grammars: x{min,max} repetition operator + tweak +/*/? to avoid duplication of original over alternates
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Olivier Chafik
parent
4cc120c744
commit
01604690c1
1 changed files with 122 additions and 34 deletions
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@ -46,8 +46,12 @@ namespace grammar_parser {
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state.rules[rule_id] = rule;
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}
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static bool is_digit_char(char c) {
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return '0' <= c && c <= '9';
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}
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static bool is_word_char(char c) {
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return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || c == '-' || ('0' <= c && c <= '9');
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return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || c == '-' || is_digit_char(c);
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}
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static std::pair<uint32_t, const char *> parse_hex(const char * src, int size) {
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@ -99,6 +103,17 @@ namespace grammar_parser {
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return pos;
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}
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static const char * parse_int(const char * src) {
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const char * pos = src;
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while (is_digit_char(*pos)) {
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pos++;
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}
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if (pos == src) {
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throw std::runtime_error(std::string("expecting name at ") + src);
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}
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return pos;
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}
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static std::pair<uint32_t, const char *> parse_char(const char * src) {
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if (*src == '\\') {
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switch (src[1]) {
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@ -137,6 +152,81 @@ namespace grammar_parser {
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bool is_nested) {
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size_t last_sym_start = out_elements.size();
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const char * pos = src;
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auto handle_repetitions = [&](size_t min_times, int max_times) {
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if (last_sym_start == out_elements.size()) {
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throw std::runtime_error(std::string("expecting preceding item to */+/?/{ at ") + pos);
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}
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// S* --> S{0,}
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// S+ --> S{1,}
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// S? --> S{0,1}
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// S{m,n} --> S' ::= Scopy Scopy Scopy... (m times) S(n-m)
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// Scopy ::= S
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// S(x) ::= Scopy S(x-1) |
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// S(x-1) ::= Scopy S(x-2) |
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// S(1) ::= Scopy |
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// S{m,} --> S' ::= Scopy Scopy Scopy (m times) Sstar
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// Scopy ::= S
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// Sstar ::= Scopy Sstar |
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uint32_t content_rule_id = 0;
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if (out_elements[last_sym_start].type == LLAMA_GRETYPE_RULE_REF) {
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// The repeated content is already a rule ref, no need to copy it
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content_rule_id = out_elements[last_sym_start].value;
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} else {
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content_rule_id = generate_symbol_id(state, rule_name);
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// add preceding symbol to generated copy rule
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std::vector<llama_grammar_element> copy_rule(out_elements.begin() + last_sym_start, out_elements.end());
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copy_rule.push_back({LLAMA_GRETYPE_END, 0});
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add_rule(state, content_rule_id, copy_rule);
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}
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uint32_t sub_rule_id = generate_symbol_id(state, rule_name);
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std::vector<llama_grammar_element> sub_rule;
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for (size_t i = 0; i < min_times; i++) {
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sub_rule.push_back({LLAMA_GRETYPE_RULE_REF, content_rule_id});
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}
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if (max_times < 0) {
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uint32_t star_rule_id = generate_symbol_id(state, rule_name + "_star");
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add_rule(state, star_rule_id, {
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{LLAMA_GRETYPE_RULE_REF, content_rule_id},
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{LLAMA_GRETYPE_RULE_REF, star_rule_id},
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{LLAMA_GRETYPE_ALT, 0},
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{LLAMA_GRETYPE_END, 0}
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});
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sub_rule.push_back({LLAMA_GRETYPE_RULE_REF, star_rule_id});
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} else {
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uint32_t last_rec_rule_id = 0;
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for (int i = 0, n = max_times - min_times; i < n; i++) {
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uint32_t rec_rule_id = generate_symbol_id(state, rule_name + "_" + std::to_string(i + 1));
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if (i == 0) {
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add_rule(state, rec_rule_id, {
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{LLAMA_GRETYPE_RULE_REF, content_rule_id},
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{LLAMA_GRETYPE_ALT, 0},
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{LLAMA_GRETYPE_END, 0}
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});
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} else {
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add_rule(state, rec_rule_id, {
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{LLAMA_GRETYPE_RULE_REF, content_rule_id},
