#include "llama-grammar.h"
#include "llama-impl.h"
#include "llama-vocab.h"
#include "llama-sampler.h"
#include <cmath>
#include <algorithm>
#include <cstdint>
#include <set>
#include <stdexcept>
#define MAX_REPETITION_THRESHOLD 2000
//
// helpers
//
// NOTE: assumes valid utf8 (but checks for overrun)
static std::pair<uint32_t, const char *> decode_utf8(const char * src) {
static const int lookup[] = { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 4 };
uint8_t first_byte = static_cast<uint8_t>(*src);
uint8_t highbits = first_byte >> 4;
int len = lookup[highbits];
uint8_t mask = (1 << (8 - len)) - 1;
uint32_t value = first_byte & mask;
const char * end = src + len; // may overrun!
const char * pos = src + 1;
for ( ; pos < end && *pos; pos++) {
value = (value << 6) + (static_cast<uint8_t>(*pos) & 0x3F);
}
return std::make_pair(value, pos);
}
static std::pair<std::vector<uint32_t>, llama_partial_utf8> decode_utf8(
const std::string & src,
llama_partial_utf8 partial_start) {
static const int lookup[] = { 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 2, 2, 3, 4 };
const char * pos = src.c_str();
std::vector<uint32_t> code_points;
// common english strings have the same number of codepoints and bytes. `+ 1` for the terminating 0.
code_points.reserve(src.size() + 1);
uint32_t value = partial_start.value;
int n_remain = partial_start.n_remain;
// continue previous decode, if applicable
while (*pos != 0 && n_remain > 0) {
uint8_t next_byte = static_cast<uint8_t>(*pos);
if ((next_byte >> 6) != 2) {
// invalid sequence, abort
code_points.push_back(0);
return std::make_pair(std::move(code_points), llama_partial_utf8{ 0, -1 });
}
value = (value << 6) + (next_byte & 0x3F);
++pos;
--n_remain;
}
if (partial_start.n_remain > 0 && n_remain == 0) {
code_points.push_back(value);
}
// decode any subsequent utf-8 sequences, which may end in an incomplete one
while (*pos != 0) {
uint8_t first_byte = static_cast<uint8_t>(*pos);
uint8_t highbits = first_byte >> 4;
n_remain = lookup[highbits] - 1;
if (n_remain < 0) {
// invalid sequence, abort
code_points.clear();
code_points.push_back(0);
return std::make_pair(std::move(code_points), llama_partial_utf8{ 0, n_remain });
}
uint8_t mask = (1 << (7 - n_remain)) - 1;
value = first_byte & mask;
++pos;
while (*pos != 0 && n_remain > 0) {
value = (value << 6) + (static_cast<uint8_t>(*pos) & 0x3F);
++pos;
--n_remain;
}
if (n_remain == 0) {
code_points.push_back(value);
}
}
code_points.push_back(0);
return std::make_pair(std::move(code_points), llama_partial_utf8{ value, n_remain });
}
static bool is_digit_char(char c) {
return '0' <= c && c <= '9';
}
static bool is_word_char(char c) {
return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || c == '-' || is_digit_char(c);
}
static std::pair<uint32_t, const char *> parse_hex(const char * src, int size) {
const char * pos = src;
const char * end = src + size;
uint32_t value = 0;
for ( ; pos < end && *pos; pos++) {
value <<= 4;
char c = *pos;
if ('a' <= c && c <= 'f') {
value += c - 'a' + 10;
} else if ('A' <= c && c <= 'F') {
value += c - 'A' + 10;
} else if ('0' <= c && c <= '9') {
value += c - '0';
} else {
break;
}
}
if (pos != end) {
throw std::runtime_error("expecting " + std::to_string(size) + " hex chars at " + src);
}
return std::make_pair(value, pos);
}
static const char * parse_space(const char * src, bool newline_ok) {
const char * pos = src;
while (*pos == ' ' || *pos == '\t' || *pos == '#' ||
(newline_ok && (*pos == '\r' || *pos == '\n'))) {
if (*pos == '#') {
while (*pos && *pos != '\r' && *pos != '\n') {
pos++;
}
} else {
pos++;
}
}
return pos;
}
static const char * parse_name(const char * src) {
const char * pos = src;
while (is_word_char(*pos)) {
pos++;
}
if (pos == src) {
throw std::runtime_error(std::string("expecting name at ") + src);
}
return pos;
}
static const char * parse_int(const char * src) {
const char * pos = src;
while (is_digit_char(*pos)) {
pos++;
}
if (pos == src) {
throw std::runtime_error(std::string("expecting integer at ") + src);
}
return pos;
}
static std::pair<uint32_t, const char *> parse_char(const char * src) {
if (*src == '\\') {
switch (src[1]) {
case 'x': return parse_hex(src + 2, 2);
case 'u': return parse_hex(src + 2, 4);
case 'U': return parse_hex(src + 2, 8);
case 't': return std::make_pair('\t', src + 2);
case 'r': return std::make_pair('\r', src + 2);
case 'n': return std::make_pair('\n', src + 2);
case '\\':
case '"':
case '[':
case ']':
return std::make_pair(src[1], src + 2);
default:
throw std::runtime_error(std::string("unknown escape at ") + src);
}
} else if (*src) {
return decode_utf8(src);
}
throw std::runtime_error("unexpected end of input");
}
static std::pair<uint32_t, const char *> parse_token(const llama_vocab * vocab, const char * src) {
const char * pos = src;
if (*pos != '<') {
throw std::runtime_error(std::string("expecting '<' at ") + pos);
}
pos++;
// Parse <[id]>
if (*pos == '[') {
pos++;
const char * int_end = parse_int(pos);
uint32_t token_id = std::stoul(std::string(pos, int_end - pos));
pos = int_end;
if (*pos != ']') {
throw std::runtime_error(std::string("expecting ']' at ") + pos);
}
pos++;
if (*pos != '>') {
throw std::runtime_error(std::string("expecting '>' at ") + pos);
}
pos++;
return std::make_pair(token_id, pos);
}
if (vocab == nullptr) {
throw std::runtime_error(std::string("no vocab to parse token at ") + src);
}
