perf(mdc-chips): Use class for MDC adapter

src/material-experimental/mdc-chips/chip-icons.ts

@@ -50,6 +50,36 @@ export class MatChipAvatar {
   }
 }
 
+class ChipTrailingActionAdapter implements MDCChipTrailingActionAdapter {
+  constructor(private _delegate: MatChipTrailingIcon) {}
+
+  focus() {
+    this._delegate._elementRef.nativeElement.focus();
+  }
+
+  getAttribute(name: string) {
+    return this._delegate._elementRef.nativeElement.getAttribute(name);
+  }
+
+  setAttribute(name: string, value: string) {
+    this._delegate._elementRef.nativeElement.setAttribute(name, value);
+  }
+
+  // TODO(crisbeto): there's also a `trigger` parameter that the chip isn't
+  // handling yet. Consider passing it along once MDC start using it.
+  notifyInteraction() {
+    // TODO(crisbeto): uncomment this code once we've inverted the
+    // dependency on `MatChip`. this._chip._notifyInteraction();
+  }
+
+  // TODO(crisbeto): there's also a `key` parameter that the chip isn't
+  // handling yet. Consider passing it along once MDC start using it.
+  notifyNavigation() {
+    // TODO(crisbeto): uncomment this code once we've inverted the
+    // dependency on `MatChip`. this._chip._notifyNavigation();
+  }
+}
+
 /**
  * Injection token that can be used to reference instances of `MatChipTrailingIcon`. It serves as
  * alternative token to the actual `MatChipTrailingIcon` class which could cause unnecessary
@@ -74,30 +104,6 @@ export const MAT_CHIP_TRAILING_ICON =
 })
 export class MatChipTrailingIcon implements OnDestroy {
   private _foundation: MDCChipTrailingActionFoundation;
-  private _adapter: MDCChipTrailingActionAdapter = {
-    focus: () => this._elementRef.nativeElement.focus(),
-    getAttribute: (name: string) =>
-        this._elementRef.nativeElement.getAttribute(name),
-    setAttribute:
-        (name: string, value: string) => {
-          this._elementRef.nativeElement.setAttribute(name, value);
-        },
-    // TODO(crisbeto): there's also a `trigger` parameter that the chip isn't
-    // handling yet. Consider passing it along once MDC start using it.
-    notifyInteraction:
-        () => {
-          // TODO(crisbeto): uncomment this code once we've inverted the
-          // dependency on `MatChip`. this._chip._notifyInteraction();
-        },
-
-    // TODO(crisbeto): there's also a `key` parameter that the chip isn't
-    // handling yet. Consider passing it along once MDC start using it.
-    notifyNavigation:
-        () => {
-          // TODO(crisbeto): uncomment this code once we've inverted the
-          // dependency on `MatChip`. this._chip._notifyNavigation();
-        }
-  };
 
   constructor(
       public _elementRef: ElementRef,
@@ -106,7 +112,7 @@ export class MatChipTrailingIcon implements OnDestroy {
       // method is removed, we can't use the chip here, because it causes a
       // circular import. private _chip: MatChip
   ) {
-    this._foundation = new MDCChipTrailingActionFoundation(this._adapter);
+    this._foundation = new MDCChipTrailingActionFoundation(new ChipTrailingActionAdapter(this));
   }
 
   ngOnDestroy() {

src/material-experimental/mdc-chips/chip-listbox.ts

@@ -31,7 +31,7 @@ import {merge, Observable, Subscription} from 'rxjs';
 import {startWith, takeUntil} from 'rxjs/operators';
 import {MatChip, MatChipEvent} from './chip';
 import {MatChipOption, MatChipSelectionChange} from './chip-option';
-import {MatChipSet} from './chip-set';
+import {MatChipSet, ChipSetAdapter} from './chip-set';
 
