Migrate extension/llm/tokenizer python users to use the new repo (#22)

Summary:

Migrate usages of

```
fbcode//executorch/extension/llm/tokenizer:tokenizer_py
```
to use:
```
fbcode//pytorch/tokenizers/pytorch_tokenizers:tokenizers
```

Differential Revision: D69820450

pytorch_tokenizers/TARGETS

@@ -0,0 +1,18 @@
+# Any targets that should be shared between fbcode and xplat must be defined in
+# targets.bzl. This file can contain xplat-only targets.
+
+load("@fbcode_macros//build_defs:python_library.bzl", "python_library")
+load(":targets.bzl", "define_common_targets")
+
+oncall("executorch")
+
+define_common_targets()
+
+python_library(
+    name = "hf_tokenizer",
+    srcs = ["hf_tokenizer.py"],
+    labels = ["autodeps2_generated"],
+    deps = [
+        "fbsource//third-party/pypi/tokenizers:tokenizers",
+    ],
+)

pytorch_tokenizers/__init__.py

@@ -0,0 +1,26 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+
+from typing import Optional
+
+from .hf_tokenizer import HuggingFaceTokenizer
+from .llama2c import Llama2cTokenizer
+from .tiktoken import TiktokenTokenizer
+
+__all__ = ["TiktokenTokenizer", "Llama2cTokenizer", "HuggingFaceTokenizer"]
+
+
+def get_tokenizer(tokenizer_path: str, tokenizer_config_path: Optional[str] = None):
+    if tokenizer_path.endswith(".json"):
+        tokenizer = HuggingFaceTokenizer(tokenizer_path, tokenizer_config_path)
+    else:
+        try:
+            tokenizer = Llama2cTokenizer(model_path=str(tokenizer_path))
+        except Exception:
+            print("Using Tiktokenizer")
+            tokenizer = TiktokenTokenizer(model_path=str(tokenizer_path))
+    return tokenizer

pytorch_tokenizers/hf_tokenizer.py

@@ -0,0 +1,56 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+import json
+import os
+from typing import List, Optional
+
+from tokenizers import Tokenizer
+
+
+class HuggingFaceTokenizer:
+    """
+    Tokenizing and encoding/decoding text using the Hugging face tokenizer.
+    """
+
+    def __init__(self, model_path: str, config_path: Optional[str] = None):
+        """
+        Initializes the Tokenizer with a tokenizer.json from HuggingFace.
+
+        Args:
+            model_path (str): The path to the Tiktoken model file.
+        """
+        assert os.path.isfile(model_path), model_path
+
+        self.model = tokenizer = Tokenizer.from_file(model_path)
+
+        self.n_words: int = tokenizer.get_vocab_size()
+        if config_path:
+            with open(config_path) as f:
+                tokenizer_config = json.load(f)
+                self.bos_id = (
+                    self.model.token_to_id(tokenizer_config["bos_token"])
+                    if tokenizer_config["bos_token"]
+                    else None
+                )
+                self.eos_id = self.model.token_to_id(tokenizer_config["eos_token"])
+        else:  # Fallback guess.
+            self.bos_id = self.model.token_to_id("<|begin_of_text|>")
+            self.eos_id = self.model.token_to_id("<|endoftext|>")
+
+        self.stop_tokens = [
+            self.eos_id,
+        ]
+
+    def encode(self, s: str, *, bos: bool, eos: bool) -> List[int]:
+        assert type(s) is str
+        return self.model.encode(s).ids
+
+    def decode(self, t: List[int]) -> str:
+        return self.model.decode(t)
+
+    def decode_token(self, t: int) -> str:
+        return self.model.decode([t])

