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Refactor parse table builder

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This commit is contained in:
Max Brunsfeld 2013-12-18 08:25:50 -08:00
parent c49913a6b1
commit 73d8cb3722
2 changed files with 27 additions and 17 deletions
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40
src/compiler/lr/parse_table_builder.cpp
View file

@ -17,7 +17,8 @@ namespace tree_sitter {
ParseTableBuilder::ParseTableBuilder(const Grammar &grammar) :
grammar(grammar),
table(ParseTable(grammar.rule_names())),
state_indices(unordered_map<const ItemSet, size_t>()) {};
state_indices(unordered_map<const ItemSet, size_t>())
{};
void ParseTableBuilder::build() {
auto item = Item(ParseTable::START, rules::sym(grammar.start_rule_name), 0);
@ -31,24 +32,31 @@ namespace tree_sitter {
state_index = table.add_state();
state_indices[item_set] = state_index;
for (auto transition : item_set.sym_transitions(grammar)) {
rules::sym_ptr symbol = static_pointer_cast<const rules::Symbol>(transition.first);
size_t new_state_index = add_item_set(*transition.second);
table.add_action(state_index, symbol->name, ParseAction::Shift(new_state_index));
}
for (Item item : item_set) {
if (item.is_done()) {
if (item.rule_name == ParseTable::START) {
table.add_action(state_index, ParseTable::END_OF_INPUT, ParseAction::Accept());
} else {
for (string rule_name : table.symbol_names)
table.add_action(state_index, rule_name, ParseAction::Reduce(item.rule_name, item.consumed_sym_count));
}
add_shift_actions(item_set, state_index);
add_reduce_actions(item_set, state_index);
}
return state_index;
}
void ParseTableBuilder::add_shift_actions(const ItemSet &item_set, size_t state_index) {
for (auto transition : item_set.sym_transitions(grammar)) {
rules::sym_ptr symbol = static_pointer_cast<const rules::Symbol>(transition.first);
size_t new_state_index = add_item_set(*transition.second);
table.add_action(state_index, symbol->name, ParseAction::Shift(new_state_index));
}
}
void ParseTableBuilder::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) {
table.add_action(state_index, ParseTable::END_OF_INPUT, ParseAction::Accept());
} else {
for (string rule_name : table.symbol_names)
table.add_action(state_index, rule_name, ParseAction::Reduce(item.rule_name, item.consumed_sym_count));
}
}
}
return state_index;
}
long ParseTableBuilder::state_index_for_item_set(const ItemSet &item_set) const {

4
src/compiler/lr/parse_table_builder.h
View file

@ -13,8 +13,10 @@ namespace tree_sitter {
ParseTable table;
std::unordered_map<const ItemSet, size_t> state_indices;
size_t add_item_set(const ItemSet &item_set);
long state_index_for_item_set(const ItemSet &item_set) const;
void add_shift_actions(const ItemSet &item_set, size_t state_index);
void add_reduce_actions(const ItemSet &item_set, size_t state_index);
size_t add_item_set(const ItemSet &item_set);
public:
ParseTableBuilder(const Grammar &grammar);
static ParseTable build_table(const Grammar &grammar);