evoplex::Value Class Reference

A class for variant data types (tagged union). More...

#include <value.h>

Public Types
enum	Type {   BOOL, CHAR, DOUBLE, INT,   STRING, INVALID }
	This enum defines the types of variable that a Value can contain.

Public Member Functions
	Value ()
	Constructs an invalid Value. More...
	Value (const Value &value)
	Constructs a copy of the value passed as the argument to this constructor.
	Value (bool value)
	Constructs a new Value with a boolean value.
	Value (char value)
	Constructs a new Value with a char value.
	Value (double value)
	Constructs a new Value with a double value.
	Value (int value)
	Constructs a new Value with an integer value.
	Value (const char *value)
	Constructs a new Value with a string value.
	Value (const QString &value)
	Constructs a new Value with a string value.
	Value (std::vector< bool >::reference value)
	Constructs a new Value with a boolean value. More...
	~Value ()
	Destroys this Value.
Type	type () const
	Returns the storage type of the data stored in the Value.
bool	isValid () const
	Returns true if the storage type of this Value is not Type::INVALID.
bool	isBool () const
	Returns true if the storage type of this Value is equal to Type::BOOL.
bool	isChar () const
	Returns true if the storage type of this Value is equal to Type::CHAR.
bool	isDouble () const
	Returns true if the storage type of this Value is equal to Type::DOUBLE.
bool	isInt () const
	Returns true if the storage type of this Value is equal to Type::INT.
bool	isString () const
	Returns true if the storage type of this Value is equal to Type::STRING.
bool	toBool () const
	Returns the Value as a boolean. More...
char	toChar () const
	Returns the Value as a char. More...
double	toDouble () const
	Returns the Value as a double. More...
int	toInt () const
	Returns the Value as an int. More...
quint32	toUInt () const
	Returns the Value as an unsigned integer. More...
const char *	toString () const
	Returns the Value as a string. More...
QString	toQString (char format='g', int precision=8) const
	Returns the Value as a QString. More...
Value &	operator= (const Value &v)
	Assigns the value v to this Value.
bool	operator== (const Value &v) const
	Checks if this Value is equal to v.
bool	operator!= (const Value &v) const
	Checks if this Value is different from v.
bool	operator< (const Value &v) const
	Checks if this Value is less than v.
bool	operator> (const Value &v) const
	Checks if this Value is greater than v.
bool	operator<= (const Value &v) const
	Checks if this Value is less or equal to v.
bool	operator>= (const Value &v) const
	Checks if this Value is greater or equal to v.

Friends
struct	std::hash< Value >

Detailed Description

A class for variant data types (tagged union).

This is a very important class in Evoplex, it defines a data type that can behave like an integer, double, char, bool or string in a very efficient way.

A Value object holds a single value of a single type() at a time. You can find out what type (T) the Value holds and get its value using one of the toT() functions (e.g., toInt()).

The functions named toT() (e.g., toInt(), toString()) are const. If you ask for the stored type, they return a copy of the stored object.

Here is some example code to demonstrate the use of Value:

Value v(123);                // The Value now contains an int
int x = v.toInt();           // x = 123
v = Value("hello");          // The Value now contains a string
int y = v.toInt();           // throws an exception as v cannot be converted to an int
QString s = v.toQString();   // s = "hello"
...
v = 1.1;                     // v.type() is equal to DOUBLE
v = v.toDouble() + 1.2;      // The Value now holds 2.3

Constructor & Destructor Documentation

Value() [1/2]

evoplex::Value::Value

(

)

Constructs an invalid Value.

See also

isValid()

Value() [2/2]

evoplex::Value::Value

(

std::vector< bool >::reference

value

)

Constructs a new Value with a boolean value.

This constructor is available just to accept the specialized vector<bool>. http://www.cplusplus.com/reference/vector/vector-bool

Member Function Documentation

toBool()

bool evoplex::Value::toBool ( ) const

inline

Returns the Value as a boolean.

It returns a boolean if the data type() is equal to Type::BOOL. Otherwise, it throws an expection.

Exceptions

std::logic_error.

toChar()

char evoplex::Value::toChar ( ) const

inline

Returns the Value as a char.

It returns a char if the data type() is equal to Type::CHAR. Otherwise, it throws an expection.

Exceptions

std::logic_error.

toDouble()

double evoplex::Value::toDouble ( ) const

inline

Returns the Value as a double.

It returns a double if the data type() is equal to Type::DOUBLE. Otherwise, it throws an expection.

Exceptions

std::logic_error.

toInt()

int evoplex::Value::toInt ( ) const

inline

Returns the Value as an int.

It returns an int if the data type() is equal to Type::INT. Otherwise, it throws an expection.

Exceptions

std::logic_error.

toQString()

QString evoplex::Value::toQString	(	char	format = 'g',
		int	precision = 8
	)		const

Returns the Value as a QString.

It returns a QString for any data type(). For example:

Value v = 123;                // v is now an integer equal to 123
QString s = v.toQString();    // s = "123"
v = true;                     // v is now a boolean
s = v.toQString();            // s = "1"
v = "hello";                  // v is now a string
s = v.toQString();            // s = "hello"

toString()

const char * evoplex::Value::toString ( ) const

inline

Returns the Value as a string.

It returns a string if the data type() is equal to Type::STRING. Otherwise, it throws an expection.

Exceptions

std::logic_error.

toUInt()

quint32 evoplex::Value::toUInt ( ) const

inline

Returns the Value as an unsigned integer.

It returns an unsigned integer if the data type() is equal to Type::INT and the value is >= 0. Otherwise, it throws an expection.

Exceptions

std::logic_error.

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The documentation for this class was generated from the following file:

• evoplex/src/core/include/value.h