Operators

Table of Contents

• Backquote Operator (``)
• Hash Element or Object Member Expression Dereference Operator ({})
• Hash Element or Object Member Literal Dereference Operator (.)
• List, String, and Binary Dereference Operator ([])
• Pre-Increment Operator (++)
• Integer Post-Increment Operator (++)
• Integer Pre-Decrement Operator (--)
• Integer Post-Decrement Operator (--)
• New Object Operator (new)
• Background Operator (background)
• Delete Operator (delete)
• Remove Operator (remove)
• Cast Operator (cast<>())
• Logical Not Operator (!)
• Binary Not Operator (~)
• Unary Minus Operator (-)
• Shift Operator (shift)
• Pop Operator (pop)
• Chomp Operator (chomp)
• Trim Operator (trim)
• Map Operator (map)
• Fold Left Operator (foldl)
• Fold Right Operator (foldr)
• Select From List Operator (select)
• Elements Operator (elements)
• Keys Operator (keys)
• Multiply Operator (*)
• Divide Operator (/)
• Modula Operator (%)
• Plus (Addition and Concatentation) Operator (+)
• Minus Operator (-)
• Shift Right Operator (>>)
• Shift Left Operator (<<)
• Class Instance Operator (instanceof)
• Exists Operator (exists)
• Less Than Operator (<)
• Greater Than Operator (>)
• Equals Operator (==)
• Not Equals Operator (!=)
• Less Than Or Equals Operator (<=)
• Greater Than Or Equals Operator (>=)
• Comparison (<=>) Operator
• Absolute Equals Operator (===)
• Absolute Not Equals Operator (!==)
• Regular Expression Match Operator (=~)
• Regular Expression No Match Operator (!~)
• Regular Expression Substitution Operator
• Regular Expression Pattern Extraction Operator
• Transliteration Operator
• Bitwise/Binary And Operator (&)
• Bitwise/Binary Or Operator (|)
• Bitwise/Binary Xor Operator (^)
• Logical And Operator (&&)
• Logical Or Operator (||)
• Conditional Operator (? :)
• Comma Operator (,)
• Unshift Operator (unshift)
• Push Operator (push)
• Splice Operator (splice)
• Extract Operator (extract)
• Assignment Operator (=)
• Plus Equals Operator (+=)
• Minus Equals Operator (-=)
• And Equals Operator (&=)
• Or Equals Operator (|=)
• Modula Equals Operator (%=)
• Multiply Equals Operator (*=)
• Divide Equals Operator (/=)
• Xor Equals Operator (^=)
• Shift Left Equals Operator (<<=)
• Shift Right Equals Operator (>>=)

The following table lists all Qore operators in order of precedence, starting with the highest precedence. The lower the precedence number, the higher the precedence, therefore the operators with precedence level 1 ("{}", "[]", ".") have the highest precedence of all Qore operators. The precedence levels in Qore are roughly equal to the precedence levels of C language operators. To explicitly specify the precedence for expression evaluation, use parentheses ().

Operators

Operator	Prec.	Description	Example
``	1	backquote/backtick operator	`ls -l`
{}	1	hash element or object member expression dereference operator	$hash{"na" + "me"}
.	1	hash element or object member literal dereference operator	$hash.name $obj.method()
[]	1	list element, string, and binary dereference operator	$list[1]
++	2	pre-increment operator	++$a
++	2	post-increment operator	$a++
--	2	pre-decrement operator	--$a
--	2	post-decrement operator	$a--
new	3	class instantiation/new object operator	new Socket()
background	3	background/thread creation operator	background mainThread()
delete	3	delete operator	delete $var
remove	3	remove operator	remove $var
cast<>()	3	cast<>() operator	cast<SubClass>($var)
!	4	logical negation operator	if (!($a > 10)) {}
~	5	binary not/bit inversion operator	$var = ~$var
- (unary minus)	6	unary minus operator	$var = -$var
shift	7	shift list element operator	shift $list
pop	7	pop list element operator	pop $list
chomp	7	chomp end-of-line character operator	chomp $string
trim	7	trim characters operator	trim $string
elements	8	number of elements operator (list, hash, string, binary)	elements $list
keys	8	hash key list operator	keys $hash
*	9	multiplication operator	$var = $a * 10
/	9	division operator	$var = $a / 10
%	10	modula operator	$var = $a % 10
+	11	plus operator: string, binary, list, and hash concatenation, integer and float addition	$a + 10 "hello" + "there" $list + "new value" $hash + ( "newkey" : 100 )
-	11	minus operator (arithmetic subtraction, hash key removal)	$a - 10
>>	12	bitwise shift right operator	0xff00 >> 8
<<	12	bitwise shift left operator	0xff00 << 8
exists	13	exists value operator	exists $var
instanceof	13	instanceof class operator	instanceof Qore::Mutex
<	14	Logical less than operator	$a < 10
>	14	Logical greater than operator	$a > 10
==	14	Logical equality operator	$a == 10
!=	14	logical inequality operator	$a != 10
<=	14	Logical less then or equals operator	$a <= 10
>=	14	logical greater than or equals operator	$a >= 10
<=>	14	logical comparison operator	$a <=> $b
===	14	absolute logical equality operator	$a === 10
!==	14	absolute logical inequality operator	$a !== 10
=~ //	14	regular expression match operator	$a =~ /text/
!~ //	14	regular expression no match operator	$a !~ /text/
=~ s///	14	regular expression substitution operator	$a =~ s/text/text/
=~ x//	14	regular expression pattern extraction operator	$a =~ x/(\w+):(\w+)/
=~ tr	14	transliteration operator	$a =~ tr/a-z/A-Z/
&	15	bitwise/binary AND operator	$a & 0xff
|	15	bitwise/binary OR operator	$a | 0xff
^	15	bitwise/binary XOR operator	$a ^ 0xff
&&	16	logical AND operator	($a = 1) && ($b < 10)
||	16	logical OR operator	($a = 1) || ($b < 10)
? :	17	conditional operator	$a == 2 ? "yes" : "no"
,	18	comma operator	1, 2, 3, 4, 5
unshift	19	unshift list element operator	unshift $list, $val
push	19	push list element operator	push $list, $val
splice	19	splice list or string operator	splice $list, 2, 2, (1, 2, 3)
extract	19	extract list or string operator	my $sublist = extract $list, 2, 2, (1, 2, 3)
map	19	map operator	map $closure($1), $list
foldl	19	fold left to right operator	foldl $closure($1 - $2), $list
foldr	19	fold right to left operator	foldr $closure($1 - $2), $list
select	19	select elements from list operator	select $list, $1 > 1
=	20	assignment operator	$var = 1
+=	21	plus-equals (add-to) operator	$var += 5
-=	21	minus-equals (subtract-from) operator	$var -= 5
&=	21	and-equals operator	$var &= 0x2000
|=	21	or-equals operator	$var |= 0x2000
%=	21	modula-equals operator	$var %= 100
*=	21	multiply-equals operator	$var *= 10
/=	21	divide-equals operator	$var /= 10
^=	21	xor-equals operator	$var ^= 0x2000
<<=	21	shift-left-equals operator	$var <<= 0x2000
>>=	21	shift-right-equals operator	$var >>= 0x2000

Note

All Qore operators perform thread-atomic actions with respect to the immediate arguments of the operator. If the operators are used in a complex expression, the entire expression is not thread-atomic unless explicit user-level locking is used. For example: $a += 5 is a thread-atomic action, but $a += $b– is not atomic, but rather made up of two atomic actions.

When an operator taking more than one argument is used with arguments of different data types, Qore automatically converts one or both data types to a data type supported by the operator in order to evaluate the result, according to the precedence lists given for each operator. That is; when an operator operates on mixed types, the types listed first in the following sections have precedence over types listed farther down in the lists. The result type will always be equal to the final operation type after any conversions due to type precedence per operator. If no type of either argument matches a supported data type for the operator, both types will be converted to the highest precedence data type for the operator and then the operator will evaluate the result. For explicit type conversion, please see the boolean(), string(), date(), int(), float(), etc functions.

