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// Copyright 2020 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef COMMON_ITYP_SPAN_H_
#define COMMON_ITYP_SPAN_H_
#include "common/TypedInteger.h"
#include "common/UnderlyingType.h"
#include <type_traits>
namespace ityp {
// ityp::span is a helper class that wraps an unowned packed array of type |Value|.
// It stores the size and pointer to first element. It has the restriction that
// indices must be a particular type |Index|. This provides a type-safe way to index
// raw pointers.
template <typename Index, typename Value>
class span {
using I = UnderlyingType<Index>;
public:
constexpr span() : mData(nullptr), mSize(0) {
}
constexpr span(Value* data, Index size) : mData(data), mSize(size) {
}
constexpr Value& operator[](Index i) const {
ASSERT(i < mSize);
return mData[static_cast<I>(i)];
}
Value* data() noexcept {
return mData;
}
const Value* data() const noexcept {
return mData;
}
Value* begin() noexcept {
return mData;
}
const Value* begin() const noexcept {
return mData;
}
Value* end() noexcept {
return mData + static_cast<I>(mSize);
}
const Value* end() const noexcept {
return mData + static_cast<I>(mSize);
}
Value& front() {
ASSERT(mData != nullptr);
ASSERT(static_cast<I>(mSize) >= 0);
return *mData;
}
const Value& front() const {
ASSERT(mData != nullptr);
ASSERT(static_cast<I>(mSize) >= 0);
return *mData;
}
Value& back() {
ASSERT(mData != nullptr);
ASSERT(static_cast<I>(mSize) >= 0);
return *(mData + static_cast<I>(mSize) - 1);
}
const Value& back() const {
ASSERT(mData != nullptr);
ASSERT(static_cast<I>(mSize) >= 0);
return *(mData + static_cast<I>(mSize) - 1);
}
Index size() const {
return mSize;
}
private:
Value* mData;
Index mSize;
};
} // namespace ityp
#endif // COMMON_ITYP_SPAN_H_