EmptyMap<K, V> class

An empty map that doesn't allow adding-operations (like putIfAbsent or the []=operator). Removing-operations (remove and clear) are ok, because the don't modify the contents of an empty map.

Constructors

EmptyMap()
const

Properties

entries → Iterable<MapEntry<K, V>>
The map entries of this.
read-only
isEmpty → bool
Returns true if there is no key/value pair in the map.
read-only
isNotEmpty → bool
Returns true if there is at least one key/value pair in the map.
read-only
keys → Iterable<K>
The keys of this. [...]
read-only
length → int
The number of key/value pairs in the map.
read-only
values → Iterable<V>
The values of this. [...]
read-only
hashCode → int
The hash code for this object.
read-only, inherited
runtimeType → Type
A representation of the runtime type of the object.
read-only, inherited

Methods

addAll(Map<K, V> other) → void
Throws an UnsupportedError; operations that add to the collection are disallowed.
addEntries(Iterable<MapEntry<K, V>> newEntries) → void
Adds all key/value pairs of newEntries to this map. [...]
cast<RK, RV>() → Map<RK, RV>
Provides a view of this map as having RK keys and RV instances, if necessary. [...]
clear() → void
empty map is empty, so nothing needs to change
containsKey(Object key) → bool
Returns true if this map contains the given key. [...]
containsValue(Object value) → bool
Returns true if this map contains the given value. [...]
forEach(void f(K key, V value)) → void
Applies f to each key/value pair of the map. [...]
map<K2, V2>(MapEntry<K2, V2> f(K key, V value)) → Map<K2, V2>
Returns a new map where all entries of this map are transformed by the given f function.
putIfAbsent(K key, V ifAbsent()) → V
Throws an UnsupportedError; operations that add to the collection are disallowed.
remove(Object key) → V
Always returns false; because value is guaranteed not to be contained in an empty collection.
removeWhere(bool predicate(K key, V value)) → void
Removes all entries of this map that satisfy the given predicate.
toString() → String
Returns a string representation of this object.
update(K key, V update(V value), { V ifAbsent() }) → V
Updates the value for the provided key. [...]
updateAll(V update(K key, V value)) → void
Updates all values. [...]
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
inherited

Operators

operator [](Object key) → V
Always returns null because no key is in the empty map
operator []=(K key, V value) → void
Throws an UnsupportedError; operations that add to the collection are disallowed.
operator ==(dynamic other) → bool
The equality operator.
inherited