From bc524d70253a4ab2fe40c3ca3e5666e267c0a4d1 Mon Sep 17 00:00:00 2001
From: Lexi Winter <lexi@le-fay.org>
Date: Sun, 29 Jun 2025 19:25:29 +0100
Subject: import catch2 3.8.1

---
 src/catch2/catch_approx.hpp | 128 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)
 create mode 100644 src/catch2/catch_approx.hpp

(limited to 'src/catch2/catch_approx.hpp')

diff --git a/src/catch2/catch_approx.hpp b/src/catch2/catch_approx.hpp
new file mode 100644
index 0000000..de4d2ab
--- /dev/null
+++ b/src/catch2/catch_approx.hpp
@@ -0,0 +1,128 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+#ifndef CATCH_APPROX_HPP_INCLUDED
+#define CATCH_APPROX_HPP_INCLUDED
+
+#include <catch2/catch_tostring.hpp>
+
+#include <type_traits>
+
+namespace Catch {
+
+    class Approx {
+    private:
+        bool equalityComparisonImpl(double other) const;
+        // Sets and validates the new margin (margin >= 0)
+        void setMargin(double margin);
+        // Sets and validates the new epsilon (0 < epsilon < 1)
+        void setEpsilon(double epsilon);
+
+    public:
+        explicit Approx ( double value );
+
+        static Approx custom();
+
+        Approx operator-() const;
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        Approx operator()( T const& value ) const {
+            Approx approx( static_cast<double>(value) );
+            approx.m_epsilon = m_epsilon;
+            approx.m_margin = m_margin;
+            approx.m_scale = m_scale;
+            return approx;
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        explicit Approx( T const& value ): Approx(static_cast<double>(value))
+        {}
+
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        friend bool operator == ( const T& lhs, Approx const& rhs ) {
+            auto lhs_v = static_cast<double>(lhs);
+            return rhs.equalityComparisonImpl(lhs_v);
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        friend bool operator == ( Approx const& lhs, const T& rhs ) {
+            return operator==( rhs, lhs );
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        friend bool operator != ( T const& lhs, Approx const& rhs ) {
+            return !operator==( lhs, rhs );
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        friend bool operator != ( Approx const& lhs, T const& rhs ) {
+            return !operator==( rhs, lhs );
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        friend bool operator <= ( T const& lhs, Approx const& rhs ) {
+            return static_cast<double>(lhs) < rhs.m_value || lhs == rhs;
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        friend bool operator <= ( Approx const& lhs, T const& rhs ) {
+            return lhs.m_value < static_cast<double>(rhs) || lhs == rhs;
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        friend bool operator >= ( T const& lhs, Approx const& rhs ) {
+            return static_cast<double>(lhs) > rhs.m_value || lhs == rhs;
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        friend bool operator >= ( Approx const& lhs, T const& rhs ) {
+            return lhs.m_value > static_cast<double>(rhs) || lhs == rhs;
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        Approx& epsilon( T const& newEpsilon ) {
+            const auto epsilonAsDouble = static_cast<double>(newEpsilon);
+            setEpsilon(epsilonAsDouble);
+            return *this;
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        Approx& margin( T const& newMargin ) {
+            const auto marginAsDouble = static_cast<double>(newMargin);
+            setMargin(marginAsDouble);
+            return *this;
+        }
+
+        template <typename T, typename = std::enable_if_t<std::is_constructible<double, T>::value>>
+        Approx& scale( T const& newScale ) {
+            m_scale = static_cast<double>(newScale);
+            return *this;
+        }
+
+        std::string toString() const;
+
+    private:
+        double m_epsilon;
+        double m_margin;
+        double m_scale;
+        double m_value;
+    };
+
+namespace literals {
+    Approx operator ""_a(long double val);
+    Approx operator ""_a(unsigned long long val);
+} // end namespace literals
+
+template<>
+struct StringMaker<Catch::Approx> {
+    static std::string convert(Catch::Approx const& value);
+};
+
+} // end namespace Catch
+
+#endif // CATCH_APPROX_HPP_INCLUDED
-- 
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