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https://github.com/rbock/sqlpp11.git
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117 lines
4.0 KiB
C++
117 lines
4.0 KiB
C++
/*
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* Copyright (c) 2013, 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_GROUP_BY_H
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#define SQLPP_GROUP_BY_H
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#include <tuple>
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#include <sqlpp11/type_traits.h>
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#include <sqlpp11/vendor/expression.h>
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#include <sqlpp11/vendor/interpret_tuple.h>
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#include <sqlpp11/vendor/interpretable_list.h>
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#include <sqlpp11/vendor/policy_update.h>
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#include <sqlpp11/detail/logic.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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// GROUP BY
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template<typename Database, typename... Expressions>
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struct group_by_t
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{
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using _is_group_by = std::true_type;
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using _is_dynamic = typename std::conditional<std::is_same<Database, void>::value, std::false_type, std::true_type>::type;
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using _parameter_tuple_t = std::tuple<Expressions...>;
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static_assert(_is_dynamic::value or sizeof...(Expressions), "at least one expression (e.g. a column) required in group_by()");
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static_assert(not ::sqlpp::detail::has_duplicates<Expressions...>::value, "at least one duplicate argument detected in group_by()");
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static_assert(::sqlpp::detail::and_t<is_expression_t, Expressions...>::value, "at least one argument is not an expression in group_by()");
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group_by_t(Expressions... expressions):
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_expressions(expressions...)
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{}
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group_by_t(const group_by_t&) = default;
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group_by_t(group_by_t&&) = default;
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group_by_t& operator=(const group_by_t&) = default;
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group_by_t& operator=(group_by_t&&) = default;
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~group_by_t() = default;
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template<typename Statement, typename Expression>
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void add_group_by(const Statement&, Expression expression)
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{
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static_assert(is_table_t<Expression>::value, "from arguments require to be tables or joins");
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_dynamic_expressions.emplace_back(expression);
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}
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const group_by_t& _group_by() const { return *this; }
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_parameter_tuple_t _expressions;
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vendor::interpretable_list_t<Database> _dynamic_expressions;
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};
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struct no_group_by_t
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{
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using _is_noop = std::true_type;
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};
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// Interpreters
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template<typename Context, typename Database, typename... Expressions>
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struct interpreter_t<Context, group_by_t<Database, Expressions...>>
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{
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using T = group_by_t<Database, Expressions...>;
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static Context& _(const T& t, Context& context)
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{
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if (sizeof...(Expressions) == 0 and t._dynamic_expressions.empty())
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return context;
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context << " GROUP BY ";
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interpret_tuple(t._expressions, ',', context);
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if (sizeof...(Expressions) and not t._dynamic_expressions.empty())
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context << ',';
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interpret_list(t._dynamic_expressions, ',', context);
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return context;
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}
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};
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template<typename Context>
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struct interpreter_t<Context, no_group_by_t>
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{
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using T = no_group_by_t;
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static Context& _(const T& t, Context& context)
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{
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return context;
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}
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};
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}
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}
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#endif
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