Class TImmutableMap

Unit

hamt.maps

Declaration

type generic TImmutableMap<TKey,TValue,TInfo> = class(specialize TReadOnlyMap<TKey,TValue,TInfo>)

Description

Generic immutable map

Data in this map can be read (see ancestor TReadOnlyMap) and modified by creating new maps.

Example:

type TImmutableMapStringString = specialize TImmutableMap<string, string, THAMTTypeInfo>;
var map, map2, map3: TImmutableMapStringString;
  p: TImmutableMapStringString.PPair;
begin
  map := TImmutableMapStringString.create;
  map2 := map.Insert('hello', 'world');
  map3 := map2.insert('foo', 'bar');

  writeln(map.get('hello', 'default')); // default
  writeln(map.get('foo', 'default')); // default

  writeln(map2.get('hello')); // world
  writeln(map2.get('foo', 'default')); // default

  writeln(map3['hello']); // world
  writeln(map3['foo']); // bar

  //enumerate all
  for p in map3 do
    writeln(pˆ.key, ': ', pˆ.value);

  map.free;
  map2.free;
  map3.free;
end.

Hierarchy

• TReadOnlyCustomSet
• TReadOnlyMap
• TImmutableMap

Overview

Methods

	function include(const key: TKey; const value: TValue; allowOverride: boolean = true): TImmutableMap; inline; overload;
	function exclude(const key: TKey): TImmutableMap; inline;
	function insert(const key: TKey; const value: TValue): TImmutableMap; inline;
	function remove(const key:TKey): TImmutableMap; inline;
	function clone: TImmutableMap;

Description

Methods

	function include(const key: TKey; const value: TValue; allowOverride: boolean = true): TImmutableMap; inline; overload;
Creates a new map containing (key, value). If the map does not contain key or allowOverride is true, the value associated with the key is value, otherwise the value is unchanged. Returns The new map

	function exclude(const key: TKey): TImmutableMap; inline;
Creates a new map without key and its associated value Returns The new map

	function insert(const key: TKey; const value: TValue): TImmutableMap; inline;
Creates a new map containing (key, value), or raises an exception if the map already contained key Returns The new map

	function remove(const key:TKey): TImmutableMap; inline;
Creates a new map without key and its associated value, or raises an exception if the map did not contain key Returns The new map

	function clone: TImmutableMap;
Creates a new map equal to self. No data is copied, till either map is modified (copy-on-write).

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