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https://github.com/RGBCube/serenity
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59080f441e
This ensures that different NaN types (e.g. 0/0, 0 * Infinity, etc) are mapped to the same Set/Map entry.
43 lines
1.5 KiB
C++
43 lines
1.5 KiB
C++
/*
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* Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2020-2021, Linus Groh <linusg@serenityos.org>
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* Copyright (c) 2020-2022, Idan Horowitz <idan.horowitz@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <LibJS/Runtime/PrimitiveString.h>
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#include <LibJS/Runtime/Value.h>
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namespace JS {
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struct ValueTraits : public Traits<Value> {
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static unsigned hash(Value value)
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{
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VERIFY(!value.is_empty());
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if (value.is_string())
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return value.as_string().string().hash();
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if (value.is_bigint())
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return value.as_bigint().big_integer().hash();
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if (value.is_negative_zero())
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value = Value(0);
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// In the IEEE 754 standard a NaN value is encoded as any value from 0x7ff0000000000001 to 0x7fffffffffffffff,
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// with the least significant bits (referred to as the 'payload') carrying some kind of diagnostic information
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// indicating the source of the NaN. Since ECMA262 does not differentiate between different kinds of NaN values,
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// Sets and Maps must not differentiate between them either.
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// This is achieved by replacing any NaN value by a canonical qNaN.
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else if (value.is_nan())
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value = js_nan();
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return u64_hash(value.encoded()); // FIXME: Is this the best way to hash pointers, doubles & ints?
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}
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static bool equals(const Value a, const Value b)
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{
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return same_value_zero(a, b);
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}
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};
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}
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