Add Flax dummy objects (#7918)

src/transformers/__init__.py

@@ -841,6 +841,11 @@ else:
 if is_flax_available():
     from .modeling_flax_bert import FlaxBertModel
     from .modeling_flax_roberta import FlaxRobertaModel
+else:
+    # Import the same objects as dummies to get them in the namespace.
+    # They will raise an import error if the user tries to instantiate / use them.
+    from .utils.dummy_flax_objects import *
+
 
 if not is_tf_available() and not is_torch_available():
     logger.warning(

src/transformers/file_utils.py

@@ -356,6 +356,12 @@ installation page: https://www.tensorflow.org/install and follow the ones that m
 """
 
 
+FLAX_IMPORT_ERROR = """
+{0} requires the FLAX library but it was not found in your enviromnent. Checkout the instructions on the
+installation page: https://github.com/google/flax and follow the ones that match your enviromnent.
+"""
+
+
 def requires_datasets(obj):
     name = obj.__name__ if hasattr(obj, "__name__") else obj.__class__.__name__
     if not is_datasets_available():
@@ -386,6 +392,12 @@ def requires_tf(obj):
         raise ImportError(TENSORFLOW_IMPORT_ERROR.format(name))
 
 
+def requires_flax(obj):
+    name = obj.__name__ if hasattr(obj, "__name__") else obj.__class__.__name__
+    if not is_flax_available():
+        raise ImportError(FLAX_IMPORT_ERROR.format(name))
+
+
 def requires_tokenizers(obj):
     name = obj.__name__ if hasattr(obj, "__name__") else obj.__class__.__name__
     if not is_tokenizers_available():

src/transformers/utils/dummy_flax_objects.py

+# This file is autogenerated by the command `make fix-copies`, do not edit.
+from ..file_utils import requires_flax
+
+
+class FlaxBertModel:
+    def __init__(self, *args, **kwargs):
+        requires_flax(self)
+
+    @classmethod
+    def from_pretrained(self, *args, **kwargs):
+        requires_flax(self)
+
+
+class FlaxRobertaModel:
+    def __init__(self, *args, **kwargs):
+        requires_flax(self)
+
+    @classmethod
+    def from_pretrained(self, *args, **kwargs):
+        requires_flax(self)

utils/check_dummies.py

@@ -72,6 +72,28 @@ def {0}(*args, **kwargs):
 """
 
 
+DUMMY_FLAX_PRETRAINED_CLASS = """
+class {0}:
+    def __init__(self, *args, **kwargs):
+        requires_flax(self)
+
+    @classmethod
+    def from_pretrained(self, *args, **kwargs):
+        requires_flax(self)
+"""
+
+DUMMY_FLAX_CLASS = """
+class {0}:
+    def __init__(self, *args, **kwargs):
+        requires_flax(self)
+"""
+
+DUMMY_FLAX_FUNCTION = """
+def {0}(*args, **kwargs):
+    requires_flax({0})
+"""
+
+
 DUMMY_SENTENCEPIECE_PRETRAINED_CLASS = """
 class {0}:
     def __init__(self, *args, **kwargs):
@@ -120,6 +142,7 @@ def {0}(*args, **kwargs):
 DUMMY_PRETRAINED_CLASS = {
     "pt": DUMMY_PT_PRETRAINED_CLASS,
     "tf": DUMMY_TF_PRETRAINED_CLASS,
+    "flax": DUMMY_FLAX_PRETRAINED_CLASS,
     "sentencepiece": DUMMY_SENTENCEPIECE_PRETRAINED_CLASS,
     "tokenizers": DUMMY_TOKENIZERS_PRETRAINED_CLASS,
 }
@@ -127,6 +150,7 @@ DUMMY_PRETRAINED_CLASS = {
 DUMMY_CLASS = {
     "pt": DUMMY_PT_CLASS,
     "tf": DUMMY_TF_CLASS,
+    "flax": DUMMY_FLAX_CLASS,
     "sentencepiece": DUMMY_SENTENCEPIECE_CLASS,
     "tokenizers": DUMMY_TOKENIZERS_CLASS,
 }
@@ -134,6 +158,7 @@ DUMMY_CLASS = {
 DUMMY_FUNCTION = {
     "pt": DUMMY_PT_FUNCTION,
     "tf": DUMMY_TF_FUNCTION,
+    "flax": DUMMY_FLAX_FUNCTION,
     "sentencepiece": DUMMY_SENTENCEPIECE_FUNCTION,
     "tokenizers": DUMMY_TOKENIZERS_FUNCTION,
 }
@@ -208,7 +233,24 @@ def read_init():
         elif line.startswith("        "):
             tf_objects.append(line[8:-2])
         line_index += 1
-    return sentencepiece_objects, tokenizers_objects, pt_objects, tf_objects
+
+    # Find where the FLAX imports begin
+    flax_objects = []
+    while not lines[line_index].startswith("if is_flax_available():"):
+        line_index += 1
+    line_index += 1
+
+    # Until we unindent, add PyTorch objects to the list
+    while len(lines[line_index]) <= 1 or lines[line_index].startswith("    "):
+        line = lines[line_index]
+        search = _re_single_line_import.search(line)
+        if search is not None:
+            flax_objects += search.groups()[0].split(", ")
+        elif line.startswith("        "):
+            flax_objects.append(line[8:-2])
+        line_index += 1
+
+    return sentencepiece_objects, tokenizers_objects, pt_objects, tf_objects, flax_objects
 