pytorch_tokenizers/llama2c.py

@@ -0,0 +1,110 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+import logging
+import os
+import struct
+from typing import List
+
+from sentencepiece import SentencePieceProcessor as SentencePieceProcessor
+
+
+class Llama2cTokenizer:
+    def __init__(self, model_path: str):
+        assert os.path.isfile(
+            model_path
+        ), f"Need a valid tokenizer model path but got {model_path}"
+        # pyre-fixme[28]: Unexpected keyword argument `model_file` to call `SentencePieceProcessor.__init__`.
+        self.sp_model = SentencePieceProcessor(model_file=model_path)
+        self.model_path = model_path
+
+        # BOS / EOS token IDs
+        self.n_words: int = self.sp_model.vocab_size()
+        self.bos_id: int = self.sp_model.bos_id()
+        self.eos_id: int = self.sp_model.eos_id()
+        logging.info(
+            f"#words: {self.n_words} - BOS ID: {self.bos_id} - EOS ID: {self.eos_id}"
+        )
+        # pyre-fixme[16]: `SentencePieceProcessor` has no attribute `get_piece_size`.
+        assert self.sp_model.vocab_size() == self.sp_model.get_piece_size()
+
+    def encode(self, s: str, bos: bool, eos: bool) -> List[int]:
+        assert type(s) is str
+        # pyre-fixme[16]: `SentencePieceProcessor` has no attribute `encode`.
+        t = self.sp_model.encode(s)
+        if bos:
+            t = [self.bos_id] + t
+        if eos:
+            t = t + [self.eos_id]
+        return t
+
+    def decode(self, t: List[int]) -> str:
+        # pyre-fixme[16]: `SentencePieceProcessor` has no attribute `encode`.
+        return self.sp_model.decode(t)
+
+    def decode_token(self, t: int) -> str:
+        # pyre-fixme[16]: `SentencePieceProcessor` has no attribute `encode`.
+        return self.sp_model.decode(t)
+
+    def export(self, output_path: str, *, prepend_padding: bool = False) -> None:
+        """
+        Export tokenizer.model to another serialization format. Here we did some lightweight
+        processing such as supporting prepend padding token, prepend max token length and
+        replace '_' back to empty space.
+
+        The binary format is:
+        1. vocab size: int32
+        2. bos token id: int32
+        3. eos token id: int32
+        4. max token length: int32
+        5. score: float32, len of bytes: int32, token bytes: [byte] for each token
+
+        :param output_path: output path of the new binary.
+        :param prepend_padding: a boolean to control if we want to prepend a padding token.
+
+        :return: None
+        """
+
+        # get all the tokens (postprocessed) and their scores as floats
+        tokens, scores = [], []
+
+        if prepend_padding:
+            # Here we use the default padding token and its score.
+            tokens.append("<pad>".encode("utf-8"))
+            scores.append(-1)
+
+        for i in range(self.n_words):
+            # decode the token and light postprocessing
+            # pyre-fixme[16]: `SentencePieceProcessor` has no attribute `id_to_piece`.
+            t = self.sp_model.id_to_piece(i)
+            # pyre-fixme[16]: `SentencePieceProcessor` has no attribute `get_score`.
+            s = self.sp_model.get_score(i)
+            # sentencepiece use '<s>' as BOS and '</s>' for EOS
+            if i == self.bos_id:
+                t = "<s>"
+            elif i == self.eos_id:
+                t = "</s>"
+            t = t.replace("▁", " ")  # sentencepiece uses this character as whitespace
+            b = t.encode("utf-8")  # bytes of this token, utf-8 encoded
+
+            tokens.append(b)
+            scores.append(s)
+
+        # record the max token length
+        max_token_length = 0 if not tokens else max(len(t) for t in tokens)
+
+        # write to a binary file
+        with open(output_path, "wb") as f:
+            # write the vocab size, bos/eos ids and max token length
+            f.write(
+                struct.pack(
+                    "IIII", self.n_words, self.bos_id, self.eos_id, max_token_length
+                )
+            )
+            for bytes, score in zip(tokens, scores):
+                f.write(struct.pack("fI", score, len(bytes)))
+                f.write(bytes)
+        logging.info(f"Wrote tokenizer to {output_path}")

pytorch_tokenizers/targets.bzl

@@ -0,0 +1,34 @@
+load("@fbsource//xplat/executorch/build:runtime_wrapper.bzl", "runtime")
+
+def define_common_targets():
+    """Defines targets that should be shared between fbcode and xplat.
+
+    The directory containing this targets.bzl file should also contain both
+    TARGETS and BUCK files that call this function.
+    """
+    runtime.python_library(
+        name = "tokenizers",
+        srcs = [
+            "__init__.py",
+            "llama2c.py",
+            "tiktoken.py",
+            "hf_tokenizer.py",
+        ],
+        base_module = "pytorch_tokenizers",
+        visibility = [
+            "//executorch/examples/...",
+            "//executorch/extension/llm/export/...",
+            "//bento/...",
+            "//bento_kernels/...",
+            "//pytorch/tokenizers/...",
+            "@EXECUTORCH_CLIENTS",
+        ],
+        _is_external_target = True,
+        external_deps = [
+            "sentencepiece-py",
+        ],
+        deps = [
+            "fbsource//third-party/pypi/tiktoken:tiktoken",
+            "fbsource//third-party/pypi/tokenizers:tokenizers",
+        ],
+    )