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#ifndef _VALUE_H
#define _VALUE_H
#include "amount.h"
#include "balance.h"
#include <exception>
namespace ledger {
// The following type is a polymorphous value type used solely for
// performance reasons. The alternative is to compute value
// expressions (valexpr.cc) in terms of the largest data type,
// balance_t. This was found to be prohibitively expensive, especially
// when large logic chains were involved, since many temporary
// allocations would occur for every operator. With value_t, and the
// fact that logic chains only need boolean values to continue, no
// memory allocations need to take place at all.
class value_t
{
public:
char data[sizeof(balance_pair_t)];
enum type_t {
BOOLEAN,
INTEGER,
AMOUNT,
BALANCE,
BALANCE_PAIR
} type;
value_t() {
*((unsigned int *) data) = 0;
type = INTEGER;
}
value_t(const value_t& value) : type(INTEGER) {
*this = value;
}
value_t(const bool value) {
*((bool *) data) = value;
type = BOOLEAN;
}
value_t(const unsigned int value) {
*((unsigned int *) data) = value;
type = INTEGER;
}
value_t(const amount_t& value) {
new((amount_t *)data) amount_t(value);
type = AMOUNT;
}
value_t(const balance_t& value) : type(INTEGER) {
*this = value;
}
value_t(const balance_pair_t& value) : type(INTEGER) {
*this = value;
}
~value_t() {
destroy();
}
void destroy();
value_t& operator=(const value_t& value);
value_t& operator=(const bool value) {
if ((bool *) data != &value) {
destroy();
*((bool *) data) = value;
type = BOOLEAN;
}
return *this;
}
value_t& operator=(const unsigned int value) {
if ((unsigned int *) data != &value) {
destroy();
*((unsigned int *) data) = value;
type = INTEGER;
}
return *this;
}
value_t& operator=(const amount_t& value) {
if ((amount_t *) data != &value) {
if (! value) {
return *this = 0U;
} else {
destroy();
new((amount_t *)data) amount_t(value);
type = AMOUNT;
}
}
return *this;
}
value_t& operator=(const balance_t& value) {
if ((balance_t *) data != &value) {
if (value.amounts.size() == 1) {
return *this = (*value.amounts.begin()).second;
} else {
destroy();
new((balance_t *)data) balance_t(value);
type = BALANCE;
}
}
return *this;
}
value_t& operator=(const balance_pair_t& value) {
if ((balance_pair_t *) data != &value) {
if (! value.cost) {
return *this = value.quantity;
} else {
destroy();
new((balance_pair_t *)data) balance_pair_t(value);
type = BALANCE_PAIR;
}
}
return *this;
}
value_t& operator+=(const value_t& value);
value_t& operator-=(const value_t& value);
value_t& operator*=(const value_t& value);
value_t& operator/=(const value_t& value);
bool operator<(const value_t& value);
bool operator<=(const value_t& value);
bool operator>(const value_t& value);
bool operator>=(const value_t& value);
bool operator==(const value_t& value);
bool operator!=(const value_t& value) {
return ! (*this == value);
}
template <typename T>
operator T() const;
void cast(type_t cast_type);
void negate();
void abs();
value_t cost() const;
};
template <typename T>
value_t::operator T() const
{
switch (type) {
case BOOLEAN:
return *((bool *) data);
case INTEGER:
return *((unsigned int *) data);
case AMOUNT:
return *((amount_t *) data);
case BALANCE:
return *((balance_t *) data);
case BALANCE_PAIR:
return *((balance_pair_t *) data);
default:
assert(0);
break;
}
assert(0);
return 0;
}
class value_error : public std::exception {
std::string reason;
public:
value_error(const std::string& _reason) throw() : reason(_reason) {}
virtual ~value_error() throw() {}
virtual const char* what() const throw() {
return reason.c_str();
}
};
} // namespace ledger
#endif // _VALUE_H
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