ladybird/Userland/Libraries/LibJS/Runtime/PromiseReaction.h

/*
 * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/JobCallback.h>
#include <LibJS/Runtime/VM.h>

namespace JS {

// 27.2.1.1 PromiseCapability Records, https://tc39.es/ecma262/#sec-promisecapability-records
struct PromiseCapability {
    Object* promise { nullptr };
    FunctionObject* resolve { nullptr };
    FunctionObject* reject { nullptr };
};

// 27.2.1.1.1 IfAbruptRejectPromise ( value, capability ), https://tc39.es/ecma262/#sec-ifabruptrejectpromise
#define TRY_OR_REJECT(vm, capability, expression)                                                                      \
    ({                                                                                                                 \
        auto _temporary_try_or_reject_result = (expression);                                                           \
        /* 1. If value is an abrupt completion, then */                                                                \
        if (_temporary_try_or_reject_result.is_error()) {                                                              \
            vm.clear_exception();                                                                                      \
            vm.stop_unwind();                                                                                          \
                                                                                                                       \
            /* a. Perform ? Call(capability.[[Reject]], undefined, « value.[[Value]] »). */                          \
            TRY(vm.call(*capability.reject, js_undefined(), _temporary_try_or_reject_result.release_error().value())); \
                                                                                                                       \
            /* b. Return capability.[[Promise]]. */                                                                    \
            return capability.promise;                                                                                 \
        }                                                                                                              \
                                                                                                                       \
        /* 2. Else if value is a Completion Record, set value to value.[[Value]]. */                                   \
        _temporary_try_or_reject_result.release_value();                                                               \
    })

// 27.2.1.5 NewPromiseCapability ( C ), https://tc39.es/ecma262/#sec-newpromisecapability
ThrowCompletionOr<PromiseCapability> new_promise_capability(GlobalObject& global_object, Value constructor);

// 27.2.1.2 PromiseReaction Records, https://tc39.es/ecma262/#sec-promisereaction-records
class PromiseReaction final : public Cell {
public:
    enum class Type {
        Fulfill,
        Reject,
    };

    static PromiseReaction* create(VM& vm, Type type, Optional<PromiseCapability> capability, Optional<JobCallback> handler)
    {
        return vm.heap().allocate_without_global_object<PromiseReaction>(type, capability, handler);
    }

    PromiseReaction(Type type, Optional<PromiseCapability> capability, Optional<JobCallback> handler);
    virtual ~PromiseReaction() = default;

    Type type() const { return m_type; }
    const Optional<PromiseCapability>& capability() const { return m_capability; }
    const Optional<JobCallback>& handler() const { return m_handler; }

private:
    virtual const char* class_name() const override { return "PromiseReaction"; }
    virtual void visit_edges(Visitor&) override;

    Type m_type;
    Optional<PromiseCapability> m_capability;
    Optional<JobCallback> m_handler;
};

}