llama.cpp/common/json-schema-to-grammar.cpp
Joe Eli McIlvain 66c2c93082
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grammar : fix JSON Schema for string regex with top-level alt. (#9903)
Prior to this commit, using a JSON Schema containing a string
with `pattern` regular expression that uses top-level alternation
(e.g. `"pattern": "^A|B|C|D$"`) would result in invalid JSON
output from the constrained sampling grammar, because it
ended up creating a grammar rule like this for the string:

```
thing ::= "\"" "A" | "B" | "C" | "D" "\"" space
```

Note that this rule will only match a starting quote for the "A" case,
and will only match an ending quote for the "D" case,
so this rule will always produce invalid JSON when used for sampling
(that is, the JSON will always be lacking the starting quote,
the ending quote, or both).

This was fixed in a simple way by adding parentheses to the
generated rule (for all string pattern rules, to keep it simple),
such that the new generated rule looks like this (correct):

```
thing ::= "\"" ("A" | "B" | "C" | "D") "\"" space
```
2024-10-16 19:03:24 +03:00

1046 lines
42 KiB
C++

#include "json-schema-to-grammar.h"
#include <algorithm>
#include <fstream>
#include <map>
#include <regex>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
using json = nlohmann::ordered_json;
template <typename Iterator>
static std::string join(Iterator begin, Iterator end, const std::string & separator);
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 = "") {
auto has_max = max_items != std::numeric_limits<int>::max();
if (min_items == 0 && max_items == 1) {
return item_rule + "?";
}
if (separator_rule.empty()) {
if (min_items == 1 && !has_max) {
return item_rule + "+";
} else if (min_items == 0 && !has_max) {
return item_rule + "*";
} else {
return item_rule + "{" + std::to_string(min_items) + "," + (has_max ? std::to_string(max_items) : "") + "}";
}
}
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;
}
/* Minimalistic replacement for std::string_view, which is only available from C++17 onwards */
class string_view {
const std::string & _str;
const size_t _start;
const size_t _end;
public:
string_view(const std::string & str, size_t start = 0, size_t end = std::string::npos) : _str(str), _start(start), _end(end == std::string::npos ? str.length() : end) {}
size_t size() const {
return _end - _start;
}
size_t length() const {
return size();
}
operator std::string() const {
return str();
}
std::string str() const {
return _str.substr(_start, _end - _start);
}
string_view substr(size_t pos, size_t len = std::string::npos) const {
return string_view(_str, _start + pos, len == std::string::npos ? _end : _start + pos + len);
}
char operator[](size_t pos) const {
auto index = _start + pos;
if (index >= _end) {
throw std::out_of_range("string_view index out of range");
}
return _str[_start + pos];
}
bool operator==(const string_view & other) const {
std::string this_str = *this;
std::string other_str = other;
return this_str == other_str;
}
};
static void _build_min_max_int(int min_value, int max_value, std::stringstream & out, int decimals_left = 16, bool top_level = true) {
auto has_min = min_value != std::numeric_limits<int>::min();
auto has_max = max_value != std::numeric_limits<int>::max();
auto digit_range = [&](char from, char to) {
out << "[";
if (from == to) {
out << from;
} else {
out << from << "-" << to;
}
out << "]";
};
auto more_digits = [&](int min_digits, int max_digits) {
out << "[0-9]";
if (min_digits == max_digits && min_digits == 1) {
return;
}
out << "{";
out << min_digits;
if (max_digits != min_digits) {
out << ",";
if (max_digits != std::numeric_limits<int>::max()) {
out << max_digits;
}
}
out << "}";
};
std::function<void(const string_view &, const string_view &)> uniform_range =
[&](const string_view & from, const string_view & to) {
size_t i = 0;
while (i < from.length() && i < to.length() && from[i] == to[i]) {
i++;
}
if (i > 0) {
out << "\"" << from.substr(0, i).str() << "\"";
}
if (i < from.length() && i < to.length()) {
if (i > 0) {
out << " ";
}
auto sub_len = from.length() - i - 1;
if (sub_len > 0) {
auto from_sub = from.substr(i + 1);
auto to_sub = to.substr(i + 1);
