56 lines
No EOL
1.8 KiB
C++
56 lines
No EOL
1.8 KiB
C++
#include "first_set.h"
|
|
#include "tree_sitter/compiler.h"
|
|
#include "rule_can_be_blank.h"
|
|
#include "rules/visitor.h"
|
|
#include "rules/seq.h"
|
|
#include "rules/choice.h"
|
|
|
|
namespace tree_sitter {
|
|
using std::set;
|
|
using namespace rules;
|
|
|
|
namespace build_tables {
|
|
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), 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);
|
|
if (rule_can_be_blank(rule->left, grammar)) {
|
|
value = set_union(value, apply(rule->right, grammar));
|
|
}
|
|
}
|
|
|
|
public:
|
|
static set<Symbol> apply(const rule_ptr rule, const Grammar &grammar) {
|
|
FirstSetVisitor visitor(grammar);
|
|
rule->accept(visitor);
|
|
return visitor.value;
|
|
}
|
|
};
|
|
|
|
set<Symbol> first_set(const rule_ptr &rule, const Grammar &grammar) {
|
|
return FirstSetVisitor::apply(rule, grammar);
|
|
}
|
|
}
|
|
} |