144 lines
6.2 KiB
C++
144 lines
6.2 KiB
C++
// Copyright Paul A. Bristow 2017.
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// Copyright John Maddock 2017.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt
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// or copy at http://www.boost.org/LICENSE_1_0.txt)
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// test_value.hpp
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#ifndef TEST_VALUE_HPP
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#define TEST_VALUE_HPP
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// BOOST_MATH_TEST_VALUE is used to create a test value of suitable type from a decimal digit string.
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// Two parameters, both a floating-point literal double like 1.23 (not long double so no suffix L)
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// and a decimal digit string const char* like "1.23" must be provided.
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// The decimal value represented must be the same of course, with at least enough precision for long double.
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// Note there are two gotchas to this approach:
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// * You need all values to be real floating-point values
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// * and *MUST* include a decimal point (to avoid confusion with an integer literal).
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// * It's slow to compile compared to a simple literal.
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// Speed is not an issue for a few test values,
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// but it's not generally usable in large tables
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// where you really need everything to be statically initialized.
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// Macro BOOST_MATH_INSTRUMENT_CREATE_TEST_VALUE provides a global diagnostic value for create_type.
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#include <boost/cstdfloat.hpp> // For float_64_t, float128_t. Must be first include!
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#ifndef BOOST_MATH_STANDALONE
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#include <boost/lexical_cast.hpp>
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#endif
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#include <limits>
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#include <type_traits>
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#ifdef BOOST_MATH_INSTRUMENT_CREATE_TEST_VALUE
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// global int create_type(0); must be defined before including this file.
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#endif
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#ifdef BOOST_HAS_FLOAT128
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typedef __float128 largest_float;
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#define BOOST_MATH_TEST_LARGEST_FLOAT_SUFFIX(x) x##Q
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#define BOOST_MATH_TEST_LARGEST_FLOAT_DIGITS 113
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#else
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typedef long double largest_float;
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#define BOOST_MATH_TEST_LARGEST_FLOAT_SUFFIX(x) x##L
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#define BOOST_MATH_TEST_LARGEST_FLOAT_DIGITS std::numeric_limits<long double>::digits
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#endif
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template <class T, class T2>
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inline T create_test_value(largest_float val, const char*, const std::true_type&, const T2&)
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{ // Construct from long double or quad parameter val (ignoring string/const char* str).
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// (This is case for MPL parameters = true_ and T2 == false_,
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// and MPL parameters = true_ and T2 == true_ cpp_bin_float)
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// All built-in/fundamental floating-point types,
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// and other User-Defined Types that can be constructed without loss of precision
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// from long double suffix L (or quad suffix Q),
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//
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// Choose this method, even if can be constructed from a string,
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// because it will be faster, and more likely to be the closest representation.
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// (This is case for MPL parameters = true_type and T2 == true_type).
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#ifdef BOOST_MATH_INSTRUMENT_CREATE_TEST_VALUE
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create_type = 1;
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#endif
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return static_cast<T>(val);
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}
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template <class T>
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inline T create_test_value(largest_float, const char* str, const std::false_type&, const std::true_type&)
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{ // Construct from decimal digit string const char* @c str (ignoring long double parameter).
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// For example, extended precision or other User-Defined types which ARE constructible from a string
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// (but not from double, or long double without loss of precision).
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// (This is case for MPL parameters = false_type and T2 == true_type).
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#ifdef BOOST_MATH_INSTRUMENT_CREATE_TEST_VALUE
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create_type = 2;
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#endif
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return T(str);
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}
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template <class T>
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inline T create_test_value(largest_float, const char* str, const std::false_type&, const std::false_type&)
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{ // Create test value using from lexical cast of decimal digit string const char* str.
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// For example, extended precision or other User-Defined types which are NOT constructible from a string
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// (NOR constructible from a long double).
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// (This is case T1 = false_type and T2 == false_type).
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#ifdef BOOST_MATH_INSTRUMENT_CREATE_TEST_VALUE
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create_type = 3;
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#endif
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#if defined(BOOST_MATH_STANDALONE)
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static_assert(sizeof(T) == 0, "Can not create a test value using lexical cast of string in standalone mode");
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return T();
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#else
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return boost::lexical_cast<T>(str);
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#endif
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}
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// T real type, x a decimal digits representation of a floating-point, for example: 12.34.
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// It must include a decimal point (or it would be interpreted as an integer).
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// x is converted to a long double by appending the letter L (to suit long double fundamental type), 12.34L.
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// x is also passed as a const char* or string representation "12.34"
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// (to suit most other types that cannot be constructed from long double without possible loss).
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// BOOST_MATH_TEST_LARGEST_FLOAT_SUFFIX(x) makes a long double or quad version, with
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// suffix a letter L (or Q) to suit long double (or quad) fundamental type, 12.34L or 12.34Q.
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// #x makes a decimal digit string version to suit multiprecision and fixed_point constructors, "12.34".
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// (Constructing from double or long double (or quad) could lose precision for multiprecision or fixed-point).
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// The matching create_test_value function above is chosen depending on the T1 and T2 mpl bool truths.
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// The string version from #x is used if the precision of T is greater than long double.
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// Example: long double test_value = BOOST_MATH_TEST_VALUE(double, 1.23456789);
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#define BOOST_MATH_TEST_VALUE(T, x) create_test_value<T>(\
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BOOST_MATH_TEST_LARGEST_FLOAT_SUFFIX(x),\
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#x,\
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std::integral_constant<bool, \
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std::numeric_limits<T>::is_specialized &&\
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(std::numeric_limits<T>::radix == 2)\
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&& (std::numeric_limits<T>::digits <= BOOST_MATH_TEST_LARGEST_FLOAT_DIGITS)\
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&& std::is_convertible<largest_float, T>::value>(),\
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std::integral_constant<bool, \
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std::is_constructible<T, const char*>::value>()\
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)
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#if LDBL_MAX_10_EXP > DBL_MAX_10_EXP
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#define BOOST_MATH_TEST_HUGE_FLOAT_SUFFIX(x) BOOST_MATH_TEST_LARGEST_FLOAT_SUFFIX(x)
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#else
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#define BOOST_MATH_TEST_HUGE_FLOAT_SUFFIX(x) 0.0
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#endif
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#define BOOST_MATH_HUGE_TEST_VALUE(T, x) create_test_value<T>(\
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BOOST_MATH_TEST_HUGE_FLOAT_SUFFIX(x),\
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#x,\
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std::integral_constant<bool, \
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std::numeric_limits<T>::is_specialized &&\
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(std::numeric_limits<T>::radix == 2)\
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&& (std::numeric_limits<T>::digits <= BOOST_MATH_TEST_LARGEST_FLOAT_DIGITS)\
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&& std::is_convertible<largest_float, T>::value>(),\
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std::integral_constant<bool, \
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std::is_constructible<T, const char*>::value>()\
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)
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#endif // TEST_VALUE_HPP
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