refactor(forms): get rid of duplicate functions (#38371)

This commit performs minor refactoring in Forms package to get rid of duplicate functions.
It looks like the functions were duplicated due to a slightly different type signatures, but
their logic is completely identical. The logic in retained functions remains the same and now
these function also accept a generic type to achieve the same level of type safety.

PR Close #38371

goldens/circular-deps/packages.json

@@ -1855,11 +1855,6 @@
     "packages/forms/src/directives/ng_model.ts",
     "packages/forms/src/directives/ng_model_group.ts"
   ],
-  [
-    "packages/forms/src/directives/normalize_validator.ts",
-    "packages/forms/src/model.ts",
-    "packages/forms/src/directives/shared.ts"
-  ],
   [
     "packages/forms/src/directives/reactive_directives/form_control_directive.ts",
     "packages/forms/src/directives/shared.ts",

packages/core/test/bundling/forms/bundle.golden_symbols.json

@@ -701,9 +701,6 @@
   {
     "name": "_keyMap"
   },
-  {
-    "name": "_mergeErrors"
-  },
   {
     "name": "_noControlError"
   },
@@ -914,6 +911,9 @@
   {
     "name": "executeTemplate"
   },
+  {
+    "name": "executeValidators"
+  },
   {
     "name": "executeViewQueryFn"
   },
@@ -1346,6 +1346,9 @@
   {
     "name": "mergeAll"
   },
+  {
+    "name": "mergeErrors"
+  },
   {
     "name": "mergeHostAttribute"
   },
@@ -1401,10 +1404,7 @@
     "name": "noop"
   },
   {
-    "name": "normalizeAsyncValidator"
-  },
-  {
-    "name": "normalizeValidator"
+    "name": "normalizeValidators"
   },
   {
     "name": "observable"

packages/forms/src/directives/normalize_validator.ts

@@ -1,27 +0,0 @@
-/**
- * @license
- * Copyright Google LLC All Rights Reserved.
- *
- * Use of this source code is governed by an MIT-style license that can be
- * found in the LICENSE file at https://angular.io/license
- */
-
-import {AbstractControl} from '../model';
-import {AsyncValidator, AsyncValidatorFn, Validator, ValidatorFn} from './validators';
-
-export function normalizeValidator(validator: ValidatorFn|Validator): ValidatorFn {
-  if (!!(<Validator>validator).validate) {
-    return (c: AbstractControl) => (<Validator>validator).validate(c);
-  } else {
-    return <ValidatorFn>validator;
-  }
-}
-
-export function normalizeAsyncValidator(validator: AsyncValidatorFn|
-                                        AsyncValidator): AsyncValidatorFn {
-  if (!!(<AsyncValidator>validator).validate) {
-    return (c: AbstractControl) => (<AsyncValidator>validator).validate(c);
-  } else {
-    return <AsyncValidatorFn>validator;
-  }
-}

packages/forms/src/directives/shared.ts

@@ -9,7 +9,8 @@
 import {isDevMode} from '@angular/core';
 
 import {FormArray, FormControl, FormGroup} from '../model';
-import {Validators} from '../validators';
+import {normalizeValidators, Validators} from '../validators';
+
 import {AbstractControlDirective} from './abstract_control_directive';
 import {AbstractFormGroupDirective} from './abstract_form_group_directive';
 import {CheckboxControlValueAccessor} from './checkbox_value_accessor';
@@ -17,7 +18,6 @@ import {ControlContainer} from './control_container';
 import {ControlValueAccessor} from './control_value_accessor';
 import {DefaultValueAccessor} from './default_value_accessor';
 import {NgControl} from './ng_control';
-import {normalizeAsyncValidator, normalizeValidator} from './normalize_validator';
 import {NumberValueAccessor} from './number_value_accessor';
 import {RadioControlValueAccessor} from './radio_control_value_accessor';
 import {RangeValueAccessor} from './range_value_accessor';
@@ -142,13 +142,15 @@ function _throwError(dir: AbstractControlDirective, message: string): void {
 }
 
 export function composeValidators(validators: Array<Validator|ValidatorFn>): ValidatorFn|null {
-  return validators != null ? Validators.compose(validators.map(normalizeValidator)) : null;
+  return validators != null ? Validators.compose(normalizeValidators<ValidatorFn>(validators)) :
+                              null;
 }
 
 export function composeAsyncValidators(validators: Array<AsyncValidator|AsyncValidatorFn>):
     AsyncValidatorFn|null {
-  return validators != null ? Validators.composeAsync(validators.map(normalizeAsyncValidator)) :
-                              null;
+  return validators != null ?
+      Validators.composeAsync(normalizeValidators<AsyncValidatorFn>(validators)) :
+      null;
 }
 
 export function isPropertyUpdated(changes: {[key: string]: any}, viewModel: any): boolean {

packages/forms/src/validators.ts

@@ -10,7 +10,7 @@ import {InjectionToken, ɵisObservable as isObservable, ɵisPromise as isPromise
 import {forkJoin, from, Observable} from 'rxjs';
 import {map} from 'rxjs/operators';
 
-import {AsyncValidatorFn, ValidationErrors, Validator, ValidatorFn} from './directives/validators';
+import {AsyncValidator, AsyncValidatorFn, ValidationErrors, Validator, ValidatorFn} from './directives/validators';
 import {AbstractControl} from './model';
 
 function isEmptyInputValue(value: any): boolean {
@@ -435,7 +435,7 @@ export class Validators {
     if (presentValidators.length == 0) return null;
 
     return function(control: AbstractControl) {
-      return _mergeErrors(_executeValidators(control, presentValidators));
+      return mergeErrors(executeValidators<ValidatorFn>(control, presentValidators));
     };
   }
 
