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-rw-r--r--AK/Checked.h347
1 files changed, 347 insertions, 0 deletions
diff --git a/AK/Checked.h b/AK/Checked.h
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+/*
+ * Copyright (C) 2011-2019 Apple Inc. All rights reserved.
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER 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 <AK/Assertions.h>
+#include <AK/NumericLimits.h>
+#include <AK/StdLibExtras.h>
+
+namespace AK {
+
+template<typename Destination, typename Source, bool destination_is_wider = (sizeof(Destination) >= sizeof(Source)), bool destination_is_signed = NumericLimits<Destination>::is_signed(), bool source_is_signed = NumericLimits<Source>::is_signed()>
+struct TypeBoundsChecker;
+
+template<typename Destination, typename Source>
+struct TypeBoundsChecker<Destination, Source, false, false, false> {
+ static constexpr bool is_within_range(Source value)
+ {
+ return value <= NumericLimits<Destination>::max();
+ }
+};
+
+template<typename Destination, typename Source>
+struct TypeBoundsChecker<Destination, Source, false, true, true> {
+ static constexpr bool is_within_range(Source value)
+ {
+ return value <= NumericLimits<Destination>::max()
+ && NumericLimits<Destination>::min() <= value;
+ }
+};
+
+template<typename Destination, typename Source>
+struct TypeBoundsChecker<Destination, Source, false, false, true> {
+ static constexpr bool is_within_range(Source value)
+ {
+ return static_cast<MakeUnsigned<Source>>(value) <= NumericLimits<Destination>::max();
+ }
+};
+
+template<typename Destination, typename Source>
+struct TypeBoundsChecker<Destination, Source, false, true, false> {
+ static constexpr bool is_within_range(Source value)
+ {
+ return value <= static_cast<Source>(NumericLimits<Destination>::max());
+ }
+};
+
+template<typename Destination, typename Source>
+struct TypeBoundsChecker<Destination, Source, true, false, false> {
+ static constexpr bool is_within_range(Source)
+ {
+ return true;
+ }
+};
+
+template<typename Destination, typename Source>
+struct TypeBoundsChecker<Destination, Source, true, true, true> {
+ static constexpr bool is_within_range(Source)
+ {
+ return true;
+ }
+};
+
+template<typename Destination, typename Source>
+struct TypeBoundsChecker<Destination, Source, true, false, true> {
+ static constexpr bool is_within_range(Source value)
+ {
+ return value >= 0;
+ }
+};
+
+template<typename Destination, typename Source>
+struct TypeBoundsChecker<Destination, Source, true, true, false> {
+ static constexpr bool is_within_range(Source value)
+ {
+ if (sizeof(Destination) > sizeof(Source))
+ return true;
+ return value <= static_cast<Source>(NumericLimits<Destination>::max());
+ }
+};
+
+template<typename Destination, typename Source>
+inline constexpr bool is_within_range(Source value)
+{
+ return TypeBoundsChecker<Destination, Source>::is_within_range(value);
+}
+
+template<typename T>
+class Checked {
+public:
+ Checked()
+ : m_value(0)
+ {
+ }
+
+ Checked(T value)
+ : m_value(value)
+ {
+ }
+
+ template<typename U>
+ Checked(U value)
+ {
+ m_overflow = !is_within_range<T>(value);
+ m_value = value;
+ }
+
+ Checked(const Checked& other)
+ : m_value(other.m_value)
+ , m_overflow(other.m_overflow)
+ {
+ }
+
+ Checked(Checked&& other)
+ : m_value(exchange(other.m_value, 0))
+ , m_overflow(exchange(other.m_overflow, false))
+ {
