Provide ability to run a single data source and check its results [WIP]

Created by: stefanoborini

This PR allows to run a single data source with numbers passed via stdin and retrieve the result via stdout.

force_bdss/bdss_application.py

@@ -6,8 +6,9 @@ from stevedore.exception import NoMatches
 
 from envisage.api import Application
 from envisage.core_plugin import CorePlugin
-from traits.api import Unicode, Bool
+from traits.api import Unicode, Bool, Either
 
+from force_bdss.core_run_datasource_driver import CoreRunDataSourceDriver
 from .factory_registry_plugin import FactoryRegistryPlugin
 from .core_evaluation_driver import CoreEvaluationDriver
 from .core_mco_driver import CoreMCODriver
@@ -28,13 +29,23 @@ class BDSSApplication(Application):
     #: coordination of the MCO itself. See design notes for more details.
     evaluate = Bool()
 
-    def __init__(self, evaluate, workflow_filepath):
+    #: This entry, if not None, drives the evaluator to run a single
+    #: data source in the workflow. It accepts input parameters on standard
+    #: input and returns the output to standard output.
+    run_datasource = Either(Unicode(), None)
+
+    def __init__(self, evaluate, run_datasource, workflow_filepath):
         self.evaluate = evaluate
+        self.run_datasource = run_datasource
         self.workflow_filepath = workflow_filepath
 
         plugins = [CorePlugin(), FactoryRegistryPlugin()]
 
-        if self.evaluate:
+        if self.run_datasource:
+            plugins.append(CoreRunDataSourceDriver(
+                run_datasource=run_datasource
+            ))
+        elif self.evaluate:
             plugins.append(CoreEvaluationDriver())
         else:
             plugins.append(CoreMCODriver())