forked from mirrors/gecko-dev
95 lines
3.5 KiB
C++
95 lines
3.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsStringFlags_h
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#define nsStringFlags_h
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#include <stdint.h>
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#include "mozilla/TypedEnumBits.h"
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namespace mozilla {
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namespace detail {
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// NOTE: these flags are declared public _only_ for convenience inside
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// the string implementation. And they are outside of the string
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// class so that the type is the same for both narrow and wide
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// strings.
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// bits for mDataFlags
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enum class StringDataFlags : uint16_t {
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// Some terminology:
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//
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// "dependent buffer" A dependent buffer is one that the string class
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// does not own. The string class relies on some
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// external code to ensure the lifetime of the
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// dependent buffer.
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//
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// "refcounted buffer" A refcounted buffer is one that the string class
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// allocates. When it allocates a refcounted string
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// buffer, it allocates some additional space at
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// the beginning of the buffer for additional
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// fields, including a reference count and a
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// buffer length. See nsStringHeader.
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//
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// "adopted buffer" An adopted buffer is a raw string buffer
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// allocated on the heap (using moz_xmalloc)
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// of which the string class subsumes ownership.
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//
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// Some comments about the string data flags:
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//
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// REFCOUNTED, OWNED, and INLINE are all mutually exlusive. They
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// indicate the allocation type of mData. If none of these flags
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// are set, then the string buffer is dependent.
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//
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// REFCOUNTED, OWNED, or INLINE imply TERMINATED. This is because
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// the string classes always allocate null-terminated buffers, and
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// non-terminated substrings are always dependent.
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//
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// VOIDED implies TERMINATED, and moreover it implies that mData
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// points to char_traits::sEmptyBuffer. Therefore, VOIDED is
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// mutually exclusive with REFCOUNTED, OWNED, and INLINE.
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//
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// INLINE requires StringClassFlags::INLINE to be set on the type.
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// IsTerminated returns true
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TERMINATED = 1 << 0,
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// IsVoid returns true
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VOIDED = 1 << 1,
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// mData points to a heap-allocated, shareable, refcounted buffer
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REFCOUNTED = 1 << 2,
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// mData points to a heap-allocated, raw buffer
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OWNED = 1 << 3,
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// mData points to a writable, inline buffer
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INLINE = 1 << 4,
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// mData points to a string literal; DataFlags::TERMINATED will also be set
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LITERAL = 1 << 5,
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// used to check for invalid flags -- all bits above the last item
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INVALID_MASK = (uint16_t) ~((LITERAL << 1) - 1)
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};
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// bits for mClassFlags
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enum class StringClassFlags : uint16_t {
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// |this|'s buffer is inline, and requires the type to be binary-compatible
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// with nsTAutoStringN
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INLINE = 1 << 0,
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// |this| requires its buffer is null-terminated
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NULL_TERMINATED = 1 << 1,
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// used to check for invalid flags -- all bits above the last item
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INVALID_MASK = (uint16_t) ~((NULL_TERMINATED << 1) - 1)
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};
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MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(StringDataFlags)
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MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(StringClassFlags)
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} // namespace detail
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} // namespace mozilla
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#endif
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