auto sub_zeros = repeat("0", sub_len);
auto sub_nines = repeat("9", sub_len);
auto to_reached = false;
out << "(";
if (from_sub == sub_zeros) {
digit_range(from[i], to[i] - 1);
out << " ";
more_digits(sub_len, sub_len);
} else {
out << "[" << from[i] << "] ";
out << "(";
uniform_range(from_sub, sub_nines);
out << ")";
if (from[i] < to[i] - 1) {
out << " | ";
if (to_sub == sub_nines) {
digit_range(from[i] + 1, to[i]);
to_reached = true;
} else {
digit_range(from[i] + 1, to[i] - 1);
}
out << " ";
more_digits(sub_len, sub_len);
}
}
if (!to_reached) {
out << " | ";
digit_range(to[i], to[i]);
out << " ";
uniform_range(sub_zeros, to_sub);
}
out << ")";
} else {
out << "[" << from[i] << "-" << to[i] << "]";
}
}
};
if (has_min && has_max) {
if (min_value < 0 && max_value < 0) {
out << "\"-\" (";
_build_min_max_int(-max_value, -min_value, out, decimals_left, /* top_level= */ true);
out << ")";
return;
}
if (min_value < 0) {
out << "\"-\" (";
_build_min_max_int(0, -min_value, out, decimals_left, /* top_level= */ true);
out << ") | ";
min_value = 0;
}
auto min_s = std::to_string(min_value);
auto max_s = std::to_string(max_value);
auto min_digits = min_s.length();
auto max_digits = max_s.length();
for (auto digits = min_digits; digits < max_digits; digits++) {
uniform_range(min_s, repeat("9", digits));
min_s = "1" + repeat("0", digits);
out << " | ";
}
uniform_range(min_s, max_s);
return;
}
auto less_decimals = std::max(decimals_left - 1, 1);
if (has_min) {
if (min_value < 0) {
out << "\"-\" (";
_build_min_max_int(std::numeric_limits<int>::min(), -min_value, out, decimals_left, /* top_level= */ false);
out << ") | [0] | [1-9] ";
more_digits(0, decimals_left - 1);
} else if (min_value == 0) {
if (top_level) {
out << "[0] | [1-9] ";
more_digits(0, less_decimals);
} else {
more_digits(1, decimals_left);
}
} else if (min_value <= 9) {
char c = '0' + min_value;
auto range_start = top_level ? '1' : '0';
if (c > range_start) {
digit_range(range_start, c - 1);
out << " ";
more_digits(1, less_decimals);
out << " | ";
}
digit_range(c, '9');
out << " ";
more_digits(0, less_decimals);
} else {
auto min_s = std::to_string(min_value);
auto len = min_s.length();
auto c = min_s[0];
if (c > '1') {
digit_range(top_level ? '1' : '0', c - 1);
out << " ";
more_digits(len, less_decimals);
out << " | ";
}
digit_range(c, c);
out << " (";
_build_min_max_int(std::stoi(min_s.substr(1)), std::numeric_limits<int>::max(), out, less_decimals, /* top_level= */ false);
out << ")";
if (c < '9') {
out << " | ";
digit_range(c + 1, '9');
out << " ";
more_digits(len - 1, less_decimals);
}
}
return;
}
if (has_max) {
if (max_value >= 0) {
if (top_level) {
out << "\"-\" [1-9] ";
more_digits(0, less_decimals);
out << " | ";
}
_build_min_max_int(0, max_value, out, decimals_left, /* top_level= */ true);
} else {
out << "\"-\" (";
_build_min_max_int(-max_value, std::numeric_limits<int>::max(), out, decimals_left, /* top_level= */ false);
out << ")";
}
return;
}
throw std::runtime_error("At least one of min_value or max_value must be set");
}
const std::string SPACE_RULE = "| \" \" | \"\\n\" [ \\t]{0,20}";
struct BuiltinRule {
std::string content;
std::vector<std::string> deps;
};
std::unordered_map<std::string, BuiltinRule> PRIMITIVE_RULES = {
{"boolean", {"(\"true\" | \"false\") space", {}}},
{"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]{8} \"-\" [0-9a-fA-F]{4} \"-\" [0-9a-fA-F]{4} \"-\" [0-9a-fA-F]{4} \"-\" [0-9a-fA-F]{12} \"\\\"\" space", {}}},
{"char", {"[^\"\\\\\\x7F\\x00-\\x1F] | [\\\\] ([\"\\\\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]{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"}}},
{"date-time-string", {"\"\\\"\" date-time \"\\\"\" space", {"date-time"}}}
};
static bool is_reserved_name(const std::string & name) {
static std::unordered_set<std::string> RESERVED_NAMES;
if (RESERVED_NAMES.empty()) {
RESERVED_NAMES.insert("root");
for (const auto &p : PRIMITIVE_RULES) RESERVED_NAMES.insert(p.first);
for (const auto &p : STRING_FORMAT_RULES) RESERVED_NAMES.insert(p.first);
}
return RESERVED_NAMES.find(name) != RESERVED_NAMES.end();
}
std::regex INVALID_RULE_CHARS_RE("[^a-zA-Z0-9-]+");
std::regex GRAMMAR_LITERAL_ESCAPE_RE("[\r\n\"]");