---

Backquote Operator (``)

Synopsis

Executes the shell command in a separate process and returns the stdout as a string. To perform the same action using a Qore expression, see the backquote() function.

Syntax

`shell_command`

Return Type

string

Example

my string $dir = `ls -l`

Arguments Processed by ``

Argument	Returns	Processing
unquoted string shell_command	string	The shell command will be executed and the stdout is returned as a string

Exceptions

BACKQUOTE-ERROR

An error occurred in fork() or creating the output pipe

---

Hash Element or Object Member Expression Dereference Operator ({})

Synopsis

Retrieves the value of hash key or object member by evaulating an expression.

Syntax

container_expression { expression }

Return Type

any

Example

printf("%s\n", $hash{getName()});

Arguments Processed by {}

Argument	Processing
container_expression	This expression must evaluate to a hash or an object; if not, the operator returns no value (NOTHING)
expression	- list: if the expression evaluates to a list, then a slice of the hash or object is returned as a hash containing keys given in the list that are present in the hash or object. If the key as given in the list (converted to a string if necessary) is not present in the hash or object, then it is also not present in the hash returned; of none of the given keys exist in the hash, an empty hash is returned. - anything other than list: the expression is converted to a string (if necessary); the value of the hash key corresponding to this string will be returned; if the key or member does not exist, then no value is returned

Exceptions

PRIVATE-MEMBER

Attempt to access a private member outside the class

---

Hash Element or Object Member Literal Dereference Operator (.)

Synopsis

Retrieves the value of a hash key or object member using a literal identifier or an expression.

Syntax

hash_or_object_expression . identifier
object_expression . method_name([args ...])
hash_or_object_expression . expression

Return Type

any

Example

printf("%s\n", $hash.name);

$obj.method("argument");

Arguments Processed by . (hash key or object member literal dereference)

Argument	Processing
hash_or_object_expression	This expression must evaluate to a hash or an object; if not, then the operator returns no value
identifier	An unquoted string taken as the literal name of the hash key or object member. If no such key exists, then no value is returned. In order to use hash keys that are not valid Qore identifiers, please use the {} operator. If the member is a private member and access is made outside the class, a run-time exception will be thrown. Also note that constants or static class member names will not be resolved, in this case the string given is used as the literal name of the hash key or object member

Arguments Processed by . (object method call)

Argument	Processing
object_expression	The object_expression must evaluate to an object or a run-time exception is thrown
method_name([args])	If the method does not exist in the class a run-time exception is thrown. Otherwise the method is called with any optional arguments given and the return value of the method is returned.

Arguments Processed by . (hash key or object member expression dereference)

Argument	Processing
hash_or_object_expression	This expression must evaluate to a hash or an object; if not, then the operator returns no value
expression	- list: if the expression evaluates to a list, then a slice of the hash or object is returned as a hash containing keys given in the list that are present in the hash or object. If the key as given in the list (converted to a string if necessary) is not present in the hash or object, then it is also not present in the hash returned; of none of the given keys exist in the hash, an empty hash is returned. - anything other than list: the expression is converted to a string (if necessary); the value of the hash key corresponding to this string will be returned; if the key or member does not exist, then no value is returned

Exceptions

PRIVATE-MEMBER	Attempt to access a private member outside the class
METHOD-DOES-NOT-EXIST	Attempt to access a method not defined for this class
METHOD-IS-PRIVATE	Attempt to access a private method from outside the class
BASE-CLASS-IS-PRIVATE	Attempt to access a method of a privately-inherited base class from outside the class
OBJECT-METHOD-EVAL-ON-NON-OBJECT	Attempt to execute a method on a non-object

---

List, String, and Binary Dereference Operator ([])

Synopsis

Retrieves the value of a list element, the given character of a string, or the integer value of a byte for a binary object. If the index value is not valid for the argument, NOTHING is returned. Note that this operator only works as a list dereferencing operator in lvalue expressions; you cannot assign a character or a byte value to strings or binaries using this operator.

Syntax

list_expression[offset_expression] string_expression[offset_expression] binary_expression[offset_expression]

Return Type

any

Example

printf("%s\n", $list[2]);

printf("%s\n", $str[2]);

printf("0x%x\n", $binary[2]);

Arguments Processed by []

Argument	Processing
list_expression	If the expression evaluates to a list, then the offset_expression will be used to return the given element from the list
string_expression	If the expression evaluates to a string, then the offset_expression will be used to return the given character from the list; note that multi-byte characters with UTF-8 are properly respected with this operator
binary_expression	If the expression evaluates to a binary, then the offset_expression will be used to return the integer value of the byte given from the binary object
offset_expression	The expression is evaluated and converted to an integer if necessary. Then the value of the given element given is returned according to the type of the first expression (as listed above; elements start at position 0)

This operator does not throw any exceptions; if the first expression does not evaluate to either a list, string, or binary, then no value (NOTHING) is returned.

---

Pre-Increment Operator (++)

Synopsis

Increments an lvalue and returns the incremented value; only works on integer and floating-point values.

Syntax

++lvalue

Return Type

int or float

Example

++$i;

Arguments Processed by ++ (pre-increement)

Argument	Processing
Float	increments lvalue and returns the result
Integer (or any other type)	First converts the value of lvalue to an integer if necessary, then increments lvalue and returns the result

This operator does not throw any exceptions.

---

Integer Post-Increment Operator (++)

Synopsis

Increments an integer or floating-point lvalue and returns the value before the increment; if the lvalue is neither a floating-point value or an integer, it will be converted to an integer

Syntax

lvalue++

Return Type

any

Example

$i++;

Arguments Processed by ++ (post-increment)

Argument	Processing
Float	saves the value of the lvalue as the result, then increments lvalue, then returns the saved original value of lvalue
Integer (or any other type)	saves the value of the lvalue as the result, then converts the value of lvalue to an integer if necessary and increments it, then returns the saved original value of lvalue

This operator does not throw any exceptions.

---

Integer Pre-Decrement Operator (--)

Synopsis

Decrements an lvalue and returns the incremented value; only works on integer and floating-point values.

Syntax

–lvalue

Return Type

int or float

Example

--$i;

Arguments Processed by – (pre-decrement)

Argument	Processing
Float	increments lvalue and returns the result
Integer (or any other type)	First converts the value of lvalue to an integer if necessary, then increments lvalue and returns the result

This operator does not throw any exceptions.

---

Integer Post-Decrement Operator (--)

Synopsis

Decrements an integer or floating-point lvalue and returns the value before the decrement; if the lvalue is neither a floating-point value or an integer, it will be converted to an integer

Syntax

lvalue–

Return Type

any

Example

$i–;

Arguments Processed by – (post-decrement)

Argument	Processing
Float	saves the value of the lvalue as the result, then decrements lvalue, then returns the saved original value of lvalue
Integer (or any other type)	saves the value of the lvalue as the result, then converts the value of lvalue to an integer if necessary and decrements it, then returns the saved original value of lvalue

This operator does not throw any exceptions.

---

New Object Operator (new)

Synopsis

Creates an instance of a class by running the class' constructor on the new class (if any exists) and returns the new object.

Note that if possible it is normally better to declare an object with its type and use the abbreviated form to construct the object as follows:

my Mutex $m();

This provides type information to the parser which allows more errors to be caught at parse time (instead of at run time), and furthermore allows Qore to improve performance by performing more work once at parse time rather than for every time the object is accessed at run time (for example, method and variant resolution), and normally requires less typing.

Syntax

new class_identifier(constructor_args ...)

