[Models] Support for tokenizers in C++ runtime (#69)

Adds supports for LLaMA, GPT-2, and OPT tokenizers using the Hugging Face configuration

CMakeLists.txt

@@ -25,6 +25,14 @@ add_library(hidet_runtime SHARED
         src/hidet/runtime/callbacks.cpp
         src/hidet/runtime/logging.cpp
         src/hidet/runtime/symbols.cpp
+        src/hidet/runtime/llm/tokenizer/decoders.cpp
+        src/hidet/runtime/llm/tokenizer/models.cpp
+        src/hidet/runtime/llm/tokenizer/normalizers.cpp
+        src/hidet/runtime/llm/tokenizer/pattern.cpp
+        src/hidet/runtime/llm/tokenizer/postprocessors.cpp
+        src/hidet/runtime/llm/tokenizer/pretokenizers.cpp
+        src/hidet/runtime/llm/tokenizer/tokenizer.cpp
+        src/hidet/runtime/llm/tokenizer/utf8.cpp
         )
 target_include_directories(hidet_runtime PRIVATE ${CMAKE_SOURCE_DIR}/include /usr/include)
 set_target_properties(hidet_runtime PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)

include/hidet/runtime/llm/tokenizer/debug.h

@@ -0,0 +1,17 @@
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#pragma once
+#include <sstream>
+
+// dbg is a stream which can be used to debug various aspects of the tokenizer; its contents are returned
+// as part of the tokenizer output.
+extern std::stringstream dbg;

include/hidet/runtime/llm/tokenizer/decoders.h

@@ -0,0 +1,85 @@
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#pragma once
+#include <cstddef>
+#include <memory>
+#include <numeric>
+#include <string>
+#include <vector>
+#include <hidet/runtime/llm/tokenizer/pattern.h>
+#include <hidet/runtime/llm/tokenizer/utf8.h>
+
+// Decoder manipulates a sequence of raw tokens to produce a human-readable form.
+class Decoder {
+   public:
+    virtual std::vector<std::string> decode_chain(std::vector<std::string> tokens) = 0;
+    virtual ~Decoder() = default;
+
+    std::string decode(std::vector<std::string> tokens) {
+        std::string ret;
+        for (std::string const &s : decode_chain(std::move(tokens))) ret += s;
+        return ret;
+    }
+};
+
+// SequenceDecoder runs a sequence of decoders sequentially, passing the output of one decoder into another.
+class SequenceDecoder: public Decoder {
+   public:
+    explicit SequenceDecoder(std::vector<std::unique_ptr<Decoder>> decoders);
+    std::vector<std::string> decode_chain(std::vector<std::string> tokens) final;
+
+   private:
+    std::vector<std::unique_ptr<Decoder>> decoders;
+};
+
+// ReplaceDecoder replaces all instances of a pattern with another on a token-by-token basis.
+class ReplaceDecoder: public Decoder {
+   public:
+    explicit ReplaceDecoder(std::string const &pattern, std::string content);
+    std::vector<std::string> decode_chain(std::vector<std::string> tokens) final;
+
+   private:
+    RegexPattern pattern;
+    std::string content;
+};
+
+// ByteLevelDecoder is meant to be used with ByteLevel pre-tokenization (for example, in GPT-2). It reverses the
+// mapping of the ByteLevel pre-tokenization step, converting the byte-level replacements back into human-readable
+// characters.
+class ByteLevelDecoder: public Decoder {
+   public:
+    ByteLevelDecoder();
+    std::vector<std::string> decode_chain(std::vector<std::string> tokens) final;
+
+   private:
+    std::map<std::string, uint8_t> chars_to_bytes;
+};
+
+class FuseDecoder: public Decoder {
+   public:
+    std::vector<std::string> decode_chain(std::vector<std::string> tokens) final;
+};
+
+class StripDecoder: public Decoder {
+    std::string content;
+    int n_begin;
+    int n_end;
+
+   public:
+    explicit StripDecoder(std::string content, int n_begin, int n_end);
+    std::vector<std::string> decode_chain(std::vector<std::string> tokens) final;
+};
+
+class ByteFallbackDecoder: public Decoder {
+   public:
+    std::vector<std::string> decode_chain(std::vector<std::string> tokens) final;
+};

