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#include <cassert>
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#include <string>
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#include <tuple>
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#include <type_traits>
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#include <vector>
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#include <sqlite3.h>
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template<size_t I>
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struct builder_impl
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{
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template<typename T, typename G>
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static void set_value(T& tup, size_t idx, G& val)
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{
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if (idx == I - 1)
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{
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std::get<I - 1>(tup) = val;
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}
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else
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{
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builder_impl<I - 1>::set_value(tup, idx, val);
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}
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}
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};
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template <>
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struct builder_impl<0>
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{
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template<typename T, typename G>
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static void set_value(T& tup, size_t idx, G& val)
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{
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assert(false);
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}
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};
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template <typename G, typename... Ts>
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void set_value_at(std::tuple<Ts...>& tup, size_t idx, G const& val)
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{
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builder_impl<sizeof...(Ts)>::set_value(tup, idx, val);
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}
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template <typename G, typename... Ts>
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void set_value_at(std::tuple<Ts...>& tup, size_t idx, G& val)
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{
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builder_impl<sizeof...(Ts)>::set_value(tup, idx, val);
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}
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class DBManager
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{
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public:
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// Constructor
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DBManager(const std::string& db_path);
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// Destructor
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~DBManager();
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// execute query
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template<typename... T>
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std::vector<std::tuple<T...>*>* execute_query(
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const std::string& sql_statement,
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int& return_code)
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{
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sqlite3_stmt* sqlite_statement;
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// Prepare the sqlite statement
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return_code = sqlite3_prepare_v2(db, sql_statement.c_str(), -1,
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&sqlite_statement, nullptr);
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if (return_code != SQLITE_OK)
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{
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return nullptr;
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}
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auto output_vector = new std::vector<std::tuple<T...>*>();
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// Iterate until we've collected all the output
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int step_return = 0;
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while ((step_return = sqlite3_step(sqlite_statement)) != SQLITE_DONE)
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{
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// Create a new result row to be populated below
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auto result_row = new std::tuple<T...>();
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// Iterate over the columns in the row
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int num_cols = sqlite3_data_count(sqlite_statement);
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for (int col_idx = 0; col_idx < num_cols; col_idx++)
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{
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switch(sqlite3_column_type(sqlite_statement, col_idx))
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{
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case SQLITE_INTEGER:
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set_value_at(*result_row, col_idx,
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sqlite3_column_int64(sqlite_statement,
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col_idx));
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break;
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case SQLITE_FLOAT:
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set_value_at(*result_row, col_idx,
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sqlite3_column_double(sqlite_statement,
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col_idx));
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break;
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case SQLITE_TEXT:
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//~ set_value_at(*result_row, col_idx,
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//~ std::string(reinterpret_cast<const char*>(sqlite3_column_text(sqlite_statement, col_idx))));
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break;
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case SQLITE_BLOB:
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break;
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case SQLITE_NULL:
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//~ set_value_at(*result_row, col_idx, std::string(""));
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break;
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}
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}
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output_vector->push_back(result_row);
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}
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return output_vector;
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}
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private:
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sqlite3 *db;
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};
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