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/* -*- 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.
//
// "refcounted buffer" A refcounted buffer is one that the string class
// allocates. When it allocates a refcounted 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:
//
// REFCOUNTED, OWNED, and INLINE are all mutually exlusive. They
// indicate the allocation type of mData. If none of these flags
// are set, then the string buffer is dependent.
//
// REFCOUNTED, OWNED, or INLINE 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 REFCOUNTED, OWNED, and INLINE.
//
// INLINE requires StringClassFlags::INLINE to be set on the type.
// IsTerminated returns true
TERMINATED = 1 << 0,
// IsVoid returns true
VOIDED = 1 << 1,
// mData points to a heap-allocated, shareable, refcounted buffer
REFCOUNTED = 1 << 2,
// mData points to a heap-allocated, raw buffer
OWNED = 1 << 3,
// mData points to a writable, inline buffer
INLINE = 1 << 4,
// mData points to a string literal; DataFlags::TERMINATED will also be set
LITERAL = 1 << 5,
// used to check for invalid flags -- all bits above the last item
INVALID_MASK = (uint16_t) ~((LITERAL << 1) - 1)
};
// bits for mClassFlags
enum class StringClassFlags : uint16_t {
// |this|'s buffer is inline, and requires the type to be binary-compatible
// with nsTAutoStringN
INLINE = 1 << 0,
// |this| requires its buffer is null-terminated
NULL_TERMINATED = 1 << 1,
// used to check for invalid flags -- all bits above the last item
INVALID_MASK = (uint16_t) ~((NULL_TERMINATED << 1) - 1)
};
MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(StringDataFlags)
MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(StringClassFlags)
} // namespace detail
} // namespace mozilla
#endif
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