feat(directionality): a provider to get the overall directionality

- Looks at the `html` and `body` elements for `dir` attribute and sets the Directionality service value to it
- Whenever someone would try to inject Directionality - if there's a Dir directive up the dom tree it would be provided

fixes #3600

Author: EladBezalel

src/lib/autocomplete/autocomplete-trigger.ts

@@ -17,7 +17,7 @@ import {ConnectedPositionStrategy} from '../core/overlay/position/connected-posi
 import {Observable} from 'rxjs/Observable';
 import {MdOptionSelectionChange, MdOption} from '../core/option/option';
 import {ENTER, UP_ARROW, DOWN_ARROW} from '../core/keyboard/keycodes';
-import {Dir} from '../core/rtl/dir';
+import {Directionality} from '../core/bidi/index';
 import {Subscription} from 'rxjs/Subscription';
 import {Subject} from 'rxjs/Subject';
 import 'rxjs/add/observable/merge';
@@ -101,7 +101,7 @@ export class MdAutocompleteTrigger implements ControlValueAccessor, OnDestroy {
 
   constructor(private _element: ElementRef, private _overlay: Overlay,
               private _viewContainerRef: ViewContainerRef,
-              @Optional() private _dir: Dir, private _zone: NgZone,
+              @Optional() private _dir: Directionality, private _zone: NgZone,
               @Optional() @Host() private _inputContainer: MdInputContainer) {}
 
   ngOnDestroy() {

src/lib/autocomplete/autocomplete.spec.ts

@@ -5,7 +5,7 @@ import {NoopAnimationsModule} from '@angular/platform-browser/animations';
 import {MdAutocompleteModule, MdAutocompleteTrigger} from './index';
 import {OverlayContainer} from '../core/overlay/overlay-container';
 import {MdInputModule} from '../input/index';
-import {Dir, LayoutDirection} from '../core/rtl/dir';
+import {Directionality, Direction} from '../core/bidi/index';
 import {FormControl, FormsModule, ReactiveFormsModule} from '@angular/forms';
 import {Subscription} from 'rxjs/Subscription';
 import {ENTER, DOWN_ARROW, SPACE, UP_ARROW} from '../core/keyboard/keycodes';
@@ -22,7 +22,7 @@ import 'rxjs/add/operator/map';
 
 describe('MdAutocomplete', () => {
   let overlayContainerElement: HTMLElement;
-  let dir: LayoutDirection;
+  let dir: Direction;
 
   beforeEach(async(() => {
     dir = 'ltr';
@@ -51,7 +51,7 @@ describe('MdAutocomplete', () => {
 
           return {getContainerElement: () => overlayContainerElement};
         }},
-        {provide: Dir, useFactory: () => {
+        {provide: Directionality, useFactory: () => {
           return {value: dir};
         }},
         {provide: ViewportRuler, useClass: FakeViewportRuler}

src/lib/core/bidi/dir.ts

@@ -0,0 +1,49 @@
+import {
+  Directive,
+  HostBinding,
+  Output,
+  Input,
+  EventEmitter
+} from '@angular/core';
+
+import {Direction, Directionality} from './directionality';
+
+/**
+ * Directive to listen for changes of direction of part of the DOM.
+ *
+ * Would provide itself in case a component looks for the Directionality service
+ */
+@Directive({
+  selector: '[dir]',
+  // TODO(hansl): maybe `$implicit` isn't the best option here, but for now that's the best we got.
+  exportAs: '$implicit',
+  providers: [
+    {provide: Directionality, useExisting: Dir}
+  ]
+})
+export class Dir implements Directionality {
+  /** Layout direction of the element. */
+  @Input('dir') _dir: Direction = 'ltr';
+
+  /** Event emitted when the direction changes. */
+  @Output() change = new EventEmitter<void>();
+
+  /** @docs-private */
+  @HostBinding('attr.dir')
+  get dir(): Direction {
+    return this._dir;
+  }
+
+  set dir(v: Direction) {
+    let old = this._dir;
+    this._dir = v;
+    if (old != this._dir) {
+      this.change.emit();
+    }
+  }
+
+  /** Current layout direction of the element. */
+  get value(): Direction { return this.dir; }
+  set value(v: Direction) { this.dir = v; }
+}
+

src/lib/core/bidi/directionality.ts

@@ -0,0 +1,60 @@
+import {
+  EventEmitter,
+  Injectable,
+  ModuleWithProviders,
+  NgModule,
+  Optional,
+  SkipSelf
+} from '@angular/core';
+
+import {Dir} from './dir';
+
+export type Direction = 'ltr' | 'rtl';
+
+/**
+ * The directionality (LTR / RTL) context for the application (or a subtree of it).
+ * Exposes the current direction and a stream of direction changes.
+ */
+@Injectable()
+export class Directionality {
+  value: Direction = 'ltr';
+  change: EventEmitter<void> = new EventEmitter<void>();
+
+  constructor() {
+    if (document) {
+    // TODO: handle auto value -
+    // We still need to account for dir="auto".
+    // It looks like HTMLElemenet.dir is also "auto" when that's set to the attribute,
+    // but getComputedStyle return either "ltr" or "rtl". avoiding getComputedStyle for now
+    // though, we're already calling it for the theming check.
+    this.value =
+      (document.body.getAttribute('dir') ||
+      document.documentElement.getAttribute('dir') ||
+      'ltr') as Direction;
+    }
+  }
+}
+
+@NgModule({
+  exports: [Dir],
+  declarations: [Dir],
+  providers: [Directionality]
+})
+export class BidiModule {
+  /** @deprecated */
+  static forRoot(): ModuleWithProviders {
+    return {
+      ngModule: BidiModule,
+      providers: [DIRECTIONALITY_PROVIDER]
+    };
+  }
+}
+
+export const DIRECTIONALITY_PROVIDER = {
+  // If there is already a Directionality available, use that. Otherwise, provide a new one.
+  provide: Directionality,
+  deps: [[new Optional(), new SkipSelf(), Directionality]],
+  useFactory: function (parentDirectionality) {
+    return parentDirectionality || new Directionality();
+  }
+};