// Parse <token> and tokenize to obtain the token id
while (*pos != 0 && *pos != '>') {
pos++;
}
if (*pos != '>') {
throw std::runtime_error(std::string("expecting '>' at ") + pos);
}
pos++;
llama_token tokens[2];
int32_t n_tokens = vocab->tokenize(src, static_cast<int32_t>(pos - src), tokens, 2, false, true);
if (n_tokens != 1) {
// must tokenize to exactly 1 token
throw std::runtime_error("invalid token '" + std::string(src, pos - src) + "'");
}
return std::make_pair(tokens[0], pos);
}
static void print_grammar_char(FILE * file, uint32_t c) {
if (0x20 <= c && c <= 0x7f) {
fprintf(file, "%c", static_cast<char>(c));
} else {
// cop out of encoding UTF-8
fprintf(file, "<U+%04X>", c);
}
}
static bool is_char_element(llama_grammar_element elem) {
switch (elem.type) {
case LLAMA_GRETYPE_CHAR: return true;
case LLAMA_GRETYPE_CHAR_NOT: return true;
case LLAMA_GRETYPE_CHAR_ALT: return true;
case LLAMA_GRETYPE_CHAR_RNG_UPPER: return true;
case LLAMA_GRETYPE_CHAR_ANY: return true;
default: return false;
}
}
static void print_rule_binary(FILE * file, const llama_grammar_rule & rule) {
for (auto elem : rule) {
switch (elem.type) {
case LLAMA_GRETYPE_END: fprintf(file, "END"); break;
case LLAMA_GRETYPE_ALT: fprintf(file, "ALT"); break;
case LLAMA_GRETYPE_RULE_REF: fprintf(file, "RULE_REF"); break;
case LLAMA_GRETYPE_CHAR: fprintf(file, "CHAR"); break;
case LLAMA_GRETYPE_CHAR_NOT: fprintf(file, "CHAR_NOT"); break;
case LLAMA_GRETYPE_CHAR_RNG_UPPER: fprintf(file, "CHAR_RNG_UPPER"); break;
case LLAMA_GRETYPE_CHAR_ALT: fprintf(file, "CHAR_ALT"); break;
case LLAMA_GRETYPE_CHAR_ANY: fprintf(file, "CHAR_ANY"); break;
case LLAMA_GRETYPE_TOKEN: fprintf(file, "TOKEN"); break;
case LLAMA_GRETYPE_TOKEN_NOT: fprintf(file, "TOKEN_NOT"); break;
}
switch (elem.type) {
case LLAMA_GRETYPE_END:
case LLAMA_GRETYPE_ALT:
case LLAMA_GRETYPE_RULE_REF:
fprintf(file, "(%u) ", elem.value);
break;
case LLAMA_GRETYPE_CHAR:
case LLAMA_GRETYPE_CHAR_NOT:
case LLAMA_GRETYPE_CHAR_RNG_UPPER:
case LLAMA_GRETYPE_CHAR_ALT:
case LLAMA_GRETYPE_CHAR_ANY:
fprintf(file, "(\"");
print_grammar_char(file, elem.value);
fprintf(file, "\") ");
break;
case LLAMA_GRETYPE_TOKEN:
fprintf(file, "<[");
fprintf(file, "%u", elem.value);
fprintf(file, "]> ");
break;
case LLAMA_GRETYPE_TOKEN_NOT:
fprintf(file, "!");
fprintf(file, "<[");
fprintf(file, "%u", elem.value);
fprintf(file, "]> ");
break;
}
}
fprintf(file, "\n");
}
static void print_rule(
FILE * file,
uint32_t rule_id,
const llama_grammar_rule & rule,
const std::map<uint32_t, std::string> & symbol_id_names) {
if (rule.empty() || rule.back().type != LLAMA_GRETYPE_END) {
throw std::runtime_error(
"malformed rule, does not end with LLAMA_GRETYPE_END: " + std::to_string(rule_id));
}
fprintf(file, "%s ::= ", symbol_id_names.at(rule_id).c_str());
for (size_t i = 0, end = rule.size() - 1; i < end; i++) {
llama_grammar_element elem = rule[i];
switch (elem.type) {
case LLAMA_GRETYPE_END:
throw std::runtime_error(
"unexpected end of rule: " + std::to_string(rule_id) + "," +
std::to_string(i));
case LLAMA_GRETYPE_ALT:
fprintf(file, "| ");
break;
case LLAMA_GRETYPE_RULE_REF:
fprintf(file, "%s ", symbol_id_names.at(elem.value).c_str());
break;
case LLAMA_GRETYPE_CHAR:
fprintf(file, "[");
print_grammar_char(file, elem.value);
break;
case LLAMA_GRETYPE_CHAR_NOT:
fprintf(file, "[^");
print_grammar_char(file, elem.value);
break;
case LLAMA_GRETYPE_CHAR_RNG_UPPER:
if (i == 0 || !is_char_element(rule[i - 1])) {
throw std::runtime_error(
"LLAMA_GRETYPE_CHAR_RNG_UPPER without preceding char: " +
std::to_string(rule_id) + "," + std::to_string(i));
}
fprintf(file, "-");
print_grammar_char(file, elem.value);
break;
case LLAMA_GRETYPE_CHAR_ALT:
if (i == 0 || !is_char_element(rule[i - 1])) {
throw std::runtime_error(
"LLAMA_GRETYPE_CHAR_ALT without preceding char: " +
std::to_string(rule_id) + "," + std::to_string(i));
}
print_grammar_char(file, elem.value);
break;
case LLAMA_GRETYPE_CHAR_ANY:
fprintf(file, ".");
break;
case LLAMA_GRETYPE_TOKEN:
fprintf(file, "<[");
fprintf(file, "%u", elem.value);
fprintf(file, "]> ");
break;
case LLAMA_GRETYPE_TOKEN_NOT:
fprintf(file, "!");
fprintf(file, "<[");
fprintf(file, "%u", elem.value);
fprintf(file, "]> ");
break;
}
if (is_char_element(elem)) {
switch (rule[i + 1].type) {
case LLAMA_GRETYPE_CHAR_ALT:
case LLAMA_GRETYPE_CHAR_RNG_UPPER:
case LLAMA_GRETYPE_CHAR_ANY:
break;
default:
fprintf(file, "] ");
}
}
}
fprintf(file, "\n");
}
//
// Regex utilities
//
size_t llama_grammar_trigger_pattern::find(const std::string & input) const {
auto find_start_pos = [](const std::smatch & match) {
// get from the first matched capturing group to the end of the string
size_t start = std::string::npos;
for (auto i = 1u; i < match.size(); i++) {
if (match.length(i) > 0) {
start = match.position(i);
break;
}
}
if (start == std::string::npos) {
start = match.position(0);
}
return start;
};
if (!pattern.empty() && pattern.front() == '^' && pattern.back() == '$') {
// match against the entire input
std::smatch match;
if (std::regex_match(input, match, regex)) {
return find_start_pos(match);
}
}
// search anywhere
std::smatch match;
if (std::regex_search(input, match, regex)) {
return find_start_pos(match);
}
return std::string::npos;
}
//
// implementation
//
uint32_t llama_grammar_parser::get_symbol_id(const char * src, size_t len) {
uint32_t next_id = static_cast<uint32_t>(symbol_ids.size());