Return Type

an object of the specific class given

Example

my Mutex $obj = new Qore::Mutex();

Arguments Processed by new

Argument

Processing

class_identifier

The class_identifier must be an existing class name; if so, the operator instantiates an object of this class, executes the constructor for the class (if any exists, along with any base class constructors, if applicable) on the new object, and returns the object (for constructor execution order in an inherited class, see Class Inheritance). If an exception is thrown in the constructor, the object is deleted immediately.

Note

See class documentation for possible exceptions

---

Background Operator (background)

Synopsis

Start a background thread and return the TID (thread ID).

Note

• expressions that have no effect cannot be used with the background operator (a parse exception will be thrown)
• it is illegal to make changes to a local variable anywhere in a background expression (a parse exception will be thrown)
• local variables and find expressions are evaluated before the new thread is started and the result of the evaluation is used in the expression in the new thread
• it is not possible to pass local variables by reference anywhere in a background expression (a parse exception will be thrown)

Syntax

background expression

Return Type

int

Example

my int $tid = background startThread();

Arguments Processed by background

Argument	Processing
expression	The expression given as an argument will be executed in a new thread. The TID of the new thread will be returned as the return value of the operator

Exceptions

THREAD-CREATION-FAILURE

If the thread table is full or if the operating system returns an error while starting the thread, this exception is thrown

---

Delete Operator (delete)

Synopsis

The delete operator deletes the contents of an lvalue. If the delete operator is called on an object, the object will be destroyed unconditionally. The delete operator does not return any value.

When called on a hash key, the key is removed from the hash entirely; when called on a list element, the element is assigned NOTHING (i.e. the list size does not change).

The delete operator will delete multiple keys from a hash (i.e. delete a slice from a hash) when called on a hash dereferenced by a list of strings, giving the keys to delete (see example below).

In the case the delete operator operates on an object, any exception can be thrown that is thrown by the class' destructor.

For a similar operator that returns the value that is removed from the data structure, and does not delete objects, see the remove operator.

Syntax

delete lvalue_expression

Return Type

Does not return any value

Example

# delete a single key from a hash
delete $value;
# delete multiple values from a hash
delete $h.("a", "b", "c");

This operator does not throw any exceptions, however exceptions could be thrown in an object's destructor method when deleted by this operator.

---

Remove Operator (remove)

Synopsis

The remove operator removes a value from a data structure, or, in the case the operand of the remove operator is a simple value, the value itself is removed from the variable and returned. The remove operator returns the value removed from the lvalue.

When called on a hash key, the key is removed from the hash entirely, and the value returned is the value of the key removed from the hash; when called on a list element, the element is assigned NOTHING (i.e. the list size does not change).

The remove operator will remove and return a slice from a hash when called on a hash dereferenced by a list of strings, giving the keys to remove (see example below).

The remove operator does not call destructors when operating on objects, but if removing an object from an lvalue or from a data structure within the lvalue causes the object to go out of scope, it will be destroyed, and then its destructor could throw an exception.

For a similar operator that deletes the value that is removed from the data structure, see the delete operator.

Syntax

remove lvalue_expression

Return Type

any

Example

# remove a single value from a hash
my any $var = remove $hash.value;
# remove a slice from a hash
my hash $nh = remove $h.("a", "b", "c");

This operator does not throw any exceptions, however exception could be thrown in an object's destructor if it goes out of scope due to the action of this operator.

---

Cast Operator (cast<>())

Synopsis

The cast<>() operator provides a way to tell the parser that the type of object is not actually the declared type but rather a subclass as given between the angle brackets.

Syntax

cast<class_identifier>(object_expression)

Return Type

the specific class given

Example

cast<SubClass>($obj).method();

Arguments Processed by cast<>()

Argument	Processing
class_identifier	This must be a literal unquoted string giving a class name or a namespace-qualified path to a class (ex: Namespace::MyClass)
object_expression	This must be an expression that evaluates to an object that can be cast to the given class; this is mostly useful at parse time to avoid non-existent-method-call warnings

Exceptions

RUNTIME-CAST-ERROR

The expression given does not evaluate to an object that can be cast to the given class

---

Logical Not Operator (!)

Synopsis

Reverses the logical sense of an expression (True becomes False and False becomes True).

Syntax

!expression

Return Type

bool

Example

if (!exists $error_code)
    do_something();

Arguments Processed by !

Argument	Processing
expression	The expression is evaluated and converted to a bool, if necessary. Then the value is logically reversed (True becomes False, False becomes True)

This operator does not throw any exceptions.

---

Binary Not Operator (~)

Synopsis

The value of each bit in an integer is reversed (0 becomes 1, 1 becomes 0).

Syntax

~expression

Return Type

int

Example

$a = ~$b;

Arguments Processed by ~

Argument	Processing
expression	The argument is converted to an integer (if necessary), and bitwise negation is performed on the argument (ex: 666 & ~27 results in 640)

This operator does not throw any exceptions

---

Unary Minus Operator (-)

Synopsis

Changes the sign of numeric values.

Syntax

-expression

Return Type

int or float

Example

$a = -$b;

Arguments Processed by - (unary minus)

Argument	Processing
Float	Gives the negative of its argument as a Float (ex: -(-1.1) = 1.1, -(1.1) = -1.1
Integer	Gives the negative of its argument as an Integer (ex: -(-1) = 1, -(1) = -1

This operator does not throw any exceptions

---

Shift Operator (shift)

Synopsis

Removes the first element from a list and returns that element.

Syntax

shift lvalue

Return Type

any

Example

my *string $a = shift $ARGV;

Arguments Processed by shift

Argument	Processing
lvalue	Returns the first element of the list, and the list is modified by having the first element removed from the list. If the lvalue is not a list, no action is performed and the operator returns no value (NOTHING)

This operator does not throw any exceptions.

---

Pop Operator (pop)

Synopsis

Removes the last element from a list and returns that element.

Syntax

pop lvalue

Return Type

any

Example

$a = pop $list;

Arguments Processed by pop

Argument	Processing
lvalue	Returns the last element of the list, and the list is modified, having the last element removed from the list. If the lvalue is not a list, no action is performed and the operator returns no value (NOTHING)

This operator does not throw any exceptions.

---

Chomp Operator (chomp)

Synopsis

Removes the end-of-line marker(s) ('\n' or '\r\n') from a string, or each string element in a list, or each hash key value in a hash (if the value is a string) and returns the number of characters removed.

To perform this operation on a non-lvalue expression, see the chomp() function.

Syntax

chomplvalue

Return Type

int

Example

chomp $str;

Arguments Processed by chomp

Argument	Processing
lvalue (String)	Removes any EOL characters from a string and returns the number of characters removed.
lvalue (List)	Removes any EOL characters from each string element of the list passed and returns the number of characters removed.
lvalue (Hash)	Removes any EOL characters from each hash key's value (where the value is a string) and returns the number of characters removed.

This operator does not throw any exceptions.

---

Trim Operator (trim)

Synopsis

Removes whitespace characters from the beginning and end of a string, or each string element in a list, or each hash key value in a hash (if the value is a string) and returns the value processed (string, list, or hash).

To perform this operation on a non-lvalue expression, see the trim() function.

The following whitespace characters are removed from the beginning and end of strings: ' ' (blank spaces), '\n', '\r', '\t', '\v' (vertical tab, ASCII 11), and '\0' (null character).

Syntax

trim lvalue

Return Type

string, list, or hash

Example

trim $str;

Arguments Processed by trim

Argument	Processing
lvalue (String)	Removes whitespace characters from the beginning and end of a string and returns the value processed.
lvalue (List)	Removes whitespace characters from the beginning and end of each string element of the list passed and returns the list.
lvalue (Hash)	Removes whitespace characters from the beginning and end of each string value of the hash passed and returns the hash.

This operator does not throw any exceptions.

