diff CSP2/CSP2_env/env-d9b9114564458d9d-741b3de822f2aaca6c6caa4325c4afce/include/kj/hash.h @ 69:33d812a61356

planemo upload commit 2e9511a184a1ca667c7be0c6321a36dc4e3d116d
author jpayne
date Tue, 18 Mar 2025 17:55:14 -0400
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/CSP2/CSP2_env/env-d9b9114564458d9d-741b3de822f2aaca6c6caa4325c4afce/include/kj/hash.h	Tue Mar 18 17:55:14 2025 -0400
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+// Copyright (c) 2018 Kenton Varda and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#pragma once
+
+#include "string.h"
+
+KJ_BEGIN_HEADER
+
+namespace kj {
+namespace _ {  // private
+
+struct HashCoder {
+  // This is a dummy type with only one instance: HASHCODER (below).  To make an arbitrary type
+  // hashable, define `operator*(HashCoder, T)` to return any other type that is already hashable.
+  // Be sure to declare the operator in the same namespace as `T` **or** in the global scope.
+  // You can use the KJ_HASHCODE() macro as syntax sugar for this.
+  //
+  // A more usual way to accomplish what we're doing here would be to require that you define
+  // a function like `hashCode(T)` and then rely on argument-dependent lookup.  However, this has
+  // the problem that it pollutes other people's namespaces and even the global namespace.  For
+  // example, some other project may already have functions called `hashCode` which do something
+  // different.  Declaring `operator*` with `HashCoder` as the left operand cannot conflict with
+  // anything.
+
+  uint operator*(ArrayPtr<const byte> s) const;
+  inline uint operator*(ArrayPtr<byte> s) const { return operator*(s.asConst()); }
+
+  inline uint operator*(ArrayPtr<const char> s) const { return operator*(s.asBytes()); }
+  inline uint operator*(ArrayPtr<char> s) const { return operator*(s.asBytes()); }
+  inline uint operator*(const Array<const char>& s) const { return operator*(s.asBytes()); }
+  inline uint operator*(const Array<char>& s) const { return operator*(s.asBytes()); }
+  inline uint operator*(const String& s) const { return operator*(s.asBytes()); }
+  inline uint operator*(const StringPtr& s) const { return operator*(s.asBytes()); }
+  inline uint operator*(const ConstString& s) const { return operator*(s.asBytes()); }
+
+  inline uint operator*(decltype(nullptr)) const { return 0; }
+  inline uint operator*(bool b) const { return b; }
+  inline uint operator*(char i) const { return i; }
+  inline uint operator*(signed char i) const { return i; }
+  inline uint operator*(unsigned char i) const { return i; }
+  inline uint operator*(signed short i) const { return i; }
+  inline uint operator*(unsigned short i) const { return i; }
+  inline uint operator*(signed int i) const { return i; }
+  inline uint operator*(unsigned int i) const { return i; }
+
+  inline uint operator*(signed long i) const {
+    if (sizeof(i) == sizeof(uint)) {
+      return operator*(static_cast<uint>(i));
+    } else {
+      return operator*(static_cast<unsigned long long>(i));
+    }
+  }
+  inline uint operator*(unsigned long i) const {
+    if (sizeof(i) == sizeof(uint)) {
+      return operator*(static_cast<uint>(i));
+    } else {
+      return operator*(static_cast<unsigned long long>(i));
+    }
+  }
+  inline uint operator*(signed long long i) const {
+    return operator*(static_cast<unsigned long long>(i));
+  }
+  inline uint operator*(unsigned long long i) const {
+    // Mix 64 bits to 32 bits in such a way that if our input values differ primarily in the upper
+    // 32 bits, we still get good diffusion. (I.e. we cannot just truncate!)
+    //
+    // 49123 is an arbitrarily-chosen prime that is vaguely close to 2^16.
+    //
+    // TODO(perf): I just made this up. Is it OK?