auto result = symbol_ids.emplace(std::string(src, len), next_id);
return result.first->second;
}
uint32_t llama_grammar_parser::generate_symbol_id(const std::string & base_name) {
uint32_t next_id = static_cast<uint32_t>(symbol_ids.size());
symbol_ids[base_name + '_' + std::to_string(next_id)] = next_id;
return next_id;
}
void llama_grammar_parser::add_rule(uint32_t rule_id, const llama_grammar_rule & rule) {
if (rules.size() <= rule_id) {
rules.resize(rule_id + 1);
}
rules[rule_id] = rule;
}
const char * llama_grammar_parser::parse_alternates(
const char * src,
const std::string & rule_name,
uint32_t rule_id,
bool is_nested) {
llama_grammar_rule rule;
const char * pos = parse_sequence(src, rule_name, rule, is_nested);
while (*pos == '|') {
rule.push_back({LLAMA_GRETYPE_ALT, 0});
pos = parse_space(pos + 1, true);
pos = parse_sequence(pos, rule_name, rule, is_nested);
}
rule.push_back({LLAMA_GRETYPE_END, 0});
add_rule(rule_id, rule);
return pos;
}
const char * llama_grammar_parser::parse_sequence(
const char * src,
const std::string & rule_name,
llama_grammar_rule & rule,
bool is_nested) {
size_t last_sym_start = rule.size();
const char * pos = src;
uint64_t n_prev_rules = 1;
// use UINT64_MAX as the empty value because we aligned to the proper uint64_t type so -1 can't be used
// (though it's technically the same as -1 now)
auto handle_repetitions = [&](uint64_t min_times, uint64_t max_times) {
bool no_max = max_times == UINT64_MAX;
if (last_sym_start == rule.size()) {
throw std::runtime_error(std::string("expecting preceding item to */+/?/{ at ") + pos);
}
// apply transformation to previous symbol (last_sym_start to end) according to
// the following rewrite rules:
// S{m,n} --> S S S (m times) S'(n-m)
// S'(x) ::= S S'(x-1) |
// (... n-m definitions of these S' rules ...)
// S'(1) ::= S |
// S{m,} --> S S S (m times) S'
// S' ::= S S' |
// S* --> S{0,}
// --> S' ::= S S' |
// S+ --> S{1,}
// --> S S'
// S' ::= S S' |
// S? --> S{0,1}
// --> S'
// S' ::= S |
llama_grammar_rule prev_rule(rule.begin() + last_sym_start, rule.end());
// Calculate the total number of rules that will be generated by this repetition
uint64_t total_rules = 1; // Start with 1 for the original rule
if (!no_max && max_times > 0) {
total_rules = max_times;
} else if (min_times > 0) {
total_rules = min_times;
}
if (n_prev_rules * total_rules >= MAX_REPETITION_THRESHOLD) {
throw std::runtime_error("number of rules that are going to be repeated multiplied by the new repetition exceeds sane defaults, please reduce the number of repetitions or rule complexity");
}
if (min_times == 0) {
rule.resize(last_sym_start);
} else {
// Repeat the previous elements (min_times - 1) times
for (uint64_t i = 1; i < min_times; i++) {
rule.insert(rule.end(), prev_rule.begin(), prev_rule.end());
}
}
uint32_t last_rec_rule_id = 0;
auto n_opt = no_max ? 1 : max_times - min_times;
llama_grammar_rule rec_rule(prev_rule);
for (uint64_t i = 0; i < n_opt; i++) {
rec_rule.resize(prev_rule.size());
uint32_t rec_rule_id = generate_symbol_id( rule_name);
if (i > 0 || no_max) {
rec_rule.push_back({LLAMA_GRETYPE_RULE_REF, no_max ? rec_rule_id : last_rec_rule_id});
}
rec_rule.push_back({LLAMA_GRETYPE_ALT, 0});
rec_rule.push_back({LLAMA_GRETYPE_END, 0});
add_rule( rec_rule_id, rec_rule);
last_rec_rule_id = rec_rule_id;
}
if (n_opt > 0) {
rule.push_back({LLAMA_GRETYPE_RULE_REF, last_rec_rule_id});
}
n_prev_rules *= total_rules;
GGML_ASSERT(n_prev_rules >= 1);
};
while (*pos) {
if (*pos == '"') { // literal string
pos++;
last_sym_start = rule.size();
n_prev_rules = 1;
while (*pos != '"') {
if (!*pos) {
throw std::runtime_error("unexpected end of input");
}
auto char_pair = parse_char(pos);
pos = char_pair.second;
rule.push_back({LLAMA_GRETYPE_CHAR, char_pair.first});
}
pos = parse_space(pos + 1, is_nested);
} else if (*pos == '[') { // char range(s)
pos++;
enum llama_gretype start_type = LLAMA_GRETYPE_CHAR;
if (*pos == '^') {
pos++;
start_type = LLAMA_GRETYPE_CHAR_NOT;
}
last_sym_start = rule.size();
n_prev_rules = 1;
while (*pos != ']') {
if (!*pos) {
throw std::runtime_error("unexpected end of input");
}
auto char_pair = parse_char(pos);
pos = char_pair.second;
enum llama_gretype type = last_sym_start < rule.size()
? LLAMA_GRETYPE_CHAR_ALT
: start_type;
rule.push_back({type, char_pair.first});
if (pos[0] == '-' && pos[1] != ']') {
if (!pos[1]) {
throw std::runtime_error("unexpected end of input");
}
auto endchar_pair = parse_char(pos + 1);
pos = endchar_pair.second;
rule.push_back({LLAMA_GRETYPE_CHAR_RNG_UPPER, endchar_pair.first});
}
}
pos = parse_space(pos + 1, is_nested);
} else if (*pos == '<' || *pos == '!') { // token
auto type = LLAMA_GRETYPE_TOKEN;
if (*pos == '!') { // token inverse
type = LLAMA_GRETYPE_TOKEN_NOT;
pos++;
}
auto token_pair = parse_token(vocab, pos);
const char * token_end = token_pair.second;
last_sym_start = rule.size();
n_prev_rules = 1;
rule.push_back({type, token_pair.first});
pos = parse_space(token_end, is_nested);
} else if (is_word_char(*pos)) { // rule reference
const char * name_end = parse_name(pos);
uint32_t ref_rule_id = get_symbol_id(pos, name_end - pos);
pos = parse_space(name_end, is_nested);
last_sym_start = rule.size();
n_prev_rules = 1;
rule.push_back({LLAMA_GRETYPE_RULE_REF, ref_rule_id});
} else if (*pos == '(') { // grouping
// parse nested alternates into synthesized rule
pos = parse_space(pos + 1, true);
uint32_t n_rules_before = symbol_ids.size();