---

Map Operator (map)

Synopsis

Executes (or maps) an expression on a list and returns the result. An optional select expression can be given to filter elements out from the result list.

If the second argument (list_expression) is an object inheriting the AbstractIterator class, the map operator iterates the object by calling AbstractIterator::next(), and the implicit argument $1 in the map_expression and any optional select_expression is the value returned by AbstractIterator::getValue().

If the second argument is not a list or an object inheriting AbstractIterator, then map_expression is executed on the single value and the result is returned, and any select_expression is ignored.

Return Type

any

Syntax

map map_expression, list_expression [, select_expression]

Examples

# returns (2, 4, 6)
my list $l = map $1 * 2, (1, 2, 3);

# prints out the keys of a hash; one to a line
map printf("%s\n", $1), $hash.keyIterator();

Arguments Processed by map

Argument	Processing
map_expression	The expression to map on the list; the implicit argument $1 represents the current element being processed (or the object itself if the map operator is iterating an object inheriting the AbstractIterator class).
list_expression	The data to process; if this is not a list then the map_expression is run on the single argument passed, unless the map_expression is an object inheriting the AbstractIterator class; in this case the map operator iterates the object by calling AbstractIterator::next()
[select_expression]	An optional expression than can be used to filter out elements of the list before the map expression is applied; if this expression evaluates to False on an element, then the element will be skipped and the map_expression will not be applied on that element.

This operator does not throw any exceptions (however note that exceptions could be thrown by expressions executed by this operator).

Since

Qore 0.8.6.2 the map operator when used with an AbstractIterator object instantiates the value returned by AbstractIterator::getValue() instead of the iterator itself

---

Fold Left Operator (foldl)

Synopsis

Folds an operation on a list from left to right and returns the result. The result of each individual operation is used as the first argument in the foldl expression for the next element in the list. The first operation of the fold is made by executing the fold expression on the first and second elements of the list, from this point onwards, the result of each successive operation is used as the first argument for the next operation, the second argument being the next element in the list.

If the second argument (list_expression) is an object inheriting the AbstractIterator class, the foldl operator iterates the object by calling AbstractIterator::next(), and the implicit arguments $1 and $2 in expression are the container values returned by AbstractBidirectionalIterator::getValue(). If the list_expression does not evaluate to a list or an object inheriting AbstractIterator, then the evaluated argument is returned immediately with no processing by the fold expression.

Syntax

foldl expression, list_expression

Return Type

any

Examples

The following returns foldl expression returns 5

my int $result = foldl $1 - $2, (10, 4, 1);

The following foldl expression joins a list with ", " or returns a single argument (if the second operand is not a list)

my string $str = foldl $1 + ", " + $2, $list;

Arguments Processed by foldl

Argument	Processing
expression	The expression to fold on the list; the implicit argument $1 represents the result of the last operation (or the first element in the list when beginning the fold), and $2 represents the next element of the list.
list_expression	The list, AbstractIterator object or other value according to the rules above to process

This operator does not throw any exceptions (however note that exceptions could be thrown by expressions executed by this operator).

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Fold Right Operator (foldr)

Synopsis

Folds an operation on a list from right to left and returns the result. The result of each individual operation is used as the first argument in the foldr expression for the next element in the list in reverse order. The first operation of the right fold is made by executing the fold expression on the last and penultimate elements of the list, from this point onwards, the result of each successive operation is used as the first argument for the next operation, the second argument being the next element in the list in reverse order.

If the second argument (list_expression) is an object inheriting the AbstractBidirectionalIterator class, the foldr operator iterates the object by calling AbstractBidirectionalIterator::prev(), and the implicit arguments $1 and $2 in expression are the container values returned by AbstractBidirectionalIterator::getValue(). If the list_expression does not evaluate to a list or an object inheriting AbstractBidirectionalIterator, then the evaluated argument is returned immediately with no processing by the fold expression.

Syntax

foldr expression, list_expression

Return Type

any

Example

# returns -13
foldr $1 - $2, (10, 4, 1);

Arguments Processed by foldr

Argument	Processing
expression	The expression to fold on the list; the implicit argument $1 represents the result of the last operation (or the last element in the list when beginning the fold), and $2 represents the next element of the list in reverse order.
list_expression	The list, AbstractIterator object or other value according to the rules above to process

This operator does not throw any exceptions (however note that exceptions could be thrown by expressions executed by this operator).

---

Select From List Operator (select)

Synopsis

Selects elements from a list that meet the given criteria and returns the new list.

If the first argument (list_expression) is an object inheriting the AbstractIterator class, the select operator iterates the object by calling AbstractIterator::next(), and the implicit argument $1 in expression is the value returned by AbstractIterator::getValue(); in this case the operator always returns a list (which may be empty if expression returns False for all elements in the iterator object or if the iterator object is empty), and the value of the object in the list returned is the value returned by AbstractIterator::getValue().

If the list expression does not evaluate to a list or an object inheriting AbstractIterator, then the select expression is evaluated using the value of the list expression as an argument, if it evalutes to true, then the value is returned, otherwise, no value is returned.

Syntax

select list_expression, expression

Return Type

any

Example

# returns (2, 4, 6)
select (1, 2, 3, 4, 5, 6), !($1 % 2);

Arguments Processed by select

Argument	Processing
list_expression	The list to process or an object inheriting AbstractIterator
expression	The expression will be evaluated on each element of the list, the implicit argument $1 represents current element of the list (or the iterator object itself when list_expression is an object inheriting AbstractIterator); only if the expression evaluates to True will the element appear in the result list

This operator does not throw any exceptions (however note that exceptions could be thrown by the expression executed by this operator).

Since

Qore 0.8.6.2 the map operator when used with an AbstractIterator object instantiates the value returned by AbstractIterator::getValue() instead of the iterator itself

---

Elements Operator (elements)

Synopsis

Returns the number of elements in a list, the number of keys in a hash, the number of characters (not bytes) in a string, or the number of bytes in a binary object.

Syntax

elements expression

Return Type

int

Example

my int $size = elements $list;

Arguments Processed by elements

Argument	Processing
expression list	Returns the number of elements in the list
expression hash	Returns the number of keys in the hash
expression string	Returns the number of characters in the string (which may be different than the number of bytes for multi-byte character encodings such as UTF-8
expression binary	Returns the number of bytes in the binary object

This operator does not throw any exceptions.

See also

<value>::size()

---

Keys Operator (keys)

Synopsis

Returns a list representing the keys in a hash.

Syntax

keys hash_expression

Return Type

list or NOTHING

Example

foreach my string $key in (keys $hash)
    printf("%s = %s\n", $key, $hash.$key);

Arguments Processed by keys

Argument	Processing
hash_expression	Returns a list of strings giving the keys in hash_expression, which must evaluate to a hash. If not, then no value is returned.

This operator does not throw any exceptions.

See also

• <hash>::keys()
• <object>::keys()

---

Multiply Operator (*)

Synopsis

Multiplies two arguments.

Syntax

expression1 * expression2

Return Type

int, float, or number

Example

$value = $x * $y;

Arguments Processed by * (in order of precedence)

Argument	Processing
number	Gives the result of multiplying its arguments; ints and floats are converted to numbers if at least one of the arguments is a number
float	Gives the result of multiplying its arguments; ints are converted to floats if at least one of the arguments is a float
int	Gives the result of multiplying its arguments
any other type	Converts argument to a number and performs the multiplication

This operator does not throw any exceptions.

---

Divide Operator (/)

Synopsis

Divides a number by another.

Syntax

expression1 / expression2

Return Type

int, float, or number

Example

$value = $x / $y;

Arguments Processed by / (in order of precedence)

Argument	Processing
number	Gives the result of dividing its arguments; ints and floats are converted to numbers if at least one of the arguments is a number
float	Gives the result of dividing its arguments; ints are converted to floats if at least one of the arguments is a float
int	Gives the result of dividing its arguments
any other type	Converts argument to a number and performs the division

Exceptions

DIVISION-BY-ZERO

division by zero error

---

Modula Operator (%)

Synopsis

Gives the integer remainder after division of one number by another.

