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implicit_cast<> only performs a cast in cases where an implicit conversion would be possible. It’s even safer than static_cast<> It’s an “explicit implicit” cast, which is not normally necsesary, but is frequently required when working with the ?: operator, functions like std::min() and std::max(), and logging and testing macros. The public style guide does not mention implicit_cast<> only because it is not part of the standard library, but would otherwise require it in these situations. Since base does provide implicit_cast<>, it should be used whenever possible. The only uses of static_cast<> not converted to implicit_cast<> are those that require static_cast<>, such as those that assign an integer constant to a variable of an enum type. R=rsesek@chromium.org Review URL: https://codereview.chromium.org/700383007
116 lines
3.7 KiB
C++
116 lines
3.7 KiB
C++
// Copyright 2014 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef CRASHPAD_UTIL_NUMERIC_CHECKED_RANGE_H_
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#define CRASHPAD_UTIL_NUMERIC_CHECKED_RANGE_H_
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#include <limits>
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#include "base/basictypes.h"
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#include "base/logging.h"
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#include "base/numerics/safe_conversions.h"
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#include "base/numerics/safe_math.h"
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namespace crashpad {
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//! \brief Ensures that a range, composed of a base and size, does not overflow
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//! its data type.
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template <typename ValueType, typename SizeType = ValueType>
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class CheckedRange {
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public:
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CheckedRange(ValueType base, SizeType size) {
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static_assert(!std::numeric_limits<SizeType>::is_signed,
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"SizeType must be unsigned");
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SetRange(base, size);
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}
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//! \brief Sets the range’s base and size to \a base and \a size,
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//! respectively.
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void SetRange(ValueType base, SizeType size) {
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base_ = base;
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size_ = size;
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}
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//! \brief The range’s base.
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ValueType base() const { return base_; }
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//! \brief The range’s size.
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SizeType size() const { return size_; }
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//! \brief The range’s end (its base plus its size).
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ValueType end() const { return base_ + size_; }
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//! \brief Returns the validity of the range.
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//!
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//! \return `true` if the range is valid, `false` otherwise.
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//!
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//! A range is valid if its size can be converted to the range’s data type
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//! without data loss, and if its end (base plus size) can be computed without
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//! overflowing its data type.
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bool IsValid() const {
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if (!base::IsValueInRangeForNumericType<ValueType, SizeType>(size_)) {
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return false;
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}
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base::CheckedNumeric<ValueType> checked_end(base_);
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checked_end += implicit_cast<ValueType>(size_);
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return checked_end.IsValid();
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}
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//! \brief Returns whether the range contains another value.
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//!
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//! \param[in] value The (possibly) contained value.
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//!
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//! \return `true` if the range contains \a value, `false` otherwise.
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//!
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//! A range contains a value if the value is greater than or equal to its
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//! base, and less than its end (base plus size).
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//!
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//! This method must only be called if IsValid() would return `true`.
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bool ContainsValue(ValueType value) const {
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DCHECK(IsValid());
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return value >= base() && value < end();
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}
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//! \brief Returns whether the range contains another range.
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//!
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//! \param[in] that The (possibly) contained range.
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//!
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//! \return `true` if `this` range, the containing range, contains \a that,
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//! the contained range. `false` otherwise.
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//!
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//! A range contains another range when the contained range’s base is greater
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//! than or equal to the containing range’s base, and the contained range’s
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//! end is less than or equal to the containing range’s end.
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//!
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//! This method must only be called if IsValid() would return `true` for both
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//! CheckedRange objects involved.
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bool ContainsRange(const CheckedRange<ValueType, SizeType>& that) const {
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DCHECK(IsValid());
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DCHECK(that.IsValid());
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return that.base() >= base() && that.end() <= end();
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}
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private:
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ValueType base_;
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SizeType size_;
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DISALLOW_COPY_AND_ASSIGN(CheckedRange);
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};
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} // namespace crashpad
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#endif // CRASHPAD_UTIL_NUMERIC_CHECKED_RANGE_H_
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