uint32_t sub_rule_id = generate_symbol_id(rule_name);
pos = parse_alternates(pos, rule_name, sub_rule_id, true);
n_prev_rules = std::max(1u, (uint32_t)symbol_ids.size() - n_rules_before);
last_sym_start = rule.size();
// output reference to synthesized rule
rule.push_back({LLAMA_GRETYPE_RULE_REF, sub_rule_id});
if (*pos != ')') {
throw std::runtime_error(std::string("expecting ')' at ") + pos);
}
pos = parse_space(pos + 1, is_nested);
} else if (*pos == '.') { // any char
last_sym_start = rule.size();
n_prev_rules = 1;
rule.push_back({LLAMA_GRETYPE_CHAR_ANY, 0});
pos = parse_space(pos + 1, is_nested);
} else if (*pos == '*') {
pos = parse_space(pos + 1, is_nested);
handle_repetitions(0, -1);
} else if (*pos == '+') {
pos = parse_space(pos + 1, is_nested);
handle_repetitions(1, -1);
} else if (*pos == '?') {
pos = parse_space(pos + 1, is_nested);
handle_repetitions(0, 1);
} else if (*pos == '{') {
pos = parse_space(pos + 1, is_nested);
if (!is_digit_char(*pos)) {
throw std::runtime_error(std::string("expecting an int at ") + pos);
}
const char * int_end = parse_int(pos);
uint64_t min_times = std::stoull(std::string(pos, int_end - pos));
pos = parse_space(int_end, is_nested);
uint64_t max_times = UINT64_MAX; // default: no max limit
if (*pos == '}') {
max_times = min_times;
pos = parse_space(pos + 1, is_nested);
} else if (*pos == ',') {
pos = parse_space(pos + 1, is_nested);
if (is_digit_char(*pos)) {
const char * int_end = parse_int(pos);
max_times = std::stoull(std::string(pos, int_end - pos));
pos = parse_space(int_end, is_nested);
}
if (*pos != '}') {
throw std::runtime_error(std::string("expecting '}' at ") + pos);
}
pos = parse_space(pos + 1, is_nested);
} else {
throw std::runtime_error(std::string("expecting ',' at ") + pos);
}
if (min_times > MAX_REPETITION_THRESHOLD) {
throw std::runtime_error(std::string("number of repetitions exceeds sane defaults, please reduce the number of repetitions"));
}
if (max_times != UINT64_MAX && max_times > MAX_REPETITION_THRESHOLD) {
max_times = UINT64_MAX;
}
handle_repetitions(min_times, max_times);
} else {
break;
}
}
return pos;
}
const char * llama_grammar_parser::parse_rule(const char * src) {
const char * name_end = parse_name(src);
const char * pos = parse_space(name_end, false);
size_t name_len = name_end - src;
uint32_t rule_id = get_symbol_id(src, name_len);
const std::string name(src, name_len);
if (!(pos[0] == ':' && pos[1] == ':' && pos[2] == '=')) {
throw std::runtime_error(std::string("expecting ::= at ") + pos);
}
pos = parse_space(pos + 3, true);
pos = parse_alternates(pos, name, rule_id, false);
if (*pos == '\r') {
pos += pos[1] == '\n' ? 2 : 1;
} else if (*pos == '\n') {
pos++;
} else if (*pos) {
throw std::runtime_error(std::string("expecting newline or end at ") + pos);
}
return parse_space(pos, true);
}
bool llama_grammar_parser::parse(const char * src) {
try {
const char * pos = parse_space(src, true);
while (*pos) {
pos = parse_rule(pos);
}
// Validate the state to ensure that all rules are defined
for (const auto & rule : rules) {
if (rule.empty()) {
throw std::runtime_error("Undefined rule");
}
for (const auto & elem : rule) {
if (elem.type == LLAMA_GRETYPE_RULE_REF) {
// Ensure that the rule at that location exists
if (elem.value >= rules.size() || rules[elem.value].empty()) {
// Get the name of the rule that is missing
for (const auto & kv : symbol_ids) {
if (kv.second == elem.value) {
throw std::runtime_error("Undefined rule identifier '" + kv.first + "'");
}
}
}
}
}
}
} catch (const std::exception & err) {
fprintf(stderr, "%s: error parsing grammar: %s\n\n%s\n", __func__, err.what(), src);
rules.clear();
return false;
}
return true;
}
void llama_grammar_parser::print(FILE * file) {
try {
std::map<uint32_t, std::string> symbol_id_names;
for (const auto & kv : symbol_ids) {
symbol_id_names[kv.second] = kv.first;
}
for (size_t i = 0, end = rules.size(); i < end; i++) {
// fprintf(file, "%zu: ", i);
// print_rule_binary(file, rules[i]);
print_rule(file, uint32_t(i), rules[i], symbol_id_names);
// fprintf(file, "\n");
}
} catch (const std::exception & err) {
fprintf(stderr, "\n%s: error printing grammar: %s\n", __func__, err.what());
}
}
llama_grammar_stack llama_grammar_parser::c_rules() const {
llama_grammar_stack ret;
ret.reserve(rules.size());
for (const auto & rule : rules) {
ret.push_back(rule.data());
}
return ret;
}
// returns true iff pos points to the end of one of the definitions of a rule
static bool llama_grammar_is_end_of_sequence(const llama_grammar_element * pos) {
switch (pos->type) {
case LLAMA_GRETYPE_END: return true; // NOLINT
case LLAMA_GRETYPE_ALT: return true; // NOLINT
default: return false;
}
}
// returns true iff chr satisfies the char range at pos (regular or inverse range)
// asserts that pos is pointing to a char range element
static std::pair<bool, const llama_grammar_element *> llama_grammar_match_char(
const llama_grammar_element * pos,
const uint32_t chr) {
bool found = false;
bool is_positive_char = pos->type == LLAMA_GRETYPE_CHAR || pos->type == LLAMA_GRETYPE_CHAR_ANY;
GGML_ASSERT(is_positive_char || pos->type == LLAMA_GRETYPE_CHAR_NOT); // NOLINT
do {
if (pos[1].type == LLAMA_GRETYPE_CHAR_RNG_UPPER) {
// inclusive range, e.g. [a-z]
found = found || (pos->value <= chr && chr <= pos[1].value);
pos += 2;
} else if (pos->type == LLAMA_GRETYPE_CHAR_ANY) {
// Any character matches "."
