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#pragma once
#include <map>
#include <unordered_set>
#include "types.hh"
namespace nix {
/* Symbol table used by the parser and evaluator to represent and look
up identifiers and attributes efficiently. SymbolTable::create()
converts a string into a symbol. Symbols have the property that
they can be compared efficiently (using a pointer equality test),
because the symbol table stores only one copy of each string. */
class Symbol {
private:
const string* s; // pointer into SymbolTable
Symbol(const string* s) : s(s){};
friend class SymbolTable;
public:
Symbol() : s(0){};
bool operator==(const Symbol& s2) const { return s == s2.s; }
bool operator!=(const Symbol& s2) const { return s != s2.s; }
bool operator<(const Symbol& s2) const { return s < s2.s; }
operator const string&() const { return *s; }
bool set() const { return s; }
bool empty() const { return s->empty(); }
friend std::ostream& operator<<(std::ostream& str, const Symbol& sym);
};
class SymbolTable {
private:
typedef std::unordered_set<string> Symbols;
Symbols symbols;
public:
Symbol create(const string& s) {
std::pair<Symbols::iterator, bool> res = symbols.insert(s);
return Symbol(&*res.first);
}
size_t size() const { return symbols.size(); }
size_t totalSize() const;
template <typename T>
void dump(T callback) {
for (auto& s : symbols) {
callback(s);
}
}
};
} // namespace nix
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