ladybird/Libraries/LibJS/Runtime/Symbol.cpp

/*
 * Copyright (c) 2020, Matthew Olsson <mattco@serenityos.org>
 * Copyright (c) 2022-2023, Linus Groh <linusg@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibGC/Heap.h>
#include <LibJS/Runtime/Symbol.h>
#include <LibJS/Runtime/VM.h>

namespace JS {

GC_DEFINE_ALLOCATOR(Symbol);

Symbol::Symbol(Optional<Utf16String> description, bool is_global)
    : m_description(move(description))
    , m_is_global(is_global)
{
}

GC::Ref<Symbol> Symbol::create(VM& vm, Optional<Utf16String> description, bool is_global)
{
    return vm.heap().allocate<Symbol>(move(description), is_global);
}

// 20.4.3.3.1 SymbolDescriptiveString ( sym ), https://tc39.es/ecma262/#sec-symboldescriptivestring
Utf16String Symbol::descriptive_string() const
{
    // 1. Let desc be sym's [[Description]] value.
    // 2. If desc is undefined, set desc to the empty String.
    // 3. Assert: desc is a String.
    auto description = m_description.value_or({});

    // 4. Return the string-concatenation of "Symbol(", desc, and ")".
    return Utf16String::formatted("Symbol({})", description);
}

// 20.4.5.1 KeyForSymbol ( sym ), https://tc39.es/ecma262/#sec-keyforsymbol
Optional<Utf16String> Symbol::key() const
{
    // 1. For each element e of the GlobalSymbolRegistry List, do
    //    a. If SameValue(e.[[Symbol]], sym) is true, return e.[[Key]].
    if (m_is_global) {
        // NOTE: Global symbols should always have a description string
        VERIFY(m_description.has_value());
        return m_description;
    }

    // 2. Assert: GlobalSymbolRegistry does not currently contain an entry for sym.
    // 3. Return undefined.
    return {};
}

}