found = true;
pos += 1;
} else {
// exact char match, e.g. [a] or "a"
found = found || pos->value == chr;
pos += 1;
}
} while (pos->type == LLAMA_GRETYPE_CHAR_ALT);
return std::make_pair(found == is_positive_char, pos);
}
// returns true iff some continuation of the given partial UTF-8 sequence could satisfy the char
// range at pos (regular or inverse range)
// asserts that pos is pointing to a char range element
static bool llama_grammar_match_partial_char(
const llama_grammar_element * pos,
const llama_partial_utf8 partial_utf8) {
bool is_positive_char = pos->type == LLAMA_GRETYPE_CHAR || pos->type == LLAMA_GRETYPE_CHAR_ANY;
GGML_ASSERT(is_positive_char || pos->type == LLAMA_GRETYPE_CHAR_NOT);
uint32_t partial_value = partial_utf8.value;
int n_remain = partial_utf8.n_remain;
// invalid sequence or 7-bit char split across 2 bytes (overlong)
if (n_remain < 0 || (n_remain == 1 && partial_value < 2)) {
return false;
}
// range of possible code points this partial UTF-8 sequence could complete to
uint32_t low = partial_value << (n_remain * 6);
uint32_t high = low | ((1 << (n_remain * 6)) - 1);
if (low == 0) {
if (n_remain == 2) {
low = 1 << 11;
} else if (n_remain == 3) {
low = 1 << 16;
}
}
do {
if (pos[1].type == LLAMA_GRETYPE_CHAR_RNG_UPPER) {
// inclusive range, e.g. [a-z]
if (pos->value <= high && low <= pos[1].value) {
return is_positive_char;
}
pos += 2;
} else if (pos->type == LLAMA_GRETYPE_CHAR_ANY) {
// Any character matches "."
return true;
} else {
// exact char match, e.g. [a] or "a"
if (low <= pos->value && pos->value <= high) {
return is_positive_char;
}
pos += 1;
}
} while (pos->type == LLAMA_GRETYPE_CHAR_ALT);
return !is_positive_char;
}
// returns true iff token matches the rule at pos (regular or inverse)
// asserts that pos is pointing to a token element
static bool llama_grammar_match_token(
const llama_grammar_element * pos,
const llama_token token) {
GGML_ASSERT(pos->type == LLAMA_GRETYPE_TOKEN || pos->type == LLAMA_GRETYPE_TOKEN_NOT);
if (pos->type == LLAMA_GRETYPE_TOKEN) {
return pos->value == static_cast<uint32_t>(token);
}
if (pos->type == LLAMA_GRETYPE_TOKEN_NOT) {
return pos->value != static_cast<uint32_t>(token);
}
return false;
}
// transforms a grammar pushdown stack into N possible stacks, all ending
// at a character range (terminal element)
static void llama_grammar_advance_stack(
const llama_grammar_rules & rules,
const llama_grammar_stack & stack,
llama_grammar_stacks & new_stacks) {
std::vector<llama_grammar_stack> todo;
todo.push_back(stack);
auto stack_cmp = [](const llama_grammar_stack & a, const llama_grammar_stack & b) {
return std::lexicographical_compare(a.begin(), a.end(), b.begin(), b.end(),
[](const llama_grammar_element * pa, const llama_grammar_element * pb) {
return pa < pb; // Compare pointer addresses
}
);
};
std::set<llama_grammar_stack, decltype(stack_cmp)> seen(stack_cmp);
while (!todo.empty()) {
llama_grammar_stack curr_stack = std::move(todo.back());
todo.pop_back();
if (seen.find( curr_stack) != seen.end()) {
continue;
}
seen.insert(curr_stack);
if (curr_stack.empty()) {
if (std::find(new_stacks.begin(), new_stacks.end(), curr_stack) == new_stacks.end()) {
new_stacks.emplace_back(std::move(curr_stack));
}
continue;
}
const llama_grammar_element * pos = curr_stack.back();
switch (pos->type) {
case LLAMA_GRETYPE_RULE_REF: {
const size_t rule_id = static_cast<size_t>(pos->value);
const llama_grammar_element * subpos = rules[rule_id].data();
do {
// init new stack without the top (pos)
llama_grammar_stack next_stack(curr_stack.begin(), curr_stack.end() - 1);
if (!llama_grammar_is_end_of_sequence(pos + 1)) {
// if this rule ref is followed by another element, add that to stack
next_stack.push_back(pos + 1);
}
if (!llama_grammar_is_end_of_sequence(subpos)) {
// if alternate is nonempty, add to stack
next_stack.push_back(subpos);
}
todo.push_back(std::move(next_stack));
while (!llama_grammar_is_end_of_sequence(subpos)) {
// scan to end of alternate def
subpos++;
}
if (subpos->type == LLAMA_GRETYPE_ALT) {
// there's another alternate def of this rule to process
subpos++;
} else {
break;
}
} while (true);
break;
}
case LLAMA_GRETYPE_CHAR:
case LLAMA_GRETYPE_CHAR_NOT:
case LLAMA_GRETYPE_CHAR_ANY:
case LLAMA_GRETYPE_TOKEN:
case LLAMA_GRETYPE_TOKEN_NOT:
if (std::find(new_stacks.begin(), new_stacks.end(), curr_stack) == new_stacks.end()) {
// only add the stack if it's not a duplicate of one we already have
new_stacks.emplace_back(std::move(curr_stack));
}
break;
default:
// end of alternate (LLAMA_GRETYPE_END, LLAMA_GRETYPE_ALT) or middle of char range
// (LLAMA_GRETYPE_CHAR_ALT, LLAMA_GRETYPE_CHAR_RNG_UPPER); stack should never be left on
// those
GGML_ABORT("fatal error");
}
}
}
static llama_grammar_candidates llama_grammar_reject_candidates(
const llama_grammar_rules & rules,
const llama_grammar_stacks & stacks,
const llama_grammar_candidates & candidates) {
GGML_ASSERT(!stacks.empty()); // REVIEW
if (candidates.empty()) {
return {};
}
auto rejects = llama_grammar_reject_candidates_for_stack(rules, stacks.front(), candidates);
for (size_t i = 1, size = stacks.size(); i < size; ++i) {
rejects = llama_grammar_reject_candidates_for_stack(rules, stacks[i], rejects);
}
return rejects;
}
static bool llama_grammar_detect_left_recursion(
const llama_grammar_rules & rules,
size_t rule_index,
std::vector<bool> * rules_visited,
std::vector<bool> * rules_in_progress,
std::vector<bool> * rules_may_be_empty) {
if ((*rules_in_progress)[rule_index]) {
return true;
}
(*rules_in_progress)[rule_index] = true;
const llama_grammar_rule & rule = rules[rule_index];
// First check if the rule might produce the empty string. This could be done combined with the second
// step but it's more readable as two steps.
