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217 lines
6.6 KiB
C++
217 lines
6.6 KiB
C++
#pragma once
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//
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// Copyright (c) 2017 Martin Moene
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//
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// https://github.com/martinmoene/optional-bare
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//
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// This code is licensed under the MIT License (MIT).
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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// Modified by Otto Winter on 18.05.18
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#include <algorithm>
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namespace esphome {
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// type for nullopt
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struct nullopt_t { // NOLINT
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struct init {}; // NOLINT
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nullopt_t(init) {}
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};
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// extra parenthesis to prevent the most vexing parse:
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const nullopt_t nullopt((nullopt_t::init())); // NOLINT
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// Simplistic optional: requires T to be default constructible, copyable.
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template<typename T> class optional { // NOLINT
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private:
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using safe_bool = void (optional::*)() const;
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public:
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using value_type = T;
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optional() {}
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optional(nullopt_t) {}
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optional(T const &arg) : has_value_(true), value_(arg) {} // NOLINT
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template<class U> optional(optional<U> const &other) : has_value_(other.has_value()), value_(other.value()) {}
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optional &operator=(nullopt_t) {
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reset();
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return *this;
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}
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template<class U> optional &operator=(optional<U> const &other) {
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has_value_ = other.has_value();
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value_ = other.value();
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return *this;
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}
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void swap(optional &rhs) {
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using std::swap;
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if (has_value() && rhs.has_value()) {
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swap(**this, *rhs);
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} else if (!has_value() && rhs.has_value()) {
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initialize(*rhs);
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rhs.reset();
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} else if (has_value() && !rhs.has_value()) {
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rhs.initialize(**this);
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reset();
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}
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}
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// observers
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value_type const *operator->() const { return &value_; }
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value_type *operator->() { return &value_; }
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value_type const &operator*() const { return value_; }
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value_type &operator*() { return value_; }
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operator safe_bool() const { return has_value() ? &optional::this_type_does_not_support_comparisons : nullptr; }
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bool has_value() const { return has_value_; }
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value_type const &value() const { return value_; }
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value_type &value() { return value_; }
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template<class U> value_type value_or(U const &v) const { return has_value() ? value() : static_cast<value_type>(v); }
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// modifiers
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void reset() { has_value_ = false; }
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private:
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void this_type_does_not_support_comparisons() const {} // NOLINT
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template<typename V> void initialize(V const &value) { // NOLINT
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value_ = value;
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has_value_ = true;
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}
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private:
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bool has_value_{false}; // NOLINT
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value_type value_; // NOLINT
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};
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// Relational operators
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template<typename T, typename U> inline bool operator==(optional<T> const &x, optional<U> const &y) {
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return bool(x) != bool(y) ? false : !bool(x) ? true : *x == *y;
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}
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template<typename T, typename U> inline bool operator!=(optional<T> const &x, optional<U> const &y) {
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return !(x == y);
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}
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template<typename T, typename U> inline bool operator<(optional<T> const &x, optional<U> const &y) {
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return (!y) ? false : (!x) ? true : *x < *y;
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}
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template<typename T, typename U> inline bool operator>(optional<T> const &x, optional<U> const &y) { return (y < x); }
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template<typename T, typename U> inline bool operator<=(optional<T> const &x, optional<U> const &y) { return !(y < x); }
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template<typename T, typename U> inline bool operator>=(optional<T> const &x, optional<U> const &y) { return !(x < y); }
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// Comparison with nullopt
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template<typename T> inline bool operator==(optional<T> const &x, nullopt_t) { return (!x); }
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template<typename T> inline bool operator==(nullopt_t, optional<T> const &x) { return (!x); }
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template<typename T> inline bool operator!=(optional<T> const &x, nullopt_t) { return bool(x); }
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template<typename T> inline bool operator!=(nullopt_t, optional<T> const &x) { return bool(x); }
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template<typename T> inline bool operator<(optional<T> const &, nullopt_t) { return false; }
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template<typename T> inline bool operator<(nullopt_t, optional<T> const &x) { return bool(x); }
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template<typename T> inline bool operator<=(optional<T> const &x, nullopt_t) { return (!x); }
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template<typename T> inline bool operator<=(nullopt_t, optional<T> const &) { return true; }
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template<typename T> inline bool operator>(optional<T> const &x, nullopt_t) { return bool(x); }
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template<typename T> inline bool operator>(nullopt_t, optional<T> const &) { return false; }
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template<typename T> inline bool operator>=(optional<T> const &, nullopt_t) { return true; }
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template<typename T> inline bool operator>=(nullopt_t, optional<T> const &x) { return (!x); }
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// Comparison with T
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template<typename T, typename U> inline bool operator==(optional<T> const &x, U const &v) {
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return bool(x) ? *x == v : false;
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}
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template<typename T, typename U> inline bool operator==(U const &v, optional<T> const &x) {
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return bool(x) ? v == *x : false;
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}
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template<typename T, typename U> inline bool operator!=(optional<T> const &x, U const &v) {
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return bool(x) ? *x != v : true;
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}
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template<typename T, typename U> inline bool operator!=(U const &v, optional<T> const &x) {
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return bool(x) ? v != *x : true;
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}
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template<typename T, typename U> inline bool operator<(optional<T> const &x, U const &v) {
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return bool(x) ? *x < v : true;
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}
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template<typename T, typename U> inline bool operator<(U const &v, optional<T> const &x) {
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return bool(x) ? v < *x : false;
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}
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template<typename T, typename U> inline bool operator<=(optional<T> const &x, U const &v) {
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return bool(x) ? *x <= v : true;
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}
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template<typename T, typename U> inline bool operator<=(U const &v, optional<T> const &x) {
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return bool(x) ? v <= *x : false;
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}
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template<typename T, typename U> inline bool operator>(optional<T> const &x, U const &v) {
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return bool(x) ? *x > v : false;
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}
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template<typename T, typename U> inline bool operator>(U const &v, optional<T> const &x) {
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return bool(x) ? v > *x : true;
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}
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template<typename T, typename U> inline bool operator>=(optional<T> const &x, U const &v) {
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return bool(x) ? *x >= v : false;
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}
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template<typename T, typename U> inline bool operator>=(U const &v, optional<T> const &x) {
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return bool(x) ? v >= *x : true;
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}
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// Specialized algorithms
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template<typename T> void swap(optional<T> &x, optional<T> &y) { x.swap(y); }
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// Convenience function to create an optional.
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template<typename T> inline optional<T> make_optional(T const &v) { return optional<T>(v); }
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} // namespace esphome
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