gecko-dev/xpcom/ds/nsVariant.h

/* -*- 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 http://mozilla.org/MPL/2.0/. */

#ifndef nsVariant_h
#define nsVariant_h

#include "nsIVariant.h"
#include "nsStringFwd.h"
#include "mozilla/Attributes.h"
#include "nsCycleCollectionParticipant.h"

/**
 * Map the nsAUTF8String, nsUTF8String classes to the nsACString and
 * nsCString classes respectively for now.  These defines need to be removed
 * once Jag lands his nsUTF8String implementation.
 */
#define nsAUTF8String nsACString
#define nsUTF8String nsCString
#define PromiseFlatUTF8String PromiseFlatCString

/**
 * nsDiscriminatedUnion is a class that nsIVariant implementors can use
 * to hold the underlying data.
 */

class nsDiscriminatedUnion
{
public:
  nsDiscriminatedUnion()
    : mType(nsIDataType::VTYPE_EMPTY)
  {
    u.mInt8Value = '\0';
  }
  nsDiscriminatedUnion(const nsDiscriminatedUnion&) = delete;
  nsDiscriminatedUnion(nsDiscriminatedUnion&&) = delete;

  ~nsDiscriminatedUnion() { Cleanup(); }

  nsDiscriminatedUnion& operator=(const nsDiscriminatedUnion&) = delete;
  nsDiscriminatedUnion& operator=(nsDiscriminatedUnion&&) = delete;

  void Cleanup();

  uint16_t GetType() const { return mType; }

  MOZ_MUST_USE nsresult ConvertToInt8(uint8_t* aResult) const;
  MOZ_MUST_USE nsresult ConvertToInt16(int16_t* aResult) const;
  MOZ_MUST_USE nsresult ConvertToInt32(int32_t* aResult) const;
  MOZ_MUST_USE nsresult ConvertToInt64(int64_t* aResult) const;
  MOZ_MUST_USE nsresult ConvertToUint8(uint8_t* aResult) const;
  MOZ_MUST_USE nsresult ConvertToUint16(uint16_t* aResult) const;
  MOZ_MUST_USE nsresult ConvertToUint32(uint32_t* aResult) const;
  MOZ_MUST_USE nsresult ConvertToUint64(uint64_t* aResult) const;
  MOZ_MUST_USE nsresult ConvertToFloat(float* aResult) const;
  MOZ_MUST_USE nsresult ConvertToDouble(double* aResult) const;
  MOZ_MUST_USE nsresult ConvertToBool(bool* aResult) const;
  MOZ_MUST_USE nsresult ConvertToChar(char* aResult) const;
  MOZ_MUST_USE nsresult ConvertToWChar(char16_t* aResult) const;

  MOZ_MUST_USE nsresult ConvertToID(nsID* aResult) const;

  MOZ_MUST_USE nsresult ConvertToAString(nsAString& aResult) const;
  MOZ_MUST_USE nsresult ConvertToAUTF8String(nsAUTF8String& aResult) const;
  MOZ_MUST_USE nsresult ConvertToACString(nsACString& aResult) const;
  MOZ_MUST_USE nsresult ConvertToString(char** aResult) const;
  MOZ_MUST_USE nsresult ConvertToWString(char16_t** aResult) const;
  MOZ_MUST_USE nsresult ConvertToStringWithSize(uint32_t* aSize, char** aStr) const;
  MOZ_MUST_USE nsresult ConvertToWStringWithSize(uint32_t* aSize, char16_t** aStr) const;

  MOZ_MUST_USE nsresult ConvertToISupports(nsISupports** aResult) const;
  MOZ_MUST_USE nsresult ConvertToInterface(nsIID** aIID, void** aInterface) const;
  MOZ_MUST_USE nsresult ConvertToArray(uint16_t* aType, nsIID* aIID,
                                       uint32_t* aCount, void** aPtr) const;

