/*
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* Copyright (C) 2015 The Android Open Source Project
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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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*/
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#ifndef ART_CMDLINE_DETAIL_CMDLINE_PARSER_DETAIL_H_
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#define ART_CMDLINE_DETAIL_CMDLINE_PARSER_DETAIL_H_
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#include <sstream>
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#include <string>
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#include <vector>
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namespace art {
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// Implementation details for some template querying. Don't look inside if you hate templates.
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namespace detail {
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template <typename T>
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typename std::remove_reference<T>::type& FakeReference();
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// SupportsInsertionOperator<T, TStream>::value will evaluate to a boolean,
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// whose value is true if the TStream class supports the << operator against T,
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// and false otherwise.
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template <typename T2, typename TStream2 = std::ostream>
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struct SupportsInsertionOperator {
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private:
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template <typename TStream, typename T>
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static std::true_type InsertionOperatorTest(TStream& os, const T& value,
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std::remove_reference<decltype(os << value)>* = 0); // NOLINT [whitespace/operators] [3]
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template <typename TStream, typename ... T>
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static std::false_type InsertionOperatorTest(TStream& os, const T& ... args);
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public:
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static constexpr bool value =
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decltype(InsertionOperatorTest(FakeReference<TStream2>(), std::declval<T2>()))::value;
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};
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template <typename TLeft, typename TRight = TLeft, bool IsFloatingPoint = false>
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struct SupportsEqualityOperatorImpl;
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template <typename TLeft, typename TRight>
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struct SupportsEqualityOperatorImpl<TLeft, TRight, false> {
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private:
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template <typename TL, typename TR>
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static std::true_type EqualityOperatorTest(const TL& left, const TR& right,
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std::remove_reference<decltype(left == right)>* = 0); // NOLINT [whitespace/operators] [3]
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template <typename TL, typename ... T>
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static std::false_type EqualityOperatorTest(const TL& left, const T& ... args);
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public:
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static constexpr bool value =
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decltype(EqualityOperatorTest(std::declval<TLeft>(), std::declval<TRight>()))::value;
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};
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// Partial specialization when TLeft/TRight are both floating points.
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// This is a work-around because decltype(floatvar1 == floatvar2)
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// will not compile with clang:
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// error: comparing floating point with == or != is unsafe [-Werror,-Wfloat-equal]
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template <typename TLeft, typename TRight>
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struct SupportsEqualityOperatorImpl<TLeft, TRight, true> {
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static constexpr bool value = true;
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};
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// SupportsEqualityOperatorImpl<T1, T2>::value will evaluate to a boolean,
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// whose value is true if T1 can be compared against T2 with ==,
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// and false otherwise.
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template <typename TLeft, typename TRight = TLeft>
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struct SupportsEqualityOperator : // NOLINT [whitespace/labels] [4]
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SupportsEqualityOperatorImpl<TLeft, TRight,
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std::is_floating_point<TLeft>::value
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&& std::is_floating_point<TRight>::value> {
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};
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// Convert any kind of type to an std::string, even if there's no
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// serialization support for it. Unknown types get converted to an
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// an arbitrary value.
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//
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// Meant for printing user-visible errors or unit test failures only.
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template <typename T>
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std::string ToStringAny(const T& value,
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typename std::enable_if<
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SupportsInsertionOperator<T>::value>::type* = nullptr) {
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std::stringstream stream;
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stream << value;
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return stream.str();
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}
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template <typename T>
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std::string ToStringAny(const std::vector<T> value,
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typename std::enable_if<
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SupportsInsertionOperator<T>::value>::type* = nullptr) {
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std::stringstream stream;
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stream << "vector{";
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for (size_t i = 0; i < value.size(); ++i) {
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stream << ToStringAny(value[i]);
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if (i != value.size() - 1) {
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stream << ',';
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}
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}
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stream << "}";
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return stream.str();
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}
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template <typename T>
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std::string ToStringAny(const T&,
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typename std::enable_if<
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!SupportsInsertionOperator<T>::value>::type* = nullptr
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) {
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return std::string("(unknown type [no operator<< implemented] for )");
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}
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} // namespace detail // NOLINT [readability/namespace] [5]
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} // namespace art
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#endif // ART_CMDLINE_DETAIL_CMDLINE_PARSER_DETAIL_H_
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