perf(api): Injector API updated to inject via an 'inject' prop.

The Injector no longer supports the 'elements' prop, it now has an 'inject' prop which allows you to
pass through either a stateless component (that will recieve the same props as the component being
wrapped) or an element.  Using the stateless component method is preferable as it will only be
executed when needed, whereas passing an element requires you to actually create the element up
front.

closes #1 BREAKING CHANGE: The Injector no longer supports the 'elements' prop, it now has an
'inject' prop which allows you to pass through either a stateless component (that will recieve the
same props as the component being wrapped) or an element. Using the stateless component method is
preferable as it will only be executed when needed, whereas passing an element requires you to
acutally create the element up front.

examples/router/src/InjectableHeader.js

@@ -7,7 +7,6 @@ const Header = ({ injected }) => (
   <div style={{ backgroundColor: `red`, color: `white` }}>
     <h1>INJECTABLE HEADER</h1>
     <div>
-      <strong>INJECTED ITEMS:</strong>
       {injected.length > 0 ? injected : <div>Nothing has been injected</div>}
     </div>
   </div>

examples/router/src/PageOne.js

@@ -9,5 +9,5 @@ const PageOne = () => (
 );
 export default Injector({
   to: InjectableHeader,
-  elements: [<div>Injection from Page One</div>]
+  inject: () => <div>Injection from Page One</div>
 })(PageOne);

examples/router/src/PageTwo.js

@@ -8,7 +8,15 @@ const PageTwo = () => (
   </div>
 );
 
+const Inject = (props) => (
+  <div>
+    Injection from Page Two.<br />
+    I also recieved these props:<br />
+  {Object.keys(props).join(`, `)}
+  </div>
+);
+
 export default Injector({
   to: InjectableHeader,
-  elements: [<div>Injection from Page Two</div>]
+  inject: Inject
 })(PageTwo);

examples/router/src/index.js

@@ -16,7 +16,7 @@ ReactDOM.render((
       <Route path="/" component={App}>
         <IndexRoute component={Home} />
         <Route path="pageOne" component={PageOne} />
-        <Route path="pageTwo" component={PageTwo} />
+        <Route path="pageTwo" component={() => <PageTwo foo bar baz />} />
       </Route>
     </Router>
   </InjectablesProvider>

src/Injectable.js

@@ -1,33 +1,36 @@
 import React, { PropTypes, Component } from 'react';
 import { containsUniq, keyedElements } from './utils';
 
-let injectionIndex = 0;
+let injectionIdIndex = 0;
 
 const Injectable = (WrappedComponent) => {
-  injectionIndex++;
-  const injectionId = `injection_${injectionIndex}`;
+  injectionIdIndex++;
+  const injectionId = `injectionId_${injectionIdIndex}`;
 
   class InjectableComponent extends Component {
     static injectionId = injectionId;
 
     static contextTypes = {
-      consumeElements: PropTypes.func.isRequired,
-      stopConsumingElements: PropTypes.func.isRequired
+      registerInjectable: PropTypes.func.isRequired,
+      removeInjectable: PropTypes.func.isRequired
     };
 
     state = {
       injected: []
     }
 
     componentWillMount() {
-      this.context.consumeElements({
-        injectionId: InjectableComponent.injectionId,
+      this.context.registerInjectable({
+        injectionId,
         injectable: this
       });
     }
 
     componentWillUnmount() {
-      this.context.stopConsumingElements({ listener: this });
+      this.context.removeInjectable({
+        injectionId,
+        injectable: this
+      });
     }
 
     consume = (elements) => {

src/Injector.js

@@ -1,29 +1,44 @@
 import React, { PropTypes, Component } from 'react';
 
-const Injector = (args: { to: Object, elements : Array<Object> }) => {
-  const { to, elements } = args;
+type Inject = Object | (props: Object) => Object;
+
+let injectorIndex = 0;
+
+const Injector = (args: { to: Object, inject: Inject }) => {
+  const { to, inject } = args;
+
+  injectorIndex++;
+  const injectorId = `injector_${injectorIndex}`;
 
   return function WrapComponent(WrappedComponent) {
     class InjectorComponent extends Component {
       static contextTypes = {
-        produceElements: PropTypes.func.isRequired,
-        removeProducer: PropTypes.func.isRequired
+        registerInjector: PropTypes.func.isRequired,
+        removeInjector: PropTypes.func.isRequired
       };
 
       componentWillMount() {
-        this.context.produceElements({
+        this.context.registerInjector({
           injectionId: to.injectionId,
-          injector: this,
-          elements
+          injectorId,
+          injector: this
         });
       }
 
       componentWillUnmount() {
-        this.context.removeProducer({
-          injectionId: to.injectionId, injector: this
+        this.context.removeInjector({
+          injectionId: to.injectionId,
+          injector: this
         });
       }
 
+      getInjectElement = () => {
+        if (typeof inject === `function`) {
+          return inject(this.props);
+        }
+        return inject;
+      }
+
       render() {
         return (<WrappedComponent {...this.props} />);
       }

src/Provider.js

@@ -1,12 +1,12 @@
 import { Children, Component, PropTypes } from 'react';
-import { compose, concatAll, find, map, uniq, without, withoutAll } from './utils';
+import { compose, find, map, uniqBy, without, withoutAll } from './utils';
 
 class InjectablesProvider extends Component {
   static childContextTypes = {
-    produceElements: PropTypes.func.isRequired,
-    removeProducer: PropTypes.func.isRequired,
-    consumeElements: PropTypes.func.isRequired,
-    stopConsumingElements: PropTypes.func.isRequired,
+    registerInjector: PropTypes.func.isRequired,
+    removeInjector: PropTypes.func.isRequired,
+    registerInjectable: PropTypes.func.isRequired,
+    removeInjectable: PropTypes.func.isRequired,
   };
 
   static propTypes = {
@@ -20,13 +20,13 @@ class InjectablesProvider extends Component {
 
   getChildContext() {
     return {
-      produceElements: (args) => this.produceElements(args),
+      registerInjector: (args) => this.registerInjector(args),
 
