build: add custom linting for symbol names (#19811)

As discussed, we want to prefix some exported class names with an underscore so it's more obvious that they're private. The problem is that our current class naming rule doesn't allow for a class to start with an underscore. These changes add a custom rule that can use a regex to validate the class name. Having our own rule allows us to validate more types of nodes as well (e.g. `type` nodes which tslint doesn't check).

Author: crisbeto

src/material/checkbox/checkbox-module.ts

@@ -17,7 +17,6 @@ import {MatCheckboxRequiredValidator} from './checkbox-required-validator';
   exports: [MatCheckboxRequiredValidator],
   declarations: [MatCheckboxRequiredValidator],
 })
-// tslint:disable-next-line:class-name
 export class _MatCheckboxRequiredValidatorModule {
 }
 

src/material/menu/menu-module.ts

@@ -28,7 +28,6 @@ import {MAT_MENU_SCROLL_STRATEGY_FACTORY_PROVIDER, MatMenuTrigger} from './menu-
   ],
   providers: [MAT_MENU_SCROLL_STRATEGY_FACTORY_PROVIDER]
 })
-// tslint:disable-next-line:class-name
 export class _MatMenuDirectivesModule {}
 
 @NgModule({

src/material/menu/menu.ts

@@ -97,7 +97,6 @@ let menuPanelUid = 0;
 
 /** Base class with all of the `MatMenu` functionality. */
 @Directive()
-// tslint:disable-next-line:class-name
 export class _MatMenuBase implements AfterContentInit, MatMenuPanel<MatMenuItem>, OnInit,
   OnDestroy {
   private _keyManager: FocusKeyManager<MatMenuItem>;
@@ -519,9 +518,7 @@ export class MatMenu extends _MatMenuBase {}
     {provide: MatMenu, useExisting: _MatMenu}
   ]
 })
-// tslint:disable-next-line:class-name
 export class _MatMenu extends MatMenu {
-
   constructor(elementRef: ElementRef<HTMLElement>, ngZone: NgZone,
       @Inject(MAT_MENU_DEFAULT_OPTIONS) defaultOptions: MatMenuDefaultOptions) {
     super(elementRef, ngZone, defaultOptions);

src/material/radio/radio.ts

@@ -96,7 +96,6 @@ export const MAT_RADIO_GROUP =
  * @docs-private
  */
 @Directive()
-// tslint:disable-next-line:class-name
 export abstract class _MatRadioGroupBase<T extends _MatRadioButtonBase> implements AfterContentInit,
   ControlValueAccessor {
   /** Selected value for the radio group. */
@@ -354,7 +353,6 @@ const _MatRadioButtonMixinBase:
  * @docs-private
  */
 @Directive()
-// tslint:disable-next-line:class-name
 export abstract class _MatRadioButtonBase extends _MatRadioButtonMixinBase implements OnInit,
   AfterViewInit, OnDestroy, CanDisableRipple, HasTabIndex {
 

src/material/slide-toggle/slide-toggle-module.ts

@@ -17,9 +17,7 @@ import {MatSlideToggleRequiredValidator} from './slide-toggle-required-validator
   exports: [MatSlideToggleRequiredValidator],
   declarations: [MatSlideToggleRequiredValidator],
 })
-// tslint:disable-next-line:class-name
-export class _MatSlideToggleRequiredValidatorModule {
-}
+export class _MatSlideToggleRequiredValidatorModule {}
 
