From 1a159553f921a9209fed8c714494e57b3649f232 Mon Sep 17 00:00:00 2001 From: staviq Date: Tue, 17 Oct 2023 17:11:01 +0200 Subject: [PATCH] tokenizer : special token handling (#3538) * Rewrite special token handling from #1931 * shorten param name, add st verification by type * use offsets instead of copy by substr * formatting, remove copying iterator on delete * llama : normalize code-style * swift fix * print pfx/sfx if verb, main: split pfx input sfx * dont add space when using special tokens * minor : comment + spacing --------- Co-authored-by: Georgi Gerganov --- common/common.cpp | 12 +- common/common.h | 6 +- common/train.cpp | 8 +- examples/batched.swift/Sources/main.swift | 2 +- examples/main/main.cpp | 40 ++- llama.cpp | 290 +++++++++++++++++++++- llama.h | 13 +- 7 files changed, 332 insertions(+), 39 deletions(-) diff --git a/common/common.cpp b/common/common.cpp index 9c4f7df20..3e4b8a8cb 100644 --- a/common/common.cpp +++ b/common/common.cpp @@ -879,21 +879,23 @@ std::tuple llama_init_from_gpt_par std::vector llama_tokenize( const struct llama_context * ctx, const std::string & text, - bool add_bos) { - return llama_tokenize(llama_get_model(ctx), text, add_bos); + bool add_bos, + bool special) { + return llama_tokenize(llama_get_model(ctx), text, add_bos, special); } std::vector llama_tokenize( const struct llama_model * model, const std::string & text, - bool add_bos) { + bool add_bos, + bool special) { // upper limit for the number of tokens int n_tokens = text.length() + add_bos; std::vector result(n_tokens); - n_tokens = llama_tokenize(model, text.data(), text.length(), result.data(), result.size(), add_bos); + n_tokens = llama_tokenize(model, text.data(), text.length(), result.data(), result.size(), add_bos, special); if (n_tokens < 0) { result.resize(-n_tokens); - int check = llama_tokenize(model, text.data(), text.length(), result.data(), result.size(), add_bos); + int check = llama_tokenize(model, text.data(), text.length(), result.data(), result.size(), add_bos, special); GGML_ASSERT(check == -n_tokens); } else { result.resize(n_tokens); diff --git a/common/common.h b/common/common.h index 36fd44166..08c603231 100644 --- a/common/common.h +++ b/common/common.h @@ -137,12 +137,14 @@ struct llama_context_params llama_context_params_from_gpt_params(const gpt_param std::vector llama_tokenize( const struct llama_context * ctx, const std::string & text, - bool add_bos); + bool add_bos, + bool special = false); std::vector llama_tokenize( const struct llama_model * model, const std::string & text, - bool add_bos); + bool add_bos, + bool special = false); // tokenizes a token into a piece // should work similar to Python's `tokenizer.id_to_piece` diff --git a/common/train.cpp b/common/train.cpp index 35a4cf9e6..972eaefe0 100644 --- a/common/train.cpp +++ b/common/train.cpp @@ -863,7 +863,7 @@ size_t tokenize_file( (int) buf.size(), out_tokens.data(), (int) out_tokens.size(), - false); + false, false); if (n_tokens < 0) { out_tokens.resize(-n_tokens); n_tokens = llama_tokenize( @@ -872,7 +872,7 @@ size_t tokenize_file( (int) buf.size(), out_tokens.data(), (int) out_tokens.size(), - false); + false, false); } if (n_tokens >= 0) { out_tokens.resize(n_tokens); @@ -966,7 +966,7 @@ size_t tokenize_file( (int) buf_sample.size(), tok_sample.data(), (int) tok_sample.size(), - false); + false, false); if (n_tokens < 0) { tok_sample.resize(-n_tokens); n_tokens = llama_tokenize(llama_get_model(lctx), @@ -974,7 +974,7 @@ size_t tokenize_file( (int) buf_sample.size(), tok_sample.data(), (int) tok_sample.size(), - false); + false, false); GGML_ASSERT(n_tokens >= 0); } GGML_ASSERT(n_tokens <= (int) tok_sample.size()); diff --git a/examples/batched.swift/Sources/main.swift b/examples/batched.swift/Sources/main.swift index 938f30512..05d1bb9d0 100644 --- a/examples/batched.swift/Sources/main.swift +++ b/examples/batched.swift/Sources/main.swift @@ -209,7 +209,7 @@ llama_print_timings(context) private func tokenize(text: String, add_bos: Bool) -> [llama_token] { let n_tokens = text.count + (add_bos ? 