Syntax

expression1 % expression2

Return Type

int

Example

$mod = $x % $y;

Arguments Processed by %

Argument	Processing
int	Gives expression1 modula expression2 (ex: 12 % 10 result in 2). Arguments are converted to integers if necessary.

This operator does not throw any exceptions.

---

Plus (Addition and Concatentation) Operator (+)

Synopsis

Numeric addition, list, string, binary, and hash concatenation operator.

Syntax

expression1 + expression2

Return Type

int, float, number, date, list, string, binary, or hash

Example

$a = 1 + 2;

$string = "hello" + "-there";

$list = (1, 2) + ("three", "four", "five");

$hash = ( "key1" : 1, "key2" : 2) + ( "key3" : "three", "key4": "four");

$bin = $bin1 + $bin2;

Arguments Processed by + (in order of precedence)

Argument	Processing
list list	Gives the result of concatenating its arguments, i.e. (1, 2) + (3, 4) = (1, 2, 3, 4)
string	Gives the result of concatenating its arguments
date	Gives the result of adding date/time values (see Date/Time Arithmetic)
number	Gives the result of adding its arguments
float	Gives the result of adding its arguments
int	Gives the result of adding its arguments
hash	Gives the result of concatenating/merging its arguments. Any common keys will be overwritten by the values in the second hash (expression2)

This operator does not throw any exceptions.

---

Minus Operator (-)

Synopsis

With float, integer, or number arguments, subtracts one number from another.

With date arguments, subtracts one date from another; if both date arguments are absolute dates, the result is a relative date (duration) giving the time between them; if the first date argument is an absolute date and the second is a relative date (duration), then the result is an absolute date. If both date arguments are relative dates, then the result is a relative date. If the first argument is a relative date and the second date is an absolute date, the result is an absolute date as if the operands were reversed.

However, if the left-hand side is a hash, and the right-hand side is a string, then the hash key represented by the string will be removed from the hash. If the left-hand side is a hash and the right-hand side is a list, then each element in the list will be converted to a string and any hash key with that name will be deleted from the hash.

Syntax

expression1 - expression2

Return Type

int, float, number, date, or hash

Example

$num = $x - $y;

$date = 2010-05-13 - P3MT14H10M;

$hash = $hash - "key";

$hash = $hash - ("key1", "key2", "key3");

Arguments Processed by - (in order of precedence)

Argument	Processing
date	date subtraction: expression1 - expression2
number	arithmetic subtraction: expression1 - expression2
float	arithmetic subtraction: expression1 - expression2
int	arithmetic subtraction: expression1 - expression2
hash - string	hash key deletion: expression1 - expression2
hash - list	hash key deletion: expression1 - expression2; all elements of the list are converted to strings (if necessary) and any keys with those names are deleted from the hash.

This operator does not throw any exceptions.

---

Shift Right Operator (>>)

Synopsis

Shifts bits in an integer towards zero (divides an integer by a power of 2)

Syntax

expression1 >> expression2

Return Type

int

Example

$a = $x >> $y;

Arguments Processed by >>

Argument	Processing
int	Gives the result of shifting expression1 right by expression2 bits. Arguments are converted to integers if necesssary.

This operator does not throw any exceptions.

---

Shift Left Operator (<<)

Synopsis

Shifts bits in an integer towards infinity (multiplies an integer by a power of 2)

Syntax

expression1 << expression2

Return Type

int

Example

$a = $x << $y;

Arguments Processed by <<

Argument	Processing
int	Gives the result of shifting expression1 left by expression2 bits. Arguments are converted to integers if necessary.

This operator does not throw any exceptions.

---

Class Instance Operator (instanceof)

Synopsis

Tests if an expression is an instance of a given class or not.

Syntax

expression instanceof class_identifier

Return Type

bool

Example

if ($obj instanceof Qore::Mutex)
    print("object is Mutex\n");

Arguments Processed by instanceof

Argument	Processing
expression	If expression is an instance of the named class, then the operator returns True, otherwise returns False. The operator will return True if the class is a base class, also even if it is privately inherited.

This operator does not throw any exceptions.

---

Exists Operator (exists)

Synopsis

Tests if an expression represents a value or not.

Syntax

exists expression

Return Type

bool

Example

if (exists $a)
    printf("a = $n\n", $a);

Arguments Processed by exists

Argument	Processing
expression	If expression evaluates to a value, then the operator returns True, otherwise returns False.

This operator does not throw any exceptions.

---

Less Than Operator (<)

Synopsis

Tests if a value is less than another; types are converted if necessary (ex: ("1" < 2) is True).

Syntax

expression1 < expression2

Return Type

bool

Example

if ($x < $y)
    printf("%n is less than %n\n", $x, $y);

Arguments Processed by < (in order of precedence)

Argument	Processing
number	If expression1 is numerically less than expression2, returns True, otherwise returns False
float	If expression1 is numerically less than expression2, returns True, otherwise returns False
int	If expression1 is numerically less than expression2, returns True, otherwise returns False
string	If expression1 comes before expression2 in string sort order, returns True, otherwise returns False
date	If expression1 is before (or a shorter amount of time than of the arguments are Relative Date/Time Values (Durations)) expression2, returns True, otherwise returns False

This operator does not throw any exceptions.

---

Greater Than Operator (>)

Synopsis

Tests if a value is greater than another; types are converted if necessary (ex: ("2" > 1) is True).

Syntax

expression1 > expression2

Return Type

bool

Example

if ($x > $y)
    printf("%n is less than %n\n", $x, $y);

Arguments Processed by > (in order of precedence)

Argument	Processing
number	If expression1 is numerically greater than expression2, returns True, otherwise returns False
float	If expression1 is numerically greater than expression2, returns True, otherwise returns False
int	If expression1 is numerically greater than expression2, returns True, otherwise returns False
string	If expression1 comes after expression2 in string sort order, returns True, otherwise returns False
date	If expression1 is after expression2, returns True, otherwise returns False

This operator does not throw any exceptions.

---

Equals Operator (==)

Synopsis

Tests if a value is equal to another; types are converted if necessary (ex: ("1" == 1) is True). For absolute equals, where types must also be equal to return true, see the Absolute Equals Operator (===).

Syntax

expression1 == expression2

Return Type

bool

Example

if ($x == $y)
    printf("%n is equal to %n\n", $x, $y);

Arguments Processed by == (in order of precedence)

Argument	Processing
string	If expression1 is equal to expression2, returns True, otherwise False
number	If expression1 is equal to expression2, returns True, otherwise False
float	If expression1 is equal to expression2, returns True, otherwise False
int	If expression1 is equal to expression2, returns True, otherwise False
date	If expression1 is equal to expression2, returns True, otherwise False
list	If each element in the each list where order is relevant satisfies this operator, the operator returns True, otherwise it returns False
hash	If each hash has the same keys and the value of each equal key in each hash satisfies this operator, the operator returns True, otherwise it returns False
binary	If expression1's memory contents and size are equal to expression2's, then returns True, otherwise False
object	If expression1 is a reference to the same object as expression2, then returns True, otherwise False
NULL	If both expressions are NULL, returns True, otherwise returns False
NOTHING	If neither expression has a value, returns True, otherwise returns False

This operator does not throw any exceptions.

---

Not Equals Operator (!=)

Synopsis

Tests if a value is not equal to another; types are converted if necessary (ex: ("1" != 1) is False).

