feat: expose version object in releases

* In releases there will be a constant called `VERSION` that holds the current version of the installed package (material or cdk)
* This is similar as for every @angular package like core, forms, compiler.

Author: devversion

src/cdk/public_api.ts

@@ -1 +1 @@
-export const __TEMP__ = -1;
+export * from './version';

src/cdk/version.ts

@@ -0,0 +1,4 @@
+import {Version} from '@angular/core';
+
+/** Current version of the Angular Component Development Kit. */
+export const VERSION = new Version('0.0.0-PLACEHOLDER');

src/lib/public_api.ts

@@ -4,6 +4,7 @@
  * Entry point for all public APIs of Angular Material.
  */
 
+export * from './version';
 export * from './core';
 export * from './module';
 

src/lib/version.ts

@@ -0,0 +1,4 @@
+import {Version} from '@angular/core';
+
+/** Current version of Angular Material. */
+export const VERSION = new Version('0.0.0-PLACEHOLDER');

tools/gulp/packaging/build-release.ts

@@ -1,7 +1,7 @@
 import {join} from 'path';
 import {copyFiles} from '../util/copy-files';
 import {addPureAnnotationsToFile} from './pure-annotations';
-import {updatePackageVersion} from './package-versions';
+import {replaceVersionPlaceholders} from './version-placeholders';
 import {inlinePackageMetadataFiles} from './metadata-inlining';
 import {createTypingsReexportFile} from './typings-reexport';
 import {createMetadataReexportFile} from './metadata-reexport';
@@ -32,7 +32,7 @@ export function composeRelease(packageName: string) {
   copyFiles(packagesDir, 'README.md', releasePath);
   copyFiles(sourcePath, 'package.json', releasePath);
 
-  updatePackageVersion(releasePath);
+  replaceVersionPlaceholders(releasePath);
   createTypingsReexportFile(releasePath, packageName);
   createMetadataReexportFile(releasePath, packageName);
   addPureAnnotationsToFile(join(releasePath, '@angular', `${packageName}.es5.js`));

tools/gulp/packaging/version-placeholders.ts

@@ -0,0 +1,32 @@
+import {readFileSync, writeFileSync} from 'fs';
+import {MATERIAL_VERSION} from '../build-config';
+import {spawnSync} from 'child_process';
+
+/** Variable that is set to the string for version placeholders. */
+const versionPlaceholderText = '0.0.0-PLACEHOLDER';
+
+/** RegExp that matches version placeholders inside of a file. */
+const versionPlaceholderRegex = new RegExp(versionPlaceholderText);
+
+/**
+ * Walks through every file in a directory and replaces the version placeholders with the current
+ * version of Material.
+ */
+export function replaceVersionPlaceholders(packageDir: string) {
+  // Resolve files that contain version placeholders using Grep since it's super fast and also
+  // does have a very simple usage.
+  const files = spawnSync('grep', ['-ril', versionPlaceholderText, packageDir]).stdout
+    .toString()
+    .split('\n')
+    .filter(String);
+
+  // Walk through every file that contains version placeholders and replace those with the current
+  // version of the root package.json file.
+  files.forEach(filePath => {
+    let fileContent = readFileSync(filePath, 'utf-8');
+
+    fileContent = fileContent.replace(versionPlaceholderRegex, MATERIAL_VERSION);
+
+    writeFileSync(filePath, fileContent);
+  });
+}