mfbt/Range.h
author Geoff Brown <gbrown@mozilla.com>
Fri, 12 May 2017 15:18:38 -0600
changeset 406366 f0f6bd0a45434bcd6159ae9f7c4f558367332fe7
parent 398844 261772d7198542e9cf1f0577a55446785a2c189d
child 505383 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1361732 - Mozharness support for a second virtualenv using python3; r=aki Currently Mozharness creates a Python 2.7 virtualenvironment with all the packages needed for Mozharness to run plus any applications that need to execute within it. For Talos, we now need a second Python virtual environment for mitmproxy, however, this package is for Python 3 and not for Python 2 (perhaps it could have worked). In any case, having the ability to support create Python 3 virtual environments will be handy. Specially since the approach of creating virtual environments is not by using 'virtualenv /path/to/venv' but by calling the venv module like 'python3 -m venv /path/to/venv'. The initial implementation only supports a list of modules. The following iteration will support requirement files and other parameters needed for pip and internal pypi hosts. Originally authored by armenzg.

/* -*- 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 mozilla_Range_h
#define mozilla_Range_h

#include "mozilla/RangedPtr.h"
#include "mozilla/TypeTraits.h"
#include "mozilla/Span.h"

#include <stddef.h>

namespace mozilla {

// Range<T> is a tuple containing a pointer and a length.
template <typename T>
class Range
{
  const RangedPtr<T> mStart;
  const RangedPtr<T> mEnd;

public:
  Range() : mStart(nullptr, 0), mEnd(nullptr, 0) {}
  Range(T* aPtr, size_t aLength)
    : mStart(aPtr, aPtr, aPtr + aLength),
      mEnd(aPtr + aLength, aPtr, aPtr + aLength)
  {}
  Range(const RangedPtr<T>& aStart, const RangedPtr<T>& aEnd)
    : mStart(aStart.get(), aStart.get(), aEnd.get()),
      mEnd(aEnd.get(), aStart.get(), aEnd.get())
  {
    // Only accept two RangedPtrs within the same range.
    aStart.checkIdenticalRange(aEnd);
    MOZ_ASSERT(aStart <= aEnd);
  }

  template<typename U,
           class = typename EnableIf<IsConvertible<U (*)[], T (*)[]>::value,
                                     int>::Type>
  MOZ_IMPLICIT Range(const Range<U>& aOther)
    : mStart(aOther.mStart),
      mEnd(aOther.mEnd)
  {}

  MOZ_IMPLICIT Range(Span<T> aSpan)
    : Range(aSpan.Elements(), aSpan.Length())
  {
  }

  template<typename U,
           class = typename EnableIf<IsConvertible<U (*)[], T (*)[]>::value,
                                     int>::Type>
  MOZ_IMPLICIT Range(const Span<U>& aSpan)
    : Range(aSpan.Elements(), aSpan.Length())
  {
  }

  RangedPtr<T> begin() const { return mStart; }
  RangedPtr<T> end() const { return mEnd; }
  size_t length() const { return mEnd - mStart; }

  T& operator[](size_t aOffset) const { return mStart[aOffset]; }

  explicit operator bool() const { return mStart != nullptr; }

  operator Span<T>() { return Span<T>(mStart.get(), length()); }

  operator Span<const T>() const { return Span<T>(mStart.get(), length()); }
};

template<class T>
Span<T>
MakeSpan(Range<T>& aRange)
{
  return aRange;
}

template<class T>
Span<const T>
MakeSpan(const Range<T>& aRange)
{
  return aRange;
}

} // namespace mozilla

#endif /* mozilla_Range_h */