darling-JavaScriptCore/wasm/WasmIndexOrName.h
2018-01-02 21:17:19 -08:00

62 lines
2.3 KiB
C++

/*
* Copyright (C) 2017 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "WasmName.h"
#include <wtf/StdLibExtras.h>
#include <wtf/text/WTFString.h>
namespace JSC { namespace Wasm {
struct IndexOrName {
typedef size_t Index;
IndexOrName()
: m_index(emptyTag)
{ }
IndexOrName(Index, const Name*);
bool isEmpty() const { return bitwise_cast<Index>(*this) & emptyTag; }
bool isIndex() const { return bitwise_cast<Index>(*this) & indexTag; }
bool isName() const { return !(isEmpty() || isName()); }
friend String makeString(const IndexOrName&);
private:
union {
Index m_index;
const Name* m_name;
};
// Use the top bits as tags. Neither pointers nor the function index space should use them.
static constexpr Index indexTag = 1ull << (CHAR_BIT * sizeof(Index) - 1);
static constexpr Index emptyTag = 1ull << (CHAR_BIT * sizeof(Index) - 2);
static constexpr Index allTags = indexTag | emptyTag;
};
String makeString(const IndexOrName&);
} } // namespace JSC::Wasm