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		01c2570678
		
	
	
	
	
		
			
			I wanted to do this for a long time. The guts of Promise are pretty complex, and it's easier to understand with the spec right next to it. Also found a couple of issues along the way :^)
		
			
				
	
	
		
			64 lines
		
	
	
	
		
			1.7 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			64 lines
		
	
	
	
		
			1.7 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| /*
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|  * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
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|  *
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|  * SPDX-License-Identifier: BSD-2-Clause
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|  */
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| 
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| #pragma once
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| 
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| #include <AK/Vector.h>
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| #include <LibJS/Runtime/Object.h>
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| 
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| namespace JS {
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| 
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| ThrowCompletionOr<Object*> promise_resolve(GlobalObject&, Object& constructor, Value);
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| 
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| class Promise : public Object {
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|     JS_OBJECT(Promise, Object);
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| 
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| public:
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|     enum class State {
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|         Pending,
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|         Fulfilled,
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|         Rejected,
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|     };
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|     enum class RejectionOperation {
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|         Reject,
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|         Handle,
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|     };
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| 
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|     static Promise* create(GlobalObject&);
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| 
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|     explicit Promise(Object& prototype);
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|     virtual ~Promise() = default;
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| 
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|     State state() const { return m_state; }
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|     Value result() const { return m_result; }
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| 
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|     struct ResolvingFunctions {
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|         FunctionObject& resolve;
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|         FunctionObject& reject;
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|     };
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|     ResolvingFunctions create_resolving_functions();
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| 
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|     Value fulfill(Value value);
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|     Value reject(Value reason);
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|     Value perform_then(Value on_fulfilled, Value on_rejected, Optional<PromiseCapability> result_capability);
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| 
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| protected:
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|     virtual void visit_edges(Visitor&) override;
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| 
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| private:
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|     bool is_settled() const { return m_state == State::Fulfilled || m_state == State::Rejected; }
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| 
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|     void trigger_reactions() const;
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| 
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|     // 27.2.6 Properties of Promise Instances, https://tc39.es/ecma262/#sec-properties-of-promise-instances
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|     State m_state { State::Pending };             // [[PromiseState]]
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|     Value m_result;                               // [[PromiseResult]]
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|     Vector<PromiseReaction*> m_fulfill_reactions; // [[PromiseFulfillReactions]]
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|     Vector<PromiseReaction*> m_reject_reactions;  // [[PromiseRejectReactions]]
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|     bool m_is_handled { false };                  // [[PromiseIsHandled]]
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| };
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| 
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| }
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