@@ -456,8 +456,9 @@ export class Validators {
     if (presentValidators.length == 0) return null;
 
     return function(control: AbstractControl) {
-      const observables = _executeAsyncValidators(control, presentValidators).map(toObservable);
-      return forkJoin(observables).pipe(map(_mergeErrors));
+      const observables =
+          executeValidators<AsyncValidatorFn>(control, presentValidators).map(toObservable);
+      return forkJoin(observables).pipe(map(mergeErrors));
     };
   }
 }
@@ -474,15 +475,7 @@ export function toObservable(r: any): Observable<any> {
   return obs;
 }
 
-function _executeValidators(control: AbstractControl, validators: ValidatorFn[]): any[] {
-  return validators.map(v => v(control));
-}
-
-function _executeAsyncValidators(control: AbstractControl, validators: AsyncValidatorFn[]): any[] {
-  return validators.map(v => v(control));
-}
-
-function _mergeErrors(arrayOfErrors: ValidationErrors[]): ValidationErrors|null {
+function mergeErrors(arrayOfErrors: (ValidationErrors|null)[]): ValidationErrors|null {
   let res: {[key: string]: any} = {};
 
   // Not using Array.reduce here due to a Chrome 80 bug
@@ -493,3 +486,30 @@ function _mergeErrors(arrayOfErrors: ValidationErrors[]): ValidationErrors|null
 
   return Object.keys(res).length === 0 ? null : res;
 }
+
+type GenericValidatorFn = (control: AbstractControl) => any;
+
+function executeValidators<V extends GenericValidatorFn>(
+    control: AbstractControl, validators: V[]): ReturnType<V>[] {
+  return validators.map(validator => validator(control));
+}
+
+function isValidatorFn<V>(validator: V|Validator|AsyncValidator): validator is V {
+  return !(validator as Validator).validate;
+}
+
+/**
+ * Given the list of validators that may contain both functions as well as classes, return the list
+ * of validator functions (convert validator classes into validator functions). This is needed to
+ * have consistent structure in validators list before composing them.
+ *
+ * @param validators The set of validators that may contain validators both in plain function form
+ *     as well as represented as a validator class.
+ */
+export function normalizeValidators<V>(validators: (V|Validator|AsyncValidator)[]): V[] {
+  return validators.map(validator => {
+    return isValidatorFn<V>(validator) ?
+        validator :
+        ((c: AbstractControl) => validator.validate(c)) as unknown as V;
+  });
+}

packages/forms/test/validators_spec.ts

@@ -8,12 +8,12 @@
 
 import {fakeAsync, tick} from '@angular/core/testing';
 import {describe, expect, it} from '@angular/core/testing/src/testing_internal';
-import {AbstractControl, AsyncValidatorFn, FormArray, FormControl, Validators} from '@angular/forms';
-import {normalizeAsyncValidator} from '@angular/forms/src/directives/normalize_validator';
-import {AsyncValidator, ValidationErrors, ValidatorFn} from '@angular/forms/src/directives/validators';
+import {AbstractControl, AsyncValidator, AsyncValidatorFn, FormArray, FormControl, ValidationErrors, ValidatorFn, Validators} from '@angular/forms';
 import {Observable, of, timer} from 'rxjs';
 import {first, map} from 'rxjs/operators';
 
+import {normalizeValidators} from '../src/validators';
+
 (function() {
 function validator(key: string, error: any): ValidatorFn {
   return (c: AbstractControl) => {
@@ -413,11 +413,12 @@ describe('Validators', () => {
          }));
 
       it('should normalize and evaluate async validator-directives correctly', fakeAsync(() => {
-           const v = Validators.composeAsync(
-               [normalizeAsyncValidator(new AsyncValidatorDirective('expected', {'one': true}))])!;
+           const normalizedValidators = normalizeValidators<AsyncValidatorFn>(
+               [new AsyncValidatorDirective('expected', {'one': true})]);
+           const validatorFn = Validators.composeAsync(normalizedValidators)!;
 
            let errorMap: {[key: string]: any}|null = undefined!;
-           (v(new FormControl('invalid')) as Observable<ValidationErrors|null>)
+           (validatorFn(new FormControl('invalid')) as Observable<ValidationErrors|null>)
                .pipe(first())
                .subscribe((errors: {[key: string]: any}|null) => errorMap = errors);
            tick();
@@ -475,11 +476,12 @@ describe('Validators', () => {
       });
 
       it('should normalize and evaluate async validator-directives correctly', () => {
-        const v = Validators.composeAsync(
-            [normalizeAsyncValidator(new AsyncValidatorDirective('expected', {'one': true}))])!;
+        const normalizedValidators = normalizeValidators<AsyncValidatorFn>(
+            [new AsyncValidatorDirective('expected', {'one': true})]);
+        const validatorFn = Validators.composeAsync(normalizedValidators)!;
 
         let errorMap: {[key: string]: any}|null = undefined!;
-        (v(new FormControl('invalid')) as Observable<ValidationErrors|null>)
+        (validatorFn(new FormControl('invalid')) as Observable<ValidationErrors|null>)
             .pipe(first())
             .subscribe((errors: {[key: string]: any}|null) => errorMap = errors)!;