Map Class

Extends Sequence.

An associative collection that maps keys to values. More details here.

Static Method #

Map.new() #

Creates a new empty map. Equivalent to {}.

Methods #

clear() #

Removes all entries from the map.

containsKey(key) #

Returns true if the map contains key or false otherwise.

count #

The number of entries in the map.

keys #

A Sequence that can be used to iterate over the keys in the map. Note that iteration order is undefined. All keys will be iterated over, but may be in any order, and may even change between invocations of Wren.

remove(key) #

Removes key and the value associated with it from the map. Returns the value.

If the key was not present, returns null.

values #

A Sequence that can be used to iterate over the values in the map. Note that iteration order is undefined. All values will be iterated over, but may be in any order, and may even change between invocations of Wren.

If multiple keys are associated with the same value, the value will appear multiple times in the sequence.

[key] operator #

Gets the value associated with key in the map. If key is not present in the map, returns null.

var map = {"george": "harrison", "ringo": "starr"}
System.print(map["ringo"]) //> starr
System.print(map["pete"])  //> null

[key]=(value) operator #

Associates value with key in the map. If key was already in the map, this replaces the previous association.

It is a runtime error if the key is not a Bool, Class, Null, Num, Range, or String.

iterate(iterator), iteratorValue(iterator) #

Implements the iterator protocol for iterating over the keys and values of a map at the same time.

When a map (as opposed to its keys or values separately) is iterated over, each key/value pair is wrapped in a MapEntry object. MapEntry is a small helper class which has read-only key and value properties and a familiar toString representation.

var map = {"paul": "mccartney"}
for (entry in map) {
  System.print(entry.type)                    // MapEntry
  System.print(entry.key + " " + entry.value) // paul mccartney
  System.print(entry)                         // paul:mccartney
}

All map entries will be iterated over, but may be in any order, and may even change between invocations of Wren.