refactor: preserve context when invoking the error state matcher

Author: crisbeto

src/lib/core/core.ts

@@ -128,7 +128,6 @@ export {
   MdError,
   ErrorStateMatcher,
   ErrorOptions,
-  defaultErrorStateMatcher,
   showOnDirtyErrorStateMatcher,
 } from './error/index';
 

src/lib/core/error/error-options.ts

@@ -12,11 +12,6 @@ import {FormGroupDirective, NgForm, NgControl} from '@angular/forms';
 export type ErrorStateMatcher =
   (control: NgControl | null, form: FormGroupDirective | NgForm | null) => boolean;
 
-/** Returns whether control is invalid and is either touched or is a part of a submitted form. */
-export const defaultErrorStateMatcher: ErrorStateMatcher = (control, form) => {
-  return control ? !!(control.invalid && (control.touched || (form && form.submitted))) : false;
-};
-
 /** Returns whether control is invalid and is either dirty or is a part of a submitted form. */
 export const showOnDirtyErrorStateMatcher: ErrorStateMatcher = (control, form) => {
   return control ? !!(control.invalid && (control.dirty || (form && form.submitted))) : false;
@@ -28,5 +23,7 @@ export const showOnDirtyErrorStateMatcher: ErrorStateMatcher = (control, form) =
  */
 @Injectable()
 export class ErrorOptions {
-  errorStateMatcher: ErrorStateMatcher = defaultErrorStateMatcher;
+  isErrorState(control: NgControl | null, form: FormGroupDirective | NgForm | null): boolean {
+    return control ? !!(control.invalid && (control.touched || (form && form.submitted))) : false;
+  }
 }

src/lib/input/input-container.spec.ts

@@ -898,7 +898,7 @@ describe('MdInputContainer with forms', () => {
         providers: [
           {
             provide: ErrorOptions,
-            useValue: { errorStateMatcher: globalErrorStateMatcher } }
+            useValue: { isErrorState: globalErrorStateMatcher } }
         ]
       });
 
@@ -929,7 +929,7 @@ describe('MdInputContainer with forms', () => {
         providers: [
           {
             provide: ErrorOptions,
-            useValue: { errorStateMatcher: showOnDirtyErrorStateMatcher }
+            useValue: { isErrorState: showOnDirtyErrorStateMatcher }
           }
         ]
       });

src/lib/input/input-container.ts

@@ -300,8 +300,9 @@ export class MdInputDirective implements OnChanges, OnDestroy, DoCheck {
   /** Re-evaluates the error state. This is only relevant with @angular/forms. */
   private _updateErrorState() {
     const oldState = this._isErrorState;
-    const errorMatcher = this.errorStateMatcher || this._errorOptions.errorStateMatcher;
-    const newState = errorMatcher(this._ngControl, this._parentFormGroup || this._parentForm);
+    const newState = this.errorStateMatcher ?
+        this.errorStateMatcher(this._ngControl, this._parentFormGroup || this._parentForm) :
+        this._errorOptions.isErrorState(this._ngControl, this._parentFormGroup || this._parentForm);
 
     if (newState !== oldState) {
       this._isErrorState = newState;

src/lib/input/input.md

@@ -139,7 +139,7 @@ cause input errors to show when the input is dirty and invalid.
 ```ts
 @NgModule({
   providers: [
-    {provide: ErrorOptions, useValue: { errorStateMatcher: showOnDirtyErrorStateMatcher }}
+    {provide: ErrorOptions, useValue: { isErrorState: showOnDirtyErrorStateMatcher }}
   ]
 })
 ```

src/lib/select/select.spec.ts

@@ -2698,7 +2698,7 @@ describe('MdSelect', () => {
 
     it('should be able to override the error matching behavior via the injection token', () => {
       const errorOptions: ErrorOptions = {
-        errorStateMatcher: jasmine.createSpy('error state matcher').and.returnValue(true)
+        isErrorState: jasmine.createSpy('error state matcher').and.returnValue(true)
       };
 
       fixture.destroy();

src/lib/select/select.ts

@@ -638,8 +638,12 @@ export class MdSelect extends _MdSelectMixinBase implements AfterContentInit, On
 
   /** Whether the select is in an error state. */
   _isErrorState(): boolean {
-    const errorMatcher = this.errorStateMatcher || this._errorOptions.errorStateMatcher;
-    return errorMatcher(this._control, this._parentFormGroup || this._parentForm);
+    if (this.errorStateMatcher) {
+      return this.errorStateMatcher(this._control, this._parentFormGroup || this._parentForm);
+    }
+
+    return this._errorOptions.isErrorState(this._control,
+        this._parentFormGroup || this._parentForm);
   }
 
   /**