bool at_rule_start = true;
for (size_t i = 0; i < rule.size(); i++) {
if (llama_grammar_is_end_of_sequence(&rule[i])) {
if (at_rule_start) {
(*rules_may_be_empty)[rule_index] = true;
break;
}
at_rule_start = true;
} else {
at_rule_start = false;
}
}
// Second, recurse into leftmost nonterminals (or next-leftmost as long as the previous nonterminal may
// be empty)
bool recurse_into_nonterminal = true;
for (size_t i = 0; i < rule.size(); i++) {
if (rule[i].type == LLAMA_GRETYPE_RULE_REF && recurse_into_nonterminal) {
if (llama_grammar_detect_left_recursion(rules, (size_t)rule[i].value, rules_visited, rules_in_progress, rules_may_be_empty)) {
return true;
}
if (!((*rules_may_be_empty)[(size_t)rule[i].value])) {
recurse_into_nonterminal = false;
}
} else if (llama_grammar_is_end_of_sequence(&rule[i])) {
recurse_into_nonterminal = true;
} else {
recurse_into_nonterminal = false;
}
}
(*rules_in_progress)[rule_index] = false;
(*rules_visited)[rule_index] = true;
return false;
}
const llama_grammar_rules & llama_grammar_get_rules(const struct llama_grammar * grammar) {
return grammar->rules;
}
llama_grammar_stacks & llama_grammar_get_stacks(struct llama_grammar * grammar) {
return grammar->stacks;
}
static void llama_grammar_accept_chr(
struct llama_grammar & grammar,
const llama_grammar_stack & stack,
uint32_t chr,
llama_grammar_stacks & new_stacks) {
if (stack.empty()) {
return;
}
const llama_grammar_element * pos = stack.back();
// ignore if this turns into a token
if (pos->type == LLAMA_GRETYPE_TOKEN || pos->type == LLAMA_GRETYPE_TOKEN_NOT) {
return;
}
auto match = llama_grammar_match_char(pos, chr);
if (match.first) {
llama_grammar_stack new_stack(stack.begin(), stack.end() - 1);
if (!llama_grammar_is_end_of_sequence(match.second)) {
new_stack.push_back(match.second);
}
llama_grammar_advance_stack(grammar.rules, new_stack, new_stacks);
}
}
void llama_grammar_accept(struct llama_grammar * grammar, uint32_t chr) {
llama_grammar_stacks stacks_new;
stacks_new.reserve(grammar->stacks.size());
for (const auto & stack : grammar->stacks) {
llama_grammar_accept_chr(*grammar, stack, chr, stacks_new);
}
grammar->stacks = std::move(stacks_new);
}
llama_grammar_candidates llama_grammar_reject_candidates_for_stack(
const llama_grammar_rules & rules,
const llama_grammar_stack & stack,
const llama_grammar_candidates & candidates) {
llama_grammar_candidates rejects;
rejects.reserve(candidates.size());
if (stack.empty()) {
for (const auto & tok : candidates) {
if (*tok.code_points != 0 || tok.partial_utf8.n_remain != 0) {
rejects.push_back(tok);
}
}
return rejects;
}
const llama_grammar_element * stack_pos = stack.back();
// if the top of the stack is a token rule, then we only need to check the token id
if (stack_pos->type == LLAMA_GRETYPE_TOKEN || stack_pos->type == LLAMA_GRETYPE_TOKEN_NOT) {
for (const auto & tok : candidates) {
if (*tok.code_points == 0) {
// reached the end of a token consumed by char rules, reject iff it ended
// in a partial response
if (tok.partial_utf8.n_remain != 0) {
rejects.push_back(tok);
}
} else if (!llama_grammar_match_token(stack_pos, tok.id)) {
rejects.push_back(tok);
}
}
return rejects;
}
llama_grammar_candidates next_candidates;
next_candidates.reserve(candidates.size());
for (const auto & tok : candidates) {
if (*tok.code_points == 0) {
// reached end of full codepoints in token, reject iff it ended in a partial sequence
// that cannot satisfy this position in grammar
if (tok.partial_utf8.n_remain != 0 &&
!llama_grammar_match_partial_char(stack_pos, tok.partial_utf8)) {
rejects.push_back(tok);
}
} else if (llama_grammar_match_char(stack_pos, *tok.code_points).first) {
next_candidates.push_back({ tok.index, tok.code_points + 1, tok.partial_utf8, tok.id });
} else {
rejects.push_back(tok);
}
}
const auto * stack_pos_after = llama_grammar_match_char(stack_pos, 0).second;
// update top of stack to next element, if any
llama_grammar_stack stack_after(stack.begin(), stack.end() - 1);
if (!llama_grammar_is_end_of_sequence(stack_pos_after)) {
stack_after.push_back(stack_pos_after);
}
llama_grammar_stacks next_stacks;
llama_grammar_advance_stack(rules, stack_after, next_stacks);
auto next_rejects = llama_grammar_reject_candidates(rules, next_stacks, next_candidates);
for (const auto & tok : next_rejects) {
rejects.push_back({ tok.index, tok.code_points - 1, tok.partial_utf8, tok.id });
}
return rejects;
}
////////////////////
struct llama_grammar * llama_grammar_init_impl(
const struct llama_vocab * vocab,
const llama_grammar_element ** rules,
size_t n_rules,
size_t start_rule_index) {
const llama_grammar_element * pos;
// copy rule definitions into vectors
llama_grammar_rules vec_rules(n_rules);
for (size_t i = 0; i < n_rules; i++) {
for (pos = rules[i]; pos->type != LLAMA_GRETYPE_END; pos++) {
vec_rules[i].push_back(*pos);
}
vec_rules[i].push_back({LLAMA_GRETYPE_END, 0});
}
// Validate that all rule references point to valid rules
for (size_t i = 0; i < n_rules; i++) {
for (const auto & elem : vec_rules[i]) {
if (elem.type == LLAMA_GRETYPE_RULE_REF) {
if (elem.value >= n_rules || vec_rules[elem.value].empty()) {
LLAMA_LOG_ERROR("invalid grammar: rule %zu references undefined rule %u\n", i, elem.value);
return nullptr;
}
}
}
}
// Check for left recursion
std::vector<bool> rules_visited(n_rules);
std::vector<bool> rules_in_progress(n_rules);
std::vector<bool> rules_may_be_empty(n_rules);
for (size_t i = 0; i < n_rules; i++) {
if (rules_visited[i]) {
continue;
}
if (llama_grammar_detect_left_recursion(vec_rules, i, &rules_visited, &rules_in_progress, &rules_may_be_empty)) {
LLAMA_LOG_ERROR("unsupported grammar, left recursion detected for nonterminal at index %zu", i);
return nullptr;
}
}
// loop over alternates of start rule to build initial stacks
llama_grammar_stacks stacks;
pos = vec_rules[start_rule_index].data();
do {
llama_grammar_stack stack;
if (!llama_grammar_is_end_of_sequence(pos)) {
// if alternate is nonempty, add to stack
stack.push_back(pos);
}
llama_grammar_advance_stack(vec_rules, stack, stacks);
while (!llama_grammar_is_end_of_sequence(pos)) {
// scan to end of alternate def
pos++;
}
if (pos->type == LLAMA_GRETYPE_ALT) {
// there's another alternate def of this rule to process
pos++;
} else {
break;
}
} while (true);
// Important: vec_rules has to be moved here, not copied, because stacks contains
// pointers to elements of vec_rules. If vec_rules were copied into llama_grammar
// then the pointers would be invalidated when the local vec_rules goes out of scope.
