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grammars: x{min,max} repetition operator (ggerganov#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 <[email protected]>

* 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 <[email protected]>

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

Co-authored-by: Clint Herron <[email protected]>

* 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 <[email protected]>

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

Co-authored-by: Clint Herron <[email protected]>

* json: fix integral-part

* grammar: add repetition tests

---------

Co-authored-by: Clint Herron <[email protected]>
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@ochafik @HanClinto
ochafik and HanClinto authored Jun 6, 2024
1 parent f5d7b26 commit 55b2d08
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138 changes: 107 additions & 31 deletions common/grammar-parser.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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) {
Expand Down Expand Up @@ -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]) {
Expand Down Expand Up @@ -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++;
Expand Down Expand Up @@ -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);
}
} 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);

// 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());
if (!is_digit_char(*pos)) {
throw std::runtime_error(std::string("expecting an int at ") + pos);
}
sub_rule.push_back({LLAMA_GRETYPE_END, 0});
add_rule(state, sub_rule_id, sub_rule);
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);

// 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});
int max_times = -1;

pos = parse_space(pos + 1, is_nested);
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;
}
Expand Down
78 changes: 20 additions & 58 deletions common/json-schema-to-grammar.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,58 +16,27 @@ static std::string join(Iterator begin, Iterator end, const std::string & separa

static std::string repeat(const std::string & str, size_t n);

static std::string build_repetition(const std::string & item_rule, int min_items, int max_items, const std::string & separator_rule = "", bool item_rule_is_literal = false) {
if (separator_rule.empty()) {
if (min_items == 0 && max_items == 1) {
return item_rule + "?";
} else if (min_items == 1 && max_items == std::numeric_limits<int>::max()) {
return item_rule + "+";
}
}
static std::string build_repetition(const std::string & item_rule, int min_items, int max_items, const std::string & separator_rule = "") {
auto has_max = max_items != std::numeric_limits<int>::max();

std::string result;
if (min_items > 0) {
if (item_rule_is_literal && separator_rule.empty()) {
result = "\"" + repeat(std::string(item_rule.begin() + 1, item_rule.end() - 1), min_items) + "\"";
} else {
std::vector<std::string> items(min_items, item_rule);
result = join(items.begin(), items.end(), separator_rule.empty() ? " " : " " + separator_rule + " ");
}
if (min_items == 0 && max_items == 1) {
return item_rule + "?";
}

std::function<std::string(int, bool)> opt_repetitions = [&](int up_to_n, bool prefix_with_sep) -> std::string {
auto content = prefix_with_sep && !separator_rule.empty() ? separator_rule + " " + item_rule : item_rule;

if (up_to_n == 0) {
return "";
} else if (up_to_n == 1) {
return "(" + content + ")?";
} else if (!separator_rule.empty() && !prefix_with_sep) {
return "(" + content + " " + opt_repetitions(up_to_n - 1, true) + ")?";
if (separator_rule.empty()) {
if (min_items == 1 && !has_max) {
return item_rule + "+";
} else if (min_items == 0 && !has_max) {
return item_rule + "*";
} else {
std::string res = repeat("(" + content + " ", up_to_n);
// strip trailing space
res = res.substr(0, res.length() - 1);
res += repeat(")?", up_to_n);
return res;
return item_rule + "{" + std::to_string(min_items) + "," + (has_max ? std::to_string(max_items) : "") + "}";
}
};

if (min_items > 0 && max_items != min_items) {
result += " ";
}

if (max_items != std::numeric_limits<int>::max()) {
result += opt_repetitions(max_items - min_items, min_items > 0);
} else {
std::string item_operator = "(" + (separator_rule.empty() ? "" : separator_rule + " ") + item_rule + ")";
if (min_items == 0 && !separator_rule.empty()) {
result = "(" + item_rule + " " + item_operator + "*)?";
} else {
result += item_operator + "*";
}
auto result = item_rule + " " + build_repetition("(" + separator_rule + " " + item_rule + ")", min_items == 0 ? 0 : min_items - 1, has_max ? max_items - 1 : max_items);
if (min_items == 0) {
result = "(" + result + ")?";
}

