mfbt/ResultExtensions.h
author Sam Sneddon <me@gsnedders.com>
Tue, 05 Mar 2019 12:19:18 +0000
changeset 464592 ed02da4c6be28b064d9c6168f54c7f84036fa9e1
parent 449035 66eb1f485c1a3ea81372758bc92292c9428b17cd
permissions -rw-r--r--
Bug 1486514 [wpt PR 12695] - Make reftests 800x600 everywhere, a=testonly Automatic update from web-platform-tests Change reftest size to 800x600 everywhere (#12695) With Firefox, with the internal reftest runner (used by default), this doesn't actually change the reftest size in Firefox versions prior to 66 (currently on the beta channel); to get the correct behaviour with older versions of Firefox, you must pass `--reftest-external` to use the external reftest runner. -- wpt-commits: d5f07ed3b5186e553940a3d5c547067850a4e3f0 wpt-pr: 12695

/* -*- 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/. */

/* Extensions to the Result type to enable simpler handling of XPCOM/NSPR
 * results. */

#ifndef mozilla_ResultExtensions_h
#define mozilla_ResultExtensions_h

#include "mozilla/Assertions.h"
#include "nscore.h"
#include "prtypes.h"

namespace mozilla {

// Allow nsresult errors to automatically convert to nsresult values, so MOZ_TRY
// can be used in XPCOM methods with Result<T, nserror> results.
template <>
class MOZ_MUST_USE_TYPE GenericErrorResult<nsresult> {
  nsresult mErrorValue;

  template <typename V, typename E2>
  friend class Result;

 public:
  explicit GenericErrorResult(nsresult aErrorValue) : mErrorValue(aErrorValue) {
    MOZ_ASSERT(NS_FAILED(aErrorValue));
  }

  operator nsresult() { return mErrorValue; }
};

// Allow MOZ_TRY to handle `PRStatus` values.
inline Result<Ok, nsresult> ToResult(PRStatus aValue);

}  // namespace mozilla

#include "mozilla/Result.h"

namespace mozilla {

inline Result<Ok, nsresult> ToResult(nsresult aValue) {
  if (NS_FAILED(aValue)) {
    return Err(aValue);
  }
  return Ok();
}

inline Result<Ok, nsresult> ToResult(PRStatus aValue) {
  if (aValue == PR_SUCCESS) {
    return Ok();
  }
  return Err(NS_ERROR_FAILURE);
}

}  // namespace mozilla

#endif  // mozilla_ResultExtensions_h