1 : 0) let tokens = UnsafeMutablePointer.allocate(capacity: n_tokens) - let tokenCount = llama_tokenize(model, text, Int32(text.count), tokens, Int32(n_tokens), add_bos) + let tokenCount = llama_tokenize(model, text, Int32(text.count), tokens, Int32(n_tokens), add_bos, /*special tokens*/ false) var swiftTokens: [llama_token] = [] for i in 0 ..< tokenCount { swiftTokens.append(tokens[Int(i)]) diff --git a/examples/main/main.cpp b/examples/main/main.cpp index 55f73356f..a5fb65548 100644 --- a/examples/main/main.cpp +++ b/examples/main/main.cpp @@ -238,7 +238,7 @@ int main(int argc, char ** argv) { if (params.interactive_first || params.instruct || !params.prompt.empty() || session_tokens.empty()) { LOG("tokenize the prompt\n"); - embd_inp = ::llama_tokenize(ctx, params.prompt, add_bos); + embd_inp = ::llama_tokenize(ctx, params.prompt, add_bos, true); } else { LOG("use session tokens\n"); embd_inp = session_tokens; @@ -260,10 +260,10 @@ int main(int argc, char ** argv) { if (ctx_guidance) { LOG("cfg_negative_prompt: \"%s\"\n", log_tostr(sparams.cfg_negative_prompt)); - guidance_inp = ::llama_tokenize(ctx_guidance, sparams.cfg_negative_prompt, add_bos); + guidance_inp = ::llama_tokenize(ctx_guidance, sparams.cfg_negative_prompt, add_bos, true); LOG("guidance_inp tokenized: %s\n", LOG_TOKENS_TOSTR_PRETTY(ctx_guidance, guidance_inp)); - std::vector original_inp = ::llama_tokenize(ctx, params.prompt, add_bos); + std::vector original_inp = ::llama_tokenize(ctx, params.prompt, add_bos, true); LOG("original_inp tokenized: %s\n", LOG_TOKENS_TOSTR_PRETTY(ctx, original_inp)); original_prompt_len = original_inp.size(); @@ -320,8 +320,8 @@ int main(int argc, char ** argv) { } // prefix & suffix for instruct mode - const auto inp_pfx = ::llama_tokenize(ctx, "\n\n### Instruction:\n\n", add_bos); - const auto inp_sfx = ::llama_tokenize(ctx, "\n\n### Response:\n\n", false); + const auto inp_pfx = ::llama_tokenize(ctx, "\n\n### Instruction:\n\n", add_bos, true); + const auto inp_sfx = ::llama_tokenize(ctx, "\n\n### Response:\n\n", false, true); LOG("inp_pfx: %s\n", LOG_TOKENS_TOSTR_PRETTY(ctx, inp_pfx)); LOG("inp_sfx: %s\n", LOG_TOKENS_TOSTR_PRETTY(ctx, inp_sfx)); @@ -383,6 +383,12 @@ int main(int argc, char ** argv) { if (!params.antiprompt.empty()) { for (const auto & antiprompt : params.antiprompt) { LOG_TEE("Reverse prompt: '%s'\n", antiprompt.c_str()); + if (params.verbose_prompt) { + auto tmp = ::llama_tokenize(ctx, antiprompt, false, true); + for (int i = 0; i < (int) tmp.size(); i++) { + LOG_TEE("%6d -> '%s'\n", tmp[i], llama_token_to_piece(ctx, tmp[i]).c_str()); + } + } } } @@ -392,10 +398,22 @@ int main(int argc, char ** argv) { if (!params.input_prefix.empty()) { LOG_TEE("Input prefix: '%s'\n", params.input_prefix.c_str()); + if (params.verbose_prompt) { + auto tmp = ::llama_tokenize(ctx, params.input_prefix, true, true); + for (int i = 0; i < (int) tmp.size(); i++) { + LOG_TEE("%6d -> '%s'\n", tmp[i], llama_token_to_piece(ctx, tmp[i]).c_str()); + } + } } if (!params.input_suffix.empty()) { LOG_TEE("Input suffix: '%s'\n", params.input_suffix.c_str()); + if (params.verbose_prompt) { + auto tmp = ::llama_tokenize(ctx, params.input_suffix, false, true); + for (int i = 0; i < (int) tmp.size(); i++) { + LOG_TEE("%6d -> '%s'\n", tmp[i], llama_token_to_piece(ctx, tmp[i]).c_str()); + } + } } } LOG_TEE("sampling: repeat_last_n = %d, repeat_penalty = %f, presence_penalty = %f, frequency_penalty = %f, top_k = %d, tfs_z = %f, top_p = %f, typical_p = %f, temp = %f, mirostat = %d, mirostat_lr = %f, mirostat_ent = %f\n", @@ -717,7 +735,7 @@ int main(int argc, char ** argv) { if (params.interactive) { if (!params.antiprompt.empty()) { // tokenize and inject first reverse prompt - const auto first_antiprompt = ::llama_tokenize(ctx, params.antiprompt.front(), false); + const auto first_antiprompt = ::llama_tokenize(ctx, params.antiprompt.front(), false, true); embd_inp.insert(embd_inp.end(), first_antiprompt.begin(), first_antiprompt.end()); is_antiprompt = true; } @@ -744,8 +762,7 @@ int main(int argc, char ** argv) { std::string buffer; if (!params.input_prefix.empty()) { LOG("appending input prefix: '%s'\n", params.input_prefix.c_str()); - buffer += params.input_prefix; - printf("%s", buffer.c_str()); + printf("%s", params.input_prefix.c_str()); } // color user input only @@ -767,7 +784,6 @@ int main(int argc, char ** argv) { // append input suffix if any if (!params.input_suffix.empty()) { LOG("appending input suffix: '%s'\n", params.input_suffix.c_str()); - buffer += params.input_suffix; printf("%s", params.input_suffix.c_str()); } @@ -782,10 +798,14 @@ int main(int argc, char ** argv) { embd_inp.insert(embd_inp.end(), inp_pfx.begin(), inp_pfx.end()); } - const auto line_inp = ::llama_tokenize(ctx, buffer, false); + const auto line_pfx = ::llama_tokenize(ctx, params.input_prefix, false, true); + const auto line_inp = ::llama_tokenize(ctx, buffer, false, false); + const auto line_sfx = ::llama_tokenize(ctx, params.input_suffix, false, true); LOG("input tokens: %s\n", LOG_TOKENS_TOSTR_PRETTY(ctx, line_inp)); + embd_inp.insert(embd_inp.end(), line_pfx.begin(), line_pfx.end()); embd_inp.insert(embd_inp.end(), line_inp.begin(), line_inp.end()); + embd_inp.insert(embd_inp.end(), line_sfx.begin(), line_sfx.end()); // instruct mode: insert response suffix if (params.instruct) { diff --git a/llama.cpp b/llama.cpp index 5329bd828..82b7638ae 100644 --- a/llama.cpp +++ b/llama.cpp @@ -75,6 +75,7 @@ #include #include #include +#include #if defined(_MSC_VER) #pragma warning(disable: 4244 4267) // possible loss of data @@ -1183,6 +1184,8 @@ struct llama_vocab { std::unordered_map token_to_id; std::vector id_to_token; + std::unordered_map special_tokens_cache; + std::map, int> bpe_ranks; // default LLaMA special tokens @@ -2125,7 +2128,7 @@ static void llm_load_hparams( } // TODO: This should probably be in llama.h -static std::vector llama_tokenize_internal(const llama_vocab & vocab, std::string raw_text, bool bos); +static std::vector llama_tokenize_internal(const llama_vocab & vocab, std::string raw_text, bool bos, bool special = false); static llama_token llama_byte_to_token(const llama_vocab & vocab, uint8_t ch); static void llm_load_vocab( @@ -2241,6 +2244,101 @@ static void llm_load_vocab( GGUF_GET_KEY(ctx, vocab.special_unk_id, gguf_get_val_u32, GGUF_TYPE_UINT32, false, kv(LLM_KV_TOKENIZER_UNK_ID)); GGUF_GET_KEY(ctx, vocab.special_sep_id, gguf_get_val_u32, GGUF_TYPE_UINT32, false, kv(LLM_KV_TOKENIZER_SEP_ID)); GGUF_GET_KEY(ctx, vocab.special_pad_id, gguf_get_val_u32, GGUF_TYPE_UINT32, false, kv(LLM_KV_TOKENIZER_PAD_ID)); + + // build special tokens cache + { + // TODO: It is unclear (to me) at this point, whether special tokes are guaranteed to be of a deterministic type, + // and will always be correctly labeled in 'added_tokens.json' etc. + // The assumption is, since special tokens aren't meant to be exposed to end user, they are designed + // to be unmatchable by the tokenizer, therefore tokens from the vocab, which are unmatchable by the tokenizer + // are special tokens. + // From testing, this appears to corelate 1:1 with special tokens. + // + + // Counting special tokens and verifying in only one direction + // is sufficient