[CTRL] warn if generation prompt does not start with a control code

see also https://github.com/salesforce/ctrl/pull/50

transformers/tokenization_ctrl.py

@@ -46,6 +46,64 @@ PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {
     'ctrl': 256,
 }
 
+CONTROL_CODES = {
+    "Pregnancy": 168629,
+    "Christianity": 7675,
+    "Explain": 106423,
+    "Fitness": 63440,
+    "Saving": 63163,
+    "Ask": 27171,
+    "Ass": 95985,
+    "Joke": 163509,
+    "Questions": 45622,
+    "Thoughts": 49605,
+    "Retail": 52342,
+    "Feminism": 164338,
+    "Writing": 11992,
+    "Atheism": 192263,
+    "Netflix": 48616,
+    "Computing": 39639,
+    "Opinion": 43213,
+    "Alone": 44967,
+    "Funny": 58917,
+    "Gaming": 40358,
+    "Human": 4088,
+    "India": 1331,
+    "Joker": 77138,
+    "Diet": 36206,
+    "Legal": 11859,
+    "Norman": 4939,
+    "Tip": 72689,
+    "Weight": 52343,
+    "Movies": 46273,
+    "Running": 23425,
+    "Science": 2090,
+    "Horror": 37793,
+    "Confession": 60572,
+    "Finance": 12250,
+    "Politics": 16360,
+    "Scary": 191985,
+    "Support": 12654,
+    "Technologies": 32516,
+    "Teenage": 66160,
+    "Event": 32769,
+    "Learned": 67460,
+    "Notion": 182770,
+    "Wikipedia": 37583,
+    "Books": 6665,
+    "Extract": 76050,
+    "Confessions": 102701,
+    "Conspiracy": 75932,
+    "Links": 63674,
+    "Narcissus": 150425,
+    "Relationship": 54766,
+    "Relationships": 134796,
+    "Reviews": 41671,
+    "News": 4256,
+    "Translation": 26820,
+    "multilingual": 128406,
+}
+
 def get_pairs(word):
     """Return set of symbol pairs in a word.
 
@@ -68,6 +126,7 @@ class CTRLTokenizer(PreTrainedTokenizer):
     vocab_files_names = VOCAB_FILES_NAMES
     pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP
     max_model_input_sizes = PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES
+    control_codes = CONTROL_CODES
 
     def __init__(self, vocab_file, merges_file, unk_token="<unk>", **kwargs):
         super(CTRLTokenizer, self).__init__(unk_token=unk_token, **kwargs)