All files / xstate/src graph.ts

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import { StateNode, State } from './index';
import { toStateValue, getActionType, flatten, keys } from './utils';
import {
  StateValue,
  Edge,
  Segment,
  PathMap,
  PathItem,
  PathsItem,
  PathsMap,
  AdjacencyMap,
  DefaultContext,
  ValueAdjacencyMap,
  Event,
  EventObject
} from './types';
 
const EMPTY_MAP = {};
 
export function getNodes(node: StateNode): StateNode[] {
  const { states } = node;
  const nodes = keys(states).reduce((accNodes: StateNode[], stateKey) => {
    const subState = states[stateKey];
    const subNodes = getNodes(states[stateKey]);
 
    accNodes.push(subState, ...subNodes);
    return accNodes;
  }, []);
 
  return nodes;
}
 
export function getEventEdges<
  TContext = DefaultContext,
  TEvents extends EventObject = EventObject
>(node: StateNode<TContext>, event: string): Array<Edge<TContext, TEvents>> {
  const transitions = node.definition.on[event];
 
  return flatten(
    transitions.map(transition => {
      const targets = transition.target
        ? ([] as string[]).concat(transition.target)
        : undefined;
 
      if (!targets) {
        return [
          {
            source: node,
            target: node,
            event,
            actions: transition.actions
              ? transition.actions.map(getActionType)
              : [],
            cond: transition.cond,
            transition
          }
        ];
      }
 
      return targets
        .map<Edge<TContext, TEvents> | undefined>(target => {
          try {
            const targetNode = target
              ? node.getRelativeStateNodes(target, undefined, false)[0]
              : node;
 
            return {
              source: node,
              target: targetNode,
              event,
              actions: transition.actions
                ? transition.actions.map(getActionType)
                : [],
              cond: transition.cond,
              transition
            };
          } catch (e) {
            // tslint:disable-next-line:no-console
            console.warn(`Target '${target}' not found on '${node.id}'`);
            return undefined;
          }
        })
        .filter(maybeEdge => maybeEdge !== undefined) as Array<
        Edge<TContext, TEvents>
      >;
    })
  );
}
 
export function getEdges<
  TContext = DefaultContext,
  TEvents extends EventObject = EventObject
>(
  node: StateNode<TContext>,
  options?: { depth: null | number }
): Array<Edge<TContext, TEvents>> {
  const { depth = null } = options || {};
  const edges: Array<Edge<TContext, TEvents>> = [];
 
  Eif (node.states && depth === null) {
    keys(node.states).forEach(stateKey => {
      edges.push(...getEdges<TContext>(node.states[stateKey]));
    });
  } else if (depth && depth > 0) {
    keys(node.states).forEach(stateKey => {
      edges.push(
        ...getEdges<TContext>(node.states[stateKey], { depth: depth - 1 })
      );
    });
  }
 
  keys(node.on).forEach(event => {
    edges.push(...getEventEdges<TContext>(node, event));
  });
 
  return edges;
}
 
export function getAdjacencyMap<TContext = DefaultContext>(
  node: StateNode<TContext>,
  context?: TContext
): AdjacencyMap {
  const adjacency: AdjacencyMap = {};
 
  const events = node.events;
 
  function findAdjacencies(stateValue: StateValue) {
    const stateKey = JSON.stringify(stateValue);
 
    if (adjacency[stateKey]) {
      return;
    }
 
    adjacency[stateKey] = {};
 
    for (const event of events) {
      const nextState = node.transition(stateValue, event, context);
      adjacency[stateKey][event as string] = { state: nextState.value };
 
      findAdjacencies(nextState.value);
    }
  }
 
  findAdjacencies(node.initialState.value);
 
  return adjacency;
}
 
function eventToString<TEvents extends EventObject = EventObject>(
  event: Event<TEvents>
): string {
  if (typeof event === 'string' || typeof event === 'number') {
    return `${event}`;
  }
 
  // @ts-ignore - TODO: fix?
  const { type, ...rest } = event;
 
  return `${type} | ${JSON.stringify(rest)}`;
}
 
export function deserializeStateString(
  valueContextString: string
): { value: StateValue; context: any } {
  const [valueString, contextString] = valueContextString.split(' | ');
 
  return {
    value: JSON.parse(valueString),
    context: JSON.parse(contextString)
  };
}
 
export function serializeState<TContext>(state: State<TContext>): string {
  const { value, context } = state;
  return JSON.stringify(value) + ' | ' + JSON.stringify(context);
}
 
export interface GetValueAdjacencyMapOptions<
  TContext,
  TEvents extends EventObject
> {
  // events: Record<string, Array<Event<TEvents>>>;
  events: { [K in TEvents['type']]: Event<TEvents> };
  filter?: (state: State<TContext>) => boolean;
}
 
export function getValueAdjacencyMap<
  TContext = DefaultContext,
  TEvents extends EventObject = EventObject
>(
  node: StateNode<TContext, any, TEvents>,
  options: GetValueAdjacencyMapOptions<TContext, TEvents>
): ValueAdjacencyMap {
  const { events, filter } = options;
  const adjacency: ValueAdjacencyMap = {};
 
  const potentialEvents = flatten(
    // @ts-ignore
    node.events.map(event => events[event] || [event])
  );
 
  function findAdjacencies(state: State<TContext, TEvents>) {
    const stateKey = serializeState(state);
 
    if (adjacency[stateKey]) {
      return;
    }
 
    adjacency[stateKey] = {};
 