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{LLAMA_GRETYPE_RULE_REF, last_rec_rule_id},
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{LLAMA_GRETYPE_ALT, 0},
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{LLAMA_GRETYPE_END, 0}
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});
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}
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last_rec_rule_id = rec_rule_id;
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}
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sub_rule.push_back({LLAMA_GRETYPE_RULE_REF, last_rec_rule_id});
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}
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sub_rule.push_back({LLAMA_GRETYPE_END, 0});
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add_rule(state, sub_rule_id, sub_rule);
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// in original rule, replace previous symbol with reference to generated rule
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out_elements.resize(last_sym_start);
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out_elements.push_back({LLAMA_GRETYPE_RULE_REF, sub_rule_id});
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};
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while (*pos) {
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if (*pos == '"') { // literal string
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pos++;
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@ -188,40 +278,38 @@ namespace grammar_parser {
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throw std::runtime_error(std::string("expecting ')' at ") + pos);
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}
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pos = parse_space(pos + 1, is_nested);
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} else if (*pos == '*' || *pos == '+' || *pos == '?') { // repetition operator
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if (last_sym_start == out_elements.size()) {
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throw std::runtime_error(std::string("expecting preceding item to */+/? at ") + pos);
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}
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// apply transformation to previous symbol (last_sym_start to end) according to
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// rewrite rules:
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// S* --> S' ::= S S' |
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// S+ --> S' ::= S S' | S
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// S? --> S' ::= S |
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uint32_t sub_rule_id = generate_symbol_id(state, rule_name);
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std::vector<llama_grammar_element> sub_rule;
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// add preceding symbol to generated rule
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sub_rule.insert(
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sub_rule.end(), out_elements.begin() + last_sym_start, out_elements.end());
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if (*pos == '*' || *pos == '+') {
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// cause generated rule to recurse
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sub_rule.push_back({LLAMA_GRETYPE_RULE_REF, sub_rule_id});
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}
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// mark start of alternate def
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sub_rule.push_back({LLAMA_GRETYPE_ALT, 0});
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if (*pos == '+') {
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// add preceding symbol as alternate only for '+' (otherwise empty)
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sub_rule.insert(
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sub_rule.end(), out_elements.begin() + last_sym_start, out_elements.end());
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}
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sub_rule.push_back({LLAMA_GRETYPE_END, 0});
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add_rule(state, sub_rule_id, sub_rule);
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// in original rule, replace previous symbol with reference to generated rule
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out_elements.resize(last_sym_start);
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out_elements.push_back({LLAMA_GRETYPE_RULE_REF, sub_rule_id});
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} else if (*pos == '*') {
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pos = parse_space(pos + 1, is_nested);
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handle_repetitions(0, -1);
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} else if (*pos == '+') {
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pos = parse_space(pos + 1, is_nested);
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handle_repetitions(1, -1);
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} else if (*pos == '?') {
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pos = parse_space(pos + 1, is_nested);
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handle_repetitions(0, 1);
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} else if (*pos == '{') {
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pos = parse_space(pos + 1, is_nested);
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size_t min_times = 0;
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int max_times = -1;
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if (is_digit_char(*pos)) {
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const char * int_end = parse_int(pos);
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min_times = std::stoul(std::string(pos, int_end - pos));
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pos = parse_space(int_end, is_nested);
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}
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if (*pos != ',') {
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throw std::runtime_error(std::string("expecting ',' at ") + pos);
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}
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pos = parse_space(pos + 1, is_nested);
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if (is_digit_char(*pos)) {
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const char * int_end = parse_int(pos);
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max_times = std::stoul(std::string(pos, int_end - pos));
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pos = parse_space(int_end, is_nested);
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}
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if (*pos != '}') {
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throw std::runtime_error(std::string("expecting '}' at ") + pos);
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}
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pos = parse_space(pos + 1, is_nested);
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handle_repetitions(min_times, max_times);
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} else {
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break;
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}
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