std::regex GRAMMAR_RANGE_LITERAL_ESCAPE_RE("[\r\n\"\\]\\-\\\\]");
std::unordered_map<char, std::string> GRAMMAR_LITERAL_ESCAPES = {
{'\r', "\\r"}, {'\n', "\\n"}, {'"', "\\\""}, {'-', "\\-"}, {']', "\\]"}
};
std::unordered_set<char> NON_LITERAL_SET = {'|', '.', '(', ')', '[', ']', '{', '}', '*', '+', '?'};
std::unordered_set<char> ESCAPED_IN_REGEXPS_BUT_NOT_IN_LITERALS = {'^', '$', '.', '[', ']', '(', ')', '|', '{', '}', '*', '+', '?'};
template <typename Iterator>
std::string join(Iterator begin, Iterator end, const std::string & separator) {
std::ostringstream result;
if (begin != end) {
result << *begin;
for (Iterator it = begin + 1; it != end; ++it) {
result << separator << *it;
}
}
return result.str();
}
static std::vector<std::string> split(const std::string & str, const std::string & delimiter) {
std::vector<std::string> tokens;
size_t start = 0;
size_t end = str.find(delimiter);
while (end != std::string::npos) {
tokens.push_back(str.substr(start, end - start));
start = end + delimiter.length();
end = str.find(delimiter, start);
}
tokens.push_back(str.substr(start));
return tokens;
}
static std::string repeat(const std::string & str, size_t n) {
if (n == 0) {
return "";
}
std::string result;
result.reserve(str.length() * n);
for (size_t i = 0; i < n; ++i) {
result += str;
}
return result;
}
static std::string replacePattern(const std::string & input, const std::regex & regex, const std::function<std::string(const std::smatch &)> & replacement) {
std::smatch match;
std::string result;
std::string::const_iterator searchStart(input.cbegin());
std::string::const_iterator searchEnd(input.cend());
while (std::regex_search(searchStart, searchEnd, match, regex)) {
result.append(searchStart, searchStart + match.position());
result.append(replacement(match));
searchStart = match.suffix().first;
}
result.append(searchStart, searchEnd);
return result;
}
static std::string format_literal(const std::string & literal) {
std::string escaped = replacePattern(literal, GRAMMAR_LITERAL_ESCAPE_RE, [&](const std::smatch & match) {
char c = match.str()[0];
return GRAMMAR_LITERAL_ESCAPES.at(c);
});
return "\"" + escaped + "\"";
}
class SchemaConverter {
private:
std::function<json(const std::string &)> _fetch_json;
bool _dotall;
std::map<std::string, std::string> _rules;
std::unordered_map<std::string, json> _refs;
std::unordered_set<std::string> _refs_being_resolved;
std::vector<std::string> _errors;
std::vector<std::string> _warnings;
std::string _add_rule(const std::string & name, const std::string & rule) {
std::string esc_name = regex_replace(name, INVALID_RULE_CHARS_RE, "-");
if (_rules.find(esc_name) == _rules.end() || _rules[esc_name] == rule) {
_rules[esc_name] = rule;
return esc_name;
} else {
int i = 0;
while (_rules.find(esc_name + std::to_string(i)) != _rules.end() && _rules[esc_name + std::to_string(i)] != rule) {
i++;
}
std::string key = esc_name + std::to_string(i);
_rules[key] = rule;
return key;
}
}
std::string _generate_union_rule(const std::string & name, const std::vector<json> & alt_schemas) {
std::vector<std::string> rules;
for (size_t i = 0; i < alt_schemas.size(); i++) {
rules.push_back(visit(alt_schemas[i], name + (name.empty() ? "alternative-" : "-") + std::to_string(i)));
}
return join(rules.begin(), rules.end(), " | ");
}
std::string _visit_pattern(const std::string & pattern, const std::string & name) {
if (!(pattern.front() == '^' && pattern.back() == '$')) {
_errors.push_back("Pattern must start with '^' and end with '$'");
return "";
}
std::string sub_pattern = pattern.substr(1, pattern.length() - 2);
std::unordered_map<std::string, std::string> sub_rule_ids;
size_t i = 0;
size_t length = sub_pattern.length();
using literal_or_rule = std::pair<std::string, bool>;
auto to_rule = [&](const literal_or_rule & ls) {
auto is_literal = ls.second;
auto s = ls.first;
return is_literal ? "\"" + s + "\"" : s;
};
std::function<literal_or_rule()> transform = [&]() -> literal_or_rule {
size_t start = i;
std::vector<literal_or_rule> seq;
auto get_dot = [&]() {
std::string rule;
if (_dotall) {
rule = "[\\U00000000-\\U0010FFFF]";
} else {
rule = "[^\\x0A\\x0D]";
}
return _add_rule("dot", rule);
};
// Joins the sequence, merging consecutive literals together.
