<nothing> Class Reference

Methods in this pseudo-class can be executed on NOTHING. More...

#include <Pseudo_QC_Nothing.dox.h>

Inheritance diagram for Qore::<nothing>:

Public Member Methods
SingleValueIterator	contextIterator ()
	Returns an empty SingleValueIterator object.
nothing	firstKey ()
	Returns NOTHING.
nothing	firstValue ()
	Returns NOTHING.
bool	hasKey (softstring key)
	Returns True if the key exists in the hash (may or may not be assigned a value), False if not.
bool	hasKeyValue (softstring key)
	Returns True if the key exists and is assigned to a value, False if not.
SingleValueIterator	keyIterator ()
	Returns an empty SingleValueIterator object.
list< string >	keys ()
	Returns an empty list.
nothing	lastKey ()
	Returns NOTHING.
nothing	lastValue ()
	Returns NOTHING.
int	lsize ()
	Returns 0.
SingleValueIterator	pairIterator ()
	Returns an empty SingleValueIterator object.
SingleValueIterator	rangeIterator ()
	Returns an empty SingleValueIterator object.
int	typeCode ()
	Returns Qore::NT_NOTHING.
list< auto >	values ()
	Returns an empty list.
Public Member Methods inherited from <value>
bool	callp ()
	Returns False; this method is reimplemented in other types and will return True if the given expression is a callable value (ie closures or call references)
bool	complexType ()
	returns True if the value has a complex type, False if not
bool	empty ()
	Returns True; this method will be reimplemented in container types where it may return False.
string	fullType (__7_ bool with_namespaces)
	returns the full type name which differs from the simple type name in case of complex types and objects
bool	intp ()
	Returns False; this method is reimplemented in other types and will return True if the given expression can be converted to an integer.
AbstractIterator	iterator ()
	Returns an iterator object for the value; the default iterator object returned is SingleValueIterator.
int	lsize ()
	Returns 1; the return value of this method should give the list size of the value, which is normally 1 for non-lists (except for NOTHING where the size will be 0) and the number of the elements in the list for lists; this method will be reimplemented in other types where it may return other values.
int	size ()
	Returns zero; this method will be reimplemented in container types where it may return a non-zero value.
bool	sizep ()
	Returns True if the type can return a non-zero size (True for containers including binary objects and strings, False for everything else)
bool	strp ()
	Returns False; this method is reimplemented in other types and will return True if the given expression can be converted to a string.
bool	toBool ()
	Returns the boolean representation of the value; the default is False.
float	toFloat ()
	Returns the floating-point representation of the value; the default is 0.0.
int	toInt ()
	Returns the integer representation of the value; the default is 0.
number	toNumber ()
	Returns the arbitrary-precision numeric representation of the value; the default is 0.
string	toString (__7_ string encoding)
	Returns the string representation of the value; the default is an empty string.
string	type ()
	Returns the string type for the value.
int	typeCode ()
	Returns the type code for the value.
bool	val ()
	Returns False; this method is reimplemented in other types and will return True if the given expression has a non-empty value.

Detailed Description

Methods in this pseudo-class can be executed on NOTHING.

Member Function Documentation

contextIterator()

SingleValueIterator <nothing>::contextIterator

(

)

Returns an empty SingleValueIterator object.

Returns

an empty SingleValueIterator object

Code Flags:

CONSTANT

Example:

map printf("+ %y\n", $1), get_hash_or_nothing().contextIterator();

See also

<hash>::contextIterator()

Since

Qore 0.8.6.2

firstKey()

nothing <nothing>::firstKey

(

)

Returns NOTHING.

Returns

NOTHING

Code Flags:

CONSTANT

Example:

*hash h = hash_or_nothing();
*string n = h.firstKey();

See also

<hash>::firstKey()

Since

Qore 0.8.7

firstValue()

nothing <nothing>::firstValue

(

)

Returns NOTHING.

