Support * event type for mapping/handling

#9

README.md

@@ -95,6 +95,16 @@ const eventsWithoutCtx = EventEmitter.of();
 }
 ```
 
+### * event type
+
+`*` is a special event type which denotes all events. This allows you to add a mapper or handler to all events. For example:
+
+```js
+events.map('*', payload => {
+  //
+});
+```
+
 ---
 
 ### API

docs/migrations/00009.md

@@ -0,0 +1,9 @@
+#### Changes made to event mappers/handlers on '*' event type
+
+The following examples will run on every event type, where previously they
+only ran on events with an explicit type '*'.
+
+```js
+events.on('*', (payload) => {});
+events.map('*', (payload) => {});
+```

src/__tests__/index.js

@@ -54,10 +54,92 @@ test('Base EventEmitter mappers', t => {
     mapCount++;
     return Object.assign(event, {a: true});
   });
-  events.emit('test', {
-    b: true,
-  });
+  events.emit('test', {b: true});
   t.equal(eventHandlerCount, 1, 'calls handler one time');
   t.equal(mapCount, 1, 'calls mapper one time');
   t.end();
 });
+
+test('Base EventEmitter * mappers', t => {
+  const events = new EventEmitter();
+  events.map('*', payload => {
+    return {...payload, a: true};
+  });
+  events.map('test', payload => {
+    return {...payload, b: true};
+  });
+  events.on('test', payload => {
+    t.deepLooseEqual(payload, {
+      a: true,
+      b: true,
+      c: true,
+    });
+    t.end();
+  });
+  events.emit('test', {c: true});
+});
+
+test('Base EventEmitter implicit * mappers', t => {
+  const events = new EventEmitter();
+  events.map(payload => {
+    return {...payload, a: true};
+  });
+  events.map('test', payload => {
+    return {...payload, b: true};
+  });
+  events.on('test', payload => {
+    t.deepLooseEqual(payload, {
+      a: true,
+      b: true,
+      c: true,
+    });
+    t.end();
+  });
+  events.emit('test', {c: true});
+});
+
+test('Base EventEmitter * handlers', t => {
+  const events = new EventEmitter();
+  let calledGlobal = false;
+  let calledNormal = false;
+  events.on(payload => {
+    t.deepLooseEqual(payload, {
+      c: true,
+    });
+    calledGlobal = true;
+  });
+
+  events.on('test', payload => {
+    t.deepLooseEqual(payload, {
+      c: true,
+    });
+    calledNormal = true;
+  });
+  events.emit('test', {c: true});
+  t.ok(calledGlobal);
+  t.ok(calledNormal);
+  t.end();
+});
+
+test('Base EventEmitter implicit * handlers', t => {
+  const events = new EventEmitter();
+  let calledGlobal = false;
+  let calledNormal = false;
+  events.on('*', payload => {
+    t.deepLooseEqual(payload, {
+      c: true,
+    });
+    calledGlobal = true;
+  });
+
+  events.on('test', payload => {
+    t.deepLooseEqual(payload, {
+      c: true,
+    });
+    calledNormal = true;
+  });
+  events.emit('test', {c: true});
+  t.ok(calledGlobal);
+  t.ok(calledNormal);
+  t.end();
+});

src/emitter.js

@@ -20,15 +20,16 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+const globalEventType = '*';
 export default class UniversalEmitter {
   constructor() {
     this.handlers = {};
     this.mappers = {};
   }
-  map(type, mapper) {
-    validateHandler(mapper);
+  map(...args) {
+    const {type, callback} = getArgs(args);
     if (!this.mappers[type]) this.mappers[type] = [];
-    this.mappers[type].push(mapper);
+    this.mappers[type].push(callback);
   }
   on(...args) {
     const {type, callback} = getArgs(args);
@@ -41,8 +42,10 @@ export default class UniversalEmitter {
     if (index > -1) this.handlers[type].splice(index, 1);
   }
   emit(type, payload, ctx) {
-    const mappers = this.mappers[type] || [];
-    const handlers = this.handlers[type] || [];
+    const globalMappers = this.mappers[globalEventType] || [];
+    const globalHandlers = this.handlers[globalEventType] || [];
+    const mappers = (this.mappers[type] || []).concat(globalMappers);
+    const handlers = (this.handlers[type] || []).concat(globalHandlers);
     const event = {
       type,
       payload: mappers.reduce((payload, mapper) => {