auto join_seq = [&]() {
std::vector<literal_or_rule> ret;
std::string literal;
auto flush_literal = [&]() {
if (literal.empty()) {
return false;
}
ret.emplace_back(literal, true);
literal.clear();
return true;
};
for (const auto & item : seq) {
auto is_literal = item.second;
if (is_literal) {
literal += item.first;
} else {
flush_literal();
ret.push_back(item);
}
}
flush_literal();
std::vector<std::string> results;
for (const auto & item : ret) {
results.push_back(to_rule(item));
}
return std::make_pair(join(results.begin(), results.end(), " "), false);
};
while (i < length) {
char c = sub_pattern[i];
if (c == '.') {
seq.emplace_back(get_dot(), false);
i++;
} else if (c == '(') {
i++;
if (i < length) {
if (sub_pattern[i] == '?') {
_warnings.push_back("Unsupported pattern syntax");
}
}
seq.emplace_back("(" + to_rule(transform()) + ")", false);
} else if (c == ')') {
i++;
if (start > 0 && sub_pattern[start - 1] != '(') {
_errors.push_back("Unbalanced parentheses");
}
return join_seq();
} else if (c == '[') {
std::string square_brackets = std::string(1, c);
i++;
while (i < length && sub_pattern[i] != ']') {
if (sub_pattern[i] == '\\') {
square_brackets += sub_pattern.substr(i, 2);
i += 2;
} else {
square_brackets += sub_pattern[i];
i++;
}
}
if (i >= length) {
_errors.push_back("Unbalanced square brackets");
}
square_brackets += ']';
i++;
seq.emplace_back(square_brackets, false);
} else if (c == '|') {
seq.emplace_back("|", false);
i++;
} else if (c == '*' || c == '+' || c == '?') {
seq.back() = std::make_pair(to_rule(seq.back()) + c, false);
i++;
} else if (c == '{') {
std::string curly_brackets = std::string(1, c);
i++;
while (i < length && sub_pattern[i] != '}') {
curly_brackets += sub_pattern[i];
i++;
}
if (i >= length) {
_errors.push_back("Unbalanced curly brackets");
}
curly_brackets += '}';
i++;
auto nums = split(curly_brackets.substr(1, curly_brackets.length() - 2), ",");
int min_times = 0;
int max_times = std::numeric_limits<int>::max();
try {
if (nums.size() == 1) {
min_times = max_times = std::stoi(nums[0]);
} else if (nums.size() != 2) {
_errors.push_back("Wrong number of values in curly brackets");
} else {
if (!nums[0].empty()) {
min_times = std::stoi(nums[0]);
}
if (!nums[1].empty()) {
max_times = std::stoi(nums[1]);
}
}
} catch (const std::invalid_argument & e) {
_errors.push_back("Invalid number in curly brackets");
return std::make_pair("", false);
}
auto &last = seq.back();
auto &sub = last.first;
auto sub_is_literal = last.second;
if (!sub_is_literal) {
std::string & sub_id = sub_rule_ids[sub];
if (sub_id.empty()) {
sub_id = _add_rule(name + "-" + std::to_string(sub_rule_ids.size()), sub);
}
sub = sub_id;
}
seq.back().first = build_repetition(
sub_is_literal ? "\"" + sub + "\"" : sub,
min_times,
max_times,
""
);
seq.back().second = false;
} else {
std::string literal;
auto is_non_literal = [&](char c) {
return NON_LITERAL_SET.find(c) != NON_LITERAL_SET.end();
};
while (i < length) {
if (sub_pattern[i] == '\\' && i < length - 1) {
char next = sub_pattern[i + 1];
if (ESCAPED_IN_REGEXPS_BUT_NOT_IN_LITERALS.find(next) != ESCAPED_IN_REGEXPS_BUT_NOT_IN_LITERALS.end()) {