return result;
}

Expand All @@ -78,30 +47,24 @@ struct BuiltinRule {
std::vector<std::string> deps;
};

const std::string _up_to_15_digits = build_repetition("[0-9]", 0, 15);

std::unordered_map<std::string, BuiltinRule> PRIMITIVE_RULES = {
{"boolean", {"(\"true\" | \"false\") space", {}}},
{"decimal-part", {"[0-9] " + _up_to_15_digits, {}}},
{"integral-part", {"[0-9] | [1-9] " + _up_to_15_digits, {}}},
{"decimal-part", {"[0-9]{1,16}", {}}},
{"integral-part", {"[0] | [1-9] [0-9]{0,15}", {}}},
{"number", {"(\"-\"? integral-part) (\".\" decimal-part)? ([eE] [-+]? integral-part)? space", {"integral-part", "decimal-part"}}},
{"integer", {"(\"-\"? integral-part) space", {"integral-part"}}},
{"value", {"object | array | string | number | boolean | null", {"object", "array", "string", "number", "boolean", "null"}}},
{"object", {"\"{\" space ( string \":\" space value (\",\" space string \":\" space value)* )? \"}\" space", {"string", "value"}}},
{"array", {"\"[\" space ( value (\",\" space value)* )? \"]\" space", {"value"}}},
{"uuid", {"\"\\\"\" [0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F] "
"\"-\" [0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F] "
"\"-\" [0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F] "
"\"-\" [0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F] "
"\"-\" [0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F] \"\\\"\" space", {}}},
{"char", {"[^\"\\\\] | \"\\\\\" ([\"\\\\/bfnrt] | \"u\" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])", {}}},
{"uuid", {"\"\\\"\" [0-9a-fA-F]{8} \"-\" [0-9a-fA-F]{4} \"-\" [0-9a-fA-F]{4} \"-\" [0-9a-fA-F]{4} \"-\" [0-9a-fA-F]{12} \"\\\"\" space", {}}},
{"char", {"[^\"\\\\] | \"\\\\\" ([\"\\\\/bfnrt] | \"u\" [0-9a-fA-F]{4})", {}}},
{"string", {"\"\\\"\" char* \"\\\"\" space", {"char"}}},
{"null", {"\"null\" space", {}}},
};

std::unordered_map<std::string, BuiltinRule> STRING_FORMAT_RULES = {
{"date", {"[0-9] [0-9] [0-9] [0-9] \"-\" ( \"0\" [1-9] | \"1\" [0-2] ) \"-\" ( \"0\" [1-9] | [1-2] [0-9] | \"3\" [0-1] )", {}}},
{"time", {"([01] [0-9] | \"2\" [0-3]) \":\" [0-5] [0-9] \":\" [0-5] [0-9] ( \".\" [0-9] [0-9] [0-9] )? ( \"Z\" | ( \"+\" | \"-\" ) ( [01] [0-9] | \"2\" [0-3] ) \":\" [0-5] [0-9] )", {}}},
{"date", {"[0-9]{4} \"-\" ( \"0\" [1-9] | \"1\" [0-2] ) \"-\" ( \"0\" [1-9] | [1-2] [0-9] | \"3\" [0-1] )", {}}},
{"time", {"([01] [0-9] | \"2\" [0-3]) \":\" [0-5] [0-9] \":\" [0-5] [0-9] ( \".\" [0-9]{3} )? ( \"Z\" | ( \"+\" | \"-\" ) ( [01] [0-9] | \"2\" [0-3] ) \":\" [0-5] [0-9] )", {}}},
{"date-time", {"date \"T\" time", {"date", "time"}}},
{"date-string", {"\"\\\"\" date \"\\\"\" space", {"date"}}},
{"time-string", {"\"\\\"\" time \"\\\"\" space", {"time"}}},
Expand Down Expand Up @@ -385,8 +348,7 @@ class SchemaConverter {
sub_is_literal ? "\"" + sub + "\"" : sub,
min_times,
max_times,
"",
sub_is_literal
""
);
seq.back().second = false;
} else {
Expand Down
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