+ }
+
+ template<typename U>
+ Checked& operator=(U value)
+ {
+ return *this = Checked(value);
+ }
+
+ Checked& operator=(const Checked& other)
+ {
+ m_value = other.value();
+ m_overflow = other.m_overflow;
+ return *this;
+ }
+
+ Checked& operator=(Checked&& other)
+ {
+ m_value = exchange(other.m_value, 0);
+ m_overflow = exchange(other.m_overflow, false);
+ return *this;
+ }
+
+ bool has_overflow() const
+ {
+ return m_overflow;
+ }
+
+ bool operator!() const
+ {
+ ASSERT(!m_overflow);
+ return !m_value;
+ }
+
+ T value() const
+ {
+ ASSERT(!m_overflow);
+ return m_value;
+ }
+
+ void add(T other)
+ {
+ m_overflow |= __builtin_add_overflow(m_value, other, &m_value);
+ }
+
+ void sub(T other)
+ {
+ m_overflow |= __builtin_sub_overflow(m_value, other, &m_value);
+ }
+
+ void mul(T other)
+ {
+ m_overflow |= __builtin_mul_overflow(m_value, other, &m_value);
+ }
+
+ void div(T other)
+ {
+ m_value /= other;
+ }
+
+ Checked& operator+=(T other)
+ {
+ add(other);
+ return *this;
+ }
+
+ Checked& operator-=(T other)
+ {
+ sub(other);
+ return *this;
+ }
+
+ Checked& operator*=(T other)
+ {
+ mul(other);
+ return *this;
+ }
+
+ Checked& operator/=(T other)
+ {
+ div(other);
+ return *this;
+ }
+
+ Checked& operator++()
+ {
+ add(1);
+ return *this;
+ }
+
+ Checked& operator++(int)
+ {
+ add(1);
+ return *this;
+ }
+
+private:
+ T m_value;
+ bool m_overflow { false };
+};
+
+template<typename T>
+inline Checked<T> operator+(const Checked<T>& a, const Checked<T>& b)
+{
+ return Checked<T>(a).add(b);
+}
+
+template<typename T>
+inline Checked<T> operator-(const Checked<T>& a, const Checked<T>& b)
+{
+ return Checked<T>(a).sub(b);
+}
+
+template<typename T>
+inline Checked<T> operator*(const Checked<T>& a, const Checked<T>& b)
+{
+ return Checked<T>(a).mul(b);
+}
+
+template<typename T>
+inline Checked<T> operator/(const Checked<T>& a, const Checked<T>& b)
+{
+ return Checked<T>(a).div(b);
+}
+
+template<typename T>
+inline bool operator<(const Checked<T>& a, T b)
+{
+ return a.value() < b;
+}
+
+template<typename T>
+inline bool operator>(const Checked<T>& a, T b)
+{
+ return a.value() > b;
+}
+
+template<typename T>
+inline bool operator>=(const Checked<T>& a, T b)
+{
+ return a.value() >= b;
+}
+
+template<typename T>
+inline bool operator<=(const Checked<T>& a, T b)
+{
+ return a.value() <= b;
+}
+
+template<typename T>
+inline bool operator==(const Checked<T>& a, T b)
+{
+ return a.value() == b;
+}
+
+template<typename T>
+inline bool operator!=(const Checked<T>& a, T b)
+{
+ return a.value() != b;
+}
+
+template<typename T>
+inline bool operator<(T a, const Checked<T>& b)
+{
+ return a < b.value();
+}
+
+template<typename T>
+inline bool operator>(T a, const Checked<T>& b)
+{
+ return a > b.value();
+}
+
+template<typename T>
+inline bool operator>=(T a, const Checked<T>& b)
+{
+ return a >= b.value();
+}
+
+template<typename T>
+inline bool operator<=(T a, const Checked<T>& b)
+{
+ return a <= b.value();
+}
+
+template<typename T>
+inline bool operator==(T a, const Checked<T>& b)
+{
+ return a == b.value();
+}
+
+template<typename T>
+inline bool operator!=(T a, const Checked<T>& b)
+{
+ return a != b.value();
+}
+
+template<typename T>
+inline Checked<T> make_checked(T value)
+{
+ return Checked<T>(value);
+}
+
+}
+
+using AK::Checked;
+using AK::make_checked;
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-16 10:32:51 +0000