Atomic States

Atomic states are used as leaves of a state tree. They do not have children.

Usage

Use atomic(...) to set up state configuration and resolveState(...) to initialize it.


 import { atomic, emitEvent, resolveState } from 'hine'; 
 
let count = 0; 
const counterConfig = atomic('counter', { 
	on: { 
		increment: () => (count += 1), 
	}, 
}); 
const counterState = resolveState(counterConfig); 
 
emitEvent(counterState, 'increment');

In this example, counterState is set up to increment count by 1 each time an 'increment' event is emitted.

Active Children

Active states are those that can receive and handle emitted events at a particular time. Atomic states themselves can handle events, but since they have no children, they have zero active child states.

They stand in contrast to compound states which have exactly one active child, and parallel states, where all children are simulataneously active.


 // Always `true` for atomic states 
console.log(counterState.activeChildren.length === 0);

Children

Atomic states have no children.


 // Always `true` for atomic states 
console.log(counterState.children.size === 0);

Hooks

Atomic states accept hooks such as afterEntry and beforeExit . Hooks respond to life-cycle events of a state.


 import { atomic, emitEvent, resolveState } from 'hine'; 
 
let count; 
const initializeCount = () => (count = 0); 
const counterConfig = atomic('counter', { 
	hooks: { 
		afterEntry: initializeCount, 
	}, 
	on: { 
		increment: () => (count += 1), 
	}, 
}); 
 
const counterState = resolveState(counterConfig); 
 
emitEvent(counterState, 'increment');

When counterState is resolved, it will enter the 'counter' state and initialize count to 0 .