mirror of
https://github.com/matrix-construct/construct
synced 2024-08-27 20:05:17 +02:00
254 lines
8.8 KiB
C++
254 lines
8.8 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_LEX_CAST_H
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//
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// Lexical conversions
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//
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namespace ircd
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{
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IRCD_EXCEPTION_HIDENAME(ircd::error, bad_lex_cast)
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template<class T> bool try_lex_cast(const string_view &);
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template<class T> T lex_cast(std::string &);
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template<class T> T lex_cast(const std::string &);
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template<class T> T lex_cast(const std::string_view &);
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template<class T> T lex_cast(const string_view &);
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// User supplied destination buffer
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template<class T> string_view lex_cast(T, const mutable_buffer &buf);
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// Circular static thread_local buffer
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const size_t LEX_CAST_BUFS {256}; // plenty
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template<class T> string_view lex_cast(const T &t);
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}
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namespace ircd
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{
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template<> bool try_lex_cast<std::string>(const string_view &); // stub always true
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template<> bool try_lex_cast<std::string_view>(const string_view &); // stub always true
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template<> bool try_lex_cast<string_view>(const string_view &); // stub always true
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template<> bool try_lex_cast<long double>(const string_view &);
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template<> bool try_lex_cast<double>(const string_view &);
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template<> bool try_lex_cast<ulong>(const string_view &);
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template<> bool try_lex_cast<long>(const string_view &);
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template<> bool try_lex_cast<uint>(const string_view &);
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template<> bool try_lex_cast<int>(const string_view &);
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template<> bool try_lex_cast<ushort>(const string_view &);
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template<> bool try_lex_cast<short>(const string_view &);
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template<> bool try_lex_cast<uint8_t>(const string_view &);
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template<> bool try_lex_cast<int8_t>(const string_view &);
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template<> bool try_lex_cast<bool>(const string_view &);
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template<> bool try_lex_cast<seconds>(const string_view &);
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template<> bool try_lex_cast<milliseconds>(const string_view &);
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template<> bool try_lex_cast<microseconds>(const string_view &);
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template<> bool try_lex_cast<nanoseconds>(const string_view &);
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template<> std::string &lex_cast(std::string &); // trivial
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template<> std::string lex_cast(const std::string &); // trivial
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template<> std::string_view lex_cast(const std::string_view &); // trivial
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template<> std::string lex_cast(const string_view &); // trivial
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template<> long double lex_cast(const string_view &);
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template<> double lex_cast(const string_view &);
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template<> ulong lex_cast(const string_view &);
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template<> long lex_cast(const string_view &);
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template<> uint lex_cast(const string_view &);
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template<> int lex_cast(const string_view &);
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template<> ushort lex_cast(const string_view &);
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template<> short lex_cast(const string_view &);
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template<> uint8_t lex_cast(const string_view &);
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template<> int8_t lex_cast(const string_view &);
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template<> bool lex_cast(const string_view &);
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template<> seconds lex_cast(const string_view &);
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template<> milliseconds lex_cast(const string_view &);
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template<> microseconds lex_cast(const string_view &);
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template<> nanoseconds lex_cast(const string_view &);
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template<> string_view lex_cast(const std::string &, const mutable_buffer &buf);
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template<> string_view lex_cast(const std::string_view &, const mutable_buffer &buf);
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template<> string_view lex_cast(const string_view &, const mutable_buffer &buf);
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template<> string_view lex_cast(seconds, const mutable_buffer &buf);
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template<> string_view lex_cast(milliseconds, const mutable_buffer &buf);
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template<> string_view lex_cast(microseconds, const mutable_buffer &buf);
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template<> string_view lex_cast(nanoseconds, const mutable_buffer &buf);
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template<> string_view lex_cast(long double, const mutable_buffer &buf);
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template<> string_view lex_cast(double, const mutable_buffer &buf);
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template<> string_view lex_cast(ulong, const mutable_buffer &buf);
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template<> string_view lex_cast(long, const mutable_buffer &buf);
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template<> string_view lex_cast(uint, const mutable_buffer &buf);
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template<> string_view lex_cast(int, const mutable_buffer &buf);
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template<> string_view lex_cast(ushort, const mutable_buffer &buf);
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template<> string_view lex_cast(short, const mutable_buffer &buf);
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template<> string_view lex_cast(uint8_t, const mutable_buffer &buf);
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template<> string_view lex_cast(int8_t, const mutable_buffer &buf);
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template<> string_view lex_cast(bool, const mutable_buffer &buf);
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}
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/// Convert a native number to a string. The returned value is a view of the
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/// string in a static ring buffer. There are LEX_CAST_BUFS number of buffers
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/// so you should not hold on to the returned view for very long.