to detect difference in those two sets. + // + uint32_t special_tokens_count_by_type = 0; + uint32_t special_tokens_count_from_verification = 0; + + bool special_tokens_definition_mismatch = false; + + for (const auto & t : vocab.token_to_id) { + const auto & token = t.first; + const auto & id = t.second; + + // Count all non-normal tokens in the vocab while iterating + if (vocab.id_to_token[id].type != LLAMA_TOKEN_TYPE_NORMAL) { + special_tokens_count_by_type++; + } + + // Skip single character tokens + if (token.length() > 1) { + bool is_tokenizable = false; + + // Split token string representation in two, in all possible ways + // and check if both halves can be matched to a valid token + for (unsigned i = 1; i < token.length();) { + const auto left = token.substr(0, i); + const auto right = token.substr(i); + + // check if we didnt partition in the middle of a utf sequence + auto utf = utf8_len(left.at(left.length() - 1)); + + if (utf == 1) { + if (vocab.token_to_id.find(left) != vocab.token_to_id.end() && + vocab.token_to_id.find(right) != vocab.token_to_id.end() ) { + is_tokenizable = true; + break; + } + i++; + } else { + // skip over the rest of multibyte utf sequence + i += utf - 1; + } + } + + if (!is_tokenizable) { + // Some tokens are multibyte, but they are utf sequences with equivalent text length of 1 + // it's faster to re-filter them here, since there are way less candidates now + + // Calculate a total "utf" length of a token string representation + size_t utf8_str_len = 0; + for (unsigned i = 0; i < token.length();) { + utf8_str_len++; + i += utf8_len(token.at(i)); + } + + // And skip the ones which are one character + if (utf8_str_len > 1) { + // At this point what we have left are special tokens only + vocab.special_tokens_cache[token] = id; + + // Count manually found special tokens + special_tokens_count_from_verification++; + + // If this manually found special token is not marked as such, flag a mismatch + if (vocab.id_to_token[id].type == LLAMA_TOKEN_TYPE_NORMAL) { + special_tokens_definition_mismatch = true; + } + } + } + } + } + + if (special_tokens_definition_mismatch || special_tokens_count_from_verification != special_tokens_count_by_type) { + fprintf(stderr, "%s: warning: Mismatch in special tokens definition ( %u/%zu vs %u/%zu ).\n", + __func__, + special_tokens_count_from_verification, vocab.id_to_token.size(), + special_tokens_count_by_type, vocab.id_to_token.size() + ); + } else { + fprintf(stderr, "%s: Special tokens definition check successful ( %u/%zu ).\n", + __func__, + special_tokens_count_from_verification, vocab.id_to_token.size() + ); + } + } } static void llm_load_print_meta(llama_model_loader & ml, llama_model & model) { @@ -6464,7 +6562,137 @@ private: llm_bigram_bpe::queue work_queue; }; -static std::vector llama_tokenize_internal(const llama_vocab & vocab, std::string raw_text, bool bos) { +typedef enum FRAGMENT_BUFFER_VARIANT_TYPE{ + FRAGMENT_BUFFER_VARIANT_TYPE_TOKEN, + FRAGMENT_BUFFER_VARIANT_TYPE_RAW_TEXT +} FRAGMENT_BUFFER_VARIANT_TYPE; + +struct fragment_buffer_variant{ + fragment_buffer_variant(llama_vocab::id _token) + : + type(FRAGMENT_BUFFER_VARIANT_TYPE_TOKEN), + token(_token), + raw_text(_dummy), + offset(0), + length(0){} + fragment_buffer_variant(const std::string & _raw_text, int64_t _offset, int64_t _length) + : + type(FRAGMENT_BUFFER_VARIANT_TYPE_RAW_TEXT), + token((llama_vocab::id)-1), + raw_text(_raw_text), + offset(_offset), + length(_length){ + GGML_ASSERT( _offset >= 0 ); + GGML_ASSERT( _length >= 1 ); + GGML_ASSERT( offset + length <= raw_text.length() ); + } + + const FRAGMENT_BUFFER_VARIANT_TYPE type; + const llama_vocab::id token; + const std::string _dummy; + const std::string & raw_text; + const uint64_t offset; + const uint64_t