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KVDatabase.cpp
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KVDatabase.cpp
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//
// KVDatabase.cpp
// Maw Kit
//
// Created by Lluís Ulzurrun de Asanza Sàez on 17/02/16.
//
//
#include "KVDatabase.hpp"
#include <iostream>
#include <map>
#include <string>
#include "Log.hpp"
namespace MK {
namespace KVDatabase {
/**
* Sets given key in database to the result of applying given binary operation
* to previous value (default value if no previous value available) and given
* value.
*
* Will return previousy stored value for given key or given default value if
* there was not such a key.
*
* @param key Key to set.
* @param value Value to pass to binary operator as second argument.
* @param op Binary operation to perform to previous and new value.
*
* @return Previous value in database for given key.
*/
const long long storeApplyingBinaryOperationAndReturningPreviousValue(
const std::string &key,
const long long value,
const std::function<const long long( const long long, const long long )> &op );
//------------------------------------------------------------------------------
// MARK: - Internal
//------------------------------------------------------------------------------
void init( const std::function<void( void )> callback )
{
static bool alreadySetup = false;
if ( !alreadySetup ) {
if ( callback != nullptr ) {
callback();
}
alreadySetup = true;
}
}
const long long storeApplyingBinaryOperationAndReturningPreviousValue(
const std::string &key,
const long long value,
const std::function<const long long( const long long, const long long )> &op )
{
auto prev = getLongValueForKey( key );
setLongValueForKey( key, op( prev, value ) );
return prev;
}
//------------------------------------------------------------------------------
// MARK: - Long
//------------------------------------------------------------------------------
const long long increaseLongValueForKey( const std::string &key, const long long amount )
{
return storeApplyingBinaryOperationAndReturningPreviousValue(
key, amount,
[]( const long long prev, const long long value ) { return prev + value; } );
}
const long long decreaseLongValueForKey( const std::string &key, const long long amount )
{
return increaseLongValueForKey( key, -amount );
}
const long long keepMaxLongValueForKey( const std::string &key, const long long proposedValue )
{
return storeApplyingBinaryOperationAndReturningPreviousValue(
key, proposedValue, []( const long long prev, const long long value ) {
return std::max( prev, value );
} );
}
const long long keepMinLongValueForKey( const std::string &key, const long long proposedValue )
{
return storeApplyingBinaryOperationAndReturningPreviousValue(
key, proposedValue, []( const long long prev, const long long value ) {
return std::min( prev, value );
} );
}
}; // namespace KVDatabase
}; // namespace MK