gecko-dev/xpcom/string/nsStringFlags.h
Eric Rahm 030b39d813 Bug 1393230 - Part 3: Convert the xpcom string classes to be templated on char type. r=njn, r=fitzgen, r=sfink
This removes the double-include macro hackery that we use to define two
separate string types (nsAString and nsACString) in favor of a templated
solution.

Annotations for Valgrind and the JS hazard analysis are updated as well as
the rust binding generations for string code.

--HG--
extra : rebase_source : 63ab2c4620cfcd4b764d42d654c82f30f984d016
extra : source : 9115364cd4aa078c49bba7911069f8178e55166f
2017-08-14 14:22:50 -07:00

77 lines
3.1 KiB
C++

/* -*- 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 nsStringFlags_h
#define nsStringFlags_h
#include <stdint.h>
#include "mozilla/TypedEnumBits.h"
namespace mozilla {
namespace detail {
// NOTE: these flags are declared public _only_ for convenience inside
// the string implementation. And they are outside of the string
// class so that the type is the same for both narrow and wide
// strings.
// bits for mDataFlags
enum class StringDataFlags : uint16_t
{
// Some terminology:
//
// "dependent buffer" A dependent buffer is one that the string class
// does not own. The string class relies on some
// external code to ensure the lifetime of the
// dependent buffer.
//
// "shared buffer" A shared buffer is one that the string class
// allocates. When it allocates a shared string
// buffer, it allocates some additional space at
// the beginning of the buffer for additional
// fields, including a reference count and a
// buffer length. See nsStringHeader.
//
// "adopted buffer" An adopted buffer is a raw string buffer
// allocated on the heap (using moz_xmalloc)
// of which the string class subsumes ownership.
//
// Some comments about the string data flags:
//
// SHARED, OWNED, and FIXED are all mutually exlusive. They
// indicate the allocation type of mData. If none of these flags
// are set, then the string buffer is dependent.
//
// SHARED, OWNED, or FIXED imply TERMINATED. This is because
// the string classes always allocate null-terminated buffers, and
// non-terminated substrings are always dependent.
//
// VOIDED implies TERMINATED, and moreover it implies that mData
// points to char_traits::sEmptyBuffer. Therefore, VOIDED is
// mutually exclusive with SHARED, OWNED, and FIXED.
TERMINATED = 1 << 0, // IsTerminated returns true
VOIDED = 1 << 1, // IsVoid returns true
SHARED = 1 << 2, // mData points to a heap-allocated, shared buffer
OWNED = 1 << 3, // mData points to a heap-allocated, raw buffer
FIXED = 1 << 4, // mData points to a fixed-size writable, dependent buffer
LITERAL = 1 << 5 // mData points to a string literal; DataFlags::TERMINATED will also be set
};
// bits for mClassFlags
enum class StringClassFlags : uint16_t
{
FIXED = 1 << 0, // |this| is of type nsTFixedString
NULL_TERMINATED = 1 << 1 // |this| requires its buffer is null-terminated
};
MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(StringDataFlags)
MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(StringClassFlags)
} // namespace detail
} // namespace mozilla
#endif