return new llama_grammar {
vocab,
std::move(vec_rules),
std::move(stacks),
/* .partial_utf8 = */ {},
/* .lazy = */ false,
/* .awaiting_trigger = */ false,
/* .trigger_buffer = */ "",
/* .trigger_buffer_positions = */ {},
/* .trigger_tokens = */ {},
/* .trigger_patterns = */ {},
};
}
struct llama_grammar * llama_grammar_init_impl(
const struct llama_vocab * vocab,
const char * grammar_str,
const char * grammar_root,
bool lazy,
const char ** trigger_patterns,
size_t num_trigger_patterns,
const llama_token * trigger_tokens,
size_t num_trigger_tokens) {
llama_grammar_parser parser(vocab);
// if there is a grammar, parse it
// rules will be empty (default) if there are parse errors
if (!parser.parse(grammar_str) || parser.rules.empty()) {
LLAMA_LOG_ERROR("failed to parse grammar\n");
return nullptr;
}
// Ensure that the grammar contains the start symbol
if (parser.symbol_ids.find(grammar_root) == parser.symbol_ids.end()) {
LLAMA_LOG_ERROR("grammar does not contain a '%s' symbol\n", grammar_root);
return nullptr;
}
std::vector<const llama_grammar_element *> grammar_rules(parser.c_rules());
const size_t n_rules = grammar_rules.size();
const size_t start_rule_index = parser.symbol_ids.at(grammar_root);
const llama_grammar_element * pos;
// copy rule definitions into vectors
llama_grammar_rules vec_rules(n_rules);
for (size_t i = 0; i < n_rules; i++) {
for (pos = grammar_rules[i]; pos->type != LLAMA_GRETYPE_END; pos++) {
vec_rules[i].push_back(*pos);
}
vec_rules[i].push_back({LLAMA_GRETYPE_END, 0});
}
// Check for left recursion
std::vector<bool> rules_visited(n_rules);
std::vector<bool> rules_in_progress(n_rules);
std::vector<bool> rules_may_be_empty(n_rules);
for (size_t i = 0; i < n_rules; i++) {
if (rules_visited[i]) {
continue;
}
if (llama_grammar_detect_left_recursion(vec_rules, i, &rules_visited, &rules_in_progress, &rules_may_be_empty)) {
LLAMA_LOG_ERROR("unsupported grammar, left recursion detected for nonterminal at index %zu\n", i);
return nullptr;
}
}
// loop over alternates of start rule to build initial stacks
llama_grammar_stacks stacks;
pos = vec_rules[start_rule_index].data();
do {
llama_grammar_stack stack;
if (!llama_grammar_is_end_of_sequence(pos)) {
// if alternate is nonempty, add to stack
stack.push_back(pos);
}
llama_grammar_advance_stack(vec_rules, stack, stacks);
while (!llama_grammar_is_end_of_sequence(pos)) {
// scan to end of alternate def
pos++;
}
if (pos->type == LLAMA_GRETYPE_ALT) {
// there's another alternate def of this rule to process
pos++;
} else {
break;
}
} while (true);
std::vector<llama_token> vec_trigger_tokens;
std::vector<llama_grammar_trigger_pattern> vec_trigger_patterns;
for (size_t i = 0; i < num_trigger_tokens; i++) {
GGML_ASSERT(trigger_tokens != nullptr);
vec_trigger_tokens.push_back(trigger_tokens[i]);
}
for (size_t i = 0; i < num_trigger_patterns; i++) {
GGML_ASSERT(trigger_patterns != nullptr);
auto & trigger = vec_trigger_patterns.emplace_back();
trigger.pattern = trigger_patterns[i];
trigger.regex = std::regex(trigger.pattern);
}
// Important: vec_rules has to be moved here, not copied, because stacks contains
// pointers to elements of vec_rules. If vec_rules were copied into llama_grammar
// then the pointers would be invalidated when the local vec_rules goes out of scope.
