build: build material-examples with bazel (#13932)

This includes a `genrule` to create the generated `ExampleModule`

tools/example-module/BUILD.bazel

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+package(default_visibility=["//visibility:public"])
+
+load("@build_bazel_rules_nodejs//:defs.bzl", "nodejs_binary")
+load("//tools:defaults.bzl", "ts_library")
+
+ts_library(
+  name = "example-module-lib",
+  srcs = glob(["**/*.ts"]),
+  deps = [
+    "@npm//@types/node",
+    "@npm//typescript",
+  ],
+  tsconfig = ":tsconfig.json",
+)
+
+nodejs_binary(
+  name = "bazel-bin",
+  entry_point = "angular_material/tools/example-module/bazel-bin.js",
+  data = [
+    "@npm//typescript",
+    "@npm//source-map-support",
+    ":example-module-lib",
+    ":example-module.template",
+  ],
+)

tools/example-module/bazel-bin.ts

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+import {generateExampleModule} from './generate-example-module';
+
+/**
+ * Entry point for the Bazel NodeJS target. Usually this would be a more generic CLI, but due to
+ * Bazel not being able to handle a lot of files on Windows (with emulated Bash), we need to
+ * read the arguments through environment variables which are handled better.
+ *
+ *   - https://github.com/bazelbuild/rules_nodejs/issues/404
+ *   - https://github.com/bazelbuild/bazel/issues/3636
+ */
+
+if (require.main === module) {
+  const {_SOURCE_FILES, _OUTPUT_FILE, _BASE_DIR} = process.env;
+
+  generateExampleModule(_SOURCE_FILES.split(' '), _OUTPUT_FILE, _BASE_DIR);
+}

tools/example-module/example-module.template

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+/* tslint:disable */
+
+/**
+ ******************************************************************************
+ * DO NOT MANUALLY EDIT THIS FILE. THIS FILE IS AUTOMATICALLY GENERATED.
+ ******************************************************************************
+ */
+
+import {NgModule} from '@angular/core';
+import {FormsModule, ReactiveFormsModule} from '@angular/forms';
+import {CommonModule} from '@angular/common';
+import {ExampleMaterialModule} from './material-module';
+
+${exampleImports}
+
+export interface LiveExample {
+  title: string;
+  component: any;
+  additionalFiles?: string[];
+  selectorName?: string;
+}
+
+export const EXAMPLE_COMPONENTS: {[key: string]: LiveExample} = ${exampleComponents};
+export const EXAMPLE_LIST = ${exampleList}
+
+@NgModule({
+  declarations: EXAMPLE_LIST,
+  entryComponents: EXAMPLE_LIST,
+  imports: [
+    ExampleMaterialModule,
+    FormsModule,
+    ReactiveFormsModule,
+    CommonModule
+  ]
+})
+export class ExampleModule { }