Syntax

expression1 != expression2

Return Type

bool

Example

if ($x != $y)
    printf("%n is not equal to %n\n", $x, $y);

Arguments Processed by != (in order of precedence)

Argument	Processing
string	If expression1 is not equal to expression2, returns True, otherwise False
number	If expression1 is not equal to expression2, returns True, otherwise False
float	If expression1 is not equal to expression2, returns True, otherwise False
int	If expression1 is not equal to expression2, returns True, otherwise False
date	If expression1 is not equal to expression2, returns True, otherwise False
list	If each element in the each list where order is relevant satisfies this operator, the operator returns True, otherwise it returns False
hash	If the hashes have different keys or the value of each equal key in each hash satisfies this operator, the operator returns True, otherwise it returns False
binary	If expression1's memory contents or size are not equal to expression2's, then returns True, otherwise False
object	If expression1 is not a reference to the same object as expression2, then returns True, otherwise False
NULL	If either expressions is not NULL, returns True, otherwise returns False
NOTHING	If one of the expressions has a value, returns True, otherwise returns False

This operator does not throw any exceptions.

---

Less Than Or Equals Operator (<=)

Synopsis

Tests if a value is less than or equals to another value; types are converted if necessary (ex: ("1" <= 2) is True).

Syntax

expression1 <= expression2

Return Type

bool

Example

if ($x <= $y)
    printf("%n is less than or equal to %n\n", $x, $y);

Arguments Processed by <= (in order of precedence)

Argument	Processing
number	If expression1 is numerically less than or equal to expression2, returns True, otherwise returns False
float	If expression1 is numerically less than or equal to expression2, returns True, otherwise returns False
int	If expression1 is numerically less than or equal to expression2, returns True, otherwise returns False
string	If expression1 comes before in string sort order or is the same as expression2, returns True, otherwise returns False
date	If expression1 is before or is the same exact date and time as expression2, returns True, otherwise returns False

This operator does not throw any exceptions.

---

Greater Than Or Equals Operator (>=)

Synopsis

Tests if a value is greater than or equals to another value; types are converted if necessary (ex: ("2" >= 1) is True).

Syntax

expression1 >= expression2

Return Type

bool

Example

if ($x >= $y)
    printf("%n is greater than or equal to %n\n", $x, $y);

Arguments Processed by >= (in order of precedence)

Argument	Processing
number	If expression1 is numerically greater than or equal to expression2, returns True, otherwise returns False
float	If expression1 is numerically greater than or equal to expression2, returns True, otherwise returns False
int	If expression1 is numerically greater than or equal to expression2, returns True, otherwise returns False
string	If expression1 comes after in string sort order or is the same as expression2, returns True, otherwise returns False
date	If expression1 is after or is the same exact date and time as expression2, returns True, otherwise returns False

This operator does not throw any exceptions.

---

Comparison (<=>) Operator

Synopsis

Tests if the left-hand value is less than, equal, or greater than the right-hand value; types are converted if necessary (ex: ("1" <=> 2) returns -1).

Syntax

expression1 <=> expression2

Return Type

int

Example

switch ($x <=> $y) {
    case -1: 
        print("$x is less than $y\n");
        break;

    case 0: 
        print("$x is equal to $y\n");
        break;

    case 1: 
        print("$x is greater than $y\n");
        break;
}

Arguments Processed by <=> (in order of precedence)

Argument	Processing
string	If expression1 comes after in string sort order as expression2, returns 1, otherwise if they are equal, returns 0, otherwise if expression1 comes before expression2, returns -1
number	If expression1 is numerically greater than expression2, returns 1, otherwise if they are equal returns 0, otherwise returns -1
float	If expression1 is numerically greater than expression2, returns 1, otherwise if they are equal returns 0, otherwise returns -1
int	If expression1 is numerically greater than expression2, returns 1, otherwise if they are equal returns 0, otherwise returns -1
date	If expression1 is after expression2, returns 1, otherwise if they are equal returns 0, otherwise returns -1

This operator does not throw any exceptions.

---

Absolute Equals Operator (===)

Synopsis

Checks two values for equality without doing any data type conversions; if the types do not match, then the result is False.

Syntax

expression1 === expression2

Return Type

bool

Example

if ($x === $y)
    printf("%n is equal to %n and has the same data type as well\n", $x, $y);

Arguments Processed by ===

Argument	Processing
All	This operator returns True only if the types and values of both sides of the operator are exactly equal, otherwise returns False. No type conversions are done.

This operator does not throw any exceptions.

---

Absolute Not Equals Operator (!==)

Synopsis

Checks two values for inequality without doing any data type conversions. If the data types do not match, then returns True.

Syntax

expression1 !== expression2

Return Type

bool

Example

if ($x !== $y)
    printf("%n is not equal to %n and may not have the data type as well\n", $x, $y);

Arguments Processed by !==

Argument	Processing
All	This operator returns True if either the types or the values of the arguments are different, otherwise it retuns False. No type conversions are done.

This operator does not throw any exceptions.

---

Regular Expression Match Operator (=~)

Synopsis

Checks for a regular expression match; returns True if the expression matches the string, False if not. See regex_options for the meaning of the i, s, x, and m options after the regular expression.

See Regular Expressions for more information about regular expression support in Qore.

Syntax

expression =~ [m]/regex/[isxm]

Return Type

bool

Example

if ($str =~ /hello/)
    printf("%s contains 'hello'\n", $str);

Arguments Processed by =~

Argument	Processing
string	This operator returns True if the regular expression in regex matches the string in expression.

This operator does not throw any exceptions.

---

Regular Expression No Match Operator (!~)

Synopsis

Checks for a regular expression non match; returns True if the expression does not match the string, False if it does. See regex_options for the meaning of the i, s, x, and m options after the regular expression.

See Regular Expressions for more information about regular expression support in Qore.

Syntax

expression !~ [m]/regex/[isxm]

Return Type

bool

Example

if ($str !~ /hello/)
    printf("%s does not contain 'hello'\n", $str);

Arguments Processed by !~

Argument	Processing
string	This operator returns True if the regular expression in regex does not match the string in expression.

This operator does not throw any exceptions.

---

Regular Expression Substitution Operator

Synopsis

Looks for a regular expression match in a string, and, if found, substitutes the matched string with a new string. Subpattern backreferences are supported in the target string, $1=first subpattern, $2=second subpattern, etc... See regex_options for the meaning of the i, s, x, and m options after the regular expression.

See Regular Expressions for more information about regular expression support in Qore.

Syntax

lvalue =~ s/regex_pattern/target_string/[isxmg]

Return Type

string or NOTHING (if the lvalue does not hold a string)

Example

$str =~ s/hello/goodbye/i;
$str =~ s/(\w+) +(\w+)/$2, $1/;

Arguments Processed by =~ s///

Argument	Processing
string	This operator substitutes text in the lvalue string if the regular expression matches. Subpattern backreferences are supported in target_string, $1=first subpattern, $2=second subpattern, etc..

This operator does not throw any exceptions.

---

Regular Expression Pattern Extraction Operator

Synopsis

Matches regular expression patterns (enclosed in parentheses) in a string and returns a list giving the text matched for each pattern. If the regular expression does not match, then no value (NOTHING) is returned. See regex_options for the meaning of the i, s, x, and m options after the regular expression.

See Regular Expressions for more information about regular expression support in Qore.

Syntax

string =~ x/regex_with_patterns/[isxm]

Return Type

list or NOTHING (if the lvalue does not hold a string or if the pattern is not matched)

Example

$list =~ x/(\w+):(\w+)/;
$list =~ x/(.*)\.(.*)/;

Arguments Processed by =~ x//

Argument	Processing
string	This operator extracts strings from string based on patterns enclosed in parentheses in the regular expression.

This operator does not throw any exceptions.

---

Transliteration Operator

Synopsis

Makes character substitutions in an lvalue; character ranges can also be used.

