root/software/sqlite_poc/DBManager.h @ 7080e544
| 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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| 143a60e7 | David Sorber | #include <sqlite3.h>
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// Helper function prototypes
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void get_value(int64_t& val, int idx, sqlite3_stmt* stmt);
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void get_value(double& val, int idx, sqlite3_stmt* stmt);
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void get_value(std::string& val, int idx, sqlite3_stmt* stmt);
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| 258a530e | David Sorber | void get_value(bool& val, int idx, sqlite3_stmt* stmt);
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| 88cf406f | David Sorber | |||
| 6e4119a4 | David Sorber | template<size_t I>
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struct builder_impl
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| 88cf406f | David Sorber | {
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| 143a60e7 | David Sorber | template<typename T>
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static void set_values_helper(T& tup, sqlite3_stmt* stmt)
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| 88cf406f | David Sorber | {
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| 143a60e7 | David Sorber | // Assign the "current" value
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get_value(std::get<I - 1>(tup), I - 1, stmt);
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// Recurse to the next value in the tuple
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builder_impl<I - 1>::set_values_helper(tup, stmt);
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| 88cf406f | David Sorber | }
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};
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| 143a60e7 | David Sorber | |||
template<>
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| 6e4119a4 | David Sorber | struct builder_impl<0>
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| 88cf406f | David Sorber | {
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| 143a60e7 | David Sorber | template<typename T>
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static void set_values_helper(T& tup, sqlite3_stmt* stmt)
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{
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// Stop recursing
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return;
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| 6e4119a4 | David Sorber | }
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| 88cf406f | David Sorber | };
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| 6e4119a4 | David Sorber | |||
| 143a60e7 | David Sorber | template <typename... Ts>
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void set_values(std::tuple<Ts...>& tup, sqlite3_stmt* stmt)
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| 6e4119a4 | David Sorber | {
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| 143a60e7 | David Sorber | builder_impl<sizeof...(Ts)>::set_values_helper(tup, stmt);
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| 88cf406f | David Sorber | }
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| 6e4119a4 | David Sorber | |||
| 88cf406f | David Sorber | class DBManager
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{
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public:
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| 143a60e7 | David Sorber | |||
| 88cf406f | David Sorber | // Constructor
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DBManager(const std::string& db_path);
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| 88cf406f | David Sorber | // Destructor
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~DBManager();
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| 143a60e7 | David Sorber | |||
// Execute query template function
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| 6e4119a4 | David Sorber | template<typename... T>
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std::vector<std::tuple<T...>*>* execute_query(
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| 88cf406f | David Sorber | 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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| 143a60e7 | David Sorber | |||
| 88cf406f | David Sorber | // Prepare the sqlite statement
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| 143a60e7 | David Sorber | return_code = sqlite3_prepare_v2(db, sql_statement.c_str(), -1,
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| 88cf406f | David Sorber | &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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| 143a60e7 | David Sorber | }
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auto output_vector = new std::vector<std::tuple<T...>*>();
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| 88cf406f | David Sorber | // Iterate until we've collected all the output
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| 6e4119a4 | David Sorber | int step_return = 0;
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while ((step_return = sqlite3_step(sqlite_statement)) != SQLITE_DONE)
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| 88cf406f | David Sorber | {
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| 143a60e7 | David Sorber | // Create a new result row
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| 6e4119a4 | David Sorber | auto result_row = new std::tuple<T...>();
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// Now populate the result row using some neato variadic
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// template function magic NOTE: a small amount of black magic
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// is in use here; animal sacrifices not necessary
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set_values(*result_row, sqlite_statement);
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// Add the result row to our vector of output rows
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| 6e4119a4 | David Sorber | output_vector->push_back(result_row);
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| 88cf406f | David Sorber | }
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| 143a60e7 | David Sorber | |||
| 88cf406f | David Sorber | return output_vector;
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}
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| 143a60e7 | David Sorber | |||
| 88cf406f | David Sorber | private:
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| 143a60e7 | David Sorber | |||
| 88cf406f | David Sorber | sqlite3 *db;
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};
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