traxys/tree-sitter
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Compute FIRST sets correctly

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This commit is contained in:
Max Brunsfeld 2014-01-13 12:57:48 -08:00
parent 4cacdcba70
commit 29f73afbc5
5 changed files with 108 additions and 9 deletions
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59
src/compiler/build_tables/next_symbols.cpp
View file

@ -6,28 +6,71 @@
using std::set;
using std::vector;
using std::dynamic_pointer_cast;
using namespace tree_sitter::rules;
namespace tree_sitter {
class Grammar;
namespace build_tables {
template<bool isNonTerminal>
set<rules::Symbol> next_symbols(const Item &item, const Grammar &grammar) {
class FirstSetVisitor : Visitor {
set<Symbol> value;
const Grammar grammar;
FirstSetVisitor(const Grammar &grammar) : grammar(grammar) {}
set<Symbol> set_union(const set<Symbol> &left, const set<Symbol> &right) {
set<Symbol> result = left;
result.insert(right.begin(), right.end());
return result;
}
void visit(const Symbol *rule) {
if (grammar.has_definition(*rule)) {
value = apply(grammar.rule(rule->name), grammar);
} else {
value = set<Symbol>({ *rule });
}
}
void visit(const Choice *rule) {
value = set_union(apply(rule->left, grammar), apply(rule->right, grammar));
}
void visit(const Seq *rule) {
value = apply(rule->left, grammar);
}
public:
static set<Symbol> apply(const rule_ptr rule, const Grammar &grammar) {
FirstSetVisitor visitor(grammar);
rule->accept(visitor);
return visitor.value;
}
};
template<bool isTerminal>
set<rules::Symbol> next_symbols(const rules::rule_ptr &rule, const Grammar &grammar) {
set<rules::Symbol> result;
for (auto pair : rule_transitions(item.rule)) {
for (auto pair : rule_transitions(rule)) {
auto symbol = dynamic_pointer_cast<const rules::Symbol>(pair.first);
if (symbol && (grammar.has_definition(*symbol) == isNonTerminal))
if (symbol && (grammar.has_definition(*symbol) == !isTerminal))
result.insert(*symbol);
}
return result;
}
set<rules::Symbol> next_terminals(const rules::rule_ptr &rule, const Grammar &grammar) {
return FirstSetVisitor::apply(rule, grammar);
}
set<rules::Symbol> next_non_terminals(const rules::rule_ptr &rule, const Grammar &grammar) {
return next_symbols<false>(rule, grammar);
}
set<rules::Symbol> next_terminals(const Item &item, const Grammar &grammar) {
return next_symbols<false>(item, grammar);
return next_terminals(item.rule, grammar);
}
set<rules::Symbol> next_non_terminals(const Item &item, const Grammar &grammar) {
return next_symbols<true>(item, grammar);
return next_non_terminals(item.rule, grammar);
}
set<rules::Symbol> next_terminals(const ItemSet &item_set, const Grammar &grammar) {

1
src/compiler/build_tables/next_symbols.h
View file

@ -9,6 +9,7 @@ namespace tree_sitter {
class Grammar;
namespace build_tables {
std::set<rules::Symbol> next_terminals(const rules::rule_ptr &rule, const Grammar &grammar);
std::set<rules::Symbol> next_terminals(const ItemSet &item_set, const Grammar &grammar);
std::set<rules::Symbol> next_terminals(const Item &item, const Grammar &grammar);
std::set<rules::Symbol> next_non_terminals(const Item &item, const Grammar &grammar);