Returns

NOTHING

Code Flags:

CONSTANT

Example:

*hash h = hash_or_nothing();
auto n = h.firstValue();

See also

<hash>::firstValue()

Since

Qore 0.8.7

hasKey()

bool <nothing>::hasKey

(

softstring

key

)

Returns True if the key exists in the hash (may or may not be assigned a value), False if not.

Code Flags:

CONSTANT

Parameters

key	the key name to check

Returns

True if the key exists in the hash (may or may not be assigned a value), False if not

Example:

*hash h = hash_or_nothing();
bool b = h.hasKey(key);

See also

<hash>::hasKey(softstring)

Since

Qore 0.8.7

hasKeyValue()

bool <nothing>::hasKeyValue

(

softstring

key

)

Returns True if the key exists and is assigned to a value, False if not.

Code Flags:

CONSTANT

Parameters

key	the key name to check

Returns

True if the key exists and is assigned to a value, False if not

Example:

*hash h = hash_or_nothing();
bool b = h.hasKeyValue(key);

See also

<hash>::hasKeyValue(softstring)

Since

Qore 0.8.7

keyIterator()

SingleValueIterator <nothing>::keyIterator

(

)

Returns an empty SingleValueIterator object.

Returns

an empty SingleValueIterator object

Code Flags:

CONSTANT

Example:

map printf("+ %y\n", $1), get_hash_or_nothing().keyIterator();

See also

<hash>::keyIterator()

Since

Qore 0.8.6.2

keys()

list< string > <nothing>::keys

(

)

Returns an empty list.

Returns

an empty list

Code Flags:

CONSTANT

Example:

*hash h = hash_or_nothing();
list<string> l = h.keys();

See also

<hash>::keys()

Since

Qore 0.8.7

lastKey()

nothing <nothing>::lastKey

(

)

Returns NOTHING.

Returns

NOTHING

Code Flags:

CONSTANT

Example:

*hash h = hash_or_nothing();
*string n = h.firstKey();

See also

<hash>::firstKey()

Since

Qore 0.8.7

lastValue()

nothing <nothing>::lastValue

(

)

Returns NOTHING.

Returns

NOTHING

Code Flags:

CONSTANT

Example:

*hash h = hash_or_nothing();
auto n = h.firstValue();

See also

<hash>::lastValue()

Since

Qore 0.8.7

lsize()

int <nothing>::lsize

(

)

Returns 0.

Returns

0

Code Flags:

CONSTANT

Example:

printf("iterating %d element%s\n", val.lsize(), val.lsize() == 1 ? "" : "s");
foreach any element in (val) {
    do_something(element);
}

pairIterator()

SingleValueIterator <nothing>::pairIterator

(

)

Returns an empty SingleValueIterator object.

Returns

an empty SingleValueIterator object

Code Flags:

CONSTANT

Example:

map printf("+ %y\n", $1), get_hash_or_nothing().pairIterator();

Since

Qore 0.8.6.2

rangeIterator()

SingleValueIterator <nothing>::rangeIterator

(

)

Returns an empty SingleValueIterator object.

Returns

an empty SingleValueIterator object

Code Flags:

CONSTANT

Example:

map printf("+ %y\n", $1), get_list_or_nothing().rangeIterator();

See also

<list>::rangeIterator()

Since

Qore 0.8.8

typeCode()

int <nothing>::typeCode

(

)

Returns Qore::NT_NOTHING.

Returns

Qore::NT_NOTHING

Code Flags:

CONSTANT

Example:

switch (n.typeCode()) {
    case NT_NOTHING:
        printf("%y: no value\n", n);
        break;
}

values()

list< auto > <nothing>::values

(

)

Returns an empty list.

Returns

an empty list

Code Flags:

CONSTANT

Example:

*hash h = hash_or_nothing();
list<auto> l = h.values();

See also

<hash>::values()

Since

Qore 0.8.7