script_promise.h | Explore in Territory

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#ifndef THIRD_PARTY_BLINK_RENDERER_BINDINGS_CORE_V8_SCRIPT_PROMISE_H_
#define THIRD_PARTY_BLINK_RENDERER_BINDINGS_CORE_V8_SCRIPT_PROMISE_H_

#include "base/memory/scoped_refptr.h"
#include "base/memory/stack_allocated.h"
#include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
#include "third_party/blink/renderer/bindings/core/v8/script_value.h"
#include "third_party/blink/renderer/bindings/core/v8/v8_binding_for_core.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/dom/dom_exception.h"
#include "third_party/blink/renderer/platform/bindings/exception_state.h"
#include "third_party/blink/renderer/platform/heap/collection_support/heap_vector.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"
#include "v8/include/v8.h"

namespace blink {

class DOMException;
class ScriptFunction;

template <typename IDLResolvedType>
class ScriptPromise;

// ScriptPromise is the class for representing Promise values in C++
// world. ScriptPromise holds a Promise. Holding a `ScriptPromise`
// is rarely needed — typically you hold a `ScriptPromiseResolver` when creating
// a Promise and passing it *to* JavaScript — but is necessary when
// holding a promise received *from* JavaScript. If a promise is exposed as an
// attribute in IDL and you need to return the same promise on multiple
// invocations, use ScriptPromiseProperty.
//
// There are cases where promises cannot work (e.g., where the thread is being
// terminated). In such cases operations will silently fail, so you should not
// use promises for critical use such as releasing a resource.
class CORE_EXPORT ScriptPromiseUntyped { … };

template <typename IDLResolvedType>
class ScriptPromise : public ScriptPromiseUntyped { … };

// Defined in to_v8_traits.h due to circular dependency.
template <typename IDLType, typename BlinkType>
ScriptPromise<IDLType> ToResolvedPromise(ScriptState*, BlinkType value);

CORE_EXPORT ScriptPromise<IDLUndefined> ToResolvedUndefinedPromise(
    ScriptState*);

// EmptyPromise() is a value similar to std::nullopt that can be used to return
// an empty ScriptPromise of any type. It is intended to be used when throwing
// an exception using an ExceptionState object, since in that case the bindings
// ignore the contents of the returned promise.
//
// The usual patterns for usage are:
//
//   if (bad thing) {
//     exception_state.ThrowRangeError("bad thing");
//     return EmptyPromise();
//   }
//
// or
//
//   FunctionThatMightThrow(script_state, exception_state);
//   if (exception_state.HadException()) {
//     return EmptyPromise();
//   }
class EmptyPromise { … };

}  // namespace blink

namespace WTF {

template <>
struct VectorTraits<blink::ScriptPromiseUntyped>
    : VectorTraitsBase<blink::ScriptPromiseUntyped> { … };

}  // namespace WTF

#endif  // THIRD_PARTY_BLINK_RENDERER_BINDINGS_CORE_V8_SCRIPT_PROMISE_H_
chromium/third_party/blink/renderer/bindings/core/v8/script_promise.h
