[Refactor]: Inherits mmcv registry

mmcls/models/builder.py

@@ -1,38 +1,34 @@
-import torch.nn as nn
-from mmcv.utils import Registry, build_from_cfg
+from mmcv.cnn import MODELS as MMCV_MODELS
+from mmcv.utils import Registry
 
-BACKBONES = Registry('backbone')
-CLASSIFIERS = Registry('classifier')
-HEADS = Registry('head')
-NECKS = Registry('neck')
-LOSSES = Registry('loss')
+MODELS = Registry('models', parent=MMCV_MODELS)
 
-
-def build(cfg, registry, default_args=None):
-    if isinstance(cfg, list):
-        modules = [
-            build_from_cfg(cfg_, registry, default_args) for cfg_ in cfg
-        ]
-        return nn.Sequential(*modules)
-    else:
-        return build_from_cfg(cfg, registry, default_args)
+BACKBONES = MODELS
+NECKS = MODELS
+HEADS = MODELS
+LOSSES = MODELS
+CLASSIFIERS = MODELS
 
 
 def build_backbone(cfg):
-    return build(cfg, BACKBONES)
+    """Build backbone."""
+    return BACKBONES.build(cfg)
 
 
-def build_head(cfg):
-    return build(cfg, HEADS)
+def build_neck(cfg):
+    """Build neck."""
+    return NECKS.build(cfg)
 
 
-def build_neck(cfg):
-    return build(cfg, NECKS)
+def build_head(cfg):
+    """Build head."""
+    return HEADS.build(cfg)
 
 
 def build_loss(cfg):
-    return build(cfg, LOSSES)
+    """Build loss."""
+    return LOSSES.build(cfg)
 
 
 def build_classifier(cfg):
-    return build(cfg, CLASSIFIERS)
+    return CLASSIFIERS.build(cfg)