feat: add common utils to schematics

npm/ng-packs/packages/schematics/src/utils/common.ts

@@ -0,0 +1,25 @@
+import { SchematicsException, Tree } from '@angular-devkit/schematics';
+import * as ts from 'typescript';
+import { Exception } from '../enums';
+
+export function interpolate(text: string, ...params: (string | number | boolean)[]) {
+  params.forEach((param, i) => {
+    const pattern = new RegExp('{\\s*' + i + '\\s*}');
+    text = text.replace(pattern, String(param));
+  });
+
+  return text;
+}
+
+export function isNullOrUndefined(value: any): value is null | undefined {
+  return value === null || value === undefined;
+}
+
+export function readFileInTree(tree: Tree, filePath: string): ts.SourceFile {
+  const buffer = tree.read(filePath);
+  if (isNullOrUndefined(buffer))
+    throw new SchematicsException(interpolate(Exception.FileNotFound, filePath));
+
+  const text = buffer.toString('utf-8');
+  return ts.createSourceFile(filePath, text, ts.ScriptTarget.Latest, true);
+}

npm/ng-packs/packages/schematics/src/utils/index.ts

@@ -1,4 +1,5 @@
 export * from './angular';
+export * from './common';
 export * from './project';
 export * from './text';
 export * from './workspace';