i++;
literal += sub_pattern[i];
i++;
} else {
literal += sub_pattern.substr(i, 2);
i += 2;
}
} else if (sub_pattern[i] == '"') {
literal += "\\\"";
i++;
} else if (!is_non_literal(sub_pattern[i]) &&
(i == length - 1 || literal.empty() || sub_pattern[i + 1] == '.' || !is_non_literal(sub_pattern[i + 1]))) {
literal += sub_pattern[i];
i++;
} else {
break;
}
}
if (!literal.empty()) {
seq.emplace_back(literal, true);
}
}
}
return join_seq();
};
return _add_rule(name, "\"\\\"\" (" + to_rule(transform()) + ") \"\\\"\" space");
}
/*
Returns a rule that matches a JSON string that is none of the provided strings
not_strings({"a"})
-> ["] ( [a] char+ | [^"a] char* )? ["] space
not_strings({"and", "also"})
-> ["] ( [a] ([l] ([s] ([o] char+ | [^"o] char*) | [^"s] char*) | [n] ([d] char+ | [^"d] char*) | [^"ln] char*) | [^"a] char* )? ["] space
*/
std::string _not_strings(const std::vector<std::string> & strings) {
struct TrieNode {
std::map<char, TrieNode> children;
bool is_end_of_string;
TrieNode() : is_end_of_string(false) {}
void insert(const std::string & string) {
auto node = this;
for (char c : string) {
node = &node->children[c];
}
node->is_end_of_string = true;
}
};
TrieNode trie;
for (const auto & s : strings) {
trie.insert(s);
}
std::string char_rule = _add_primitive("char", PRIMITIVE_RULES.at("char"));
std::ostringstream out;
out << "[\"] ( ";
std::function<void(const TrieNode &)> visit = [&](const TrieNode & node) {
std::ostringstream rejects;
auto first = true;
for (const auto & kv : node.children) {
rejects << kv.first;
if (first) {
first = false;
} else {
out << " | ";
}
out << "[" << kv.first << "]";
if (!kv.second.children.empty()) {
out << " (";
visit(kv.second);
out << ")";
} else if (kv.second.is_end_of_string) {
out << " " << char_rule << "+";
}
}
if (!node.children.empty()) {
if (!first) {
out << " | ";
}
out << "[^\"" << rejects.str() << "] " << char_rule << "*";
}
};
visit(trie);
out << " )";
if (!trie.is_end_of_string) {
out << "?";
}
out << " [\"] space";
return out.str();
}
std::string _resolve_ref(const std::string & ref) {
std::string ref_name = ref.substr(ref.find_last_of('/') + 1);
if (_rules.find(ref_name) == _rules.end() && _refs_being_resolved.find(ref) == _refs_being_resolved.end()) {
_refs_being_resolved.insert(ref);
json resolved = _refs[ref];
ref_name = visit(resolved, ref_name);
_refs_being_resolved.erase(ref);
}
return ref_name;
}
std::string _build_object_rule(
const std::vector<std::pair<std::string, json>> & properties,
const std::unordered_set<std::string> & required,
const std::string & name,
const json & additional_properties)
{
std::vector<std::string> required_props;
std::vector<std::string> optional_props;
std::unordered_map<std::string, std::string> prop_kv_rule_names;
std::vector<std::string> prop_names;
for (const auto & kv : properties) {
const auto &prop_name = kv.first;
const auto &prop_schema = kv.second;
std::string prop_rule_name = visit(prop_schema, name + (name.empty() ? "" : "-") + prop_name);
prop_kv_rule_names[prop_name] = _add_rule(
name + (name.empty() ? "" : "-") + prop_name + "-kv",
