зеркало из https://github.com/mozilla/gecko-dev.git
123 строки
3.6 KiB
C++
123 строки
3.6 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_dom_localstorage_LSValue_h
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#define mozilla_dom_localstorage_LSValue_h
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#include <cstdint>
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#include "ErrorList.h"
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#include "SnappyUtils.h"
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#include "mozilla/Assertions.h"
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#include "mozilla/Span.h"
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#include "nsString.h"
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#include "nsStringFwd.h"
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#include "nsTStringRepr.h"
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class mozIStorageStatement;
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namespace IPC {
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template <typename>
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struct ParamTraits;
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}
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namespace mozilla {
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namespace dom {
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/**
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* Represents a LocalStorage value. From content's perspective, values (if
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* present) are always DOMStrings. This is also true from a quota-tracking
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* perspective. However, for memory and disk efficiency it's preferable to store
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* the value in alternate compressed or utf-8 encoding representations. The
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* LSValue type exists to support these alternate representations, dynamically
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* decompressing/re-encoding to utf-16 while still tracking value size on a
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* utf-16 basis for quota purposes.
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*/
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class LSValue final {
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friend struct IPC::ParamTraits<LSValue>;
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nsCString mBuffer;
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uint32_t mUTF16Length;
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bool mCompressed;
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public:
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LSValue() : mUTF16Length(0), mCompressed(false) { SetIsVoid(true); }
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bool InitFromString(const nsAString& aBuffer);
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nsresult InitFromStatement(mozIStorageStatement* aStatement, uint32_t aIndex);
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bool IsVoid() const { return mBuffer.IsVoid(); }
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void SetIsVoid(bool aVal) { mBuffer.SetIsVoid(aVal); }
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/**
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* This represents the "physical" length that the parent process uses for
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* the size of value/item computation. This can also be used to see how much
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* memory the value is using at rest or what the cost is for sending the value
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* over IPC.
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*/
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uint32_t Length() const { return mBuffer.Length(); }
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/*
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* This represents the "logical" length that content sees and that is also
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* used for quota management purposes.
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*/
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uint32_t UTF16Length() const { return mUTF16Length; }
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bool IsCompressed() const { return mCompressed; }
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bool Equals(const LSValue& aOther) const {
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return mBuffer == aOther.mBuffer &&
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mBuffer.IsVoid() == aOther.mBuffer.IsVoid() &&
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mUTF16Length == aOther.mUTF16Length &&
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mCompressed == aOther.mCompressed;
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}
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bool operator==(const LSValue& aOther) const { return Equals(aOther); }
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bool operator!=(const LSValue& aOther) const { return !Equals(aOther); }
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operator const nsCString&() const { return mBuffer; }
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operator Span<const char>() const { return mBuffer; }
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class Converter {
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nsString mBuffer;
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public:
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explicit Converter(const LSValue& aValue) {
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if (aValue.mBuffer.IsVoid()) {
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mBuffer.SetIsVoid(true);
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} else if (aValue.mCompressed) {
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nsCString buffer;
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MOZ_ALWAYS_TRUE(SnappyUncompress(aValue.mBuffer, buffer));
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CopyUTF8toUTF16(buffer, mBuffer);
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} else {
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CopyUTF8toUTF16(aValue.mBuffer, mBuffer);
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}
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}
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Converter(Converter&& aOther) = default;
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~Converter() = default;
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operator const nsString&() const { return mBuffer; }
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private:
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Converter() = delete;
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Converter(const Converter&) = delete;
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Converter& operator=(const Converter&) = delete;
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Converter& operator=(const Converter&&) = delete;
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};
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Converter AsString() const { return Converter{*this}; }
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};
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const LSValue& VoidLSValue();
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} // namespace dom
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} // namespace mozilla
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#endif // mozilla_dom_localstorage_LSValue_h
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