root/software/sqlite_poc/DBManager.h @ 9471fa32
| 88cf406f | David Sorber | ||
#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 visit_impl
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{
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template <typename T, typename V>
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static void visit(T& tup, size_t idx, V value)
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{
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if (idx == I - 1)
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{
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if (std::is_same<std::get<I - 1>(tup), value>)
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{
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std::get<I - 1>(tup) = value;
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}
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else
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{
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assert(false);
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}
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}
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else
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{
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visit_impl<I - 1>::visit(tup, idx, value);
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}
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}
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};
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template <>
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struct visit_impl<0>
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{
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template <typename T, typename V>
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static void visit(T& tup, size_t idx, V fun) { assert(false); }
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};
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//~ template <typename V, typename... Ts>
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//~ void visit_at(std::tuple<Ts...> const& tup, size_t idx, V value)
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//~ {
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//~ visit_impl<sizeof...(Ts)>::visit(tup, idx, value);
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//~ }
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template <typename V, typename... Ts>
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void visit_at(std::tuple<Ts...>& tup, size_t idx, V value)
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{
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visit_impl<sizeof...(Ts)>::visit(tup, idx, value);
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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<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<T*>();
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int step_return = 0;
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// Iterate until we've collected all the output
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do
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{
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// Gran the
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step_return = sqlite3_step(sqlite_statement);
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// Create a new result row to be populated below
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auto result_row = new 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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visit_at(*result_row, col_idx,
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sqlite3_column_int64(sqlite_statement, col_idx));
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//~ std::get<col_idx>(result_row) =
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//~ sqlite3_column_int64(sqlite_statement, col_idx);
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break;
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case SQLITE_FLOAT:
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visit_at(*result_row, col_idx, sqlite3_column_double(sqlite_statement, col_idx));
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//~ std::get<col_idx>(result_row) =
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//~ sqlite3_column_double(sqlite_statement, col_idx);
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break;
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case SQLITE_TEXT:
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visit_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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//~ std::get<col_idx>(result_row) =
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//~ std::string(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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break;
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}
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}
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}
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while (step_return == SQLITE_ROW);
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return output_vector;
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}
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void test();
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// templatized member function!
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template<typename T>
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std::vector<T> func(T& foo)
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{
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std::cout << "Does this work??? " << std::get<2>(foo) << std::endl;
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std::vector<T> bar;
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bar.push_back(foo);
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return bar;
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}
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private:
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sqlite3 *db;
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uint32_t numba;
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};
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