format_literal(json(prop_name).dump()) + " space \":\" space " + prop_rule_name
);
if (required.find(prop_name) != required.end()) {
required_props.push_back(prop_name);
} else {
optional_props.push_back(prop_name);
}
prop_names.push_back(prop_name);
}
if ((additional_properties.is_boolean() && additional_properties.get<bool>()) || additional_properties.is_object()) {
std::string sub_name = name + (name.empty() ? "" : "-") + "additional";
std::string value_rule =
additional_properties.is_object() ? visit(additional_properties, sub_name + "-value")
: _add_primitive("value", PRIMITIVE_RULES.at("value"));
auto key_rule =
prop_names.empty() ? _add_primitive("string", PRIMITIVE_RULES.at("string"))
: _add_rule(sub_name + "-k", _not_strings(prop_names));
std::string kv_rule = _add_rule(sub_name + "-kv", key_rule + " \":\" space " + value_rule);
prop_kv_rule_names["*"] = kv_rule;
optional_props.push_back("*");
}
std::string rule = "\"{\" space ";
for (size_t i = 0; i < required_props.size(); i++) {
if (i > 0) {
rule += " \",\" space ";
}
rule += prop_kv_rule_names[required_props[i]];
}
if (!optional_props.empty()) {
rule += " (";
if (!required_props.empty()) {
rule += " \",\" space ( ";
}
std::function<std::string(const std::vector<std::string> &, bool)> get_recursive_refs = [&](const std::vector<std::string> & ks, bool first_is_optional) {
std::string res;
if (ks.empty()) {
return res;
}
std::string k = ks[0];
std::string kv_rule_name = prop_kv_rule_names[k];
std::string comma_ref = "( \",\" space " + kv_rule_name + " )";
if (first_is_optional) {
res = comma_ref + (k == "*" ? "*" : "?");
} else {
res = kv_rule_name + (k == "*" ? " " + comma_ref + "*" : "");
}
if (ks.size() > 1) {
res += " " + _add_rule(
name + (name.empty() ? "" : "-") + k + "-rest",
get_recursive_refs(std::vector<std::string>(ks.begin() + 1, ks.end()), true)
);
}
return res;
};
for (size_t i = 0; i < optional_props.size(); i++) {
if (i > 0) {
rule += " | ";
}
rule += get_recursive_refs(std::vector<std::string>(optional_props.begin() + i, optional_props.end()), false);
}
if (!required_props.empty()) {
rule += " )";
}
rule += " )?";
}
rule += " \"}\" space";
return rule;
}
std::string _add_primitive(const std::string & name, const BuiltinRule & rule) {
auto n = _add_rule(name, rule.content);
for (const auto & dep : rule.deps) {
BuiltinRule dep_rule;
auto it = PRIMITIVE_RULES.find(dep);
if (it == PRIMITIVE_RULES.end()) {
it = STRING_FORMAT_RULES.find(dep);
if (it == STRING_FORMAT_RULES.end()) {
_errors.push_back("Rule " + dep + " not known");
continue;
}
}
if (_rules.find(dep) == _rules.end()) {
_add_primitive(dep, it->second);
}
}
return n;
}
public:
SchemaConverter(
const std::function<json(const std::string &)> & fetch_json,
bool dotall)
: _fetch_json(fetch_json), _dotall(dotall)
{
_rules["space"] = SPACE_RULE;
}
void resolve_refs(json & schema, const std::string & url) {
/*
* Resolves all $ref fields in the given schema, fetching any remote schemas,
* replacing each $ref with absolute reference URL and populates _refs with the
* respective referenced (sub)schema dictionaries.
