perf(forms): avoid direct references to the Validators class (angul…

…ar#41189)

Currently the `Validators` class contains a number of static methods that represent different validators as well as some helper methods. Since class methods are not tree-shakable, any reference to the `Validator` class retains all of its methods (even if you've used just one).

This commit refactors the code to extract the logic into standalone functions and use these functions in the code instead of referencing them via `Validators` class. That should make the code more tree-shakable. The `Validators` class still retains its structure and calls these standalone methods internally to keep this change backwards-compatible.

PR Close angular#41189

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

@@ -734,6 +734,12 @@
   {
     "name": "collectStylingFromTAttrs"
   },
+  {
+    "name": "compose"
+  },
+  {
+    "name": "composeAsync"
+  },
   {
     "name": "composeAsyncValidators"
   },
@@ -1346,6 +1352,9 @@
   {
     "name": "notFoundValueOrThrow"
   },
+  {
+    "name": "nullValidator"
+  },
   {
     "name": "observable"
   },

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

@@ -167,9 +167,6 @@
   {
     "name": "DomSharedStylesHost"
   },
-  {
-    "name": "EMAIL_REGEXP"
-  },
   {
     "name": "EMPTY_ARRAY"
   },
@@ -569,9 +566,6 @@
   {
     "name": "VE_ViewContainerRef"
   },
-  {
-    "name": "Validators"
-  },
   {
     "name": "Version"
   },
@@ -1052,9 +1046,6 @@
   {
     "name": "hasTagAndTypeMatch"
   },
-  {
-    "name": "hasValidLength"
-  },
   {
     "name": "hostReportError"
   },
@@ -1136,9 +1127,6 @@
   {
     "name": "isDirectiveHost"
   },
-  {
-    "name": "isEmptyInputValue"
-  },
   {
     "name": "isForwardRef"
   },

packages/forms/src/directives/validators.ts

@@ -10,7 +10,7 @@ import {Directive, forwardRef, Input, OnChanges, SimpleChanges, StaticProvider}
 import {Observable} from 'rxjs';
 
 import {AbstractControl} from '../model';
-import {NG_VALIDATORS, Validators} from '../validators';
+import {emailValidator, maxLengthValidator, minLengthValidator, NG_VALIDATORS, nullValidator, patternValidator, requiredTrueValidator, requiredValidator} from '../validators';
 
 
 /**
@@ -181,7 +181,7 @@ export class RequiredValidator implements Validator {
    * @nodoc
    */
   validate(control: AbstractControl): ValidationErrors|null {
-    return this.required ? Validators.required(control) : null;
+    return this.required ? requiredValidator(control) : null;
   }
 
   /**
@@ -228,7 +228,7 @@ export class CheckboxRequiredValidator extends RequiredValidator {
    * @nodoc
    */
   validate(control: AbstractControl): ValidationErrors|null {
-    return this.required ? Validators.requiredTrue(control) : null;
+    return this.required ? requiredTrueValidator(control) : null;
   }
 }
 
@@ -289,7 +289,7 @@ export class EmailValidator implements Validator {
    * @nodoc
    */
   validate(control: AbstractControl): ValidationErrors|null {
-    return this._enabled ? Validators.email(control) : null;
+    return this._enabled ? emailValidator(control) : null;
   }
 
   /**
@@ -360,7 +360,7 @@ export const MIN_LENGTH_VALIDATOR: any = {
   host: {'[attr.minlength]': 'minlength ? minlength : null'}
 })
 export class MinLengthValidator implements Validator, OnChanges {
-  private _validator: ValidatorFn = Validators.nullValidator;
+  private _validator: ValidatorFn = nullValidator;
   private _onChange?: () => void;
 
   /**
@@ -396,7 +396,7 @@ export class MinLengthValidator implements Validator, OnChanges {
   }
 
   private _createValidator(): void {
-    this._validator = Validators.minLength(
+    this._validator = minLengthValidator(
         typeof this.minlength === 'number' ? this.minlength : parseInt(this.minlength, 10));
   }
 }
@@ -438,7 +438,7 @@ export const MAX_LENGTH_VALIDATOR: any = {
   host: {'[attr.maxlength]': 'maxlength ? maxlength : null'}
 })
 export class MaxLengthValidator implements Validator, OnChanges {
-  private _validator: ValidatorFn = Validators.nullValidator;
+  private _validator: ValidatorFn = nullValidator;
   private _onChange?: () => void;
 
   /**
@@ -473,7 +473,7 @@ export class MaxLengthValidator implements Validator, OnChanges {
   }
 
   private _createValidator(): void {
-    this._validator = Validators.maxLength(
+    this._validator = maxLengthValidator(
         typeof this.maxlength === 'number' ? this.maxlength : parseInt(this.maxlength, 10));
   }
 }
@@ -518,7 +518,7 @@ export const PATTERN_VALIDATOR: any = {
   host: {'[attr.pattern]': 'pattern ? pattern : null'}
 })
 export class PatternValidator implements Validator, OnChanges {
-  private _validator: ValidatorFn = Validators.nullValidator;
+  private _validator: ValidatorFn = nullValidator;
   private _onChange?: () => void;
 
   /**
@@ -553,6 +553,6 @@ export class PatternValidator implements Validator, OnChanges {
   }
 
   private _createValidator(): void {
-    this._validator = Validators.pattern(this.pattern);
+    this._validator = patternValidator(this.pattern);
   }
 }