 @NgModule({
   imports: [

src/material/tabs/ink-bar.ts

@@ -14,7 +14,6 @@ import {ANIMATION_MODULE_TYPE} from '@angular/platform-browser/animations';
  * Interface for a a MatInkBar positioner method, defining the positioning and width of the ink
  * bar in a set of tabs.
  */
-// tslint:disable-next-line class-name Using leading underscore to denote internal interface.
 export interface _MatInkBarPositioner {
   (element: HTMLElement): { left: string, width: string };
 }

src/material/tabs/tab-body.ts

@@ -109,7 +109,6 @@ export class MatTabBodyPortal extends CdkPortalOutlet implements OnInit, OnDestr
  * @docs-private
  */
 @Directive()
-// tslint:disable-next-line:class-name
 export abstract class _MatTabBodyBase implements OnInit, OnDestroy {
   /** Current position of the tab-body in the tab-group. Zero means that the tab is visible. */
   private _positionIndex: number;

src/material/tabs/tab-group.ts

@@ -79,7 +79,6 @@ interface MatTabGroupBaseHeader {
  * @docs-private
  */
 @Directive()
-// tslint:disable-next-line:class-name
 export abstract class _MatTabGroupBase extends _MatTabGroupMixinBase implements AfterContentInit,
     AfterContentChecked, OnDestroy, CanColor, CanDisableRipple {
 

src/material/tabs/tab-header.ts

@@ -39,7 +39,6 @@ import {MatPaginatedTabHeader} from './paginated-tab-header';
  * @docs-private
  */
 @Directive()
-// tslint:disable-next-line:class-name
 export abstract class _MatTabHeaderBase extends MatPaginatedTabHeader implements
   AfterContentChecked, AfterContentInit, AfterViewInit, OnDestroy {
 

src/material/tabs/tab-nav-bar/tab-nav-bar.ts

@@ -54,7 +54,6 @@ import {startWith, takeUntil} from 'rxjs/operators';
  * @docs-private
  */
 @Directive()
-// tslint:disable-next-line:class-name
 export abstract class _MatTabNavBase extends MatPaginatedTabHeader implements AfterContentChecked,
   AfterContentInit, OnDestroy {
 
@@ -192,7 +191,6 @@ const _MatTabLinkMixinBase:
 
 /** Base class with all of the `MatTabLink` functionality. */
 @Directive()
-// tslint:disable-next-line:class-name
 export class _MatTabLinkBase extends _MatTabLinkMixinBase implements AfterViewInit, OnDestroy,
   CanDisable, CanDisableRipple, HasTabIndex, RippleTarget, FocusableOption {
 

tools/tslint-rules/symbolNamingRule.ts

@@ -0,0 +1,28 @@
+import * as ts from 'typescript';
+import * as Lint from 'tslint';
+
+/** Lint rule that checks the names of classes and interfaces against a pattern. */
+export class Rule extends Lint.Rules.AbstractRule {
+  /** Pattern that we should validate against. */
+  private _pattern: RegExp;
+
+  constructor(options: Lint.IOptions) {
+    super(options);
+    this._pattern = new RegExp(options.ruleArguments[0] || '.*');
+  }
+
+  apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
+    return this.applyWithFunction(sourceFile, checkSourceFile, this._pattern);
+  }
+}
+
+function checkSourceFile(context: Lint.WalkContext<RegExp>) {
+  context.sourceFile.forEachChild(function walk(node) {
+    if ((ts.isClassDeclaration(node) || ts.isInterfaceDeclaration(node) ||
+      ts.isTypeAliasDeclaration(node)) && node.name && !context.options.test(node.name.text)) {
+      context.addFailureAtNode(node.name, `Symbol name must match pattern ${context.options}`);
+    }
+
+    node.forEachChild(walk);
+  });
+}

tslint.json

@@ -19,7 +19,6 @@
     // TSLint now shows warnings if types for properties are inferred. This rule needs to be
     // disabled because all properties need to have explicit types set to work for Dgeni.
     "no-inferrable-types": false,
-    "class-name": true,
     "comment-format": [
       true,
       "check-space"
@@ -143,6 +142,7 @@
     "member-naming": [true, {
       "private": "^_"
     }],
+    "symbol-naming": [true, "^_?[A-Z][a-zA-Z0-9]*$"],
     "validate-decorators": [true, {
       "Component": {
         "argument": 0,