length; +}; + +// #define PRETOKENIZERDEBUG + +static void tokenizer_st_partition(const llama_vocab & vocab, std::forward_list & buffer) +{ + // for each special token + for (const auto & st: vocab.special_tokens_cache) { + const auto & special_token = st.first; + const auto & special_id = st.second; + + // for each text fragment + std::forward_list::iterator it = buffer.begin(); + while (it != buffer.end()) { + auto & fragment = (*it); + + // if a fragment is text ( not yet processed ) + if (fragment.type == FRAGMENT_BUFFER_VARIANT_TYPE_RAW_TEXT) { + auto * raw_text = &(fragment.raw_text); + + auto raw_text_base_offset = fragment.offset; + auto raw_text_base_length = fragment.length; + + // loop over the text + while (true) { + // find the first occurence of a given special token in this fragment + // passing offset argument only limit the "search area" but match coordinates + // are still relative to the source full raw_text + auto match = raw_text->find(special_token, raw_text_base_offset); + + // no occurences found, stop processing this fragment for a given special token + if (match == std::string::npos) break; + + // check if match is within bounds of offset <-> length + if (match + special_token.length() > raw_text_base_offset + raw_text_base_length) break; + +#ifdef PRETOKENIZERDEBUG + fprintf(stderr, "FF: (%ld %ld %ld) '%s'\n", raw_text->length(), raw_text_base_offset, raw_text_base_length, raw_text->substr(raw_text_base_offset, raw_text_base_length).c_str()); +#endif + auto source = std::distance(buffer.begin(), it); + + // if match is further than base offset + // then we have some text to the left of it + if (match > raw_text_base_offset) { + // left + const int64_t left_reminder_offset = raw_text_base_offset + 0; + const int64_t left_reminder_length = match - raw_text_base_offset; + buffer.emplace_after(it, (*raw_text), left_reminder_offset, left_reminder_length); + +#ifdef PRETOKENIZERDEBUG + fprintf(stderr, "FL: (%ld %ld) '%s'\n", left_reminder_offset, left_reminder_length, raw_text->substr(left_reminder_offset, left_reminder_length).c_str()); +#endif + it++; + } + + // special token + buffer.emplace_after(it, special_id); + it++; + + // right + if (match + special_token.length() < raw_text_base_offset + raw_text_base_length) { + const int64_t right_reminder_offset = match + special_token.length(); + const int64_t right_reminder_length = raw_text_base_length - ((match - raw_text_base_offset) + special_token.length()); + buffer.emplace_after(it, (*raw_text), right_reminder_offset, right_reminder_length); + +#ifdef PRETOKENIZERDEBUG + fprintf(stderr, "FR: (%ld %ld) '%s'\n", right_reminder_offset, right_reminder_length, raw_text->substr(right_reminder_offset, right_reminder_length).c_str()); +#endif + + it++; + + if (source == 0) { + buffer.erase_after(buffer.before_begin()); + } else { + buffer.erase_after(std::next(buffer.begin(), (source-1))); + } + + // repeat for the right side + raw_text_base_offset = right_reminder_offset; + raw_text_base_length = right_reminder_length; + +#ifdef PRETOKENIZERDEBUG + fprintf(stderr, "RR: (%ld %ld) '%s'\n", raw_text_base_offset, raw_text_base_length, raw_text->substr(raw_text_base_offset, raw_text_base_length).c_str()); +#endif + } else { + if (source == 0) { + buffer.erase_after(buffer.before_begin()); + } else { + buffer.erase_after(std::next(buffer.begin(), (source-1))); + } + break; + } + } + } + it++; + } + } +} + +static std::vector llama_tokenize_internal(const llama_vocab & vocab, std::string raw_text, bool bos, bool special) { std::vector output; // OG tokenizer behavior: @@ -6480,20 +6708,58 @@ static std::vector llama_tokenize_internal(const llama_vocab & return output; } + std::forward_list fragment_buffer; + fragment_buffer.emplace_front( raw_text, 