+    return static_cast<uint>(i) + static_cast<uint>(i >> 32) * 49123;
+  }
+
+  template <typename T>
+  uint operator*(T* ptr) const {
+    static_assert(!isSameType<Decay<T>, char>(), "Wrap in StringPtr if you want to hash string "
+        "contents. If you want to hash the pointer, cast to void*");
+    if (sizeof(ptr) == sizeof(uint)) {
+      // TODO(cleanup): In C++17, make the if() above be `if constexpr ()`, then change this to
+      //   reinterpret_cast<uint>(ptr).
+      return reinterpret_cast<unsigned long long>(ptr);
+    } else {
+      return operator*(reinterpret_cast<unsigned long long>(ptr));
+    }
+  }
+
+  template <typename T, typename = decltype(instance<const HashCoder&>() * instance<const T&>())>
+  uint operator*(ArrayPtr<T> arr) const;
+  template <typename T, typename = decltype(instance<const HashCoder&>() * instance<const T&>())>
+  uint operator*(const Array<T>& arr) const;
+  template <typename T, typename = EnableIf<__is_enum(T)>>
+  inline uint operator*(T e) const;
+
+  template <typename T, typename Result = decltype(instance<T>().hashCode())>
+  inline Result operator*(T&& value) const { return kj::fwd<T>(value).hashCode(); }
+};
+static KJ_CONSTEXPR(const) HashCoder HASHCODER = HashCoder();
+
+}  // namespace _ (private)
+
+#define KJ_HASHCODE(...) operator*(::kj::_::HashCoder, __VA_ARGS__)
+// Defines a hash function for a custom type.  Example:
+//
+//    class Foo {...};
+//    inline uint KJ_HASHCODE(const Foo& foo) { return kj::hashCode(foo.x, foo.y); }
+//
+// This allows Foo to be passed to hashCode().
+//
+// The function should be declared either in the same namespace as the target type or in the global
+// namespace. It can return any type which itself is hashable -- that value will be hashed in turn
+// until a `uint` comes out.
+
+inline uint hashCode(uint value) { return value; }
+template <typename T>
+inline uint hashCode(T&& value) { return hashCode(_::HASHCODER * kj::fwd<T>(value)); }
+template <typename T, size_t N>
+inline uint hashCode(T (&arr)[N]) {
+  static_assert(!isSameType<Decay<T>, char>(), "Wrap in StringPtr if you want to hash string "
+      "contents. If you want to hash the pointer, cast to void*");
+  static_assert(isSameType<Decay<T>, char>(), "Wrap in ArrayPtr if you want to hash a C array. "
+      "If you want to hash the pointer, cast to void*");
+  return 0;
+}
+template <typename... T>
+inline uint hashCode(T&&... values) {
+  uint hashes[] = { hashCode(kj::fwd<T>(values))... };
+  return hashCode(kj::ArrayPtr<uint>(hashes).asBytes());
+}
+// kj::hashCode() is a universal hashing function, like kj::str() is a universal stringification
+// function. Throw stuff in, get a hash code.
+//
+// Hash codes may differ between different processes, even running exactly the same code.
+//
+// NOT SUITABLE FOR CRYPTOGRAPHY. This is for hash tables, not crypto.
+
+// =======================================================================================
+// inline implementation details
+
+namespace _ {  // private
+
+template <typename T, typename>
+inline uint HashCoder::operator*(ArrayPtr<T> arr) const {
+  // Hash each array element to create a string of hashes, then murmur2 over those.
+  //
+  // TODO(perf): Choose a more-modern hash. (See hash.c++.)
+
+  constexpr uint m = 0x5bd1e995;
+  constexpr uint r = 24;
+  uint h = arr.size() * sizeof(uint);
+
+  for (auto& e: arr) {
+    uint k = kj::hashCode(e);
+    k *= m;
+    k ^= k >> r;
+    k *= m;
+    h *= m;
+    h ^= k;
+  }
+
+  h ^= h >> 13;
+  h *= m;
+  h ^= h >> 15;
+  return h;
+}
+template <typename T, typename>
+inline uint HashCoder::operator*(const Array<T>& arr) const {
+  return operator*(arr.asPtr());
+}
+
+template <typename T, typename>
+inline uint HashCoder::operator*(T e) const {
+  return operator*(static_cast<__underlying_type(T)>(e));
+}
+
+}  // namespace _ (private)
+} // namespace kj
+
+KJ_END_HEADER