refactor(compiler-cli): extend AST object and value helpers (#39518)

This introduces `AstObject.toMap` as an alternative to `AstObject
.toLiteral`, and adds `AstValue.getSymbolName` to query the symbol name
of a value using the encapsulated AST host.

PR Close #39518

packages/compiler-cli/linker/src/ast/ast_value.ts

@@ -122,6 +122,18 @@ export class AstObject<TExpression> {
     return result;
   }
 
+  /**
+   * Converts the AstObject to a JavaScript Map, mapping each property value (as an
+   * `AstValue`) to the generic type (`T`) via the `mapper` function.
+   */
+  toMap<T>(mapper: (value: AstValue<TExpression>) => T): Map<string, T> {
+    const result = new Map<string, T>();
+    for (const [key, expression] of this.obj) {
+      result.set(key, mapper(new AstValue(expression, this.host)));
+    }
+    return result;
+  }
+
   private getRequiredProperty(propertyName: string): TExpression {
     if (!this.obj.has(propertyName)) {
       throw new FatalLinkerError(
@@ -136,7 +148,15 @@ export class AstObject<TExpression> {
  * access to the underlying value of the wrapped expression.
  */
 export class AstValue<TExpression> {
-  constructor(private expression: TExpression, private host: AstHost<TExpression>) {}
+  constructor(readonly expression: TExpression, private host: AstHost<TExpression>) {}
+
+  /**
+   * Get the name of the symbol represented by the given expression node, or `null` if it is not a
+   * symbol.
+   */
+  getSymbolName(): string|null {
+    return this.host.getSymbolName(this.expression);
+  }
 
   /**
    * Is this value a number?

packages/compiler-cli/linker/test/ast/ast_value_spec.ts

@@ -141,9 +141,37 @@ describe('AstObject', () => {
       });
     });
   });
+
+  describe('toMap()', () => {
+    it('should convert the AstObject to a Map with each property mapped', () => {
+      expect(obj.toMap(value => value.getOpaque())).toEqual(new Map([
+        ['a', obj.getOpaque('a')],
+        ['b', obj.getOpaque('b')],
+        ['c', obj.getOpaque('c')],
+        ['d', obj.getOpaque('d')],
+        ['e', obj.getOpaque('e')],
+      ]));
+    });
+  });
 });
 
 describe('AstValue', () => {
+  describe('getSymbolName', () => {
+    it('should return the name of an identifier', () => {
+      expect(new AstValue(factory.createIdentifier('Foo'), host).getSymbolName()).toEqual('Foo');
+    });
+
+    it('should return the name of a property access', () => {
+      const propertyAccess = factory.createPropertyAccess(
+          factory.createIdentifier('Foo'), factory.createIdentifier('Bar'));
+      expect(new AstValue(propertyAccess, host).getSymbolName()).toEqual('Bar');
+    });
+
+    it('should return null if no symbol name is available', () => {
+      expect(new AstValue(factory.createLiteral('a'), host).getSymbolName()).toBeNull();
+    });
+  });
+
   describe('isNumber', () => {
     it('should return true if the value is a number', () => {
       expect(new AstValue(factory.createLiteral(42), host).isNumber()).toEqual(true);