<hash> Class Reference

Methods in this pseudo-class can be executed on hash values. More...

#include <Pseudo_QC_Hash.dox.h>

Inheritance diagram for Qore::<hash>:

Public Member Methods
bool	compareKeys (hash< auto > oh)
	Returns True if the hash argument passed has the same keys in the same order as the current hash, False if not. More...
bool	complexType ()
	returns True if the hash has a complex type (Hashdecl: Type-Safe Hash Declarations or Hash With Declared Value Type), False if not More...
HashListIterator	contextIterator ()
	Returns a HashListIterator object for the hash. More...
bool	empty ()
	Returns True if the hash has no keys, False if it does. More...
*string	firstKey ()
	Returns the first key name in the hash or NOTHING if the hash has no keys. More...
auto	firstValue ()
	Returns the value assigned to the first key in the hash if any or NOTHING if the hash has no keys. More...
bool	hasKey (softstring key)
	Returns True if the key exists in the hash (may or may not be assigned a value), False if not. More...
bool	hasKeyValue (softstring key)
	Returns True if the key exists and is assigned to a value, False if not. More...
AbstractIterator	iterator ()
	Returns a HashIterator object for the hash. More...
HashKeyIterator	keyIterator ()
	Returns a HashKeyIterator object for the hash. More...
list< string >	keys ()
	Returns a list of key names of the hash. More...
*string	lastKey ()
	Returns the last key name in the hash or NOTHING if the hash has no keys. More...
auto	lastValue ()
	Returns the value assigned to the last key in the hash if any or NOTHING if the hash has no keys. More...
HashPairIterator	pairIterator ()
	Returns a HashPairIterator object for the hash. More...
int	size ()
	Returns the number of keys in the hash. More...
bool	sizep ()
	Returns True since hashes can return a non-zero size. More...
int	typeCode ()
	Returns Qore::NT_HASH. More...
bool	val ()
	Returns False if the hash has no keys, True if it does. More...
list< auto >	values ()
	Returns a list of values of the hash. More...
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) More...
bool	complexType ()
	returns True if the value has a complex type, False if not More...
bool	empty ()
	Returns True; this method will be reimplemented in container types where it may return False. More...
string	fullType (*bool with_namespaces)
	returns the full type name which differs from the simple type name in case of complex types and objects More...
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. More...
AbstractIterator	iterator ()
	Returns an iterator object for the value; the default iterator object returned is SingleValueIterator. More...
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. More...
int	size ()
	Returns zero; this method will be reimplemented in container types where it may return a non-zero value. More...
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) More...
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. More...
bool	toBool ()
	Returns the boolean representation of the value; the default is False. More...
float	toFloat ()
	Returns the floating-point representation of the value; the default is 0.0. More...
int	toInt ()
	Returns the integer representation of the value; the default is 0. More...
number	toNumber ()
	Returns the arbitrary-precision numeric representation of the value; the default is 0. More...
string	toString ()
	Returns the string representation of the value; the default is an empty string. More...
string	type ()
	Returns the string type for the value. More...
int	typeCode ()
	Returns the type code for the value. More...
bool	val ()
	Returns False; this method is reimplemented in other types and will return True if the given expression has a non-empty value. More...

Detailed Description

Methods in this pseudo-class can be executed on hash values.

Member Function Documentation

compareKeys()

bool <hash>::compareKeys

(

hash< auto >

oh

)

Returns True if the hash argument passed has the same keys in the same order as the current hash, False if not.

Code Flags:

CONSTANT

Example:

bool b = h.compareKeys(oh);

Values are not compraed, only the key names and order

Parameters

oh	a hash to compare the keys against

Returns

True if the hash argument passed has the same keys in the same order as the current hash, False if not

Since

Qore 0.8.8

complexType()

bool <hash>::complexType

(

)

returns True if the hash has a complex type (Hashdecl: Type-Safe Hash Declarations or Hash With Declared Value Type), False if not

Code Flags:

CONSTANT

Example:

bool b = n.complexType();

Returns

True if the hash has a complex type (Hashdecl: Type-Safe Hash Declarations or Hash With Declared Value Type), False if not

See also

• <value>::fullType()

Since

Qore 0.8.13

contextIterator()

HashListIterator <hash>::contextIterator

(

)

Returns a HashListIterator object for the hash.

Returns

a HashListIterator object for the hash

Code Flags:

CONSTANT

Example:

*hash<auto> q = db.select("select * from table_name");
map printf("+ %s\n", $1), h.contextIterator();

Note

• a hash with non-list values will be iterated as if each key value were a single element list
• this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)
• this pseudo-method is very useful when iterating query results from Datasource::select() or DatasourcePool::select() with the map operator, for example

Since

Qore 0.8.6.2

empty()

bool <hash>::empty

(

)

Returns True if the hash has no keys, False if it does.

Returns

True if the hash has no keys, False if it does

Code Flags:

CONSTANT

Example:

bool b = h.empty();

Note

this pseudo-method is also implemented in <value>, so it's safe to use on all data types

firstKey()

*string <hash>::firstKey

(

)

Returns the first key name in the hash or NOTHING if the hash has no keys.

