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tokenizer : special token handling (#3538)

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* 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 <ggerganov@gmail.com>
This commit is contained in:
staviq
2023-10-17 17:11:01 +02:00
committed by GitHub
parent 281ef73c25
commit 1a159553f9
7 changed files with 332 additions and 39 deletions
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290
llama.cpp
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@@ -75,6 +75,7 @@
#include <thread>
#include <unordered_map>
#include <set>
#include <forward_list>
#if defined(_MSC_VER)
#pragma warning(disable: 4244 4267) // possible loss of data
@@ -1183,6 +1184,8 @@ struct llama_vocab {
std::unordered_map<token, id> token_to_id;
std::vector<token_data> id_to_token;
std::unordered_map<token, id> special_tokens_cache;
std::map<std::pair<std::string, std::string>, 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_vocab::id> llama_tokenize_internal(const llama_vocab & vocab, std::string raw_text, bool bos);
static std::vector<llama_vocab::id> 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_vocab::id> 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<fragment_buffer_variant> & 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<fragment_buffer_variant>::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_vocab::id> llama_tokenize_internal(const llama_vocab & vocab, std::string raw_text, bool bos, bool special) {
std::vector<llama_vocab::id> output;
// OG tokenizer behavior:
@@ -6480,20 +6708,58 @@ static std::vector<llama_vocab::id> llama_tokenize_internal(const llama_vocab &
return output;
}
std::forward_list<fragment_buffer_variant> 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__);