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Separate syntax rules into flat lists of symbols

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This way, every ParseItem can be associated with a particular production
for its non-terminal. That lets us keep track of which productions are
involved in shift/reduce conflicts.
This commit is contained in:
Max Brunsfeld 2015-01-11 23:21:58 -08:00
parent 68a0e16d1e
commit 52daffb3f3
37 changed files with 842 additions and 426 deletions
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23
src/compiler/build_tables/build_parse_table.cc
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@ -40,12 +40,8 @@ class ParseTableBuilder {
: grammar(grammar), lex_grammar(lex_grammar) {}
pair<ParseTable, vector<Conflict>> build() {
auto start_symbol = grammar.rules.empty()
? make_shared<Symbol>(0, rules::SymbolOptionToken)
: make_shared<Symbol>(0);
ParseItem start_item(rules::START(), start_symbol, 0);
add_parse_state(
item_set_closure(start_item, { rules::END_OF_INPUT() }, grammar));
ParseItem start_item(rules::START(), 0, -2, 0);
add_parse_state(item_set_closure(start_item, { rules::END_OF_INPUT() }, grammar));
while (!item_sets_to_process.empty()) {
auto pair = item_sets_to_process.back();
@ -100,12 +96,13 @@ class ParseTableBuilder {
const ParseItem &item = pair.first;
const set<Symbol> &lookahead_symbols = pair.second;
if (item.is_done()) {
if (item_is_done(item)) {
ParseAction action =
(item.lhs == rules::START())
? ParseAction::Accept()
: ParseAction::Reduce(item.lhs, item.consumed_symbol_count,
item.precedence());
item_precedence(item));
for (const auto &lookahead_sym : lookahead_symbols)
if (should_add_action(state_id, lookahead_sym, action, ParseItemSet()))
@ -170,11 +167,19 @@ class ParseTableBuilder {
for (const auto &pair : item_set) {
const ParseItem &item = pair.first;
if (item.consumed_symbol_count > 0)
result.insert(item.precedence());
result.insert(item_precedence(item));
}
return result;
}
bool item_is_done(const ParseItem &item) {
return item.consumed_symbol_count == grammar.productions(item.lhs)[item.production_index].size();
}
int item_precedence(const ParseItem &item) {
return grammar.productions(item.lhs)[item.production_index].precedence_at(item.consumed_symbol_count - 1);
}
void record_conflict(const Symbol &sym, const ParseAction &left,
const ParseAction &right, const ParseItemSet &item_set) {
conflicts.insert(