    for (const event of potentialEvents) {
      const nextState = node.transition(state, event);
 
      if (!filter || filter(nextState)) {
        adjacency[stateKey][eventToString(event)] = {
          value: nextState.value,
          context: nextState.context
        };
 
        findAdjacencies(nextState);
      }
    }
  }
 
  findAdjacencies(node.initialState);
 
  return adjacency;
}
 
export function getShortestValuePaths<
  TContext = DefaultContext,
  TEvents extends EventObject = EventObject
>(
  machine: StateNode<TContext>,
  options: GetValueAdjacencyMapOptions<TContext, TEvents>
): PathMap {
  if (!machine.states) {
    return EMPTY_MAP;
  }
  const adjacency = getValueAdjacencyMap(machine, options);
  const pathMap: PathMap = {};
  const visited: Set<string> = new Set();
 
  function util(state: State<TContext>): PathMap {
    const stateKey = serializeState(state);
    visited.add(stateKey);
    const eventMap = adjacency[stateKey];
 
    for (const event of keys(eventMap)) {
      const { value, context } = eventMap[event];
 
      if (!value) {
        continue;
      }
 
      const nextState = State.from(value, context);
      const nextStateId = serializeState(nextState);
 
      if (
        !pathMap[nextStateId] ||
        pathMap[nextStateId].length > pathMap[stateKey].length + 1
      ) {
        pathMap[nextStateId] = [
          ...(pathMap[stateKey] || []),
          { state: value, event }
        ];
      }
    }
 
    for (const event of keys(eventMap)) {
      const { value, context } = eventMap[event];
 
      if (!value) {
        continue;
      }
 
      const nextState = State.from(value, context);
      const nextStateId = serializeState(State.from(value, context));
 
      if (visited.has(nextStateId)) {
        continue;
      }
 
      util(nextState);
    }
 
    return pathMap;
  }
 
  util(machine.initialState);
 
  return pathMap;
}
 
export function getShortestPaths<TContext = DefaultContext>(
  machine: StateNode<TContext>,
  context?: TContext
): PathMap {
  Iif (!machine.states) {
    return EMPTY_MAP;
  }
  const adjacency = getAdjacencyMap(machine, context);
  const initialStateId = JSON.stringify(machine.initialState.value);
  const pathMap: PathMap = {
    [initialStateId]: []
  };
  const visited: Set<string> = new Set();
 
  function util(stateValue: StateValue): PathMap {
    const stateId = JSON.stringify(stateValue);
    visited.add(stateId);
    const eventMap = adjacency[stateId];
 
    for (const event of keys(eventMap)) {
      const nextStateValue = eventMap[event].state;
 
      Iif (!nextStateValue) {
        continue;
      }
 
      const nextStateId = JSON.stringify(
        toStateValue(nextStateValue, machine.delimiter)
      );
 
      if (
        !pathMap[nextStateId] ||
        pathMap[nextStateId].length > pathMap[stateId].length + 1
      ) {
        pathMap[nextStateId] = [
          ...(pathMap[stateId] || []),
          { state: stateValue, event }
        ];
      }
    }
 
    for (const event of keys(eventMap)) {
      const nextStateValue = eventMap[event].state;
 
      Iif (!nextStateValue) {
        continue;
      }
 
      const nextStateId = JSON.stringify(nextStateValue);
 
      if (visited.has(nextStateId)) {
        continue;
      }
 
      util(nextStateValue);
    }
 
    return pathMap;
  }
 
  util(machine.initialState.value);
 
  return pathMap;
}
 
export function getShortestPathsAsArray<TContext = DefaultContext>(
  machine: StateNode<TContext>,
  context?: TContext
): PathItem[] {
  const result = getShortestPaths(machine, context);
  return keys(result).map(key => ({
    state: JSON.parse(key),
    path: result[key]
  }));
}
 
export function getSimplePaths<TContext = DefaultContext>(
  machine: StateNode<TContext>,
  context?: TContext
): PathsMap {
  Iif (!machine.states) {
    return EMPTY_MAP;
  }
 
  const adjacency = getAdjacencyMap(machine, context);
  const visited = new Set();
  const path: Segment[] = [];
  const paths: PathsMap = {};
 
  function util(fromPathId: string, toPathId: string) {
    visited.add(fromPathId);
 
    if (fromPathId === toPathId) {
      paths[toPathId] = paths[toPathId] || [];
      paths[toPathId].push([...path]);
    } else {
      for (const subEvent of keys(adjacency[fromPathId])) {
        const nextStateValue = adjacency[fromPathId][subEvent].state;
 
        Iif (!nextStateValue) {
          continue;
        }
 
        const nextStateId = JSON.stringify(nextStateValue);
 
        if (!visited.has(nextStateId)) {
          path.push({ state: JSON.parse(fromPathId), event: subEvent });
          util(nextStateId, toPathId);
        }
      }
    }
 
    path.pop();
    visited.delete(fromPathId);
  }
 
  const initialStateId = JSON.stringify(machine.initialState.value);
 
  keys(adjacency).forEach(nextStateId => {
    util(initialStateId, nextStateId);
  });
 
  return paths;
}
 
export function getSimplePathsAsArray<TContext = DefaultContext>(
  machine: StateNode<TContext>,
  context?: TContext
): PathsItem[] {
  const result = getSimplePaths(machine, context);
  return keys(result).map(key => ({
    state: JSON.parse(key),
    paths: result[key]
  }));
}