0, raw_text.length() ); + + if (special) tokenizer_st_partition( vocab, fragment_buffer ); + switch (vocab.type) { case LLAMA_VOCAB_TYPE_SPM: { - // without adding this leading whitespace, we do not get the same results as the original tokenizer - raw_text = " " + raw_text; + for (const auto & fragment: fragment_buffer) + { + if (fragment.type == FRAGMENT_BUFFER_VARIANT_TYPE_RAW_TEXT) + { + // without adding this leading whitespace, we do not get the same results as the original tokenizer - llm_tokenizer_spm tokenizer(vocab); - llama_escape_whitespace(raw_text); - tokenizer.tokenize(raw_text, output); + // TODO: It's likely possible to get rid of this string copy entirely + // by modifying llm_tokenizer_x to operate with string offsets like pre-tokenizer + // and passing 'add space prefix' as bool argument + // + auto raw_text = (special ? "" : " ") + fragment.raw_text.substr(fragment.offset, fragment.length); + +#ifdef PRETOKENIZERDEBUG + fprintf(stderr,"TT: (%ld %ld %ld) '%s'\n", raw_text.length(), fragment.offset, fragment.length, raw_text.c_str()); +#endif + llm_tokenizer_spm tokenizer(vocab); + llama_escape_whitespace(raw_text); + tokenizer.tokenize(raw_text, output); + } + else // if (fragment.type == FRAGMENT_BUFFER_VARIANT_TYPE_TOKEN) + { + output.push_back(fragment.token); + } + } } break; case LLAMA_VOCAB_TYPE_BPE: { - llm_tokenizer_bpe tokenizer(vocab); - tokenizer.tokenize(raw_text, output); + for (const auto & fragment: fragment_buffer) + { + if (fragment.type == FRAGMENT_BUFFER_VARIANT_TYPE_RAW_TEXT) + { + auto raw_text = fragment.raw_text.substr(fragment.offset, fragment.length); + +#ifdef PRETOKENIZERDEBUG + fprintf(stderr,"TT: (%ld %ld %ld) '%s'\n", raw_text.length(), fragment.offset, fragment.length, raw_text.c_str()); +#endif + llm_tokenizer_bpe tokenizer(vocab); + tokenizer.tokenize(raw_text, output); + } + else // if (fragment.type == FRAGMENT_BUFFER_VARIANT_TYPE_TOKEN) + { + output.push_back(fragment.token); + } + } } break; } @@ -9407,15 +9673,15 @@ llama_token llama_token_eot(const struct llama_context * ctx) { return ctx->model.vocab.special_eot_id; } - int llama_tokenize( const struct llama_model * model, const char * text, int text_len, llama_token * tokens, int n_max_tokens, - bool add_bos) { - auto res = llama_tokenize_internal(model->vocab, std::string(text, text_len), add_bos); + bool add_bos, + bool special) { + auto res = llama_tokenize_internal(model->vocab, std::string(text, text_len), add_bos, special); if (n_max_tokens < (int) res.size()) { // LLAMA_LOG_ERROR("%s: too many tokens\n", __func__); diff --git a/llama.h b/llama.h index a78015ada..b13f23123 100644 --- a/llama.h +++ b/llama.h @@ -511,17 +511,20 @@ extern "C" { // Tokenization // - // Convert the provided text into tokens. - // The tokens pointer must be large enough to hold the resulting tokens. - // Returns the number of tokens on success, no more than n_max_tokens - // Returns a negative number on failure - the number of tokens that would have been returned + /// @details Convert the provided text into tokens. + /// @param tokens The tokens pointer must be large enough to hold the resulting tokens. + /// @return Returns the number of tokens on success, no more than n_max_tokens + /// @return Returns a negative number on failure - the number of tokens that would have been returned + /// @param special Allow tokenizing special and/or control tokens which otherwise are not exposed and treated as plaintext. + /// Does not insert a leading space. LLAMA_API int llama_tokenize( const struct llama_model * model, const char * text, int text_len, llama_token * tokens, int n_max_tokens, - bool add_bos); + bool add_bos, + bool special); // Token Id -> Piece. // Uses the vocabulary in the provided context.