8000 Strip leading space when de-tokenizing. · iamudesharma/llama-cpp-python@8ac5946 · GitHub
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Strip leading space when de-tokenizing.
1 parent c2d1dea commit 8ac5946

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2 files changed

+21
-9
lines changed

2 files changed

+21
-9
lines changed

llama_cpp/llama.py

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -445,17 +445,17 @@ def detokenize(self, tokens: List[int]) -> bytes:
445445
"""
446446
assert self.ctx is not None
447447
output = b""
448-
buffer_size = 32
448+
buffer_size = 8
449449
buffer = (ctypes.c_char * buffer_size)()
450450
for token in tokens:
451-
if token == llama_cpp.llama_token_bos(self.ctx):
452-
continue
453451
n = llama_cpp.llama_token_to_str(
454452
self.ctx, llama_cpp.llama_token(token), buffer, buffer_size
455453
)
456454
assert n <= buffer_size
457455
output += bytes(buffer[:n])
458-
return output
456+
# NOTE: Llama1 models automatically added a space at the start of the prompt
457+
# this line removes a leading space if the first token is a beginning of sentence token
458+
return output[1:] if len(tokens) > 0 and tokens[0] == self.token_bos() else output
459459

460460
def set_cache(self, cache: Optional[BaseLlamaCache]):
461461
"""Set the cache.
@@ -886,7 +886,7 @@ def _create_completion(
886886
created: int = int(time.time())
887887
completion_tokens: List[int] = []
888888
# Add blank space to start of prompt to match OG llama tokenizer
889-
prompt_tokens: List[int] = self.tokenize(b" " + prompt.encode("utf-8"))
889+
prompt_tokens: List[int] = self.tokenize(prompt.encode("utf-8")) if prompt != "" else [self.token_bos()]
890890
text: bytes = b""
891891
returned_tokens: int = 0
892892
stop = (

tests/test_llama.py

Lines changed: 16 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,20 +1,32 @@
1+
import pytest
12
import llama_cpp
23

34
MODEL = "./vendor/llama.cpp/models/ggml-vocab-llama.gguf"
45

56

6-
def test_llama():
7-
llama = llama_cpp.Llama(model_path=MODEL, vocab_only=True)
7+
def test_llama_cpp_tokenization():
8+
llama = llama_cpp.Llama(model_path=MODEL, vocab_only=True, verbose=False)
89

910
assert llama
1011
assert llama.ctx is not None
1112

1213
text = b"Hello World"
1314

14-
assert llama.detokenize(llama.tokenize(text)) == text
15+
tokens = llama.tokenize(text)
16+
assert tokens[0] == llama.token_bos()
17+
assert tokens == [1, 15043, 2787]
18+
detokenized = llama.detokenize(tokens)
19+
assert detokenized == text
20+
21+
tokens = llama.tokenize(text, add_bos=False)
22+
assert tokens[0] != llama.token_bos()
23+
assert tokens == [15043, 2787]
24+
25+
detokenized = llama.detokenize(tokens)
26+
assert detokenized != text
1527

1628

17-
# @pytest.mark.skip(reason="need to update sample mocking")
29+
@pytest.mark.skip(reason="bug in tokenization where leading space is always inserted even if not after eos")
1830
def test_llama_patch(monkeypatch):
1931
llama = llama_cpp.Llama(model_path=MODEL, vocab_only=True)
2032
n_vocab = llama_cpp.llama_n_vocab(llama.ctx)

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