forked from boostorg/beast
110 lines
2.8 KiB
C++
110 lines
2.8 KiB
C++
//
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// Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef BEAST_STRING_PARAM_HPP
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#define BEAST_STRING_PARAM_HPP
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#include <beast/config.hpp>
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#include <beast/core/string.hpp>
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#include <beast/core/static_string.hpp>
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#include <beast/core/detail/static_ostream.hpp>
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#include <beast/core/detail/type_traits.hpp>
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#include <boost/optional.hpp>
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namespace beast {
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/** A function parameter which efficiently converts to string.
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This is used as a function parameter type to allow callers
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notational convenience: objects other than strings may be
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passed in contexts where a string is expected. The conversion
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to string is made using `operator<<` to a non-dynamically
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allocated static buffer if possible, else to a `std::string`
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on overflow.
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*/
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class string_param
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{
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string_view sv_;
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char buf_[128];
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boost::optional<detail::static_ostream> os_;
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template<class T>
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typename std::enable_if<
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std::is_integral<T>::value>::type
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print(T const&);
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template<class T>
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typename std::enable_if<
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! std::is_integral<T>::value &&
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! std::is_convertible<T, string_view>::value
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>::type
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print(T const&);
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void
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print(string_view const&);
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template<class T>
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typename std::enable_if<
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std::is_integral<T>::value>::type
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print_1(T const&);
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template<class T>
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typename std::enable_if<
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! std::is_integral<T>::value>::type
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print_1(T const&);
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void
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print_n()
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{
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}
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template<class T0, class... TN>
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void
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print_n(T0 const&, TN const&...);
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template<class T0, class T1, class... TN>
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void
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print(T0 const&, T1 const&, TN const&...);
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public:
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/// Copy constructor (disallowed)
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string_param(string_param const&) = delete;
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/// Copy assignment (disallowed)
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string_param& operator=(string_param const&) = delete;
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/** Constructor
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This function constructs a string as if by concatenating
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the result of streaming each argument in order into an
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output stream. It is used as a notational convenience
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at call sites which expect a parameter with the semantics
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of a @ref string_view.
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The implementation uses a small, internal static buffer
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to avoid memory allocations especially for the case where
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the list of arguments to be converted consists of a single
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integral type.
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@param args One or more arguments to convert
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*/
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template<class... Args>
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string_param(Args const&... args);
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/// Implicit conversion to @ref string_view
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operator string_view const() const
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{
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return sv_;
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}
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};
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} // beast
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#include <beast/core/impl/string_param.ipp>
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#endif
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