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algorithms.ixx File

Core algorithms and hash functions for the helios engine. More...

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#include <cstdint> #include <string>

Namespaces Index​

namespacehelios
namespacecore

Core utilities shared across the helios engine. More...

namespacealgorithms

Description​

Core algorithms and hash functions for the helios engine.

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The file content with the documentation metadata removed is:

1/**
2 * @file algorithms.ixx
3 * @brief Core algorithms and hash functions for the helios engine.
4 */
5module;
6
7#include <cstdint>
8#include <string>
9
10export module helios.core.algorithms;
11
12
13
14export namespace helios::core::algorithms {
15
16 /**
17 * @brief Computes a 32-bit FNV-1a hash from a string.
18 *
19 * @details Implements the Fowler–Noll–Vo hash function (FNV-1a variant),
20 * a fast, non-cryptographic hash suitable for hash tables and identifier
21 * generation. The function is `constexpr`, enabling compile-time hashing
22 * of string literals.
23 *
24 * ## Algorithm
25 *
26 * 1 Initialize hash with FNV offset basis (2166136261)
27 * 2 For each byte: XOR with hash, then multiply by FNV prime (16777619)
28 *
29 * ## Usage
30 *
31 * ```cpp
32 * // Compile-time hash for type-safe IDs
33 * constexpr uint32_t id = fnv1a_hash("enemy_spawn");
34 *
35 * // Used internally by strongly-typed ID constructors
36 * constexpr GameObjectPoolId POOL{"bullets"}; // calls fnv1a_hash
37 * ```
38 *
39 * @param str The string view to hash.
40 *
41 * @return 32-bit hash value.
42 *
43 * @note This is not a cryptographic hash. Do not use for security purposes.
44 *
45 * @see https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
46 * @see GameObjectPoolId
47 * @see SpawnProfileId
48 * @see SpawnRuleId
49 */
50 [[nodiscard]] constexpr uint32_t fnv1a_hash(const std::string_view str) noexcept {
51 uint32_t hash = 2166136261U;
52 for (char c: str) {
53 hash ^= static_cast<uint8_t>(c);
54 hash *= 16777619U;
55 }
56 return hash;
57 }
58
59
60}

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