78 lines
No EOL
3 KiB
C++
78 lines
No EOL
3 KiB
C++
#include "parse_table_builder.h"
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#include <unordered_map>
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#include "item_set.h"
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#include "rules.h"
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#include "item_set.h"
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#include "grammar.h"
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using namespace std;
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namespace tree_sitter {
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namespace lr {
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static int NOT_FOUND = -1;
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class ParseTableBuilder {
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const Grammar grammar;
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std::unordered_map<const ItemSet, size_t> state_indices;
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ParseTable table;
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long state_index_for_item_set(const ItemSet &item_set) const {
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auto entry = state_indices.find(item_set);
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return (entry == state_indices.end()) ? NOT_FOUND : entry->second;
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}
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void add_shift_actions(const ItemSet &item_set, size_t state_index) {
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for (auto transition : item_set.sym_transitions(grammar)) {
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rules::Symbol symbol = *transition.first;
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ItemSet item_set = *transition.second;
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size_t new_state_index = add_item_set(item_set);
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table.add_action(state_index, symbol.name, ParseAction::Shift(new_state_index));
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}
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}
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void add_reduce_actions(const ItemSet &item_set, size_t state_index) {
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for (Item item : item_set) {
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if (item.is_done()) {
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if (item.rule_name == ParseTable::START) {
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table.add_action(state_index, ParseTable::END_OF_INPUT, ParseAction::Accept());
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} else {
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for (string rule_name : table.symbol_names)
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table.add_action(state_index, rule_name, ParseAction::Reduce(item.rule_name, item.consumed_sym_count));
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}
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}
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}
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}
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size_t add_item_set(const ItemSet &item_set) {
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auto state_index = state_index_for_item_set(item_set);
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if (state_index == NOT_FOUND) {
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state_index = table.add_state();
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state_indices[item_set] = state_index;
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add_shift_actions(item_set, state_index);
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add_reduce_actions(item_set, state_index);
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}
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return state_index;
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}
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public:
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ParseTableBuilder(const Grammar &grammar) :
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grammar(grammar),
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table(ParseTable(grammar.rule_names())),
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state_indices(unordered_map<const ItemSet, size_t>())
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{};
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ParseTable build() {
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auto item = Item(ParseTable::START, rules::sym(grammar.start_rule_name), 0);
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auto item_set = ItemSet(item, grammar);
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add_item_set(item_set);
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return table;
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}
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};
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ParseTable build_tables(const tree_sitter::Grammar &grammar) {
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return ParseTableBuilder(grammar).build();
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}
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}
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} |