019-27-12
+**********
+
+How to manage variables resolutions
+"""""""""""""""""""""""""""""""""""
+
+I have to admit that I am a little bit stuck with how to manage variable resolution with PythonEvaluator.
+What is expected by the expression depends on the expression itself.
+
+Let's see an example
+
+::
+
+    def concept one as 1
+    def concept two as 2
+
+    eval one + two

evaluators/EvalEvaluator.py

@@ -12,8 +12,6 @@ class EvalEvaluator(AllReturnValuesEvaluator):
 
     def __init__(self):
         super().__init__(self.NAME, [BuiltinConcepts.AFTER_EVALUATION], 80)
-        self.successful_return_value = None
-        self.to_eval = []
         self.eval_requested = None
 
     def matches(self, context, return_values):
@@ -21,18 +19,25 @@ class EvalEvaluator(AllReturnValuesEvaluator):
         for ret in return_values:
             if ret.status and sheerka.isinstance(ret.body, BuiltinConcepts.CONCEPT_EVAL_REQUESTED):
                 self.eval_requested = ret
-            elif ret.status and isinstance(ret.body, Concept) and ret.body.body:
-                self.to_eval.append(ret)
+                return True
 
-        return self.eval_requested is not None and len(self.to_eval) > 0
+        return False
 
-    def eval(self, context, return_value):
+    def eval(self, context, return_values):
         sheerka = context.sheerka
         result = []
-        context.log(self.verbose_log, f"{len(self.to_eval)} return value(s) to eval", who=self)
 
-        for ret_val in self.to_eval:
-            context.log(self.verbose_log, f"{ret_val}", who=self)
-            result.append(sheerka.ret(self.name, True, ret_val.body.body, parents=[ret_val, self.eval_requested]))
+        for ret_val in return_values:
+            if ret_val.status and isinstance(ret_val.body, Concept) and ret_val.body.body:
+                context.log(self.verbose_log, f"Evaluating {ret_val}", who=self)
+                result.append(sheerka.ret(self.name, True, ret_val.body.body, parents=[ret_val, self.eval_requested]))
 
-        return result
+        if len(result) > 0:
+            return result
+        else:
+            # suppress the successful BuiltinConcepts.CONCEPT_EVAL_REQUESTED
+            return sheerka.ret(
+                self.name,
+                False,
+                sheerka.new(BuiltinConcepts.CONCEPT_EVAL_REQUESTED),
+                parents=[self.eval_requested])

tests/test_EvalEvaluator.py

@@ -49,11 +49,32 @@ def test_i_can_match_and_eval():
 
 @pytest.mark.parametrize("return_values, expected", [
     ([r(Concept("foo", body="bar")), eval_requested], True),
-    ([r(Concept("status is false", body="bar"), False), eval_requested], False),
-    ([r("string_value"), eval_requested], False),
-    ([r(Concept("no body")), eval_requested], False),
+    ([r(Concept("status is false", body="bar"), False), eval_requested], True),
+    ([r("string_value"), eval_requested], True),
+    ([r(Concept("no body")), eval_requested], True),
     ([r(Concept("eval requested missing", body="bar"))], False),
 ])
 def test_i_cannot_match_if_eval_request_is_not_present(return_values, expected):
     context = get_context()
     assert EvalEvaluator().matches(context, return_values) == expected
+
+
+def test_concept_eval_requested_is_reduced_when_nothing_to_reduce():
+    context = get_context()
+
+    return_values = [
+        ReturnValueConcept("some_name", True, "not to eval"),
+        ReturnValueConcept("some_name", True, Concept(name="not to eval")),
+        ReturnValueConcept("some_name", False, Concept(name="1", body="not to eval")),
+        eval_requested
+    ]
+
+    evaluator = EvalEvaluator()
+    assert evaluator.matches(context, return_values)
+
+    evaluated = evaluator.eval(context, return_values)
+    assert evaluated == ReturnValueConcept(
+        "evaluators.Eval",
+        False,
+        context.sheerka.new(BuiltinConcepts.CONCEPT_EVAL_REQUESTED))
+    assert evaluated.parents == [eval_requested]

tests/test_sheerka_call_evaluators.py

@@ -162,6 +162,28 @@ class EvaluatorAllReduceFooBar(EvaluatorAllWithPriority):
         return ret
 
 
+class EvaluatorAllSuppressFooEntry(EvaluatorAllWithPriority):
+
+    def __init__(self):
+        super().__init__("suppress", 100)
+
+    def matches(self, context, return_values):
+        super().matches(context, return_values)
+        return True
+
+    def eval(self, context, return_values):
+        super().eval(context, return_values)
+        foo = None
+        for ret in return_values:
+            if ret.body.name == "foo":
+                foo = ret
+
+        if foo:
+            return context.sheerka.ret(self.name, False, Concept("does not matter"), parents=[foo])
+        else:
+            return None
+
+
 def test_that_return_values_is_unchanged_when_no_evaluator():
     sheerka = get_sheerka()
     sheerka.evaluators = []

tests/test_sheerka_non_reg.py

@@ -400,3 +400,19 @@ def test_i_can_say_that_a_concept_isa_another_concept():
     res = sheerka.evaluate_user_input("foo isa bar")
     assert res[0].status
     assert sheerka.isinstance(res[0].body, BuiltinConcepts.SUCCESS)
+
+
+def test_eval_does_not_break_valid_result():
+    sheerka = get_sheerka()
+    sheerka.evaluate_user_input("def concept one as 1")
+    sheerka.evaluate_user_input("def concept two as 2")
+
+    res = sheerka.evaluate_user_input("one + two")
+    assert len(res) == 1
+    assert res[0].status
+    assert res[0].body == 3
+
+    res = sheerka.evaluate_user_input("eval one + two")
+    assert len(res) == 1
+    assert res[0].status
+    assert res[0].body == 3