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mcc/mcc_utils.h

@@ -355,4 +355,48 @@ std::pair<double, double> parseAnglePair(R&& str, bool hms1 = false, bool hms2 =
 }
 
 
+template <traits::mcc_input_char_range R>
+static constexpr size_t FNV1aHash(const R& r)
+{
+    static_assert(sizeof(size_t) == 8 || sizeof(size_t) == 4, "ONLY FOR 32 or 64-bit size_t!!!");
+
+    size_t hash = 0, prime = 0;
+    if constexpr (sizeof(size_t) == 8) {  // 64-bit
+        prime = 1099511628211UL;
+        hash = 14695981039346656037UL;
+    } else if constexpr (sizeof(size_t) == 4) {  // 32-bit
+        prime = 16777619;
+        hash = 2166136261;
+    }
+
+    for (const char& ch : r) {
+        hash ^= ch;
+        hash *= prime;
+    }
+
+    return hash;
+}
+
+static constexpr size_t FNV1aHash(std::forward_iterator auto begin, std::sentinel_for<decltype(begin)> auto end)
+    requires std::same_as<std::remove_cv_t<std::iter_value_t<decltype(begin)>>, char>
+{
+    static_assert(sizeof(size_t) == 8 || sizeof(size_t) == 4, "ONLY FOR 32 or 64-bit size_t!!!");
+
+    size_t hash = 0, prime = 0;
+    if constexpr (sizeof(size_t) == 8) {  // 64-bit
+        prime = 1099511628211UL;
+        hash = 14695981039346656037UL;
+    } else if constexpr (sizeof(size_t) == 4) {  // 32-bit
+        prime = 16777619;
+        hash = 2166136261;
+    }
+
+    for (auto it = begin; it != end; ++it) {
+        hash ^= *it;
+        hash *= prime;
+    }
+
+    return hash;
+}
+
 }  // namespace mcc::utils