*/
std::function<void(json &)> visit_refs = [&](json & n) {
if (n.is_array()) {
for (auto & x : n) {
visit_refs(x);
}
} else if (n.is_object()) {
if (n.contains("$ref")) {
std::string ref = n["$ref"];
if (_refs.find(ref) == _refs.end()) {
json target;
if (ref.find("https://") == 0) {
std::string base_url = ref.substr(0, ref.find('#'));
auto it = _refs.find(base_url);
if (it != _refs.end()) {
target = it->second;
} else {
// Fetch the referenced schema and resolve its refs
auto referenced = _fetch_json(ref);
resolve_refs(referenced, base_url);
_refs[base_url] = referenced;
}
if (ref.find('#') == std::string::npos || ref.substr(ref.find('#') + 1).empty()) {
return;
}
} else if (ref.find("#/") == 0) {
target = schema;
n["$ref"] = url + ref;
ref = url + ref;
} else {
_errors.push_back("Unsupported ref: " + ref);
return;
}
std::string pointer = ref.substr(ref.find('#') + 1);
std::vector<std::string> tokens = split(pointer, "/");
for (size_t i = 1; i < tokens.size(); ++i) {
std::string sel = tokens[i];
if (target.is_null() || !target.contains(sel)) {
_errors.push_back("Error resolving ref " + ref + ": " + sel + " not in " + target.dump());
return;
}
target = target[sel];
}
_refs[ref] = target;
}
} else {
for (auto & kv : n.items()) {
visit_refs(kv.value());
}
}
}
};
visit_refs(schema);
}
std::string _generate_constant_rule(const json & value) {
return format_literal(value.dump());
}
std::string visit(const json & schema, const std::string & name) {
json schema_type = schema.contains("type") ? schema["type"] : json();
std::string schema_format = schema.contains("format") ? schema["format"].get<std::string>() : "";
std::string rule_name = is_reserved_name(name) ? name + "-" : name.empty() ? "root" : name;
if (schema.contains("$ref")) {
return _add_rule(rule_name, _resolve_ref(schema["$ref"]));
} else if (schema.contains("oneOf") || schema.contains("anyOf")) {
std::vector<json> alt_schemas = schema.contains("oneOf") ? schema["oneOf"].get<std::vector<json>>() : schema["anyOf"].get<std::vector<json>>();
return _add_rule(rule_name, _generate_union_rule(name, alt_schemas));
} else if (schema_type.is_array()) {
std::vector<json> schema_types;
for (const auto & t : schema_type) {
json schema_copy(schema);
schema_copy["type"] = t;
schema_types.push_back(schema_copy);
}
return _add_rule(rule_name, _generate_union_rule(name, schema_types));
} else if (schema.contains("const")) {
return _add_rule(rule_name, _generate_constant_rule(schema["const"]) + " space");
} else if (schema.contains("enum")) {
std::vector<std::string> enum_values;
for (const auto & v : schema["enum"]) {
enum_values.push_back(_generate_constant_rule(v));
}
return _add_rule(rule_name, "(" + join(enum_values.begin(), enum_values.end(), " | ") + ") space");
} else if ((schema_type.is_null() || schema_type == "object")
&& (schema.contains("properties") ||
(schema.contains("additionalProperties") && schema["additionalProperties"] != true))) {
std::unordered_set<std::string> required;
if (schema.contains("required") && schema["required"].is_array()) {
for (const auto & item : schema["required"]) {
if (item.is_string()) {
required.insert(item.get<std::string>());
}
}
}
std::vector<std::pair<std::string, json>> properties;
if (schema.contains("properties")) {
for (const auto & prop : schema["properties"].items()) {
properties.emplace_back(prop.key(), prop.value());
}
}
return _add_rule(rule_name,
_build_object_rule(
properties, required, name,
schema.contains("additionalProperties") ? schema["additionalProperties"] : json()));
} else if ((schema_type.is_null() || schema_type == "object") && schema.contains("allOf")) {
std::unordered_set<std::string> required;
std::vector<std::pair<std::string, json>> properties;
std::string hybrid_name = name;
std::function<void(const json &, bool)> add_component = [&](const json & comp_schema, bool is_required) {
if (comp_schema.contains("$ref")) {
add_component(_refs[comp_schema["$ref"]], is_required);
} else if (comp_schema.contains("properties")) {
for (const auto & prop : comp_schema["properties"].items()) {
properties.emplace_back(prop.key(), prop.value());
if (is_required) {
required.insert(prop.key());
}
}
} else {
// todo warning
}
};
for (auto & t : schema["allOf"]) {
if (t.contains("anyOf")) {
for (auto & tt : t["anyOf"]) {
add_component(tt, false);
}
} else {
add_component(t, true);
}
}
return _add_rule(rule_name, _build_object_rule(properties, required, hybrid_name, json()));
} else if ((schema_type.is_null() || schema_type == "array") && (schema.contains("items") || schema.contains("prefixItems"))) {
json items = schema.contains("items") ? schema["items"] : schema["prefixItems"];
if (items.is_array()) {
std::string rule = "\"[\" space ";
for (size_t i = 0; i < items.size(); i++) {
if (i > 0) {
rule += " \",\" space ";
}
rule += visit(items[i], name + (name.empty() ? "" : "-") + "tuple-" + std::to_string(i));
}
rule += " \"]\" space";
return _add_rule(rule_name, rule);
} else {
std::string item_rule_name = visit(items, name + (name.empty() ? "" : "-") + "item");
int min_items = schema.contains("minItems") ? schema["minItems"].get<int>() : 0;
json max_items_json = schema.contains("maxItems") ? schema["maxItems"] : json();
int max_items = max_items_json.is_number_integer() ? max_items_json.get<int>() : std::numeric_limits<int>::max();
return _add_rule(rule_name, "\"[\" space " + build_repetition(item_rule_name, min_items, max_items, "\",\" space") + " \"]\" space");
}
} else if ((schema_type.is_null() || schema_type == "string") && schema.contains("pattern")) {
return _visit_pattern(schema["pattern"], rule_name);
} else if ((schema_type.is_null() || schema_type == "string") && std::regex_match(schema_format, std::regex("^uuid[1-5]?$"))) {
return _add_primitive(rule_name == "root" ? "root" : schema_format, PRIMITIVE_RULES.at("uuid"));
} else if ((schema_type.is_null() || schema_type == "string") && STRING_FORMAT_RULES.find(schema_format + "-string") != STRING_FORMAT_RULES.end()) {
auto prim_name = schema_format + "-string";
return _add_rule(rule_name, _add_primitive(prim_name, STRING_FORMAT_RULES.at(prim_name)));
} else if (schema_type == "string" && (schema.contains("minLength") || schema.contains("maxLength"))) {
std::string char_rule = _add_primitive("char", PRIMITIVE_RULES.at("char"));
int min_len = schema.contains("minLength") ? schema["minLength"].get<int>() : 0;
int max_len = schema.contains("maxLength") ? schema["maxLength"].get<int>() : std::numeric_limits<int>::max();
return _add_rule(rule_name, "\"\\\"\" " + build_repetition(char_rule, min_len, max_len) + " \"\\\"\" space");
} else if (schema_type == "integer" && (schema.contains("minimum") || schema.contains("exclusiveMinimum") || schema.contains("maximum") || schema.contains("exclusiveMaximum"))) {
int min_value = std::numeric_limits<int>::min();
int max_value = std::numeric_limits<int>::max();
if (schema.contains("minimum")) {
min_value = schema["minimum"].get<int>();
} else if (schema.contains("exclusiveMinimum")) {
min_value = schema["exclusiveMinimum"].get<int>() + 1;
}
if (schema.contains("maximum")) {
max_value = schema["maximum"].get<int>();
} else if (schema.contains("exclusiveMaximum")) {
max_value = schema["exclusiveMaximum"].get<int>() - 1;
}
std::stringstream out;
out << "(";
_build_min_max_int(min_value, max_value, out);
out << ") space";
return _add_rule(rule_name, out.str());
} else if (schema.empty() || schema_type == "object") {
return _add_rule(rule_name, _add_primitive("object", PRIMITIVE_RULES.at("object")));
} else {
if (!schema_type.is_string() || PRIMITIVE_RULES.find(schema_type.get<std::string>()) == PRIMITIVE_RULES.end()) {
_errors.push_back("Unrecognized schema: " + schema.dump());
return "";
}
// TODO: support minimum, maximum, exclusiveMinimum, exclusiveMaximum at least for zero
return _add_primitive(rule_name == "root" ? "root" : schema_type.get<std::string>(), PRIMITIVE_RULES.at(schema_type.get<std::string>()));
}
}
void check_errors() {
if (!_errors.empty()) {
throw std::runtime_error("JSON schema conversion failed:\n" + join(_errors.begin(), _errors.end(), "\n"));
}
if (!_warnings.empty()) {
fprintf(stderr, "WARNING: JSON schema conversion was incomplete: %s\n", join(_warnings.begin(), _warnings.end(), "; ").c_str());
}
}
std::string format_grammar() {
std::stringstream ss;
for (const auto & kv : _rules) {
ss << kv.first << " ::= " << kv.second << std::endl;
}
return ss.str();
}
};
std::string json_schema_to_grammar(const json & schema) {
SchemaConverter converter([](const std::string &) { return json::object(); }, /* dotall= */ false);
auto copy = schema;
converter.resolve_refs(copy, "input");
converter.visit(copy, "");
converter.check_errors();
return converter.format_grammar();
}