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Start work on lexing

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Max Brunsfeld 2013-12-27 17:31:08 -08:00
parent 323184f981
commit a5e39d2512
20 changed files with 719 additions and 334 deletions
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115
src/compiler/lr/table_builder.cpp Normal file
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#include "table_builder.h"
#include <unordered_map>
#include "item_set.h"
#include "rules.h"
#include "item_set.h"
#include "grammar.h"
using namespace std;
namespace tree_sitter {
namespace lr {
static int NOT_FOUND = -1;
class ParseTableBuilder {
const Grammar grammar;
std::unordered_map<const ItemSet, size_t> parse_state_indices;
std::unordered_map<const ItemSet, size_t> lex_state_indices;
ParseTable parse_table;
LexTable lex_table;
long parse_state_index_for_item_set(const ItemSet &item_set) const {
auto entry = parse_state_indices.find(item_set);
return (entry == parse_state_indices.end()) ? NOT_FOUND : entry->second;
}
long lex_state_index_for_item_set(const ItemSet &item_set) const {
auto entry = lex_state_indices.find(item_set);
return (entry == lex_state_indices.end()) ? NOT_FOUND : entry->second;
}
void add_shift_actions(const ItemSet &item_set, size_t state_index) {
for (auto transition : item_set.sym_transitions(grammar)) {
rules::Symbol symbol = *transition.first;
ItemSet item_set = *transition.second;
size_t new_state_index = add_parse_state(item_set);
parse_table.add_action(state_index, symbol.name, ParseAction::Shift(new_state_index));
}
}
void add_advance_actions(const ItemSet &item_set, size_t state_index) {
for (auto transition : item_set.char_transitions(grammar)) {
rules::Character rule = *transition.first;
ItemSet item_set = *transition.second;
size_t new_state_index = add_lex_state(item_set);
lex_table.add_action(state_index, rule.value, LexAction::Advance(new_state_index));
}
}
void add_accept_token_actions(const ItemSet &item_set, size_t state_index) {
for (Item item : item_set) {
if (item.is_done()) {
lex_table.add_default_action(state_index, LexAction::Accept(item.rule_name));
}
}
}
void add_reduce_actions(const ItemSet &item_set, size_t state_index) {
for (Item item : item_set) {
if (item.is_done()) {
if (item.rule_name == ParseTable::START) {
parse_table.add_action(state_index, ParseTable::END_OF_INPUT, ParseAction::Accept());
} else {
parse_table.add_default_action(state_index, ParseAction::Reduce(item.rule_name, item.consumed_sym_count));
}
}
}
}
size_t add_lex_state(const ItemSet &item_set) {
auto state_index = lex_state_index_for_item_set(item_set);
if (state_index == NOT_FOUND) {
state_index = lex_table.add_state();
lex_state_indices[item_set] = state_index;
add_advance_actions(item_set, state_index);
add_accept_token_actions(item_set, state_index);
}
return state_index;
}
size_t add_parse_state(const ItemSet &item_set) {
auto state_index = parse_state_index_for_item_set(item_set);
if (state_index == NOT_FOUND) {
state_index = parse_table.add_state();
parse_state_indices[item_set] = state_index;
parse_table.states[state_index].lex_state_index = add_lex_state(item_set);
add_shift_actions(item_set, state_index);
add_reduce_actions(item_set, state_index);
}
return state_index;
}
public:
ParseTableBuilder(const Grammar &grammar) :
grammar(grammar),
parse_table(ParseTable(grammar.rule_names())),
lex_table(LexTable(grammar.rule_names())),
parse_state_indices(unordered_map<const ItemSet, size_t>()),
lex_state_indices(unordered_map<const ItemSet, size_t>())
{};
std::pair<ParseTable, LexTable> build() {
auto item = Item(ParseTable::START, rules::sym(grammar.start_rule_name), 0);
auto item_set = ItemSet(item, grammar);
add_parse_state(item_set);
return std::pair<ParseTable, LexTable>(parse_table, lex_table);
}
};
std::pair<ParseTable, LexTable> build_tables(const tree_sitter::Grammar &grammar) {
return ParseTableBuilder(grammar).build();
}
}
}