feat(interceptors): add default FX_UNDO/REDO side fx

thi-ng · Apr 14, 2018 · a102eb7 · a102eb7
1 parent ba0c876
commit a102eb7
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Showing 2 changed files with 27 additions and 4 deletions.
diff --git a/packages/interceptors/src/api.ts b/packages/interceptors/src/api.ts
@@ -27,17 +27,17 @@ export const FX_STATE = "--state";
 /**
  * Currently unused
  */
-export const FX_REDO_RESTORE = "--redo-restore";
+export const FX_REDO = "--redo";
 
 /**
  * Currently unused
  */
-export const FX_UNDO_STORE = "--undo-store";
+export const FX_UNDO = "--undo";
 
 /**
  * Currently unused
  */
-export const FX_UNDO_RESTORE = "--undo-restore";
+export const FX_UNDO_STORE = "--undo-store";
 
 export interface Event extends Array<any> {
     [0]: PropertyKey;
@@ -61,5 +61,8 @@ export interface InterceptorContext {
     [FX_DISPATCH]?: Event | Event[];
     [FX_DISPATCH_NOW]?: Event | Event[];
     [FX_DISPATCH_ASYNC]?: AsyncEffectDef | AsyncEffectDef[];
+    [FX_UNDO_STORE]?: string | string[];
+    [FX_UNDO]?: string | string[];
+    [FX_REDO]?: string | string[];
     [id: string]: any;
 }
diff --git a/packages/interceptors/src/event-bus.ts b/packages/interceptors/src/event-bus.ts
@@ -551,6 +551,22 @@ export class EventBus extends StatelessEventBus implements
      * Resets state atom to provided value (only a single update per
      * processing frame)
      *
+     * #### `FX_UNDO`
+     *
+     * Calls `ctx[fxarg].undo()` where `fxarg` is the value assigned to
+     * the `FX_UNDO` side effect by an event handler, e.g.
+     *
+     * ```
+     * // example event handler
+     * // assumes that `ctx.history` is a @thi.ng/atom/History instance or similar
+     * (state, e, bus, ctx) => ({ [FX_UNDO]: "history" })
+     * ```
+     *
+     * #### `FX_REDO`
+     *
+     * Similar to `FX_UNDO`, but calls `ctx[fxarg].redo()` where `fxarg`
+     * is the value assigned to the `FX_REDO` side effect by an event
+     * handler.
      */
     addBuiltIns(): any {
         super.addBuiltIns();
@@ -563,7 +579,11 @@ export class EventBus extends StatelessEventBus implements
                 ({ [FX_STATE]: updateIn(state, path, fn, ...args) }));
 
         // effects
-        this.addEffect(FX_STATE, (x) => this.state.reset(x), -1000);
+        this.addEffects({
+            [FX_STATE]: [(x) => this.state.reset(x), -1000],
+            [api.FX_UNDO]: [(x, _, ctx) => ctx[x].undo(), -1000],
+            [api.FX_REDO]: [(x, _, ctx) => ctx[x].redo(), -1000],
+        });
     }
 
     /**