include/hidet/runtime/llm/tokenizer/models.h

@@ -0,0 +1,98 @@
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#pragma once
+#include <iomanip>
+#include <limits>
+#include <map>
+#include <queue>
+#include <sstream>
+#include <string>
+#include <utility>
+#include <vector>
+#include <hidet/runtime/llm/tokenizer/utf8.h>
+
+// Model takes in a chunk of text from the pre-tokenization step and splits it into a set of tokens,
+// each of which are described by their unsigned 32-bit IDs.
+class Model {
+   public:
+    virtual std::vector<uint32_t> tokenize(std::string const &sequence) = 0;
+    virtual std::string id_to_token(uint32_t id) = 0;
+    virtual ~Model() = default;
+};
+
+// BPEWord corresponds roughly to the Hugging Face "Word" implementation. It describes how a chunk of
+// text from the pre-tokenization step is split. Initially a chunk of text is split character-wise, and
+// the BPE algorithm works to merge these characters into successively larger tokens.
+//
+// The underlying representation is a doubly-linked list of "Piece" nodes, which point to the previous
+// and next token in the sequence. It leverages the fact that the linked list never grows in size to
+// avoid dynamic memory allocation entirely -- instead, it uses a fixed-size vector to store the nodes,
+// which are then addressed by their index in this vector.
+class BPEWord {
+   public:
+    explicit BPEWord(std::vector<uint32_t> const &ids);
+
+    // merge merges the node at i with the node which follows after it, creating a new node with the given ID.
+    int merge(int i, uint32_t new_id);
+
+    // ids provides IDs for all tokens currently in the BPEWord.
+    std::vector<uint32_t> ids() const;
+
+    uint32_t at(int i) const { return data[i].id; }
+    int prev(int i) const { return data[i].prev; }
+    int next(int i) const { return data[i].next; }
+    bool valid(int i) const { return data[i].id != std::numeric_limits<uint32_t>::max(); }
+    int begin() const { return 0; }
+    int end() const { return data.size() - 1; }
+
+   private:
+    // Piece corresponds to a single token in the BPEWord. It contains the ID of the token, as well as
+    // the "addresses" of the previous and next tokens in the sequence.
+    struct Piece {
+        // The default ID is the maximum value of a 32-bit unsigned integer, which is also used to invalidate
+        // a Piece node and indicate that is no longer in use, as the result of some merges.
+        uint32_t id{std::numeric_limits<uint32_t>::max()};
+        int prev{};
+        int next{};
+
+        Piece() = default;
+        Piece(uint32_t id, int prev, int next) : id{id}, prev{prev}, next{next} {};
+    };
+
+    // The underlying data structure for the BPEWord.
+    std::vector<Piece> data;
+};
+
+// BPEModel
+class BPEModel: public Model {
+   public:
+    BPEModel(std::map<std::string, uint32_t> vocab, std::vector<std::pair<std::string, std::string>> const &merges,
+             bool byte_fallback);
+    std::vector<uint32_t> tokenize(std::string const &sequence) final;
+    std::string id_to_token(uint32_t id) final;
+
+   private:
+    // The vocabulary that assigns a number to each token.
+    std::map<std::string, uint32_t> vocab;
+    // Reversed vocabulary, to rebuild sentences.
+    std::map<uint32_t, std::string> vocab_r;
+    // Contains the mapping between pairs of IDs and their (score, new_id) after
+    // merging.
+    std::map<std::pair<uint32_t, uint32_t>, std::pair<int, uint32_t>> merges;
+    // Caches the results of calls to tokenize.
+    std::map<std::string, std::vector<uint32_t>> cache;
+    // Whether byte fallbacks (e.g. <0xFA>) should be used for characters not in the vocabulary.
+    bool byte_fallback;
+
+    // Helper for tokenize
+    void merge_word(BPEWord &word);
+};

