xpcom/base/nsQueryObject.h
author Nathan Froyd <froydnj@mozilla.com>
Thu, 14 Nov 2019 11:16:38 -0400
changeset 501561 d64119136e15458d4aea5c548b4d10d7099d78f6
parent 448947 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1579189 - raise the minimum clang version to 5; r=#build We need this for "full" C++17 support (everything is supported, but some C++17 features still have bugs) and this change also brings Linux into parity with our Mac requirements. MANUAL PUSH: build toolchains on inbound to avoid clogging autoland Differential Revision: https://phabricator.services.mozilla.com/D51450

/* -*- 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 nsQueryObject_h
#define nsQueryObject_h

#include "mozilla/Attributes.h"

#include "nsCOMPtr.h"
#include "mozilla/RefPtr.h"

/*****************************************************************************/

template <class T>
class MOZ_STACK_CLASS nsQueryObject final : public nsCOMPtr_helper {
 public:
  explicit nsQueryObject(T* aRawPtr) : mRawPtr(aRawPtr) {}

  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID,
                                          void** aResult) const override {
    nsresult status = mRawPtr ? mRawPtr->QueryInterface(aIID, aResult)
                              : NS_ERROR_NULL_POINTER;
    return status;
  }

 private:
  T* MOZ_NON_OWNING_REF mRawPtr;
};

template <class T>
class MOZ_STACK_CLASS nsQueryObjectWithError final : public nsCOMPtr_helper {
 public:
  nsQueryObjectWithError(T* aRawPtr, nsresult* aErrorPtr)
      : mRawPtr(aRawPtr), mErrorPtr(aErrorPtr) {}

  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID,
                                          void** aResult) const override {
    nsresult status = mRawPtr ? mRawPtr->QueryInterface(aIID, aResult)
                              : NS_ERROR_NULL_POINTER;
    if (mErrorPtr) {
      *mErrorPtr = status;
    }
    return status;
  }

 private:
  T* MOZ_NON_OWNING_REF mRawPtr;
  nsresult* mErrorPtr;
};

/*****************************************************************************/

/*****************************************************************************/

template <class T>
inline nsQueryObject<T> do_QueryObject(T* aRawPtr) {
  return nsQueryObject<T>(aRawPtr);
}

template <class T>
inline nsQueryObject<T> do_QueryObject(nsCOMPtr<T>& aRawPtr) {
  return nsQueryObject<T>(aRawPtr);
}

template <class T>
inline nsQueryObject<T> do_QueryObject(RefPtr<T>& aRawPtr) {
  return nsQueryObject<T>(aRawPtr);
}

template <class T>
inline nsQueryObjectWithError<T> do_QueryObject(T* aRawPtr,
                                                nsresult* aErrorPtr) {
  return nsQueryObjectWithError<T>(aRawPtr, aErrorPtr);
}

template <class T>
inline nsQueryObjectWithError<T> do_QueryObject(nsCOMPtr<T>& aRawPtr,
                                                nsresult* aErrorPtr) {
  return nsQueryObjectWithError<T>(aRawPtr, aErrorPtr);
}

template <class T>
inline nsQueryObjectWithError<T> do_QueryObject(RefPtr<T>& aRawPtr,
                                                nsresult* aErrorPtr) {
  return nsQueryObjectWithError<T>(aRawPtr, aErrorPtr);
}

/*****************************************************************************/

#endif  // !defined(nsQueryObject_h)