Create classes_util API, change discover to return a list instead of a dict.

tools/telemetry/telemetry/core/discover.py

Index: tools/telemetry/telemetry/core/discover.py
diff --git a/tools/telemetry/telemetry/core/discover.py b/tools/telemetry/telemetry/core/discover.py
index 546aa6372327899f6fa4e8535dba88010d4eeaef..53393200acea97da5606898005e0efd6d93d5f35 100644
--- a/tools/telemetry/telemetry/core/discover.py
+++ b/tools/telemetry/telemetry/core/discover.py
@@ -7,12 +7,9 @@ import inspect
 import os
 import re
 
-from telemetry import decorators
-from telemetry.internal.util import camel_case
 from telemetry.internal.util import classes as classes_module
 
 
-@decorators.Cache
 def DiscoverModules(start_dir, top_level_dir, pattern='*'):
   """Discover all modules in |start_dir| which match |pattern|.
 
@@ -49,12 +46,8 @@ def DiscoverModules(start_dir, top_level_dir, pattern='*'):
       modules.append(module)
   return modules
 
-
-# TODO(dtu): Normalize all discoverable classes to have corresponding module
-# and class names, then always index by class name.
-@decorators.Cache
 def DiscoverClasses(start_dir, top_level_dir, base_class, pattern='*',
-                    index_by_class_name=True, directly_constructable=False):
+                    one_class_per_module=False, directly_constructable=False):
   """Discover all classes in |start_dir| which subclass |base_class|.
 
   Base classes that contain subclasses are ignored by default.
@@ -64,24 +57,21 @@ def DiscoverClasses(start_dir, top_level_dir, base_class, pattern='*',
     top_level_dir: The top level of the package, for importing.
     base_class: The base class to search for.
     pattern: Unix shell-style pattern for filtering the filenames to import.
-    index_by_class_name: If True, use class name converted to
-        lowercase_with_underscores instead of module name in return dict keys.
+    one_class_per_module: If True, will only include the first class found in
+                each module.
     directly_constructable: If True, will only return classes that can be
         constructed without arguments
 
-  Returns:
-    dict of {module_name: class} or {underscored_class_name: class}
+  Returns: A list of classes.
   """
   modules = DiscoverModules(start_dir, top_level_dir, pattern)
-  classes = {}
+  classes = []
   for module in modules:
-    new_classes = DiscoverClassesInModule(
-        module, base_class, index_by_class_name, directly_constructable)
-    classes = dict(classes.items() + new_classes.items())
+    classes.extend(DiscoverClassesInModule(
+        module, base_class, one_class_per_module, directly_constructable))
   return classes
 
-@decorators.Cache
-def DiscoverClassesInModule(module, base_class, index_by_class_name=False,
+def DiscoverClassesInModule(module, base_class, one_class_per_module=False,
                             directly_constructable=False):
   """Discover all classes in |module| which subclass |base_class|.
 
@@ -90,13 +80,12 @@ def DiscoverClassesInModule(module, base_class, index_by_class_name=False,
   Args:
     module: The module to search.
     base_class: The base class to search for.
-    index_by_class_name: If True, use class name converted to
-        lowercase_with_underscores instead of module name in return dict keys.
+    one_class_per_module: If True, will only include the first class found in
+                each module.
 
-  Returns:
-    dict of {module_name: class} or {underscored_class_name: class}
+  Returns: A list of classes.
   """
-  classes = {}
+  classes = []
   for _, obj in inspect.getmembers(module):
     # Ensure object is a class.
     if not inspect.isclass(obj):
@@ -115,14 +104,11 @@ def DiscoverClassesInModule(module, base_class, index_by_class_name=False,
     if obj.__module__ != module.__name__:
       continue
 
-    if index_by_class_name:
-      key_name = camel_case.ToUnderscore(obj.__name__)
-    else:
-      key_name = module.__name__.split('.')[-1]
     if (not directly_constructable or
         classes_module.IsDirectlyConstructable(obj)):
-      classes[key_name] = obj
-
+      classes.append(obj)
+      if one_class_per_module:
+        return classes
   return classes