src/lib/core/bidi/index.ts

@@ -0,0 +1,7 @@
+export {
+  Directionality,
+  BidiModule,
+  DIRECTIONALITY_PROVIDER,
+  Direction
+} from './directionality';
+export {Dir} from './dir';

src/lib/core/core.ts

@@ -1,6 +1,6 @@
 import {NgModule, ModuleWithProviders} from '@angular/core';
 import {MdLineModule} from './line/line';
-import {RtlModule} from './rtl/dir';
+import {BidiModule} from './bidi/index';
 import {ObserveContentModule} from './observe-content/observe-content';
 import {MdOptionModule} from './option/option';
 import {PortalModule} from './portal/portal-directives';
@@ -11,7 +11,7 @@ import {MdRippleModule} from './ripple/index';
 
 
 // RTL
-export {Dir, LayoutDirection, RtlModule} from './rtl/dir';
+export {Dir, Direction, Directionality, BidiModule} from './bidi/index';
 
 // Mutation Observer
 export {ObserveContentModule, ObserveContent} from './observe-content/observe-content';
@@ -117,7 +117,7 @@ export {CompatibilityModule, NoConflictStyleCompatibilityMode} from './compatibi
 @NgModule({
   imports: [
     MdLineModule,
-    RtlModule,
+    BidiModule,
     MdRippleModule,
     ObserveContentModule,
     PortalModule,
@@ -128,7 +128,7 @@ export {CompatibilityModule, NoConflictStyleCompatibilityMode} from './compatibi
   ],
   exports: [
     MdLineModule,
-    RtlModule,
+    BidiModule,
     MdRippleModule,
     ObserveContentModule,
     PortalModule,

src/lib/core/overlay/overlay-directives.spec.ts

@@ -5,7 +5,7 @@ import {ConnectedOverlayDirective, OverlayModule} from './overlay-directives';
 import {OverlayContainer} from './overlay-container';
 import {ConnectedPositionStrategy} from './position/connected-position-strategy';
 import {ConnectedOverlayPositionChange} from './position/connected-position';
-import {Dir} from '../rtl/dir';
+import {Directionality} from '../bidi/index';
 
 
 describe('Overlay directives', () => {
@@ -22,7 +22,7 @@ describe('Overlay directives', () => {
           overlayContainerElement = document.createElement('div');
           return {getContainerElement: () => overlayContainerElement};
         }},
-        {provide: Dir, useFactory: () => {
+        {provide: Directionality, useFactory: () => {
           return dir = { value: 'ltr' };
         }}
       ],

src/lib/core/overlay/overlay-directives.ts

@@ -22,7 +22,7 @@ import {
 import {PortalModule} from '../portal/portal-directives';
 import {ConnectedPositionStrategy} from './position/connected-position-strategy';
 import {Subscription} from 'rxjs/Subscription';
-import {Dir, LayoutDirection} from '../rtl/dir';
+import {Directionality, Direction} from '../bidi/index';
 import {Scrollable} from './scroll/scrollable';
 import {coerceBooleanProperty} from '../coercion/boolean-property';
 
@@ -154,7 +154,7 @@ export class ConnectedOverlayDirective implements OnDestroy {
       private _overlay: Overlay,
       templateRef: TemplateRef<any>,
       viewContainerRef: ViewContainerRef,
-      @Optional() private _dir: Dir) {
+      @Optional() private _dir: Directionality) {
     this._templatePortal = new TemplatePortal(templateRef, viewContainerRef);
   }
 
@@ -164,7 +164,7 @@ export class ConnectedOverlayDirective implements OnDestroy {
   }
 
   /** The element's layout direction. */
-  get dir(): LayoutDirection {
+  get dir(): Direction {
     return this._dir ? this._dir.value : 'ltr';
   }
 

src/lib/core/overlay/overlay-state.ts

@@ -1,5 +1,5 @@
 import {PositionStrategy} from './position/position-strategy';
-import {LayoutDirection} from '../rtl/dir';
+import {Direction} from '../bidi/index';
 
 
 /**
@@ -29,7 +29,7 @@ export class OverlayState {
   minHeight: number | string;
 
   /** The direction of the text in the overlay panel. */
-  direction: LayoutDirection = 'ltr';
+  direction: Direction = 'ltr';
 
   // TODO(jelbourn): configuration still to add
   // - focus trap