refactor(drop-down): Clean up injection tokens and inheritance

It seems that Ivy does not like forwardRefs in some cases

Author: rkaraivanov

projects/igniteui-angular/src/lib/combo/combo.api.ts

@@ -1,8 +1,10 @@
 import { IgxComboBase } from './combo.common';
+import { Injectable } from '@angular/core';
 
 /**
  * @hidden
  */
+@Injectable()
 export class IgxComboAPIService {
     protected combo: IgxComboBase;
 

projects/igniteui-angular/src/lib/combo/combo.common.ts

@@ -1,8 +1,8 @@
-import { ElementRef, EventEmitter } from '@angular/core';
+import { ElementRef, EventEmitter, InjectionToken } from '@angular/core';
 import { CancelableEventArgs, CancelableBrowserEventArgs } from '../core/utils';
 import { IFilteringExpression } from '../data-operations/filtering-expression.interface';
 
-export const IGX_COMBO_COMPONENT = 'IgxComboComponentToken';
+export const IGX_COMBO_COMPONENT = new InjectionToken<IgxComboBase>('IgxComboComponentToken');
 
 /** @hidden @internal TODO: Evaluate */
 export interface IgxComboBase {

projects/igniteui-angular/src/lib/combo/combo.component.ts

@@ -2,7 +2,7 @@ import { ConnectedPositioningStrategy } from './../services/overlay/position/con
 import { CommonModule } from '@angular/common';
 import {
     AfterViewInit, ChangeDetectorRef, Component, ContentChild, ElementRef, EventEmitter, HostBinding, HostListener,
-    Input, NgModule, OnInit, OnDestroy, Output, TemplateRef, ViewChild, Optional, Inject, Injector, forwardRef, Type
+    Input, NgModule, OnInit, OnDestroy, Output, TemplateRef, ViewChild, Optional, Inject, Injector, Type
 } from '@angular/core';
 import {
     IgxComboItemDirective,
@@ -127,7 +127,7 @@ const noop = () => { };
     providers: [
         IgxComboAPIService,
         { provide: IGX_COMBO_COMPONENT, useExisting: IgxComboComponent },
-        { provide: NG_VALUE_ACCESSOR, useExisting: forwardRef(() => IgxComboComponent), multi: true }
+        { provide: NG_VALUE_ACCESSOR, useExisting: IgxComboComponent, multi: true }
     ]
 })
 export class IgxComboComponent extends DisplayDensityBase implements IgxComboBase, AfterViewInit, ControlValueAccessor, OnInit,
@@ -1638,6 +1638,5 @@ export class IgxComboComponent extends DisplayDensityBase implements IgxComboBas
         IgxComboClearIconDirective],
     imports: [IgxRippleModule, CommonModule, IgxInputGroupModule, FormsModule, ReactiveFormsModule,
         IgxForOfModule, IgxToggleModule, IgxCheckboxModule, IgxDropDownModule, IgxButtonModule, IgxIconModule],
-    providers: [IgxSelectionAPIService]
 })
 export class IgxComboModule { }

projects/igniteui-angular/src/lib/drop-down/drop-down-item.component.ts

@@ -1,6 +1,5 @@
 import {
     Component,
-    DoCheck,
     HostListener,
     HostBinding
 } from '@angular/core';
@@ -14,7 +13,7 @@ import { IgxDropDownItemBase } from './drop-down-item.base';
     selector: 'igx-drop-down-item',
     templateUrl: 'drop-down-item.component.html'
 })
-export class IgxDropDownItemComponent extends IgxDropDownItemBase implements DoCheck {
+export class IgxDropDownItemComponent extends IgxDropDownItemBase {
     /**
      * @inheritdoc
      */

projects/igniteui-angular/src/lib/drop-down/drop-down.common.ts

@@ -1,7 +1,7 @@
 import { CancelableEventArgs, CancelableBrowserEventArgs, IBaseEventArgs } from '../core/utils';
 import { IgxDropDownItemBase } from './drop-down-item.base';
 import { IToggleView } from '../core/navigation/IToggleView';
-import { EventEmitter } from '@angular/core';
+import { EventEmitter, InjectionToken } from '@angular/core';
 import { DisplayDensityBase } from '../core/density';
 
 /** @hidden */
@@ -39,7 +39,7 @@ export interface IDropDownNavigationDirective {
     onHomeKeyDown(event?: KeyboardEvent): void;
 }
 
-export const IGX_DROPDOWN_BASE = 'IgxDropDownBaseToken';
+export const IGX_DROPDOWN_BASE = new InjectionToken<IDropDownBase>('IgxDropDownBaseToken');
 
 /**
  * @hidden

projects/igniteui-angular/src/lib/expansion-panel/expansion-panel.common.ts

@@ -1,4 +1,4 @@
-import { EventEmitter } from '@angular/core';
+import { EventEmitter, InjectionToken } from '@angular/core';
 import { AnimationReferenceMetadata } from '@angular/animations';
 import { IBaseEventArgs } from '../core/utils';
 
@@ -17,7 +17,7 @@ export interface IgxExpansionPanelBase {
 }
 
 /** @hidden */
-export const IGX_EXPANSION_PANEL_COMPONENT = 'IgxExpansionPanelToken';
+export const IGX_EXPANSION_PANEL_COMPONENT = new InjectionToken<IgxExpansionPanelBase>('IgxExpansionPanelToken');
 
 export interface IExpansionPanelEventArgs extends IBaseEventArgs {
     event: Event;

projects/igniteui-angular/src/lib/expansion-panel/expansion-panel.component.ts

@@ -6,7 +6,6 @@ import {
     Input,
     Output,
     ContentChild,
-    forwardRef,
     AfterContentInit
 } from '@angular/core';
 import { AnimationBuilder, AnimationReferenceMetadata, useAnimation } from '@angular/animations';
@@ -161,15 +160,13 @@ export class IgxExpansionPanelComponent implements IgxExpansionPanelBase, AfterC
     /**
      * @hidden
      */
-    @ContentChild(forwardRef(() => IgxExpansionPanelBodyComponent),
-        { read: forwardRef(() => IgxExpansionPanelBodyComponent), static: false })
+    @ContentChild(IgxExpansionPanelBodyComponent, { read: IgxExpansionPanelBodyComponent, static: false })
     public body: IgxExpansionPanelBodyComponent;
 
     /**
      * @hidden
      */
-    @ContentChild(forwardRef(() => IgxExpansionPanelHeaderComponent),
-        { read: forwardRef(() => IgxExpansionPanelHeaderComponent), static: false })
+    @ContentChild(IgxExpansionPanelHeaderComponent, { read: IgxExpansionPanelHeaderComponent, static: false })
     public header: IgxExpansionPanelHeaderComponent;
 
     constructor(private cdr: ChangeDetectorRef, private builder: AnimationBuilder) { }