include/hidet/runtime/llm/tokenizer/normalizers.h

@@ -0,0 +1,53 @@
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#pragma once
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+#include <hidet/runtime/llm/tokenizer/pattern.h>
+
+// Normalizer takes in an input text and applies a transformation to normalize it.
+// This is the first step in the tokenization pipeline, coming before the pre-tokenizer.
+class Normalizer {
+   public:
+    virtual void normalize(std::string &s) = 0;
+    virtual ~Normalizer() = default;
+};
+
+// SequenceNormalizer runs a pre-defined set of normalizers in sequence.
+class SequenceNormalizer: public Normalizer {
+    std::vector<std::unique_ptr<Normalizer>> normalizers;
+
+   public:
+    explicit SequenceNormalizer(std::vector<std::unique_ptr<Normalizer>> normalizers);
+    void normalize(std::string &s) final;
+};
+
+// PrependNormalizer prepends a prefix to a string.
+class PrependNormalizer: public Normalizer {
+    std::string prefix;
+
+   public:
+    explicit PrependNormalizer(std::string prefix);
+    void normalize(std::string &s) final;
+};
+
+// ReplaceNormalizer replaces all instances of a pattern with the given content.
+class ReplaceNormalizer: public Normalizer {
+    RegexPattern pattern;
+    std::string content;
+
+   public:
+    explicit ReplaceNormalizer(const std::string &pattern, std::string content);
+    void normalize(std::string &s) final;
+};

include/hidet/runtime/llm/tokenizer/pattern.h

@@ -0,0 +1,54 @@
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#pragma once
+#include <regex>
+#include <string>
+#include <vector>
+
+// SplitDelimiterBehavior defines how the delimiter is treated when splitting a string.
+enum class SplitDelimiterBehavior {
+    Removed,             // A.B -> [A B]
+    Isolated,            // A.B -> [A . B]
+    MergedWithPrevious,  // A.B -> [A. B]
+    MergedWithNext,      // A.B -> [A .B]
+};
+
+// PatternMatch represent a segment of a string that is either a match or not.
+struct PatternMatch {
+    // The starting index of the segment, inclusive.
+    int start;
+    // The ending index of the segment, exclusive.
+    int end;
+    // Whether the segment is a match or not.
+    bool is_match;
+
+    PatternMatch(int start, int end, bool is_match) : start{start}, end{end}, is_match{is_match} {}
+};
+
+class Pattern {
+   public:
+    // Suppose the string has length n, report a partition of [0, n) into intervals that are all either match/no match.
+    // For example with inside = "abaca" and the pattern "ba", the result is [0 1 F], [1 3 T], [3 5 F].
+    virtual std::vector<PatternMatch> find_matches(std::string const &inside) const = 0;
+
+    std::vector<std::string> split(const std::string &s, SplitDelimiterBehavior behaviour) const;
+
+    virtual ~Pattern() = default;
+};
+
+class RegexPattern: public Pattern {
+    std::regex pattern;
+
+   public:
+    explicit RegexPattern(std::regex pattern);
+    std::vector<PatternMatch> find_matches(std::string const &inside) const final;
+};

include/hidet/runtime/llm/tokenizer/postprocessors.h

@@ -0,0 +1,46 @@
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#pragma once
+#include <cstdint>
+#include <map>
+#include <stdexcept>
+#include <string>
+#include <vector>
+
+// PostProcessor takes the output of the BPE algorithm (a sequence of token IDs) and applies a transformation to it
+// to prepare it for consumption by a language model. Usually, this involves prepending/appending special
+// starting/ending tokens.
+class PostProcessor {
+   public:
+    virtual std::vector<uint32_t> process(std::vector<uint32_t> encoding) = 0;
+    virtual ~PostProcessor() = default;
+};
+
+// ByteLevelPostProcessor is a no-op post-processor that returns the input encoding as-is. The provided functionality
+// by Hugging Face maps IDs back to their source offsets, which we don't need to do here.
+class ByteLevelPostProcessor: public PostProcessor {
+   public:
+    std::vector<uint32_t> process(std::vector<uint32_t> encoding) final { return encoding; };
+};
+
+// TemplateProcessingPostProcessor is a post-processor that takes a vector of strings (called the "template"), which
+// define the output of the model. The template is a list of strings, where each string is either a special token or
+// "A". If the string is "A", the output of the model is inserted into the output. If the string is a special token,
+// the ID of the special token is inserted into the output.
+class TemplateProcessingPostProcessor: public PostProcessor {
+    std::vector<std::string> tmpl;
+    std::map<std::string, uint32_t> special_tokens;
+
+   public:
+    TemplateProcessingPostProcessor(std::vector<std::string> tmpl, std::map<std::string, uint32_t> special_tokens);
+    std::vector<uint32_t> process(std::vector<uint32_t> encoding) final;
+};