--- a
+++ b/dataLoader/utils.py
@@ -0,0 +1,93 @@
+import random
+
+
+def code2index(tokens, token2idx, mask_token=None):
+    output_tokens = []
+    for i, token in enumerate(tokens):
+        if token==mask_token:
+            output_tokens.append(token2idx['UNK'])
+        else:
+            output_tokens.append(token2idx.get(token, token2idx['UNK']))
+    return tokens, output_tokens
+
+
+def random_mask(tokens, token2idx):
+    output_label = []
+    output_token = []
+    for i, token in enumerate(tokens):
+        prob = random.random()
+        # mask token with 15% probability
+        if prob < 0.15:
+            prob /= 0.15
+
+            # 80% randomly change token to mask token
+            if prob < 0.8:
+                output_token.append(token2idx["MASK"])
+
+            # 10% randomly change token to random token
+            elif prob < 0.9:
+                output_token.append(random.choice(list(token2idx.values())))
+
+            # -> rest 10% randomly keep current token
+
+            # append current token to output (we will predict these later
+            output_label.append(token2idx.get(token, token2idx['UNK']))
+        else:
+            # no masking token (will be ignored by loss function later)
+            output_label.append(-1)
+            output_token.append(token2idx.get(token, token2idx['UNK']))
+
+    return tokens, output_token, output_label
+
+
+def index_seg(tokens, symbol='SEP'):
+    flag = 0
+    seg = []
+
+    for token in tokens:
+        if token == symbol:
+            seg.append(flag)
+            if flag == 0:
+                flag = 1
+            else:
+                flag = 0
+        else:
+            seg.append(flag)
+    return seg
+
+
+def position_idx(tokens, symbol='SEP'):
+    pos = []
+    flag = 0
+
+    for token in tokens:
+        if token == symbol:
+            pos.append(flag)
+            flag += 1
+        else:
+            pos.append(flag)
+    return pos
+
+
+def seq_padding(tokens, max_len, token2idx=None, symbol=None, unkown=True):
+    if symbol is None:
+        symbol = 'PAD'
+
+    seq = []
+    token_len = len(tokens)
+    for i in range(max_len):
+        if token2idx is None:
+            if i < token_len:
+                seq.append(tokens[i])
+            else:
+                seq.append(symbol)
+        else:
+            if i < token_len:
+                # 1 indicate UNK
+                if unkown:
+                    seq.append(token2idx.get(tokens[i], token2idx['UNK']))
+                else:
+                    seq.append(token2idx.get(tokens[i]))
+            else:
+                seq.append(token2idx.get(symbol))
+    return seq
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