Syntax

lvalue =~ tr/source_chars/target_chars/

Return Type

string or NOTHING (if the lvalue does not hold a string)

Example

$str =~ tr/a-z/A-Z/;

Arguments Processed by =~ tr//

Argument	Processing
string	This operator substitutes characters in the lvalue string. Note that if there are more characters in source_chars than in target_chars, then the last character in target_chars will be used for any source matches where the source character position is greater than the length of target_chars.

This operator does not throw any exceptions.

---

Bitwise/Binary And Operator (&)

Synopsis

Performs a bitwise (binary) AND operation on two integers.

Syntax

expression1 & expression2

Return Type

int

Example

$a = $x & $y;

Arguments Processed by &

Argument	Processing
int	Gives the result of the binary (bitwise) AND operation between expression1 and expression2 (ex: 0xffb2 & 0xa1 = 0xa1); operands are converted to integers if necessary.

This operator does not throw any exceptions.

---

Bitwise/Binary Or Operator (|)

Synopsis

Performs a bitwise (binary) OR operation on two integers.

Syntax

expression1 | expression2

Return Type

int

Example

$a = $x | $y;

Arguments Processed by |

Argument	Processing
int	Gives the result of the binary (bitwise) OR operation between expression1 and expression2 (ex: 0xb001	0xfea = 0xbfeb); operands are converted to integers if necessary

This operator does not throw any exceptions.

---

Bitwise/Binary Xor Operator (^)

Synopsis

Performs a bitwise (binary) XOR operation on two integers.

Syntax

expression1 ^ expression2

Return Type

int

Example

$a = $x ^ $y;

Arguments Processed by ^

Argument	Processing
int	Gives the result of the binary (bitwise) EXCLUSIVE OR operation between expression1 and expression2 (ex: 0xaef1 & 0xfb32 = 0x55c3); operands are converted to integers if necessary

This operator does not throw any exceptions.

---

Logical And Operator (&&)

Synopsis

Checks to see if two expressions are True with logical short-circuiting.

Syntax

expression1 && expression2

Return Type

bool

Example

if ($x && $y)
    printf("%n and %n are both True\n", $x, $y);

Arguments Processed by &&

Argument	Processing
bool	Returns True if both expressions are True, False if otherwise. Logical short-circuiting is implemented; if expression1 is False, then expression2 is not evaluated, and the operator returns False.

This operator does not throw any exceptions.

---

Logical Or Operator (||)

Synopsis

Returns True if either of the arguments are True with logical short-circuiting.

Syntax

expression1 || expression2

Return Type

bool

Example

if ($x || $y)
    printf("either %n or %n or both are True\n", $x, $y);

Arguments Processed by ||

Argument	Processing
bool	Returns True if either or both expressions evaluate to True, False if otherwise. Logical short-circuiting is implemented; if expression1 is True, then expression2 is not evaluated, and the operator returns True.

This operator does not throw any exceptions.

---

Conditional Operator (? :)

Synopsis

Evaluates and returns the value of one of two expressions depending on the value of a conditional expression.

Syntax

expression ? if_true_expression : if_false_expression

Return Type

any

Example

$a = ($z > 100 ? "Big" : "Small");

Arguments Processed by ? :

Argument	Processing
All	If expression is evaluated to be True, then the if_true_expression is evaluated and returned. Otherwise the if_false_expression is evaluated and returned.

This operator does not throw any exceptions.

---

Comma Operator (,)

Synopsis

Makes a list from more than one element.

Syntax

expression1, expression2

Return Type

list

Example

$a = 1, 2, "three";

Arguments Processed by ,

Argument	Processing
All	The comma operator builds lists of arguments

This operator does not throw any exceptions.

---

Unshift Operator (unshift)

Synopsis

Inserts an element into the first position of a list and moves all other elements up one position.

Syntax

unshift lvalue, expression

Return Type

any

Example

unshift $list, "one";

Arguments Processed by unshift

Argument	Processing
All	Inserts the value of expression as the first element in the list given by lvalue. All other elements in the list are moved forward.

---

Push Operator (push)

Synopsis

Adds one element to the end of a list and returns the list processed (or NOTHING if the lvalue is not a list).

Syntax

push lvalue, expression

Return Type

list or NOTHING (if the lvalue is not a list)

Example

push $list, "last";

Arguments Processed by push

Argument	Processing
All	Appends the value of the expression as the last element in the list given by lvalue. If expression evaluates to a list, this list will be appended as the last element of lvalue. To concatenate lists, use the plus operator.

---

Splice Operator (splice)

Synopsis

Removes and optionally inserts elements in lists, strings, and binary objects and returns the lvalue after processing. For a similar operator that returns the values removed, see the extract operator.

Works on strings, lists, and binary data in a similar way; removes elements from a list, characters from a string, or bytes from binary data and optionally inserts new ones. If no length_expression is given, splice removes all elements/characters/bytes from the list, string, or binary data lvalue starting at offset_expression (offsets begin at 0). Otherwise, a number of elements/characters/bytes equal to length_expression is removed (or up to the end of the list/string/data if applicable). If substitution_expression is present, then the removed elements/characters/bytes are substituted with the elements/string/bytes given by this expression.

Note that string splice takes character offsets, which may not be the same as byte offsets for multi-byte character encodings, such as UTF-8

Syntax

splice lvalue, offset_expression, [length_expression, [substitution_expression]]

Return Type

list, string, or binary (returns lvalue after processing)

Example

splice $list, 2, 2;

splice $string, 2, 2, "-text-";

splice $bin, 2, 2, <deadbeef>;

Arguments Processed by splice

Argument	Processing
lvalue (list, string, or binary)	If the lvalue is a list, list elements are processed, if it is a string, characters in the string are processed, and for binary data, bytes are processed. For any other data type, no action is taken.
offset_expression	The start element/character/byte position for removing elements/characters/bytes from the list, string, or binary data; if this value is negative, it gives the element offset from the end of the data
length_expression	The number of elements/characters/bytes to remove. If this expression is not present, then all elements/characters/bytes from the offset to the end of the list/string/binary data are removed. If this expression is present and evaluates to 0, no characters/elements/byte are removed; if this value is negative, then it gives an offset from the end of the data (ie -2 means remove all elements/characters/bytes up to but not including the last two)
substitution_expression	For list splice, an optional element or list to substitute for the removed elements (to insert a list in a single element's position, make sure that the list to be inserted is the first and only element of another list used as the argument in this position; in other words, pass a list within a single-element list). For string splice, an optional string to substitute for the removed characters. For binary splice, string or binary data to substitute for any removed bytes.

---

Extract Operator (extract)

Synopsis

Removes and optionally inserts elements in lists and strings. For a similar operator that removes values from an lvalue and returns the lvalue (instead of the value removed), see the splice operator.

Works on either strings, lists, and binary data in a similar way; removes elements from a list, characters from a string, and bytes from binary data and optionally inserts new ones. If no length_expression is given, extract removes all elements/characters/bytes from the lvalue starting at offset_expression (offsets begin at 0). Otherwise, a number of elements/characters/bytes equal to length_expression is removed (or up to the end of the data if applicable). If substitution_expression is present, then the removed elements/characters/bytes are substituted with the data given by this expression.

When operating on lists, a list is returned of any elements extracted (if no elements are extracted, then an empty list is returned); when operating on strings, a string is extracted of all characters extracted from the string (if no characters are extracted, then an empty string is returned). When operating on binary data, a binary object is returned.

