utils - Add utils for ast and object hashing

src/utils.ts

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+import * as ts from "typescript";
+
+// Copied from ts-ast-viewer
+export function forEachChild(node: ts.Node) {
+  const nodes: ts.Node[] = [];
+  node.forEachChild(child => {
+    nodes.push(child);
+    return undefined;
+  });
+  return nodes;
+}
+
+// Copied from ts-ast-viewer
+function getSyntaxKindNameMapping() {
+  // some SyntaxKinds are repeated, so only use the first one
+  const kindNames: { [kind: number]: string } = {};
+  for (const name of Object.keys(ts.SyntaxKind).filter(k =>
+    isNaN(parseInt(k, 10))
+  )) {
+    const value = (ts.SyntaxKind as any)[name] as number;
+    if (kindNames[value] == null) kindNames[value] = name;
+  }
+  return kindNames;
+}
+
+export const syntaxKindNameMapping = getSyntaxKindNameMapping();
+
+export class ObjectHash {
+  static ObjectIDMap = new WeakMap<Object, number>();
+  static maxID = 0;
+
+  static getHash(obj: Object) {
+    let returnID = ObjectHash.ObjectIDMap.get(obj);
+    if (returnID === undefined) {
+      this.maxID++;
+      returnID = this.maxID;
+
+      this.ObjectIDMap.set(obj, returnID);
+    }
+
+    return returnID;
+  }
+}