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Interface: Map

rules.Map

interface   static

Map type, used for simple key-value mappings.

Keys must be of type rules.String.

In addition to the methods listed below, maps have the following operators:

Operator Usage
x == y Compare maps x and y
x[k] Index operator, get value at key name k
x.k Get value at key name k
k in x Check if key k exists in map x

Methods

diff

diff(map_to_compare) returns rules.MapDiff

Return a rules.MapDiff representing the result of comparing the current Map to a comparison Map.

Parameter

map_to_compare

rules.Map

A Map to which the current (calling) Map will be compared.

Value must not be null.
Returns

non-null rules.MapDiff object representing the result of the comparison.

get

get(key, default_value) returns value

Returns the value associated with a given search key string.

For nested Maps, involving keys and sub-keys, returns the value associated with a given sub-key string. The sub-key is identified using a list, the first item of which is a top-level key and the last item the sub-key whose value is to be looked up and returned. See the nested Map example below.

The function requires a default value to return if no match to the given search key is found.

Parameter

key

(non-null rules.String or non-null rules.List)

Either a key specified as a string, or for nested Maps, a sub-key specified using list syntax.

default_value

default_value

Value to return if the Map does not contain the given search key. Can be any Rules language type.
Returns

value Value corresponding to the given key, or the default return value specified by default_value if no match to the given key is found. Since Map contents are user-defined, the data type of the returned value can be any Rules language type.

Example 

// "c" is not a key in the supplied Map, returns default value 7.
{"a": 3,"b": 2}.get("c", 7) == 7

// Default result can be any type, e.g. a list such as [1, 1].
{"a": [2, 7], "b": [9, 12]}.get("c", [1, 1]) == [1, 1]

// Return a list on a successful match.
{"a": [2, 7],"b": [9, 12]}.get("b", [1, 1]) == [9, 12]

// For nested Maps, use list ["a", "b"] to specify lookup on sub-key "b".
{"a": {"b": 1},"c": 2}.get(["a", "b"], 7) == 1

keys

keys() returns rules.List

Get the list of keys in the map.

Returns

non-null rules.List list of keys.

size

size() returns rules.Integer

Get the number of entries in the map.

Returns

non-null rules.Integer number of entries.

values

values() returns rules.List

Get the list of values in the map.

Returns

non-null rules.List list of values.