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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef mozilla_dom_XMLHttpRequestString_h
#define mozilla_dom_XMLHttpRequestString_h
#include "mozilla/Mutex.h"
#include "nsString.h"
struct JSContext;
class JSString;
namespace mozilla::dom {
class ArrayBufferBuilder;
class BlobImpl;
class DOMString;
class XMLHttpRequestStringBuffer;
class XMLHttpRequestStringSnapshot;
class XMLHttpRequestStringWriterHelper;
// We want to avoid the dup of strings when XHR in workers has access to
// responseText for events dispatched during the loading state. For this reason
// we use this class, able to create snapshots of the current size of itself
// without making extra copies.
class XMLHttpRequestString final {
friend class XMLHttpRequestStringWriterHelper;
void Truncate();
uint32_t Length() const;
void Append(const nsAString& aString);
// This method should be called only when the string is really needed because
// it can cause the duplication of the strings in case the loading of the XHR
// is not completed yet.
[[nodiscard]] bool GetAsString(nsAString& aString) const;
size_t SizeOfThis(MallocSizeOf aMallocSizeOf) const;
const char16_t* Data() const;
bool IsEmpty() const;
void CreateSnapshot(XMLHttpRequestStringSnapshot& aSnapshot);
XMLHttpRequestString(const XMLHttpRequestString&) = delete;
XMLHttpRequestString& operator=(const XMLHttpRequestString&) = delete;
XMLHttpRequestString& operator=(const XMLHttpRequestString&&) = delete;
RefPtr<XMLHttpRequestStringBuffer> mBuffer;
// This class locks the buffer and allows the callee to write data into it.
class MOZ_STACK_CLASS XMLHttpRequestStringWriterHelper final {
explicit XMLHttpRequestStringWriterHelper(XMLHttpRequestString& aString);
* The existing length of the string. Do not call during BulkWrite().
uint32_t Length() const;
mozilla::Result<mozilla::BulkWriteHandle<char16_t>, nsresult> BulkWrite(
uint32_t aCapacity);
XMLHttpRequestStringWriterHelper(const XMLHttpRequestStringWriterHelper&) =
XMLHttpRequestStringWriterHelper& operator=(
const XMLHttpRequestStringWriterHelper&) = delete;
XMLHttpRequestStringWriterHelper& operator=(
const XMLHttpRequestStringWriterHelper&&) = delete;
RefPtr<XMLHttpRequestStringBuffer> mBuffer;
MutexAutoLock mLock;
// This class is the internal XMLHttpRequestStringBuffer of the
// XMLHttpRequestString plus the current length. GetAsString will return the
// string with that particular length also if the XMLHttpRequestStringBuffer is
// grown in the meantime.
class XMLHttpRequestStringSnapshot final {
friend class XMLHttpRequestStringBuffer;
XMLHttpRequestStringSnapshot& operator=(const XMLHttpRequestStringSnapshot&) =
void Reset() { ResetInternal(false /* isVoid */); }
void SetVoid() { ResetInternal(true /* isVoid */); }
bool IsVoid() const { return mVoid; }
bool IsEmpty() const { return !mLength; }
[[nodiscard]] bool GetAsString(DOMString& aString) const;
JSString* GetAsJSStringCopy(JSContext* aCx) const;
XMLHttpRequestStringSnapshot(const XMLHttpRequestStringSnapshot&) = delete;
XMLHttpRequestStringSnapshot& operator=(
const XMLHttpRequestStringSnapshot&&) = delete;
void Set(XMLHttpRequestStringBuffer* aBuffer, uint32_t aLength);
void ResetInternal(bool aIsVoid);
RefPtr<XMLHttpRequestStringBuffer> mBuffer;
uint32_t mLength;
bool mVoid;
} // namespace mozilla::dom
#endif // mozilla_dom_XMLHttpRequestString_h