Struct StringId¶

Defined in File string_id.h

Struct Documentation¶

struct StringId¶

Compile-time string identifier using 64-bit hash for efficient lookups.

StringId enables using strings as identifiers (for resources, entities, events, etc.) while maintaining performance comparable to integer keys. The design philosophy is: the hash is the identity, the string is for debugging.

Two StringId instances are equal if their id (hash) fields match. The string field is purely for logging, debugging, and UI display - it does not participate in equality or hash map operations.

Compile-Time Hashing: Use the STRING_ID() macro for string literals known at compile time. On GCC/Clang, the hash is computed at compile time (constexpr) and baked into the binary, resulting in zero runtime cost. On MSVC, the hash is computed at runtime due to compiler limitations with constexpr, but is still highly optimized (inlined).

Runtime Construction: For runtime strings (user input, loaded data), construct using the same macro: STRING_ID(str). This stores the string in the global StringRegistry for lifetime management and debug lookup.

Hash Collisions: The system assumes 64-bit rapidhash collisions are astronomically unlikely (2^64 keyspace). There is no runtime collision detection - equality is purely hash-based.

Example - Compile-time string IDs:

// Hash computed at compile-time (on GCC/Clang)
constexpr auto player_id = STRING_ID("game/player");
constexpr auto texture_id = STRING_ID("textures/ground.png");

// Use as resource keys
auto* player_mesh = resources.get<Mesh>(player_id);
auto* ground_tex = resources.get<Texture>(texture_id);

Example - Runtime string IDs:

// Runtime string from user input
std::string entity_name = read_from_config();
StringId entity_id = STRING_ID(entity_name);

// String is stored in registry for debugging
LOG_INFO("Created entity: {}", entity_id);  // Prints: Created entity: id("MyEntity")

Example - Using as hash map key:

// Works with both LLVM DenseMap and std::unordered_map
llvm::DenseMap<StringId, Entity*> entities;
std::unordered_map<StringId, Texture*> textures;

entities[STRING_ID("player")] = player_entity;