-      removeProducer: (args) => this.removeProducer(args),
+      removeInjector: (args) => this.removeInjector(args),
 
-      consumeElements: (args) => this.consumeElements(args),
+      registerInjectable: (args) => this.registerInjectable(args),
 
-      stopConsumingElements: (args) => this.stopConsumingElements(args)
+      removeInjectable: (args) => this.removeInjectable(args)
     };
   }
 
@@ -38,11 +38,10 @@ class InjectablesProvider extends Component {
       )(this.registrations);
 
     if (!registration) {
-      // Need to create the registration.
       registration = {
         injectionId,
         injectables: [],
-        injectors: []
+        injections: []
       };
 
       this.registrations.push(registration);
@@ -51,15 +50,14 @@ class InjectablesProvider extends Component {
     return registration;
   }
 
-  notifyConsumers(args: { registration: Object }) {
+  runInjections(args: { registration: Object }) {
     const { registration } = args;
-    const { injectables, injectors } = registration;
+    const { injectables, injections } = registration;
 
     const elements = compose(
-      uniq,
-      concatAll,
-      map(x => x.elements)
-    )(injectors);
+      map(x => x.injector.getInjectElement()),
+      uniqBy(`injectorId`)
+    )(injections);
 
     injectables.forEach(injectable => {
       injectable.consume(elements);
@@ -71,56 +69,66 @@ class InjectablesProvider extends Component {
     this.registrations = without(registration)(this.registrations);
   }
 
-  consumeElements(args: { injectionId: string, injectable: Object}) {
+  registerInjectable(args: { injectionId: string, injectable: Object}) {
     const { injectionId, injectable } = args;
     const registration = this.getRegistration({ injectionId });
 
     if (withoutAll(registration.injectables)([injectable]).length > 0) {
       registration.injectables = [...registration.injectables, injectable];
-      this.notifyConsumers({ registration });  // First time consumption.
+      this.runInjections({ registration });  // First time consumption.
     }
   }
 
-  stopConsumingElements(args: { injectionId: string, injectable: Object }) {
+  removeInjectable(args: { injectionId: string, injectable: Object }) {
     const { injectionId, injectable } = args;
     const registration = this.getRegistration({ injectionId });
 
     const injectables = without(injectable)(registration.injectables);
 
-    if (injectables.length === 0 && registration.injectors.length === 0) {
+    if (injectables.length === 0 && registration.injections.length === 0) {
       this.removeRegistration({ registration });
     } else {
       registration.injectables = injectables;
     }
   }
 
-  findProducer({ registration, injector }) {
-    return find(x => Object.is(x.injector, injector))(registration.injectors);
+  findInjection({ registration, injector }) {
+    return find(x => Object.is(x.injector, injector))(registration.injections);
   }
 
-  produceElements(args: { injectionId: string, injector: Object, elements: Array<Object> }) {
-    const { injectionId, injector, elements } = args;
+  registerInjector(args: { injectionId: string, injectorId: string, injector: Object }) {
+    const { injectionId, injectorId, injector } = args;
     const registration = this.getRegistration({ injectionId });
-    const existingProducer = this.findProducer({ registration, injector });
+    const existingInjection = this.findInjection({ registration, injector });
 
-    if (existingProducer) {
+    if (existingInjection) {
       return;
     }
 
-    const newInjector = { injector, elements };
-    registration.injectors = [
-      ...registration.injectors,
-      newInjector
+    const newInjection = { injector, injectorId };
+    registration.injections = [
+      ...registration.injections,
+      newInjection
     ];
-    this.notifyConsumers({ registration });
+
+    this.runInjections({ registration });
   }
 
-  removeProducer(args: { injectionId: string, injector: Object }) {
+  removeInjector(args: { injectionId: string, injector: Object }) {
     const { injectionId, injector } = args;
     const registration = this.getRegistration({ injectionId });
-    const existingInjector = this.findProducer({ registration, injector });
-    registration.injectors = without(existingInjector)(registration.injectors);
-    this.notifyConsumers({ registration });
+    const injection = this.findInjection({ registration, injector });
+
+    if (injection) {
+      registration.injections = without(injection)(registration.injections);
+      this.runInjections({ registration });
+    } else {
+      /* istanbul ignore next */
+      if (process.env.NODE_ENV === `development`) {
+        throw new Error(
+          `Trying to remove an injector which has not been registered`);
+      }
+    }
   }
 
   render() {

src/utils/index.js → src/utils.js

@@ -14,6 +14,7 @@ import React, { Children } from 'react';
  */
 export function compose(...funcs) {
   return (...args) => {
+    /* istanbul ignore next */
     if (funcs.length === 0) {
       return args[0];
     }
@@ -47,8 +48,21 @@ export const withoutAll = (toRemove) => (point) =>
       (x) => all(y => !Object.is(x, y))(toRemove)
     )(point);
 
-// :: [a] -> [a]
-export const uniq = y => Array.from(new Set(y));
+// :: a -> [b]
+export const uniqBy = x => y => {
+  const checked = new Set();
+  const result = [];
+
+  y.forEach(a => {
+    const prop = a[x];
+    if (!checked.has(prop)) {
+      checked.add(prop);
+      result.push(a);
+    }
+  });
+
+  return result;
+};
 
 /**
  * :: [a] -> [a] -> boolean