symbol.hpp

#import "util.hpp"
namespace SH {

// A symbol represents a component of a scope e.g. "js" or "string"
// Symbols are stored in the SymbolRegistry in an array
// Components can never be removed, they last the life of the process.
using Symbol = uint32_t;

struct SymbolRecord {
  Symbol key;
  Str value;
  SymbolRecord(Symbol key, Str value) : key(key), value(value) { }
};

struct SymbolRegistry {
public:
  using ReverseMapType = HashMap<Str, SymbolRecord*>;
  using RecordsType = Arr<SymbolRecord*>;

  static SymbolRegistry& shared() {
    static SymbolRegistry _shared;
    return _shared;
  }

  const RecordsType& getRecords() const { return records; };
  const ReverseMapType& getReverseMap() const { return reverseMap; };

  // This function is slow
  Symbol addSymbol(const Str& str) {
    const auto& it = reverseMap.find(str);
    if (it != reverseMap.end())
      return it->second->key;
    
    Symbol key = records.size();
    auto* record = new SymbolRecord(key, str);

    records.push_back(record);
    reverseMap[str] = record;
    return key;
  }
  
  // Look up a symbol and return a temporary string for immediate consumption
  const Str& lookupTemp(Symbol sym) {
    return records[sym]->value;
  }
  const char* lookupTempCstr(Symbol sym) {
    return records[sym]->value.c_str();
  }
  
  // Look up a symbol and return an owned string
  Str lookupOwned(Symbol sym) {
    return records[sym]->value;
  }

private:
  SymbolRegistry() { }
  RecordsType records;
  ReverseMapType reverseMap;
};

}