Fixed #41 : Implement concept 'and'

src/core/builtin_helpers.py

@@ -18,6 +18,22 @@ EVAL_STEPS = PARSE_STEPS + [BuiltinConcepts.BEFORE_EVALUATION, BuiltinConcepts.E
 PARSERS = ["EmptyString", "ShortTermMemory", "Sequence", "Bnf", "Sya", "Python"]
 
 
+def remove_python_nodes(context, return_values):
+    """
+    Try to reduce the number of return_values by removing return values with python node
+    :param context:
+    :param return_values:
+    :return:
+    """
+    res = []
+    for ret_val in return_values:
+        value = context.sheerka.objvalue(ret_val)
+        if not hasattr(value, "get_python_node"):
+            res.append(ret_val)
+
+    return res
+
+
 def is_same_success(context, return_values):
     """
     Returns True if all returns values are successful and have the same value
@@ -89,12 +105,25 @@ def expect_one(context, return_values):
 
     # too many winners, which one to choose ?
     if number_of_successful > 1:
+        # first, try to remove python node results.
+        # In case of conflict, the concept take precedence over the natural Python result
+        # as it is considered as an override (overload ?)
+        successful_results = remove_python_nodes(context, successful_results)
+
+        if len(successful_results) == 1:
+            return sheerka.ret(
+                context.who,
+                True,
+                successful_results[0].body,
+                parents=return_values)
+
         if is_same_success(context, successful_results):
             return sheerka.ret(
                 context.who,
                 True,
                 successful_results[0].value,
                 parents=return_values)
+
         else:
             if context.logger and context.logger.isEnabledFor(logging.DEBUG):
                 context.log(f"Too many successful results found by expect_one()", context.who)