tools/example-module/generate-example-module.ts

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+import * as fs from 'fs';
+import * as path from 'path';
+import {parseExampleFile} from './parse-example-file';
+
+interface ExampleMetadata {
+  component: string;
+  sourcePath: string;
+  id: string;
+  title: string;
+  additionalComponents: string[];
+  additionalFiles: string[];
+  selectorName: string[];
+}
+
+/** Build ES module import statements for the given example metadata. */
+function buildImportsTemplate(data: ExampleMetadata): string {
+  const components = data.additionalComponents.concat(data.component);
+  const relativeSrcPath = data.sourcePath.replace(/\\/g, '/').replace('.ts', '');
+
+  return `import {${components.join(',')}} from './${relativeSrcPath}';`;
+}
+
+/** Inlines the example module template with the specified parsed data. */
+function inlineExampleModuleTemplate(parsedData: ExampleMetadata[]): string {
+  const exampleImports = parsedData.map(m => buildImportsTemplate(m)).join('\n');
+  const exampleList = parsedData.reduce((result, data) => {
+    return result.concat(data.component).concat(data.additionalComponents);
+  }, [] as string[]).join(',');
+
+  const exampleComponents = parsedData.reduce((result, data) => {
+    result[data.id] = {
+      title: data.title,
+      component: data.component,
+      additionalFiles: data.additionalFiles,
+      selectorName: data.selectorName.join(', '),
+    };
+
+    return result;
+  }, {} as any);
+
+  return fs.readFileSync(require.resolve('./example-module.template'), 'utf8')
+    .replace('${exampleImports}', exampleImports)
+    .replace('${exampleComponents}', JSON.stringify(exampleComponents))
+    .replace('${exampleList}', `[${exampleList}]`);
+}
+
+/** Converts a given camel-cased string to a dash-cased string. */
+function convertToDashCase(name: string): string {
+  name = name.replace(/[A-Z]/g, ' $&');
+  name = name.toLowerCase().trim();
+  return name.split(' ').join('-');
+}
+
+/** Collects the metadata of the given source files by parsing the given TypeScript files. */
+function collectExampleMetadata(sourceFiles: string[], baseFile: string): ExampleMetadata[] {
+  const exampleMetadata: ExampleMetadata[] = [];
+
+  for (const sourceFile of sourceFiles) {
+    const sourceContent = fs.readFileSync(sourceFile, 'utf-8');
+    const {primaryComponent, secondaryComponents} = parseExampleFile(sourceFile, sourceContent);
+
+    if (primaryComponent) {
+      // Generate a unique id for the component by converting the class name to dash-case.
+      const exampleId = convertToDashCase(primaryComponent.component.replace('Example', ''));
+      const example: ExampleMetadata = {
+        sourcePath: path.relative(baseFile, sourceFile),
+        id: exampleId,
+        component: primaryComponent.component,
+        title: primaryComponent.title.trim(),
+        additionalComponents: [],
+        additionalFiles: [],
+        selectorName: []
+      };
+
+      if (secondaryComponents.length) {
+        example.selectorName.push(example.component);
+
+        for (const meta of secondaryComponents) {
+          example.additionalComponents.push(meta.component);
+
+          if (meta.templateUrl) {
+            example.additionalFiles.push(meta.templateUrl);
+          }
+
+          if (meta.styleUrls) {
+            example.additionalFiles.push(...meta.styleUrls);
+          }
+
+          example.selectorName.push(meta.component);
+        }
+      }
+
+      exampleMetadata.push(example);
+    }
+  }
+
+  return exampleMetadata;
+}
+
+/**
+ * Generates the example module from the given source files and writes it to a specified output
+ * file.
+ */
+export function generateExampleModule(sourceFiles: string[], outputFile: string,
+                                      baseDir: string = path.dirname(outputFile)) {
+  const results = collectExampleMetadata(sourceFiles, baseDir);
+  const generatedModuleFile = inlineExampleModuleTemplate(results);
+
+  fs.writeFileSync(outputFile, generatedModuleFile);
+}

tools/example-module/parse-example-file.ts

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+import * as ts from 'typescript';
+
+interface ParsedMetadata {
+  primary: boolean;
+  component: string;
+  title: string;
+  templateUrl: string;
+  styleUrls: string[];
+}
+
+interface ParsedMetadataResults {
+  primaryComponent: ParsedMetadata;
+  secondaryComponents: ParsedMetadata[];
+}
+
+/** Parse the AST of the given source file and collect Angular component metadata. */
+export function parseExampleFile(fileName: string, content: string): ParsedMetadataResults {
+  const sourceFile = ts.createSourceFile(fileName, content, ts.ScriptTarget.Latest, false);
+  const metas: any[] = [];
+
+  const visitNode = (node: any): void => {
+    if (node.kind === ts.SyntaxKind.ClassDeclaration) {
+      const meta: any = {
+        component: node.name.text
+      };
+
+      if (node.jsDoc && node.jsDoc.length) {
+        for (const doc of node.jsDoc) {
+          if (doc.tags && doc.tags.length) {
+            for (const tag of doc.tags) {
+              const tagValue = tag.comment;
+              const tagName = tag.tagName.text;
+              if (tagName === 'title') {
+                meta.title = tagValue;
+                meta.primary = true;
+              }
+            }
+          }
+        }
+      }
+
+      if (node.decorators && node.decorators.length) {
+        for (const decorator of node.decorators) {
+          if (decorator.expression.expression.text === 'Component') {
+            for (const arg of decorator.expression.arguments) {
+              for (const prop of arg.properties) {
+                const propName = prop.name.text;
+
+                // Since additional files can be also stylesheets, we need to properly parse
+                // the styleUrls metadata property.
+                if (propName === 'styleUrls' && ts.isArrayLiteralExpression(prop.initializer)) {
+                  meta[propName] = prop.initializer.elements
+                    .map((literal: ts.StringLiteral) => literal.text);
+                } else {
+                  meta[propName] = prop.initializer.text;
+                }
+              }
+            }
+
+            metas.push(meta);
+          }
+        }
+      }
+    }
+
+    ts.forEachChild(node, visitNode);
+  };
+
+  visitNode(sourceFile);
+
+  return {
+    primaryComponent: metas.find(m => m.primary),
+    secondaryComponents: metas.filter(m => !m.primary)
+  };
+}

tools/example-module/tsconfig.json

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+{
+  "compilerOptions": {
+    "lib": ["es2015"],
+    "module": "commonjs",
+    "target": "es5",
+    "sourceMap": true,
+    "types": ["node"]
+  },
+  "bazelOptions": {
+    "suppressTsconfigOverrideWarnings": true
+  }
+}