build: auto generate example module

* No longer pushes the example-module.ts file to the GitHub repository. The file will be auto-generated once the `material-examples` build package is being built.

References #9574.

Author: devversion

.gitignore

@@ -6,6 +6,9 @@
 /deploy
 /screenshots
 
+# Example module file will be auto-generated.
+/src/material-examples/example-module.ts
+
 # dependencies
 node_modules
 /bower_components

src/material-examples/example-data.ts

@@ -1,6 +1,7 @@
+// The example-module file will be auto-generated. As soon as the
+// examples are being compiled, the module file will be generated.
 import {EXAMPLE_COMPONENTS} from './example-module';
 
-
 /**
  * Example data
  *   with information about Component name, selector, files used in example, and path to examples

src/material-examples/example-module.ts

@@ -1,4 +1,7 @@
 export * from './example-data';
+
+// The example-module file will be auto-generated. As soon as the
+// examples are being compiled, the module file will be generated.
 export * from './example-module';
 
 export * from './list-overview/list-overview-example';

src/material-examples/public-api.ts

@@ -12,7 +12,7 @@ createPackageBuildTasks(cdkPackage);
 createPackageBuildTasks(cdkExperimentalPackage);
 createPackageBuildTasks(materialPackage);
 createPackageBuildTasks(materialExperimentalPackage);
-createPackageBuildTasks(examplesPackage);
+createPackageBuildTasks(examplesPackage, ['build-examples-module']);
 createPackageBuildTasks(momentAdapterPackage);
 
 import './tasks/aot';
@@ -24,7 +24,7 @@ import './tasks/default';
 import './tasks/development';
 import './tasks/docs';
 import './tasks/e2e';
-import './tasks/examples';
+import './tasks/example-module';
 import './tasks/lint';
 import './tasks/material-release';
 import './tasks/payload';

tools/gulp/gulpfile.ts

@@ -1,9 +1,10 @@
 import {task} from 'gulp';
 import {sync as glob} from 'glob';
+import {buildConfig} from 'material2-build-tools';
 import * as fs from 'fs';
 import * as path from 'path';
 import * as ts from 'typescript';
-import {buildConfig} from 'material2-build-tools';
+
 const {packagesDir} = buildConfig;
 
 interface ExampleMetadata {

tools/gulp/tasks/examples.ts renamed to tools/gulp/tasks/example-module.ts

@@ -18,8 +18,12 @@ const htmlMinifierOptions = {
   removeAttributeQuotes: false
 };
 
-/** Creates a set of gulp tasks that can build the specified package. */
-export function createPackageBuildTasks(buildPackage: BuildPackage) {
+/**
+ * Creates a set of gulp tasks that can build the specified package.
+ * @param buildPackage Build package for which the gulp tasks will be generated
+ * @param preBuildTasks List of gulp tasks that should run before building the package.
+ */
+export function createPackageBuildTasks(buildPackage: BuildPackage, preBuildTasks: string[] = []) {
   // Name of the package build tasks for Gulp.
   const taskName = buildPackage.name;
 
@@ -42,6 +46,8 @@ export function createPackageBuildTasks(buildPackage: BuildPackage) {
   task(`${taskName}:clean-build`, sequenceTask('clean', `${taskName}:build`));
 
   task(`${taskName}:build`, sequenceTask(
+    // Run the pre build gulp tasks.
+    ...preBuildTasks,
     // Build all required packages before building.
     ...dependencyNames.map(pkgName => `${pkgName}:build`),
     // Build ESM and assets output.