ladybird/Userland/Libraries/LibWeb/Streams/QueueOperations.h

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/*
* Copyright (c) 2023, Matthew Olsson <mattco@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <LibJS/Runtime/Error.h>
#include <LibWeb/WebIDL/ExceptionOr.h>
namespace Web::Streams {
// https://streams.spec.whatwg.org/#value-with-size
struct ValueWithSize {
JS::Value value;
double size;
};
// https://streams.spec.whatwg.org/#dequeue-value
template<typename T>
JS::Value dequeue_value(T& container)
{
// 1. Assert: container has [[queue]] and [[queueTotalSize]] internal slots.
// 2. Assert: container.[[queue]] is not empty.
VERIFY(!container.queue().is_empty());
// 3. Let valueWithSize be container.[[queue]][0].
// 4. Remove valueWithSize from container.[[queue]].
auto value_with_size = container.queue().take_first();
// 5. Set container.[[queueTotalSize]] to container.[[queueTotalSize]] valueWithSizes size.
container.set_queue_total_size(container.queue_total_size() - value_with_size.size);
// 6. If container.[[queueTotalSize]] < 0, set container.[[queueTotalSize]] to 0. (This can occur due to rounding errors.)
if (container.queue_total_size() < 0.0)
container.set_queue_total_size(0.0);
// 7. Return valueWithSizes value.
return value_with_size.value;
}
// https://streams.spec.whatwg.org/#enqueue-value-with-size
template<typename T>
WebIDL::ExceptionOr<void> enqueue_value_with_size(T& container, JS::Value value, double size)
{
// 1. Assert: container has [[queue]] and [[queueTotalSize]] internal slots.
// 2. If ! IsNonNegativeNumber(size) is false, throw a RangeError exception.
if (size < 0.0)
return WebIDL::SimpleException { WebIDL::SimpleExceptionType::RangeError, "Chunk has negative size"sv };
// 3. If size is +∞, throw a RangeError exception.
if (size == HUGE_VAL)
return WebIDL::SimpleException { WebIDL::SimpleExceptionType::RangeError, "Chunk has infinite size"sv };
// 4. Append a new value-with-size with value value and size size to container.[[queue]].
container.queue().append({ value, size });
// 5. Set container.[[queueTotalSize]] to container.[[queueTotalSize]] + size.
container.set_queue_total_size(container.queue_total_size() + size);
return {};
}
// https://streams.spec.whatwg.org/#peek-queue-value
template<typename T>
JS::Value peek_queue_value(T& container)
{
// 1. Assert: container has [[queue]] and [[queueTotalSize]] internal slots.
// 2. Assert: container.[[queue]] is not empty.
VERIFY(!container.queue().is_empty());
// 3. Let valueWithSize be container.[[queue]][0].
auto& value_with_size = container.queue().first();
// 4. Return valueWithSizes value.
return value_with_size.value;
}
// https://streams.spec.whatwg.org/#reset-queue
template<typename T>
void reset_queue(T& container)
{
// 1. Assert: container has [[queue]] and [[queueTotalSize]] internal slots.
// 2. Set container.[[queue]] to a new empty list.
container.queue().clear();
// 3. Set container.[[queueTotalSize]] to 0.
container.set_queue_total_size(0);
}
}