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Optimize remove_duplicate_parse_states method

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Signed-off-by: Nathan Sobo <nathan@github.com>
This commit is contained in:
Max Brunsfeld 2016-11-15 17:51:52 -08:00 • committed by Nathan Sobo
parent e7217f1bac
commit 42d37656ea
4 changed files with 163 additions and 2 deletions
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87
src/compiler/build_tables/build_parse_table.cc
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@ -172,9 +172,13 @@ class ParseTableBuilder {
new_action->state_index = add_parse_state(next_item_set);
}
} else {
parse_table.set_nonterminal_action(state_id, symbol.index, add_parse_state(next_item_set));
ParseStateId next_state = add_parse_state(next_item_set);
parse_table.set_nonterminal_action(state_id, symbol.index, next_state);
}
}
ParseState &state = parse_table.states[state_id];
state.compute_shift_actions_signature();
}
void add_reduce_actions(const ParseItemSet &item_set, ParseStateId state_id) {
@ -250,7 +254,86 @@ class ParseTableBuilder {
}
void remove_duplicate_parse_states() {
remove_duplicate_states<ParseTable>(&parse_table);
map<size_t, set<ParseStateId>> state_indices_by_signature;
for (ParseStateId i = 0, n = parse_table.states.size(); i < n; i++) {
ParseState &state = parse_table.states[i];
state_indices_by_signature[state.shift_actions_signature].insert(i);
}
set<ParseStateId> deleted_states;
while (true) {
std::map<ParseStateId, ParseStateId> state_replacements;
for (auto &pair : state_indices_by_signature) {
auto &state_group = pair.second;
for (ParseStateId i : state_group) {
for (ParseStateId j : state_group) {
if (j == i) break;
if (!state_replacements.count(j) && parse_table.merge_state(j, i)) {
state_replacements.insert({ i, j });
deleted_states.insert(i);
break;
}
}
}
}
if (state_replacements.empty()) break;
for (ParseStateId i = 0, n = parse_table.states.size(); i < n; i++) {
ParseState &state = parse_table.states[i];
bool did_update_state = false;
if (state_replacements.count(i)) {
auto &old_group = state_indices_by_signature[state.shift_actions_signature];
old_group.erase(i);
} else {
state.each_referenced_state([&state_replacements, &did_update_state](int64_t *state_index) {
auto new_replacement = state_replacements.find(*state_index);
if (new_replacement != state_replacements.end()) {
*state_index = new_replacement->second;
did_update_state = true;
}
});
if (did_update_state) {
auto &old_group = state_indices_by_signature[state.shift_actions_signature];
old_group.erase(i);
state.compute_shift_actions_signature();
state_indices_by_signature[state.shift_actions_signature].insert(i);
}
}
}
}
vector<ParseStateId> new_state_ids(parse_table.states.size());
size_t deleted_state_count = 0;
auto deleted_state_iter = deleted_states.begin();
for (size_t i = 0; i < new_state_ids.size(); i++) {
while (deleted_state_iter != deleted_states.end() && *deleted_state_iter < i) {
deleted_state_count++;
deleted_state_iter++;
}
new_state_ids[i] = i - deleted_state_count;
}
ParseStateId original_state_index = 0;
auto iter = parse_table.states.begin();
while (iter != parse_table.states.end()) {
if (deleted_states.count(original_state_index)) {
iter = parse_table.states.erase(iter);
} else {
ParseState &state = *iter;
state.each_referenced_state([&new_state_ids](int64_t *state_index) {
*state_index = new_state_ids[*state_index];
});
++iter;
}
original_state_index++;
}
}
ParseAction *add_terminal_action(ParseStateId state_id, Symbol::Index lookahead,