 
 /** Change event object that is emitted when the chip listbox value has changed. */
@@ -212,7 +212,7 @@ export class MatChipListbox extends MatChipSet implements AfterContentInit, Cont
       this._setSelected(index, selected);
     };
     // Reinitialize the foundation with our overridden adapter
-    this._chipSetFoundation = new MDCChipSetFoundation(this._chipSetAdapter);
+    this._chipSetFoundation = new MDCChipSetFoundation(new ChipSetAdapter(this));
     this._updateMdcSelectionClasses();
   }
 

src/material-experimental/mdc-chips/chip-set.ts

@@ -31,6 +31,47 @@ import {MatChip, MatChipEvent} from './chip';
 
 let uid = 0;
 
+/** @docs-private */
+export class ChipSetAdapter implements MDCChipSetAdapter {
+
+  constructor(private _delegate: MatChipSet) {}
+
+  hasClass(className: string) {
+    return this._delegate._hasMdcClass(className);
+  }
+
+  // No-op. We keep track of chips via ContentChildren, which will be updated when a chip is
+  // removed.
+  removeChipAtIndex() {
+    return;
+  }
+
+  // No-op for base chip set. MatChipListbox overrides the adapter to provide this method.
+  selectChipAtIndex() {
+    return;
+  }
+
+  getIndexOfChipById(id: string) {
+    return this._delegate._chips.toArray().findIndex(chip => chip.id === id);
+  }
+
+  focusChipPrimaryActionAtIndex() {}
+
+  focusChipTrailingActionAtIndex() {}
+
+  removeFocusFromChipAtIndex() {}
+
+  isRTL() {
+    return !!this._delegate._dir && this._delegate._dir.value === 'rtl';
+  }
+
+  getChipListCount() {
+    return this._delegate._chips.length;
+  }
+
+  // TODO(mmalerba): Implement using LiveAnnouncer.
+  announceMessage() {}
+}
 
 /**
  * Boilerplate for applying mixins to MatChipSet.
@@ -90,22 +131,7 @@ export class MatChipSet extends _MatChipSetMixinBase implements AfterContentInit
    * Implementation of the MDC chip-set adapter interface.
    * These methods are called by the chip set foundation.
    */
-  protected _chipSetAdapter: MDCChipSetAdapter = {
-    hasClass: (className) => this._hasMdcClass(className),
-    // No-op. We keep track of chips via ContentChildren, which will be updated when a chip is
-    // removed.
-    removeChipAtIndex: () => {},
-    // No-op for base chip set. MatChipListbox overrides the adapter to provide this method.
-    selectChipAtIndex: () => {},
-    getIndexOfChipById: (id: string) => this._chips.toArray().findIndex(chip => chip.id === id),
-    focusChipPrimaryActionAtIndex: () => {},
-    focusChipTrailingActionAtIndex: () => {},
-    removeFocusFromChipAtIndex: () => {},
-    isRTL: () => !!this._dir && this._dir.value === 'rtl',
-    getChipListCount: () => this._chips.length,
-    // TODO(mmalerba): Implement using LiveAnnouncer.
-    announceMessage: () => {},
-  };
+  protected _chipSetAdapter: MDCChipSetAdapter;
 
   /** The aria-describedby attribute on the chip list for improved a11y. */
   _ariaDescribedby: string;
@@ -161,9 +187,9 @@ export class MatChipSet extends _MatChipSetMixinBase implements AfterContentInit
 
   constructor(protected _elementRef: ElementRef,
               protected _changeDetectorRef: ChangeDetectorRef,
-              @Optional() protected _dir: Directionality) {
+              @Optional() readonly _dir: Directionality) {
     super(_elementRef);
-    this._chipSetFoundation = new MDCChipSetFoundation(this._chipSetAdapter);
+    this._chipSetFoundation = new MDCChipSetFoundation(new ChipSetAdapter(this));
   }
 
   ngAfterViewInit() {
@@ -214,7 +240,7 @@ export class MatChipSet extends _MatChipSetMixinBase implements AfterContentInit
   }
 
   /** Adapter method that returns true if the chip set has the given MDC class. */
-  protected _hasMdcClass(className: string) {
+  _hasMdcClass(className: string) {
     return this._elementRef.nativeElement.classList.contains(className);
   }