Returns

the first key name in the hash or NOTHING if the hash has no keys

Code Flags:

CONSTANT

Example:

*string n = h.firstKey();

Note

this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)

See also

<hash>::lastKey()

firstValue()

auto <hash>::firstValue

(

)

Returns the value assigned to the first key in the hash if any or NOTHING if the hash has no keys.

Returns

the value assigned to the first key in the hash if any or NOTHING if the hash has no keys

Code Flags:

CONSTANT

Example:

auto v = h.firstValue();

Note

this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)

See also

<hash>::lastValue()

hasKey()

bool <hash>::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:

RET_VALUE_ONLY

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:

bool b = h.hasKey(key);

Note

this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)

See also

<hash>::hasKeyValue(softstring)

hasKeyValue()

bool <hash>::hasKeyValue

(

softstring

key

)

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

Code Flags:

RET_VALUE_ONLY

Parameters

key	the key name to check

Returns

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

Example:

bool b = h.hasKeyValue(key);

Note

this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)

See also

<hash>::hasKey(softstring)

iterator()

AbstractIterator <hash>::iterator

(

)

Returns a HashIterator object for the hash.

Returns

a HashIterator object for the hash

Code Flags:

CONSTANT

Example:

map printf("value: %y\n", $1), h.iterator();

Note

this pseudo-method is also implemented in <value>, so it's safe to use on all data types

Since

Qore 0.8.6

keyIterator()

HashKeyIterator <hash>::keyIterator

(

)

Returns a HashKeyIterator object for the hash.

Returns

a HashKeyIterator object for the hash

Code Flags:

CONSTANT

Example:

map printf("key: %s\n", $1), h.keyIterator();

Note

• this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)
• this pseudo-method is very useful when using a hash as a simulation for a set of strings and quickly iterating the hash with the map operator, for example

Since

Qore 0.8.6.2

keys()

list< string > <hash>::keys

(

)

Returns a list of key names of the hash.

Returns

a list of key names of the hash

Code Flags:

CONSTANT

Example:

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

Note

this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)

See also

<hash>::values()

lastKey()

*string <hash>::lastKey

(

)

Returns the last key name in the hash or NOTHING if the hash has no keys.

Returns

the last key name in the hash or NOTHING if the hash has no keys

Code Flags:

CONSTANT

Example:

*string n = h.lastKey();

Note

this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)

See also

<hash>::firstKey()

lastValue()

auto <hash>::lastValue

(

)

Returns the value assigned to the last key in the hash if any or NOTHING if the hash has no keys.

Returns

the value assigned to the last key in the hash if any or NOTHING if the hash has no keys

Code Flags:

CONSTANT

Example:

auto v = h.lastValue();

Note

this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)

See also

<hash>::firstValue()

pairIterator()

HashPairIterator <hash>::pairIterator

(

)

Returns a HashPairIterator object for the hash.

Returns

a HashPairIterator object for the hash

Code Flags:

CONSTANT

Example:

map printf("%s: %y\n", $1.key, $1.value), h.pairIterator());

Note

this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)

Since

Qore 0.8.6.2

size()

int <hash>::size

(

)

Returns the number of keys in the hash.

The opposite of <hash>::val()

Returns

the number of keys in the hash

Code Flags:

CONSTANT

Example:

int num = h.size();

Note

this pseudo-method is also implemented in <value>, so it's safe to use on all data types

See also

<hash>::sizep()

sizep()

bool <hash>::sizep

(

)

Returns True since hashes can return a non-zero size.

Code Flags:

CONSTANT

Returns

True since hashes can return a non-zero size

See also

<hash>::size()

Since

Qore 0.8.9

typeCode()

int <hash>::typeCode

(

)

Returns Qore::NT_HASH.

Returns

Qore::NT_HASH

Code Flags:

CONSTANT

Example:

switch (h.typeCode()) {
    case NT_HASH:
        printf("%y: is a hash\n", h);
        break;
}

Note

this pseudo-method is also implemented in <value>, so it's safe to use on all data types

val()

bool <hash>::val

(

)

Returns False if the hash has no keys, True if it does.

The opposite of <hash>::empty()

Returns

False if the hash has no keys, True if it does

Code Flags:

CONSTANT

Example:

bool b = h.val();

Note

this pseudo-method is also implemented in <value>, so it's safe to use on all data types

See also

• %perl-bool-eval
• %strict-bool-eval

values()

list< auto > <hash>::values

(

)

Returns a list of values of the hash.

Returns

a list of values of the hash

Code Flags:

CONSTANT

Example:

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

Note

• equivalent to hash_values()
• this pseudo-method is also implemented in <nothing>, so it's safe to use where the value could be a hash or NOTHING (ex: *hash)
• a hash with a declared value type will have a plain untyped list returned; this will be fixed in a future version of Qore

See also

<hash>::keys()