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Diffstat (limited to 'xpcom/string/nsStringFlags.h')
| -rw-r--r-- | xpcom/string/nsStringFlags.h | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/xpcom/string/nsStringFlags.h b/xpcom/string/nsStringFlags.h new file mode 100644 index 0000000000..d0ba05c8db --- /dev/null +++ b/xpcom/string/nsStringFlags.h @@ -0,0 +1,95 @@ +/* -*- 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 |