Operator Semantics

The following sections list all the operators and their semantic depending on the types of the operands. The left column represents the left-hand side operand type while the top row represents the right-hand side operand type. The values describe the semantic of the operation or list error if the corresponding operator cannot be applied with the given operand types.

Arithmetic Operators

The following arithmetic operators are covered in this section:

+

+	Number	String	Array	Hash	Res Collection	Other
Number	Addition	Error	Error	Error	Error	Error
String	Concatenation	Concatenation	Error	Error	Error	Error
Date/Time	Addition (seconds)	Error	Error	Error	Error	Error
Array	Error	Error	Concatenation	Error	Error	Error
Hash	Error	Error	Error	merge left into right	Error	Error
Res Collection	Error	Error	Error	Error	Concatenation	Error
Other	Error	Error	Error	Error	Error	Error

-

-	Number	Date/Time	Array	Res Collection	Other
Number	Subtraction	Error	Error	Error	Error
Date/Time	Subtraction (seconds)	Subtraction (seconds)	Error	Error	Error
Array	Error	Error	Array Difference	Error	Error
Res Collection	Error	Error	Error	Coll Difference	Error
Other	Error	Error	Error	Error	Error

*

*	Number	Other
Number	Multiplication	Error
Other	Error	Error

/

/	Number	Other
Number	Division (integral, if both numbers are integers)	Error
Other	Error	Error

%

%	Number	Other
Number	Modulo (non integer numbers are rounded)	Error
Other	Error	Error

^

-	Number	Other
Number	Power	Error
Other	Error	Error

Collection and Array Operators

The following collection and array operators are covered in this section:

<<

<<	All
Array	Append object in right-hand side to array in left-hand side
Other	Error

[ ]

The slice operator returns elements of an array, a hash or a resource collection using an index or a range (array and resource collection) or a key (hash). A range is specified using x..y where x and y are optional (no x means from the start of the array or collection, no y means to the end of the array or collection).

note

Retrieving elements of a resource collection creates a new resource collection consisting of these elements.

[ ]	Number	String	Range	Other
Res Collection	Creates a new collection consisting of the element at a given index	Error	Creates a new collection consisting of the element in the given range ( x\.\.y where x and y are optional)	Error
Array	Value at given index	Error	Creates a new array consisting of the element in the given range ( x\.\.y where x and y are optional)	Error
Hash	Error	Value associated with given key if any, null otherwise	Error	Error
String	Creates a string composed of a character at a given index	Error	Create a string made of characters in the given range. Range bounds may have negative values (from last or from beginning).	Error
Other	Error	Error	Error	Error

[ ]=

The slice assign operator replaces an element of an array, hash or resource collection or a range of an array or resource collection with given elements.

[ ] =	Number	String	Range	Other
Res Collection	Replaces the resource at a given index. Right-hand side must be a resource collection.	Error	Replace elements in the given range with elements of the right-hand side resource collection.	Error
Array	Replace the value at a given index.	Error	Replace the elements in the given range with elements of the given array. The right-hand side must be an array.	Error
Hash	Error	Replace/set the value associated with a given key.	Error	Error
Other	Error	Error	Error	Error

Regular Expression-Include Operators

The following regular expression-include operators are covered in this section:

=~

=~	String	Array	Other
String	true if regular expression given in right-operand matches string given in left operand	Error	Error
Array	true if array contains string	true if array contains array	true if array contains value
Hash	true if hash has that key	Error	Error
Other	Error	Error	Error

The right-hand side of a regular expression comparison may use the symbol / to delineate the pattern. The ending / may be followed by the following options:

• i for case insensitive matching
• m for multi-line string matching
• x for extended syntax support (whitespaces in the pattern are ignored)

Examples:

"foo" =~ "foo" # true 
"foo" =~ /foo/ # true 
"foo" =~ /FOO/i # true 

!~

a !~ b is equivalent to !(a =~ b).

Relational and Equality Operators

The following relational and equality operators are covered in this section:

==, !=

Equality comparison is done recursively if values are arrays or hashes.

==	All
All	true if operands have same value, false otherwise

<, <=, >, >=

<	Number	String	Date/Time	Res Collection	Array	Other
Number	Less than	Error	Error	Error	Error	Error
String	Error	Lexicographical less than	Error	Error	Error	Error
Date/Time	Error	Error	Less than	Error	Error	Error
Res Collection	Error	Error	Error	@a &lt; @b : true if all elements of @a are also elements of @b .	Error	Error
Array	Error	Error	Error	Error	@a &lt; @b : true if all elements of @a are also elements of @b .	Error
Other						Error

note

>, <=, and >= are omitted for brevity (greater than, lesser or equal than, greater or equal than, respectively).

Logical Operators

The following logical operators are covered in this section:

<

“Bitwise and”. Applied to resource collections (or arrays) it returns all elements that appear in both resource collections (or arrays).

<	false	null	true	Array	Res Collection	Other
false	false	false	false	false	false	false
null	false	false	false	false	false	false
true	false	false	true	true	true	true
Array	error	error	error	intersection of two arrays	error	error
Res Collection	error	error	error	error	new collection with common hrefs or error if collections are of different types	error
Other	error	error	error	error	error	error

<<

“Logical and”. Returns the right-hand side operand if the left-hand side is neither false nor null (otherwise returns left-hand side operand). In the following table, (1) and (2) refer to the position of that particular argument in the expression.

<<	false	null	true	Other (1)
false	false	false	false	false
null	null	null	null	null
true	false	null	true	(1)
Other (2)	false	null	true	(2)

|

“Bitwise or”. Applied to resource collections (or arrays), returns all elements that appear in either resource collection (or array).

note

The “|” operator differs from the “+” operator when applied to a collection. “|” will produce only one instance of each element in each collection even if the same element appears in both.

|	false	null	true	Other
false	false	false	true	true
null	false	false	true	true
true	true	true	true	true
Other	error	error	error	error

||

“Logical or”. Returns the left-hand side operand if it is neither false nor null (otherwise returns right-hand side operand). In the following table, (1) and (2) refer to the position of that particular argument in the expression.

||	false	null	true	Other (2)
false	false	null	true	(2)
null	false	null	true	(2)
true	true	true	true	true
Other (1)	(1)	(1)	(1)	(1)

Unary Operators

The following unary operators are covered in this section:

-

“-” is the unary minus operator.

-	Value
Number	Opposite value
Other	Error

!

! is the logical not operator.

note

“!” applies to all types (negating a non-boolean value returns true if it is either false or null, false otherwise).

!	Value
false	true
null	true
Other	false