Note that string extract takes character offsets, which may not be the same as byte offsets for multi-byte character encodings, such as UTF-8

Syntax

extract lvalue, offset_expression, [length_expression, [substitution_expression]]

Return Type

list, string, or binary (the value(s) removed from lvalue)

Example

my list $sublist = extract $list, 2, 2;

my string $substring = extract $string, 2, 2, "-text-";

my binary $b = extract $bin, 2, 2, <deadbeef>;

Arguments Processed by extract

Argument	Processing
lvalue (list, string, or binary)	If the lvalue is a list, list elements are processed, if it is a string, characters in the string are processed, and for binary data, bytes are processed. For any other data type, no action is taken.
offset_expression	The start element/character/byte position for removing elements/characters/bytes from the list, string, or binary data; if this value is negative, it gives the element offset from the end of the data
length_expression	The number of elements/characters/bytes to remove. If this expression is not present, then all elements/characters/bytes from the offset to the end of the list/string/binary data are removed. If this expression is present and evaluates to 0, no characters/elements/byte are removed; if this value is negative, then it gives an offset from the end of the data (ie -2 means remove all elements/characters/bytes up to but not including the last two)
substitution_expression	For list extract, an optional element or list to substitute for the removed elements (to insert a list in a single element's position, make sure that the list to be inserted is the first and only element of another list used as the argument in this position; in other words, pass a list within a single-element list). For string splice, an optional string to substitute for the removed characters. For binary splice, string or binary data to substitute for any removed bytes.

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Assignment Operator (=)

Synopsis

Assigns a value to an lvalue and returns the value assigned.

Syntax

lvalue = expression

Return Type

any

Example

$a = 1;

Arguments Processed by =

Argument	Processing
All	Assigns the value of expression to lvalue

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Plus Equals Operator (+=)

Synopsis

Increments and concatentates an lvalue with the value of an expression depending on the data type of the lvalue, unless the lvalue is NOTHING, in which case this operator acts like the assignment operator (simply assigns the value of the right hand side to the lvalue).

Syntax

lvalue += expression

Return Type

int, float, number, date, list, string, binary, hash, or object

Example

$a += 10;

$date += P1M2DT45M;

$list += $new_element;

$string += ".foo";

$binary += <0c67a374>

$hash += ("new-key" : 1, "other" : "two");

$object += $hash;

Arguments Processed by +=

Argument	Processing
lvalue (list)	the expression will be evaluated and concatenated to the lvalue. If expression is a list, the lists will be concatenated, to ensure adding a single element to a list, use the push operator
lvalue (hash or (object)	the expression will be evaluated, and, if it is a hash or object, then it's members will be added to the lvalue, any duplicate elements in the lvalue will be overridden by elements in the expression.
lvalue (string)	the expression will be evaluated and converted to a string if necessary and concatenated to the lvalue.
lvalue (number)	the expression will be evaluated and converted to a number if necessary and added to the lvalue.
lvalue (float)	the expression will be evaluated and converted to a float if necessary and added to the lvalue.
lvalue (binary)	the expression will be evaluated and converted to a binary if necessary and added to the lvalue.
lvalue (date)	the expression will be evaluated and converted to a date if necessary and added to the lvalue.
lvalue (NOTHING)	the lvalue will be assigned to the value of expression.
lvalue (all other types)	the lvalue's type will be converted to an integer, and the expression will be evaluated and converted to an integer if necessary, and then the result will be added to the lvalue.

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Minus Equals Operator (-=)

Synopsis

For a float or integer argument, decrements the value of an lvalue by the value of an expression. However if the lvalue is a hash or object and the expression is a string, removes the key represented by the string from the hash or object.

Syntax

lvalue -= expression

Return Type

int, float, number, date, hash, or object

Example

$a -= 10;

$date -= PT45H213S;

$hash -= "key";

$hash -= ("key1", "key2");

$object -= "key";

$object -= $list_of_keys;

Arguments Processed by -=

Argument	Processing
lvalue (number)	the expression will be evaluated and converted to a number if necessary and subtracted from the lvalue
lvalue (float)	the expression will be evaluated and converted to a float if necessary and subtracted from the lvalue
lvalue (date)	the expression will be evaluated and converted to a date if necessary and subtracted from the lvalue
lvalue (hash or (object), expression (string)	the hash key represented by expression will be removed from the lvalue
lvalue (hash or (object), expression (list)	each element in the list will be converted to a string (if necessary) and the key represented by each string will be removed from the hash or object
lvalue (NOTHING), expression (any type)	the expression will be assigned to lvalue
lvalue (all other types)	the lvalue's type will be converted to an integer (if necessary), and the expression will be evaluated and converted to an integer (if necessary), and then the result will be subtracted from the lvalue

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And Equals Operator (&=)

Synopsis

Performs a bitwise (binary) AND operation on an lvalue using the value of an expression and returns the new value.

Syntax

lvalue &= expression

Return Type

int

Example

$a &= 0xfe;

Arguments Processed by &=

Argument	Processing
All	the lvalue's type will be converted to an integer if necessary, and the expression will be evaluated and converted to an integer as well if necessary, and then the result will be binary and'ed to the lvalue

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Or Equals Operator (|=)

Synopsis

Performs a bitwise (binary) OR operation on an lvalue using the value of an expression and returns the new value.

Syntax

lvalue |= expression

Return Type

int

Example

$a |= 0xba;

Arguments Processed by |=

Argument	Processing
All	the lvalue's type will be converted to an integer if necessary, and the expression will be evaluated and converted to an integer as well if necessary, and then the result will be binary or'ed to the lvalue

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Modula Equals Operator (%=)

Synopsis

Performs a modula calculation on an lvalue using the value of an expression and returns the new value.

Syntax

lvalue %= expression

Return Type

int

Example

$a %= 100;

Arguments Processed by %=

Argument	Processing
All	the lvalue's type will be converted to an integer if necessary, and the expression will be evaluated and converted to an integer as well if necessary, and then the result will be used to divide the lvalue's value and the remainder will be saved to the lvalue

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Multiply Equals Operator (*=)

Synopsis

Performs a multiplication operation on an lvalue using the value of an expression and returns the value assigned.

Syntax

lvalue *= expression

Return Type

int, float, or number

Example

$a *= 10;

Arguments Processed by *=

Argument	Processing
All	The type precedence from highest to lowest is number, float float, and int, other types are converted to int. The expression will be evaluated and multiplied by the lvalue, and the result will be saved to the lvalue.

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Divide Equals Operator (/=)

Synopsis

Performs a division operation on an lvalue using the value of an expression and returns the value assigned.

Syntax

lvalue /= expression

Return Type

int, float, or number

Example

$a /= 10;

Arguments Processed by /=

Argument	Processing
All	The type precedence from highest to lowest is number, float float, and int, other types are converted to int; The expression will be evaluated and multiplied by the lvalue, and the result will be saved to the lvalue. The expression will be evaluated and used to divide the lvalue, and the result will be saved to the lvalue.

Exceptions

DIVISION-BY-ZERO

If the divisor expression evaluates to zero, this exception is thrown

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Xor Equals Operator (^=)

Synopsis

Performs an exclusive-or operation on an lvalue using the value of an expression.

Syntax

lvalue ^= expression

Return Type

int

Example

$a ^= 0xf9034ba7;

Arguments Processed by ^=

Argument	Processing
All	Values are converted to integers if necessary. The expression will be evaluated and exclusive-or'ed with the lvalue, and the result will be saved to the lvalue

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Shift Left Equals Operator (<<=)

Synopsis

Performs a shift-left operation on an lvalue using the value of an expression and returns the value assigned.

Syntax

lvalue <<= expression

Return Type

int

Example

$a <<= 3;

Arguments Processed by <<=

Argument	Processing
All	Values are converted to integers if necessary. The expression will be evaluated and this value will determine how many bits the lvalue will be shifted left. The result will be saved to the lvalue.

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Shift Right Equals Operator (>>=)

Synopsis

Performs a shift-right operation on an lvalue using the value of an expression and returns the value assigned.

Syntax

lvalue >>= expression

Return Type

int

Example$

$a >>= 3;

Arguments Processed by >>=

Argument	Processing
All	Values are converted to integers if necessary. The expression will be evaluated and this value will determine how many bits the lvalue will be shifted right. The result will be saved to the lvalue.