vbatts/llama.cpp
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grammars: x{min,max} repetition operator (#6640)

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* grammars: x{min,max} repetition operator + tweak +/*/? to avoid duplication of original over alternates

* grammars: handle `x{n}` and fix `x{n,n}`

* grammars: document new repetition operators

* grammars: uniform use of int for min & max

* grammars: refactor parser test

* grammar: parsing tests w/ natural pretty print of updated expectations

* grammars: much prettier print of expectations (+ TEST_GRAMMAR_PARSER_PRINT_ALL=1 to force all)

* grammars: improve test pretty print again

* grammars: pretty print rules and chars

* grammars: fix copy rule skipping

* grammars: disallow `a{,}` (not allowed in regexps)

* Update common/grammar-parser.cpp

Co-authored-by: Clint Herron <hanclinto@gmail.com>

* grammars: fix copy rule skipping (again) & display of expectations

* grammars: more test cases

* grammars: update reps parsing to bring ? / * / + closer to before

* json: use new GBNF repetitions{m,n} syntax

* grammars: update performance gotchas w/ repetition advice

* Update examples/json_schema_to_grammar.py

Co-authored-by: Clint Herron <hanclinto@gmail.com>

* Update examples/server/public/json-schema-to-grammar.mjs

Co-authored-by: Clint Herron <hanclinto@gmail.com>

* grammars: comment on rule repetitions

* grammars: ensure unambiguous number alternatives

* grammar: nit typo switched error msgs

* grammar: nit numbering in comment

* json: update numeric rule to be unambiguous

* Apply suggestions from code review

Co-authored-by: Clint Herron <hanclinto@gmail.com>

* Update examples/server/public/json-schema-to-grammar.mjs

Co-authored-by: Clint Herron <hanclinto@gmail.com>

* json: fix integral-part

* grammar: add repetition tests

---------

Co-authored-by: Clint Herron <hanclinto@gmail.com>
This commit is contained in:
Olivier Chafik 2024-06-06 10:07:06 +01:00 • committed by GitHub
parent f5d7b268ec
commit 55b2d0849d
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9 changed files with 736 additions and 418 deletions
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144
common/grammar-parser.cpp
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@ -46,8 +46,12 @@ namespace grammar_parser {
state.rules[rule_id] = rule;
}
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 == '-' || ('0' <= c && c <= '9');
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) {
@ -99,6 +103,17 @@ namespace grammar_parser {
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]) {
@ -137,6 +152,60 @@ namespace grammar_parser {
bool is_nested) {
size_t last_sym_start = out_elements.size();
const char * pos = src;
auto handle_repetitions = [&](int min_times, int max_times) {
if (last_sym_start == out_elements.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 |
std::vector<llama_grammar_element> previous_elements(out_elements.begin() + last_sym_start, out_elements.end());
if (min_times == 0) {
out_elements.resize(last_sym_start);
} else {
// Repeat the previous elements (min_times - 1) times
for (int i = 1; i < min_times; i++) {
out_elements.insert(out_elements.end(), previous_elements.begin(), previous_elements.end());
}
}
uint32_t last_rec_rule_id = 0;
auto n_opt = max_times < 0 ? 1 : max_times - min_times;
std::vector<llama_grammar_element> rec_rule(previous_elements);
for (int i = 0; i < n_opt; i++) {
rec_rule.resize(previous_elements.size());
uint32_t rec_rule_id = generate_symbol_id(state, rule_name);
if (i > 0 || max_times < 0) {
rec_rule.push_back({LLAMA_GRETYPE_RULE_REF, max_times < 0 ? 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(state, rec_rule_id, rec_rule);
last_rec_rule_id = rec_rule_id;
}
if (n_opt > 0) {
out_elements.push_back({LLAMA_GRETYPE_RULE_REF, last_rec_rule_id});
}
};
while (*pos) {
if (*pos == '"') { // literal string
pos++;
@ -197,40 +266,47 @@ namespace grammar_parser {
throw std::runtime_error(std::string("expecting ')' at ") + pos);
}
pos = parse_space(pos + 1, is_nested);
} else if (*pos == '*' || *pos == '+' || *pos == '?') { // repetition operator
if (last_sym_start == out_elements.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
// rewrite rules:
// S* --> S' ::= S S' |
// S+ --> S' ::= S S' | S
// S? --> S' ::= S |
uint32_t sub_rule_id = generate_symbol_id(state, rule_name);
std::vector<llama_grammar_element> sub_rule;
// add preceding symbol to generated rule
sub_rule.insert(
sub_rule.end(), out_elements.begin() + last_sym_start, out_elements.end());
if (*pos == '*' || *pos == '+') {
// cause generated rule to recurse
sub_rule.push_back({LLAMA_GRETYPE_RULE_REF, sub_rule_id});
}
// mark start of alternate def
sub_rule.push_back({LLAMA_GRETYPE_ALT, 0});
if (*pos == '+') {
// add preceding symbol as alternate only for '+' (otherwise empty)
sub_rule.insert(
sub_rule.end(), out_elements.begin() + last_sym_start, out_elements.end());
}
sub_rule.push_back({LLAMA_GRETYPE_END, 0});
add_rule(state, sub_rule_id, sub_rule);
// in original rule, replace previous symbol with reference to generated rule
out_elements.resize(last_sym_start);
out_elements.push_back({LLAMA_GRETYPE_RULE_REF, sub_rule_id});
} 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);
int min_times = std::stoul(std::string(pos, int_end - pos));
pos = parse_space(int_end, is_nested);
int max_times = -1;
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::stoul(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);
}
handle_repetitions(min_times, max_times);
} else {
break;
}