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#pragma once
#include <assert.h>
#include <sqlite3.h>
namespace Database
{
namespace Specializations
{
template<typename ReturnType>
ReturnType getResult(int location, sqlite3_stmt* statement);
template<>
inline int getResult<int>(int location, sqlite3_stmt* statement)
{
return sqlite3_column_int(statement, location);
}
template<>
inline std::string getResult<std::string>(int location, sqlite3_stmt* statement)
{
return std::string(reinterpret_cast<const char*>(sqlite3_column_text(statement, location)));
}
template<typename ValueType>
void bind(ValueType value, int location, sqlite3_stmt* statement);
template<>
inline void bind<int>(int value, int location, sqlite3_stmt* statement)
{
int rc = sqlite3_bind_int(statement, location, value);
assert(rc == SQLITE_OK);
}
template<>
inline void bind<float>(float value, int location, sqlite3_stmt* statement)
{
int rc = sqlite3_bind_double(statement, location, static_cast<double>(value));
assert(rc == SQLITE_OK);
}
}
template<typename ...ReturnTypes>
class Query
{
public:
explicit Query(std::string query) : statement(nullptr), content(query)
{}
/*
Calls sqlite3_finalize on the statement.
*/
~Query()
{
int rc = sqlite3_finalize(statement);
assert(rc == SQLITE_OK);
}
/*
Calls sqlite3_prepare_v2 to prepare this query.
*/
void prepare(sqlite3* db)
{
// Preparation of the statement.
int rc = sqlite3_prepare_v2(db, content.c_str(), static_cast<int>(content.size()), &statement, NULL);
assert(rc == SQLITE_OK);
}
/*
Steps the execution of this query once. Returns true if the return code is SQLITE_ROW.
*/
bool step() const
{
// Execution of the statement
int rc = sqlite3_step(statement);
if(rc == SQLITE_ROW)
return true;
if(rc == SQLITE_DONE)
return false;
assert(!"The return code of step was not SQLITE_ROW (100) or SQLITE_DONE (101)!");
return false;
}
/*
Resets this query back to its initial state.
*/
void reset() const
{
sqlite3_reset(statement);
}
/*
A template for implementing the binding of values to parameters in the sqlite statement.
*/
template<typename ValueType>
void bind(ValueType value, int location)
{
Specializations::bind<ValueType>(value, location, statement);
}
/**
* \brief Returns the result of ReturnType at the given location in the query result row.
* \tparam ReturnType The type of the entry in the row.
* \param location The index of the entry in the row.
* \return The result of the query at the given location.
*/
template<typename ReturnType>
ReturnType getResult(int location)
{
return Specializations::getResult<ReturnType>(location, statement);
}
private:
// The sqlite3 statement that corresponds to this query.
sqlite3_stmt* statement;
// The sql string that will be executed.
std::string content;
};
}
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