Improve flow analysis a bit.

jedi/evaluate/__init__.py

@@ -183,6 +183,9 @@ class Evaluator(object):
         debug.dbg('eval_element %s', element)
         if isinstance(element, (pr.Name, pr.Literal)) or pr.is_node(element, 'atom'):
             return self._eval_atom(element)
+        elif isinstance(element, pr.Keyword):
+            # For False/True/None
+            return [compiled.builtin.get_by_name(element.value)]
         elif element.type == python_symbols.power:
             types = self._eval_atom(element.children[0])
             for trailer in element.children[1:]:

jedi/evaluate/analysis.py

@@ -180,7 +180,7 @@ def _check_for_exception_catch(evaluator, jedi_obj, exception, payload=None):
     while obj is not None and not obj.isinstance(pr.Function, pr.Class):
         if obj.isinstance(pr.Flow):
             # try/except catch check
-            if obj.command == 'try' and check_try_for_except(obj):
+            if obj.isinstance(pr.TryStmt) and check_try_for_except(obj):
                 return True
             # hasattr check
             if exception == AttributeError and obj.command in ('if', 'while'):

jedi/evaluate/finder.py

@@ -82,7 +82,7 @@ class NameFinder(object):
         for name in reversed(sorted(names, key=lambda name: name.start_pos)):
             check = flow_analysis.break_check(self._evaluator,
                                               scope,
-                                              er.wrap(self._evaluator, scope),
+                                              name.get_definition(),
                                               self.scope)
             if check is not flow_analysis.UNREACHABLE:
                 last_names.append(name)
@@ -154,7 +154,7 @@ class NameFinder(object):
                     else:
                         check = flow_analysis.break_check(self._evaluator,
                                                           name_list_scope,
-                                                          er.wrap(self._evaluator, scope),
+                                                          stmt,
                                                           self.scope)
                         if check is not flow_analysis.UNREACHABLE:
                             names.append(name)

jedi/evaluate/flow_analysis.py

@@ -1,4 +1,4 @@
-from jedi.parser.representation import Flow
+from jedi.parser import representation as pr
 
 
 class Status(object):
@@ -32,10 +32,10 @@ UNREACHABLE = Status(False, 'unreachable')
 UNSURE = Status(None, 'unsure')
 
 
-def break_check(evaluator, base_scope, element_scope, origin_scope=None):
+def break_check(evaluator, base_scope, stmt, origin_scope=None):
     from jedi.evaluate.representation import wrap
     base_scope = wrap(evaluator, base_scope)
-    element_scope = wrap(evaluator, element_scope)
+    element_scope = wrap(evaluator, stmt.parent)
 
     # Direct parents get resolved, we filter scopes that are separate branches.
     # This makes sense for autocompletion and static analysis. For actual
@@ -48,17 +48,18 @@ def break_check(evaluator, base_scope, element_scope, origin_scope=None):
         s = s.parent
 
     reachable = REACHABLE
-    if isinstance(element_scope, Flow):
-        if element_scope.command == 'else':
-            check_scope = element_scope
-            while check_scope.previous is not None:
-                check_scope = check_scope.previous
-                reachable = _check_flow(evaluator, check_scope)
+    if isinstance(element_scope, pr.IfStmt):
+        if element_scope.node_after_else(stmt):
+            for check_node in element_scope.check_nodes():
+                reachable = _check_if(evaluator, check_node)
                 if reachable in (REACHABLE, UNSURE):
                     break
             reachable = reachable.invert()
         else:
-            reachable = _check_flow(evaluator, element_scope)
+            node = element_scope.node_in_which_check_node(stmt)
+            reachable = _check_if(evaluator, node)
+    elif isinstance(element_scope, (pr.TryStmt, pr.WhileStmt)):
+        return UNSURE
 
     # Only reachable branches need to be examined further.
     if reachable in (UNREACHABLE, UNSURE):
@@ -69,15 +70,10 @@ def break_check(evaluator, base_scope, element_scope, origin_scope=None):
     return reachable
 
 
-def _check_flow(evaluator, flow):
-    if flow.command in ('elif', 'if') and flow.inputs:
-        types = evaluator.eval_statement(flow.inputs[0])
-        values = set(x.py__bool__() for x in types)
-        if len(values) == 1:
-            return Status.lookup_table[values.pop()]
-        else:
-            return UNSURE
-    elif flow.command in ('try', 'except', 'finally', 'while'):
+def _check_if(evaluator, node):
+    types = evaluator.eval_element(node)
+    values = set(x.py__bool__() for x in types)
+    if len(values) == 1:
+        return Status.lookup_table[values.pop()]
+    else:
         return UNSURE
-    else:  # for loop
-        return REACHABLE

jedi/evaluate/representation.py

@@ -581,7 +581,7 @@ class FunctionExecution(Executed):
 
         types = list(docstrings.find_return_types(self._evaluator, func))
         for r in self.returns:
-            check = flow_analysis.break_check(self._evaluator, self, r.parent)
+            check = flow_analysis.break_check(self._evaluator, self, r)
             if check is flow_analysis.UNREACHABLE:
                 debug.dbg('Return unreachable: %s', r)
             else:

jedi/parser/representation.py

@@ -845,7 +845,34 @@ class Flow(Simple):
 
 
 class IfStmt(Flow):
-    pass
+    def check_nodes(self):
+        """
+        Returns all the `test` nodes that are defined as x, here:
+
+            if x:
+                pass
+            elif x:
+                pass
+        """
+        for i, c in enumerate(self.children):
+            if c in ('elif', 'if'):
+                yield self.children[i + 1]
+
+    def node_in_which_check_node(self, node):
+        for check_node in reversed(list(self.check_nodes())):
+            if check_node.start_pos < node.start_pos:
+                return check_node
+
+    def node_after_else(self, node):
+        """
+        Checks if a node is defined after `else`.
+        """
+        for c in self.children:
+            if c == 'else':
+                if node.start_pos > c.start_pos:
+                    return True
+        else:
+            return False
 
 
 class WhileStmt(Flow):