mirror of
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114 lines
3.4 KiB
C++
114 lines
3.4 KiB
C++
/*
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* Copyright (c) 2013-2014, Roland Bock
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice, this
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* list of conditions and the following disclaimer in the documentation and/or
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* other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef SQLPP_AVG_H
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#define SQLPP_AVG_H
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#include <sqlpp11/type_traits.h>
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namespace sqlpp
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{
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namespace vendor
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{
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template<typename Flag, typename Expr>
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struct avg_t: public floating_point::template expression_operators<avg_t<Flag, Expr>>
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{
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static_assert(is_noop<Flag>::value or std::is_same<sqlpp::distinct_t, Flag>::value, "avg() used with flag other than 'distinct'");
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static_assert(is_numeric_t<Expr>::value, "avg() requires a value expression as argument");
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struct _value_type: public floating_point
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{
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using _is_named_expression = std::true_type;
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};
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using _table_set = typename Expr::_table_set;
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struct _name_t
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{
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static constexpr const char* _get_name() { return "AVG"; }
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template<typename T>
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struct _member_t
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{
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T avg;
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T& operator()() { return avg; }
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const T& operator()() const { return avg; }
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};
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};
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avg_t(Expr expr):
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_expr(expr)
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{}
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avg_t(const avg_t&) = default;
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avg_t(avg_t&&) = default;
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avg_t& operator=(const avg_t&) = default;
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avg_t& operator=(avg_t&&) = default;
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~avg_t() = default;
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Expr _expr;
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};
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}
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namespace vendor
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{
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template<typename Context, typename Flag, typename Expr>
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struct serializer_t<Context, vendor::avg_t<Flag, Expr>>
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{
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using T = vendor::avg_t<Flag, Expr>;
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static Context& _(const T& t, Context& context)
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{
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context << "AVG(";
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if (std::is_same<sqlpp::distinct_t, Flag>::value)
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{
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serialize(Flag(), context);
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context << ' ';
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}
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serialize(t._expr, context);
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context << ")";
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return context;
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}
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};
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}
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template<typename T>
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auto avg(T t) -> typename vendor::avg_t<vendor::noop, vendor::wrap_operand_t<T>>
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{
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static_assert(is_numeric_t<vendor::wrap_operand_t<T>>::value, "avg() requires a value expression as argument");
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return { t };
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}
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template<typename T>
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auto avg(const sqlpp::distinct_t&, T t) -> typename vendor::avg_t<sqlpp::distinct_t, vendor::wrap_operand_t<T>>
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{
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static_assert(is_numeric_t<vendor::wrap_operand_t<T>>::value, "avg() requires a value expression as argument");
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return { t };
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}
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}
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#endif
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