sebastienros.jint/Jint/Native/Symbol/SymbolPrototype.cs

#pragma warning disable CA1859 // Use concrete types when possible for improved performance -- most of prototype methods return JsValue

using Jint.Collections;
using Jint.Native.Object;
using Jint.Runtime;
using Jint.Runtime.Descriptors;
using Jint.Runtime.Interop;

namespace Jint.Native.Symbol;

/// <summary>
/// https://tc39.es/ecma262/#sec-properties-of-the-symbol-prototype-object
/// </summary>
internal sealed class SymbolPrototype : Prototype
{
    private readonly SymbolConstructor _constructor;

    internal SymbolPrototype(
        Engine engine,
        Realm realm,
        SymbolConstructor symbolConstructor,
        ObjectPrototype objectPrototype)
        : base(engine, realm)
    {
        _prototype = objectPrototype;
        _constructor = symbolConstructor;
    }

    protected override void Initialize()
    {
        const PropertyFlag lengthFlags = PropertyFlag.Configurable;
        const PropertyFlag propertyFlags = PropertyFlag.Configurable;
        SetProperties(new PropertyDictionary(5, checkExistingKeys: false)
        {
            ["length"] = new PropertyDescriptor(JsNumber.PositiveZero, propertyFlags),
            ["constructor"] = new PropertyDescriptor(_constructor, PropertyFlag.Configurable | PropertyFlag.Writable),
            ["description"] = new GetSetPropertyDescriptor(new ClrFunction(Engine, "description", Description, 0, lengthFlags), Undefined, propertyFlags),
            ["toString"] = new PropertyDescriptor(new ClrFunction(Engine, "toString", ToSymbolString, 0, lengthFlags), PropertyFlag.Configurable | PropertyFlag.Writable),
            ["valueOf"] = new PropertyDescriptor(new ClrFunction(Engine, "valueOf", ValueOf, 0, lengthFlags), PropertyFlag.Configurable | PropertyFlag.Writable)
        });

        SetSymbols(new SymbolDictionary(1)
            {
                [GlobalSymbolRegistry.ToPrimitive] = new PropertyDescriptor(new ClrFunction(Engine, "[Symbol.toPrimitive]", ToPrimitive, 1, lengthFlags), propertyFlags), [GlobalSymbolRegistry.ToStringTag] = new PropertyDescriptor(new JsString("Symbol"), propertyFlags)
            }
        );
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-symbol.prototype.description
    /// </summary>
    private JsValue Description(JsValue thisObject, JsCallArguments arguments)
    {
        var sym = ThisSymbolValue(thisObject);
        return sym._value;
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-symbol.prototype.tostring
    /// </summary>
    private JsValue ToSymbolString(JsValue thisObject, JsCallArguments arguments)
    {
        var sym = ThisSymbolValue(thisObject);
        return new JsString(sym.ToString());
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-symbol.prototype.valueof
    /// </summary>
    private JsValue ValueOf(JsValue thisObject, JsCallArguments arguments)
    {
        return ThisSymbolValue(thisObject);
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-symbol.prototype-@@toprimitive
    /// </summary>
    private JsValue ToPrimitive(JsValue thisObject, JsCallArguments arguments)
    {
        return ThisSymbolValue(thisObject);
    }

    private JsSymbol ThisSymbolValue(JsValue thisObject)
    {
        if (thisObject is JsSymbol s)
        {
            return s;
        }

        if (thisObject is SymbolInstance instance)
        {
            return instance.SymbolData;
        }

        ExceptionHelper.ThrowTypeError(_realm);
        return null;
    }
}