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template<class T>
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ircd::string_view
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ircd::lex_cast(const T &t)
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{
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return lex_cast<T>(t, null_buffer);
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}
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/// Conversion to an std::string creates a copy when the input is a
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/// string_view. Note this is not considered an "unnecessary lexical cast"
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/// even though nothing is being converted, so there will be no warning.
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template<>
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inline std::string
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ircd::lex_cast<std::string>(const string_view &s)
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{
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return std::string{s};
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}
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/// Template basis for a string_view input
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template<class T>
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T
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ircd::lex_cast(const string_view &s)
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{
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return s;
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}
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/// Specialization of a string_view to string_view conversion which is just
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/// a trivial copy of the view.
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template<>
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inline std::string_view
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ircd::lex_cast<std::string_view>(const std::string_view &s)
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{
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return s;
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}
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/// Specialization of a string to string conversion which generates a warning
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/// because the conversion has to copy the string while no numerical conversion
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/// has taken place. The developer should remove the offending lex_cast.
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template<>
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__attribute__((warning("unnecessary lexical cast")))
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inline std::string
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ircd::lex_cast<std::string>(const std::string &s)
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{
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return s;
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}
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/// Template basis for a const std::string input
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template<class T>
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T
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ircd::lex_cast(const std::string &s)
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{
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return lex_cast<T>(string_view{s});
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}
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/// Template basis for an lvalue string. If we can get this binding rather
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/// than the const std::string alternative some trivial conversions are
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/// easier to make in the specializations.
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template<class T>
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T
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ircd::lex_cast(std::string &s)
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{
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return lex_cast<T>(string_view{s});
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}
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/// Specialization of a string to string conversion without a warning because
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/// we can trivially pass through a reference from input to output.
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template<>
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inline std::string &
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ircd::lex_cast(std::string &s)
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{
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return s;
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}
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/// Specialization of a string to string conversion to user's buffer;
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/// marked as unnecessary because no numerical conversion takes place yet
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/// data is still copied. (note: warning may be removed; may be intentional)
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template<>
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__attribute__((warning("unnecessary lexical cast")))
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inline ircd::string_view
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ircd::lex_cast(const string_view &s,
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const mutable_buffer &buf)
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{
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s.copy(data(buf), size(buf));
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return { data(buf), s.size() };
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}
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/// Specialization of a string to string conversion to user's buffer;
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/// marked as unnecessary because no numerical conversion takes place yet
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/// data is still copied. (note: warning may be removed; may be intentional)
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template<>
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__attribute__((warning("unnecessary lexical cast")))
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inline ircd::string_view
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ircd::lex_cast(const std::string_view &s,
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const mutable_buffer &buf)
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{
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s.copy(data(buf), size(buf));
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return { data(buf), s.size() };
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}
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/// Specialization of a string to string conversion to user's buffer;
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/// marked as unnecessary because no numerical conversion takes place yet
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/// data is still copied. (note: warning may be removed; may be intentional)
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template<>
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__attribute__((warning("unnecessary lexical cast")))
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inline ircd::string_view
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ircd::lex_cast(const std::string &s,
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const mutable_buffer &buf)
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{
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s.copy(data(buf), size(buf));
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return { data(buf), s.size() };
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}
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/// Template basis; if no specialization is matched there is no fallback here
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template<class T>
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__attribute__((error("unsupported lexical cast")))
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ircd::string_view
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ircd::lex_cast(T t,
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const mutable_buffer &buf)
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{
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assert(0);
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return {};
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}
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/// Template basis; if no specialization is matched there is no fallback here
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template<class T>
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__attribute__((error("unsupported lexical cast")))
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bool
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ircd::try_lex_cast(const string_view &s)
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{
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assert(0);
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return false;
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}
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/// Trivial conversion; always returns true
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template<>
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inline bool
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ircd::try_lex_cast<ircd::string_view>(const string_view &)
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{
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return true;
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}
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/// Trivial conversion; always returns true
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template<>
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inline bool
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ircd::try_lex_cast<std::string_view>(const string_view &)
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{
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return true;
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}
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/// Trivial conversion; always returns true
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template<>
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inline bool
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ircd::try_lex_cast<std::string>(const string_view &s)
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{
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return true;
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}
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