 
 def create_dummy_object(name, type="pt"):
@@ -224,7 +266,7 @@ def create_dummy_object(name, type="pt"):
         "Model",
         "Tokenizer",
     ]
-    assert type in ["pt", "tf", "sentencepiece", "tokenizers"]
+    assert type in ["pt", "tf", "sentencepiece", "tokenizers", "flax"]
     if name.isupper():
         return DUMMY_CONSTANT.format(name)
     elif name.islower():
@@ -244,7 +286,7 @@ def create_dummy_object(name, type="pt"):
 
 def create_dummy_files():
     """ Create the content of the dummy files. """
-    sentencepiece_objects, tokenizers_objects, pt_objects, tf_objects = read_init()
+    sentencepiece_objects, tokenizers_objects, pt_objects, tf_objects, flax_objects = read_init()
 
     sentencepiece_dummies = "# This file is autogenerated by the command `make fix-copies`, do not edit.\n"
     sentencepiece_dummies += "from ..file_utils import requires_sentencepiece\n\n"
@@ -262,17 +304,22 @@ def create_dummy_files():
     tf_dummies += "from ..file_utils import requires_tf\n\n"
     tf_dummies += "\n".join([create_dummy_object(o, type="tf") for o in tf_objects])
 
-    return sentencepiece_dummies, tokenizers_dummies, pt_dummies, tf_dummies
+    flax_dummies = "# This file is autogenerated by the command `make fix-copies`, do not edit.\n"
+    flax_dummies += "from ..file_utils import requires_flax\n\n"
+    flax_dummies += "\n".join([create_dummy_object(o, type="flax") for o in flax_objects])
+
+    return sentencepiece_dummies, tokenizers_dummies, pt_dummies, tf_dummies, flax_dummies
 
 
 def check_dummies(overwrite=False):
     """ Check if the dummy files are up to date and maybe `overwrite` with the right content. """
-    sentencepiece_dummies, tokenizers_dummies, pt_dummies, tf_dummies = create_dummy_files()
+    sentencepiece_dummies, tokenizers_dummies, pt_dummies, tf_dummies, flax_dummies = create_dummy_files()
     path = os.path.join(PATH_TO_TRANSFORMERS, "utils")
     sentencepiece_file = os.path.join(path, "dummy_sentencepiece_objects.py")
     tokenizers_file = os.path.join(path, "dummy_tokenizers_objects.py")
     pt_file = os.path.join(path, "dummy_pt_objects.py")
     tf_file = os.path.join(path, "dummy_tf_objects.py")
+    flax_file = os.path.join(path, "dummy_flax_objects.py")
 
     with open(sentencepiece_file, "r", encoding="utf-8") as f:
         actual_sentencepiece_dummies = f.read()
@@ -282,6 +329,8 @@ def check_dummies(overwrite=False):
         actual_pt_dummies = f.read()
     with open(tf_file, "r", encoding="utf-8") as f:
         actual_tf_dummies = f.read()
+    with open(flax_file, "r", encoding="utf-8") as f:
+        actual_flax_dummies = f.read()
 
     if sentencepiece_dummies != actual_sentencepiece_dummies:
         if overwrite:
@@ -327,6 +376,17 @@ def check_dummies(overwrite=False):
                 "Run `make fix-copies` to fix this.",
             )
 
+    if flax_dummies != actual_flax_dummies:
+        if overwrite:
+            print("Updating transformers.utils.dummy_flax_objects.py as the main __init__ has new objects.")
+            with open(flax_file, "w", encoding="utf-8") as f:
+                f.write(flax_dummies)
+        else:
+            raise ValueError(
+                "The main __init__ has objects that are not present in transformers.utils.dummy_flax_objects.py.",
+                "Run `make fix-copies` to fix this.",
+            )
+
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser()