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Diffstat (limited to 'examples/grammar-parser.cpp')
| -rw-r--r-- | examples/grammar-parser.cpp | 423 |
1 files changed, 423 insertions, 0 deletions
diff --git a/examples/grammar-parser.cpp b/examples/grammar-parser.cpp new file mode 100644 index 0000000..e76bd11 --- /dev/null +++ b/examples/grammar-parser.cpp @@ -0,0 +1,423 @@ +#include "grammar-parser.h" +#include <cstdint> +#include <cwchar> +#include <string> +#include <utility> +#include <stdexcept> +#include <exception> + +namespace grammar_parser { + // NOTE: assumes valid utf8 (but checks for overrun) + // copied from llama.cpp + 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); + } + + uint32_t get_symbol_id(parse_state & state, const char * src, size_t len) { + uint32_t next_id = static_cast<uint32_t>(state.symbol_ids.size()); + auto result = state.symbol_ids.insert(std::make_pair(std::string(src, len), next_id)); + return result.first->second; + } + + uint32_t generate_symbol_id(parse_state & state, const std::string & base_name) { + uint32_t next_id = static_cast<uint32_t>(state.symbol_ids.size()); + state.symbol_ids[base_name + '_' + std::to_string(next_id)] = next_id; + return next_id; + } + + void add_rule( + parse_state & state, + uint32_t rule_id, + const std::vector<llama_grammar_element> & rule) { + if (state.rules.size() <= rule_id) { + state.rules.resize(rule_id + 1); + } + state.rules[rule_id] = rule; + } + + bool is_word_char(char c) { + return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || c == '-' || ('0' <= c && c <= '9'); + } + + 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); + } + + 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; + } + + 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; + } + + 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"); + } + + const char * parse_alternates( + parse_state & state, + const char * src, + const std::string & rule_name, + uint32_t rule_id, + bool is_nested); + + const char * parse_sequence( + parse_state & state, + const char * src, + const std::string & rule_name, + std::vector<llama_grammar_element> & out_elements, + bool is_nested) { + size_t last_sym_start = out_elements.size(); + const char * pos = src; + while (*pos) { + if (*pos == '"') { // literal string + pos++; + last_sym_start = out_elements.size(); + while (*pos != '"') { + auto char_pair = parse_char(pos); + pos = char_pair.second; + out_elements.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 = out_elements.size(); + while (*pos != ']') { + auto char_pair = parse_char(pos); + pos = char_pair.second; + enum llama_gretype type = last_sym_start < out_elements.size() + ? LLAMA_GRETYPE_CHAR_ALT + : start_type; + + out_elements.push_back({type, char_pair.first}); + if (pos[0] == '-' && pos[1] != ']') { + auto endchar_pair = parse_char(pos + 1); + pos = endchar_pair.second; + out_elements.push_back({LLAMA_GRETYPE_CHAR_RNG_UPPER, endchar_pair.first}); + } + } + pos = parse_space(pos + 1, 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(state, pos, name_end - pos); + pos = parse_space(name_end, is_nested); + last_sym_start = out_elements.size(); + out_elements.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 sub_rule_id = generate_symbol_id(state, rule_name); + pos = parse_alternates(state, pos, rule_name, sub_rule_id, true); + last_sym_start = out_elements.size(); + // output reference to synthesized rule + out_elements.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 == '*' || *pos == '+' || *pos == '?') { // repetition operator + if (last_sym_start == out_elements.size()) { + throw std::runtime_error(std::string("expecting preceeding 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}); + + pos = parse_space(pos + 1, is_nested); + } else { + break; + } + } + return pos; + } + + const char * parse_alternates( + parse_state & state, + const char * src, + const std::string & rule_name, + uint32_t rule_id, + bool is_nested) { + std::vector<llama_grammar_element> rule; + const char * pos = parse_sequence(state, src, rule_name, rule, is_nested); + while (*pos == '|') { + rule.push_back({LLAMA_GRETYPE_ALT, 0}); + pos = parse_space(pos + 1, true); + pos = parse_sequence(state, pos, rule_name, rule, is_nested); + } + rule.push_back({LLAMA_GRETYPE_END, 0}); + add_rule(state, rule_id, rule); + return pos; + } + + const char * parse_rule(parse_state & state, 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(state, 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(state, 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); + } + + parse_state parse(const char * src) { + try { + parse_state state; + const char * pos = parse_space(src, true); + while (*pos) { + pos = parse_rule(state, pos); + } + return state; + } catch (const std::exception & err) { + fprintf(stderr, "%s: error parsing grammar: %s\n", __func__, err.what()); + return parse_state(); + } + } + + 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); + } + } + + 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; + default: return false; + } + } + + void print_rule_binary(FILE * file, const std::vector<llama_grammar_element> & 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; + } + 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: + fprintf(file, "(\""); + print_grammar_char(file, elem.value); + fprintf(file, "\") "); + break; + } + } + fprintf(file, "\n"); + } + + void print_rule( + FILE * file, + uint32_t rule_id, + const std::vector<llama_grammar_element> & 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; + } + if (is_char_element(elem)) { + switch (rule[i + 1].type) { + case LLAMA_GRETYPE_CHAR_ALT: + case LLAMA_GRETYPE_CHAR_RNG_UPPER: + break; + default: + fprintf(file, "] "); + } + } + } + fprintf(file, "\n"); + } + + void print_grammar(FILE * file, const parse_state & state) { + try { + std::map<uint32_t, std::string> symbol_id_names; + for (auto kv : state.symbol_ids) { + symbol_id_names[kv.second] = kv.first; + } + for (size_t i = 0, end = state.rules.size(); i < end; i++) { + // fprintf(file, "%zu: ", i); + // print_rule_binary(file, state.rules[i]); + print_rule(file, uint32_t(i), state.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()); + } + } + + std::vector<const llama_grammar_element *> parse_state::c_rules() { + std::vector<const llama_grammar_element *> ret; + for (const auto & rule : rules) { + ret.push_back(rule.data()); + } + return ret; + } +} |