return new llama_grammar {
vocab,
std::move(vec_rules),
std::move(stacks),
/* .partial_utf8 = */ {},
/* .lazy = */ lazy,
/* .awaiting_trigger = */ lazy,
/* .trigger_buffer = */ "",
/* .trigger_buffer_positions = */ {},
std::move(vec_trigger_tokens),
std::move(vec_trigger_patterns),
};
}
void llama_grammar_free_impl(struct llama_grammar * grammar) {
if (grammar == nullptr) {
return;
}
delete grammar;
}
struct llama_grammar * llama_grammar_clone_impl(const struct llama_grammar & grammar) {
auto * result = new llama_grammar {
grammar.vocab,
grammar.rules,
grammar.stacks,
grammar.partial_utf8,
grammar.lazy,
grammar.awaiting_trigger,
grammar.trigger_buffer,
grammar.trigger_buffer_positions,
grammar.trigger_tokens,
grammar.trigger_patterns,
};
// redirect elements in stacks to point to new rules
for (size_t is = 0; is < result->stacks.size(); is++) {
for (size_t ie = 0; ie < result->stacks[is].size(); ie++) {
for (size_t ir0 = 0; ir0 < grammar.rules.size(); ir0++) {
for (size_t ir1 = 0; ir1 < grammar.rules[ir0].size(); ir1++) {
if (grammar.stacks[is][ie] == &grammar.rules[ir0][ir1]) {
result->stacks[is][ie] = &result->rules[ir0][ir1];
}
}
}
}
}
return result;
}
void llama_grammar_apply_impl(const struct llama_grammar & grammar, llama_token_data_array * cur_p) {
GGML_ASSERT(grammar.vocab != nullptr);
if (grammar.awaiting_trigger) {
return;
}
bool allow_eog = false;
for (const auto & stack : grammar.stacks) {
if (stack.empty()) {
allow_eog = true;
break;
}
}
std::vector<std::pair<std::vector<uint32_t>, llama_partial_utf8>> candidates_decoded;
candidates_decoded.reserve(cur_p->size);
llama_grammar_candidates candidates_grammar;
candidates_grammar.reserve(cur_p->size);
for (size_t i = 0; i < cur_p->size; ++i) {
const llama_token id = cur_p->data[i].id;
const std::string & piece = grammar.vocab->token_to_piece(id);
if (grammar.vocab->is_eog(id)) {
if (!allow_eog) {
cur_p->data[i].logit = -INFINITY;
}
} else if (piece.empty() || piece[0] == 0) {
cur_p->data[i].logit = -INFINITY;
} else {
candidates_decoded.push_back(decode_utf8(piece, grammar.partial_utf8));
candidates_grammar.push_back({ i, candidates_decoded.back().first.data(), candidates_decoded.back().second, id });
}
}
const auto rejects = llama_grammar_reject_candidates(grammar.rules, grammar.stacks, candidates_grammar);
for (const auto & reject : rejects) {
cur_p->data[reject.index].logit = -INFINITY;
}
}
void llama_grammar_accept_impl(struct llama_grammar & grammar, llama_token token) {
GGML_ASSERT(grammar.vocab != nullptr);
const auto & piece = grammar.vocab->token_to_piece(token);
if (grammar.awaiting_trigger) {
if (std::find(grammar.trigger_tokens.begin(), grammar.trigger_tokens.end(), token) != grammar.trigger_tokens.end()) {
grammar.awaiting_trigger = false;
grammar.trigger_buffer.clear();
llama_grammar_accept_token(grammar, token, piece);
LLAMA_LOG_DEBUG("Grammar triggered on token %u (`%s`)", token, piece.c_str());
return;
} else {
auto position = std::make_pair(grammar.trigger_buffer.size(), grammar.trigger_buffer.size() + piece.size());
grammar.trigger_buffer_positions.push_back(std::make_pair(token, position));
grammar.trigger_buffer += piece;
for (const auto & trigger_pattern : grammar.trigger_patterns) {
auto start = trigger_pattern.find(grammar.trigger_buffer);
if (start != std::string::npos) {
grammar.awaiting_trigger = false;
// replay tokens that overlap with [start, end)
for (const auto & [tok, tok_pos] : grammar.trigger_buffer_positions) {
auto [tok_start, tok_end] = tok_pos;
if (tok_end <= start) {
continue;
}
size_t piece_start = (tok_start < start) ? start : tok_start; // allow for partial token pieces
size_t piece_len = tok_end - piece_start;
auto tok_piece = grammar.trigger_buffer.substr(piece_start, piece_len);
llama_grammar_accept_token(grammar, tok, tok_piece);
}
auto constrained_str = grammar.trigger_buffer.substr(start);
grammar.trigger_buffer.clear();
grammar.trigger_buffer_positions.clear();
LLAMA_LOG_DEBUG("Grammar triggered on regex: '%s'\n", constrained_str.c_str());
return;
}
}
LLAMA_LOG_DEBUG("Grammar still awaiting trigger after token %d (`%s`)\n", token, piece.c_str());
return;
}
}
if (grammar.vocab->is_eog(token)) {
for (const auto & stack : grammar.stacks) {
if (stack.empty()) {
return;
}
}
GGML_ABORT("fatal error");
}
llama_grammar_accept_token(grammar, token, piece);
}
void llama_grammar_accept_str(struct llama_grammar & grammar, const std::string & piece) {
// Note terminating 0 in decoded string
const auto decoded = decode_utf8(piece, grammar.partial_utf8);
const auto & code_points = decoded.first;
for (auto it = code_points.begin(), end = code_points.end() - 1; it != end; ++it) {
llama_grammar_accept(&grammar, *it);
}
grammar.partial_utf8 = decoded.second;
if (grammar.stacks.empty()) {
throw std::runtime_error("Unexpected empty grammar stack after accepting piece: " + piece);
}
}
void llama_grammar_accept_token(struct llama_grammar & grammar, llama_token token, const std::string & piece) {
// Note terminating 0 in decoded string
const auto decoded = decode_utf8(piece, grammar.partial_utf8);
const auto & code_points = decoded.first;
llama_grammar_stacks stacks_new;
stacks_new.reserve(grammar.stacks.size());
for (const auto & stack : grammar.stacks) {
if (stack.empty()) {
continue;
}
const llama_grammar_element * pos = stack.back();
if (pos->type == LLAMA_GRETYPE_TOKEN || pos->type == LLAMA_GRETYPE_TOKEN_NOT) {
if (llama_grammar_match_token(pos, token)) {
llama_grammar_stack new_stack(stack.begin(), stack.end() - 1);
if (!llama_grammar_is_end_of_sequence(pos + 1)) {
new_stack.push_back(pos + 1);
}
llama_grammar_advance_stack(grammar.rules, new_stack, stacks_new);
}
} else {
llama_grammar_stacks current_stacks = {stack};
for (auto it = code_points.begin(), end = code_points.end() - 1; it != end; ++it) {
llama_grammar_stacks next_stacks;
for (const auto & cur_stack : current_stacks) {
llama_grammar_accept_chr(grammar, cur_stack, *it, next_stacks);
}
current_stacks = std::move(next_stacks);
if (current_stacks.empty()) {
break;
}
}
for (auto & surviving_stack : current_stacks) {
if (std::find(stacks_new.begin(), stacks_new.end(), surviving_stack) == stacks_new.end()) {
stacks_new.emplace_back(surviving_stack);
}
}
}
}
grammar.stacks = std::move(stacks_new);
grammar.partial_utf8 = decoded.second;
if (grammar.stacks.empty()) {
throw std::runtime_error("Unexpected empty grammar stack after accepting piece: " + piece + " (" + std::to_string(token) + ")");
}
}