  MOZ_MUST_USE nsresult SetFromVariant(nsIVariant* aValue);

  void SetFromInt8(uint8_t aValue);
  void SetFromInt16(int16_t aValue);
  void SetFromInt32(int32_t aValue);
  void SetFromInt64(int64_t aValue);
  void SetFromUint8(uint8_t aValue);
  void SetFromUint16(uint16_t aValue);
  void SetFromUint32(uint32_t aValue);
  void SetFromUint64(uint64_t aValue);
  void SetFromFloat(float aValue);
  void SetFromDouble(double aValue);
  void SetFromBool(bool aValue);
  void SetFromChar(char aValue);
  void SetFromWChar(char16_t aValue);
  void SetFromID(const nsID& aValue);
  void SetFromAString(const nsAString& aValue);
  void SetFromAUTF8String(const nsAUTF8String& aValue);
  void SetFromACString(const nsACString& aValue);
  MOZ_MUST_USE nsresult SetFromString(const char* aValue);
  MOZ_MUST_USE nsresult SetFromWString(const char16_t* aValue);
  void SetFromISupports(nsISupports* aValue);
  void SetFromInterface(const nsIID& aIID, nsISupports* aValue);
  MOZ_MUST_USE nsresult SetFromArray(uint16_t aType, const nsIID* aIID,
                                     uint32_t aCount, void* aValue);
  MOZ_MUST_USE nsresult SetFromStringWithSize(uint32_t aSize,
                                              const char* aValue);
  MOZ_MUST_USE nsresult SetFromWStringWithSize(uint32_t aSize,
                                               const char16_t* aValue);

  // Like SetFromWStringWithSize, but leaves the string uninitialized. It does
  // does write the null-terminator.
  void AllocateWStringWithSize(uint32_t aSize);

  void SetToVoid();
  void SetToEmpty();
  void SetToEmptyArray();

  void Traverse(nsCycleCollectionTraversalCallback& aCb) const;

private:
  MOZ_MUST_USE nsresult
  ToManageableNumber(nsDiscriminatedUnion* aOutData) const;
  void FreeArray();
  MOZ_MUST_USE bool String2ID(nsID* aPid) const;
  MOZ_MUST_USE nsresult ToString(nsACString& aOutString) const;

public:
  union
  {
    int8_t         mInt8Value;
    int16_t        mInt16Value;
    int32_t        mInt32Value;
    int64_t        mInt64Value;
    uint8_t        mUint8Value;
    uint16_t       mUint16Value;
    uint32_t       mUint32Value;
    uint64_t       mUint64Value;
    float          mFloatValue;
    double         mDoubleValue;
    bool           mBoolValue;
    char           mCharValue;
    char16_t       mWCharValue;
    nsIID          mIDValue;
    nsAString*     mAStringValue;
    nsAUTF8String* mUTF8StringValue;
    nsACString*    mCStringValue;
    struct
    {
      // This is an owning reference that cannot be an nsCOMPtr because
      // nsDiscriminatedUnion needs to be POD.  AddRef/Release are manually
      // called on this.
      nsISupports* MOZ_OWNING_REF mInterfaceValue;
      nsIID        mInterfaceID;
    } iface;
    struct
    {
      nsIID        mArrayInterfaceID;
      void*        mArrayValue;
      uint32_t     mArrayCount;
      uint16_t     mArrayType;
    } array;
    struct
    {
      char*        mStringValue;
      uint32_t     mStringLength;
    } str;
    struct
    {
      char16_t*    mWStringValue;
      uint32_t     mWStringLength;
    } wstr;
  } u;
  uint16_t       mType;
};

/**
 * nsVariant implements the generic variant support. The xpcom module registers
 * a factory (see NS_VARIANT_CONTRACTID in nsIVariant.idl) that will create
 * these objects. They are created 'empty' and 'writable'.
 *
 * nsIVariant users won't usually need to see this class.
 */
class nsVariantBase : public nsIWritableVariant
{
public:
  NS_DECL_NSIVARIANT
  NS_DECL_NSIWRITABLEVARIANT

  nsVariantBase();

protected:
  ~nsVariantBase() {};

  nsDiscriminatedUnion mData;
  bool mWritable;
};

class nsVariant final : public nsVariantBase
{
public:
  NS_DECL_ISUPPORTS

  nsVariant() {};

private:
  ~nsVariant() {};
};

class nsVariantCC final : public nsVariantBase
{
public:
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_CLASS(nsVariantCC)

  nsVariantCC() {};

private:
  ~nsVariantCC() {};
};

/**
 * Users of nsIVariant should be using the contractID and not this CID.
 *  - see NS_VARIANT_CONTRACTID in nsIVariant.idl.
 */

#define NS_VARIANT_CID \
{ /* 0D6EA1D0-879C-11d5-90EF-0010A4E73D9A */ \
    0xd6ea1d0,                               \
    0x879c,                                  \
    0x11d5,                                  \
    {0x90, 0xef, 0x0, 0x10, 0xa4, 0xe7, 0x3d, 0x9a}}

#endif // nsVariant_h